ACSIS Hardware and Software Interfaces

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					ACSIS




    ACSIS Hardware and Software Interfaces




Document Id:   CDR03A
Version:       2.0
Date:          June 23, 2012
Author:        Gary Hovey, T. Burgess, W. Dent, B. Force, J. Lightfoot, T. Willis, P.
               Dewdney
Filename:      cdr03interfacesAv10.doc
ACSIS                                                        ACSIS Hardware and Software Interfaces




                                              Revision History


 Ver.                                       Changes                                           Date       Initials
1.1     Amalgamating versions, updating table details, and editing.                          00Nov27     P. Dewdney
2.0     Created Hardware and Software doc from ver 1.1 by deleting Mech. Elec. and Thermal   01-Mar-20   G. Hovey
        info. Also removed some previous edits and updated RTS cable/connector specs.
ACSIS                                       ACSIS Hardware and Software Interfaces




                                    Table of Contents

Introduction ___________________________________________________________________ 1
System Interfaces ______________________________________________________________ 1
IF System Interfaces ____________________________________________________________ 5
 IF Hardware Inputs and Outputs _____________________________________________________ 5
   IF H/W Data I/Os __________________________________________________________________________ 5
      Inputs _________________________________________________________________________________ 5
      Outputs________________________________________________________________________________ 5
   IF H/W Control I/Os _______________________________________________________________________ 6
 IF Software Inputs and Outputs ______________________________________________________ 7
   IF S/W Data I/Os __________________________________________________________________________ 7
      Monitor and Status Outputs ________________________________________________________________ 7
   IF S/W Control I/Os ________________________________________________________________________ 8
      Configuration Input Parameters _____________________________________________________________ 8
      Command Inputs and Parameters ___________________________________________________________ 9
      IF Configuration File Elements ____________________________________________________________ 10
Correlator System Interfaces ____________________________________________________ 11
 Corr. Hardware Inputs and Outputs __________________________________________________ 11
   Corr. H/W Data I/Os ______________________________________________________________________ 11
   Corr. H/W Control I/Os ____________________________________________________________________ 11
 Corr. Software Inputs and Outputs ___________________________________________________ 12
   Corr. S/W Data I/Os _______________________________________________________________________ 12
     Monitor and Status Outputs _______________________________________________________________ 12
   Corr. S/W Control I/Os ____________________________________________________________________ 13
     Configuration Input Parameter ____________________________________________________________ 13
     Command Inputs and Parameters __________________________________________________________ 14
     Corr. Configuration File Elements __________________________________________________________ 14
Reduction System Interfaces _____________________________________________________ 15
 Red. Sys. Software Inputs and Outputs ________________________________________________ 16
   Red. Sys. S/W Data I/Os ___________________________________________________________________ 16
     Data Inputs ____________________________________________________________________________ 16
     Purpose Protocol ______________________________________________________________________ 16
     Data Outputs __________________________________________________________________________ 16
   Red. Sys. Control I/Os _____________________________________________________________________ 30
     Control Inputs and Parameters _____________________________________________________________ 30
     Purpose Protocol ______________________________________________________________________ 30
     Red. Sys. Configuration File ______________________________________________________________ 31
     Red. Sys. Control Output _________________________________________________________________ 37
The Real-Time Display _________________________________________________________ 38
 RTD Software Inputs and Outputs ___________________________________________________ 38
   RTD Data I/Os ___________________________________________________________________________ 38
   RTD Control I/Os _________________________________________________________________________ 38
     Command Inputs and Parameters __________________________________________________________ 38
     Control Output _________________________________________________________________________ 39
     RTD Configuration Element ______________________________________________________________ 39
Appendix A: The System Configuration File _________________________________________ 1
ACSIS                                             ACSIS Hardware and Software Interfaces


Introduction
ACSIS is an Auto-Correlation Spectrometer Imaging System for the James Clerk Maxwell Telescope
(JCMT). The main components of ACSIS are the IF system, the correlator, the reduction system, and the
real-time display. These components are tightly integrated with other instruments at the JCMT and it is this
ensemble of instruments that allows one to make ACSIS observations. The ACSIS instruments are
programmable, and can accept commands from the JCMT Observing Control System (OCS) to configure
and control their behaviour.

This document describes the external interfaces to ACSIS. The initial section describes the overall system
hardware and software interfaces, while the remaining sections document the interface to each ACSIS
system.


System Interfaces

A diagram showing the ACSIS system interfaces is given in Figure 1. The system inputs and outputs can be
divided data flows and control flows, or signals. The primary data flow consists of processing the receiver
input signals to produce spectral data cubes. Associated data flows, used in processing the data, are from
the Front-End and antenna control system (Portable Telescope Control System). Auxiliary data flows (such
as temperatures, voltages, etc) are also gathered by the system and are used for monitoring and diagnostic
purposes. Most data produced by the system are stored in files and may be viewed on the Real-Time
Display.
Control data consist of software configuration files, DRAMA commands and Real-Time Sequencer (RTS)
hardware signals. These data are produced by a collection of hardware and software called the Observing
Control System (OCS), which includes the Telescope Observing Designer Driver (TODD) and the RTS.
The TODD executes an observing recipe which provides high-level control of instruments during an
observation, while the RTS controls the timing of a set of integrations, called sequences, in real-time. The
general observing algorithm consists of:

        1. Initialising the system to reset it and force it into a known state.

        2. Configuring the system for a particular mode of operation.

        3. Sequencing the system through a series of integrations.

        4. Looping back to step 2 until the observation is over.

At the start of an observation the TODD issues DRAMA commands to each ACSIS instrument that cause
them to initialise and configure themselves, according to parameters stored in a configuration file (see
Appendix A). The TODD then issues a sequence command, which causes the instruments to perform and
process a series of integrations under control of the RTS. At the end of the sequence, the TODD can re-
configure the instruments, typically the Front-End or Telescope, and issue further sequence commands.
This process is continued until the observation is over.
ACSIS                                                     ACSIS Hardware and Software Interfaces




                                                                                                    Analog Signals
              OCS                                                                                   Software Data
                                                                                                    Hardware Control Signals
                     TODD                                  RTS                                      Software Control Commands
                                                                                                    and Parameters


                                                                                  Antenna
                       DRAMA Commands                 Sequence                    Control
                                                    Control Signals               System


                                                                                  ANT DATA


                     ACSIS                                                                        Status +
                                                                                                  Scalar +
                                                                                                 Spectra +
   Frontend       RF Signals          IF     IF Signals    Correlator   CM DATA   Reduction     Image Data             RT
    System                          System                  System                 System                            Display


                                                                  IF DATA
                                                                                                     Gridded
                                                                  FE DATA                     Raw     DATA
                                                                                             DATA


                          Configuration
                           Parameters
                                                                                                                        Spectral
                                                                                                                         FITS
                                                                                                                         Files
                                XML                                                               AIPS++
                            Configuration                                                     Measurement-Set
                                File                                                               Files




Figure 1: ACSIS System Interface Diagram

Several types of software and hardware protocols are used throughout the system, they are:

             The Real-Time Sequencer (RTS) hardware timing protocol [RTS?], which is used to control
              integration timing.

             TCP/IP and Ethernet 100 base-T, which is used for network communications.

             The DRAMA distributed process communications software, which is used to send commands,
              parameters, and data between programs. Data is communicated via SDS (Self-defining Data
              Structure) records, a DRAMA data structure.

             Internal messaging is done using Glish (see Glish 2.7 User Manual, D. Shiebel & B. Paxson,
              National Radio Astronomy Observatory).

             Extended Markup Language standard (XML), which is used to describe configuration
              parameters in ASCII text files.

             FITS files, which are used to store gridded data cubes.

                                                                                                                               2
   System Interfaces
ACSIS                                            ACSIS Hardware and Software Interfaces

           AIPS++ Measurements Set files, which are used to store raw data.

The interfaces to each ACSIS system are detailed in the following sections. The interfaces for each system
are divided into the following categories:

           Hardware Inputs and Outputs (I/Os)

           Software Inputs and Outputs (I/Os)




                                                                                                             3
   System Interfaces
ACSIS                                          ACSIS Hardware and Software Interfaces


IF System Interfaces
The IF system has 32 RF inputs and 32 baseband outputs, and is housed in two side-by-side cabinets. The
system is controlled by a microprocessor, and communicates with other computers using DRAMA, via
TCP/IP on a 100 Base-T Ethernet. The system can output total power and other auxiliary data to the ACSIS
reduction system and any other DRAMA task that requests it. Configuration parameters for the system are
contained in XML formatted text files, which are read (from an NFS mounted disk) when commanded by a
DRAMA control task such as the TODD. The operation of the system can be synchronised externally,
using RTS control signals, or alternatively, run asynchronously for test and other purposes.

Band center frequencies are determined by the Second LO setting. The frequency of this LO has a
resolution of 4000/4096 kHz (976.5625 kHz).



IF Hardware Inputs and Outputs
IF H/W Data I/Os
Inputs

Cass Cabin RF Switch Inputs

   Quantity                                      12
   Selectablity                                  any 2 out of 12
   Max bandwidth per input                       3.2 GHz
   Power level                                   –20 dBm

Nasmyth RF Switch Inputs

   Quantity                                      16
   Selectablity                                  any 4 out of 16
   Max bandwidth per input                       3.2 GHz
   Power level                                   –20 dBm

Non-Switchable Dedicated RF Inputs

   Quantity                                      28
   Selectablity                                  none all available
   Max bandwidth per input                       16 at 1.8 GHz, 28 at 800 MHz
   Power level                                   –20 dBm



Outputs

Baseband Outputs

   Quantity            32
   3dB bandwidth       900 MHz or 250 MHz (to be measured)
   Power level         +13 dBm




                                                                                                       5
   IF System Interfaces
ACSIS                                    ACSIS Hardware and Software Interfaces

IF H/W Control I/Os

RTS Control Signals

   Signal Levels               Differential TTL
   Type                        isolated RS-422
   Connnector                  RJ-45 receptacle
   Cable                       Cat-5 cable

 Sequence Control (SC) Input

   Purpose                     Advances sequence number of IF system
   Pin numbers                 SC+ pin 2, SC- pin7

 Data Valid (DV) Input

   Purpose                     Controls Total Power Detector integration period
   Pin numbers                 SC+ pin 4, SC- pin 9

 System Ready (SR) Output

   Purpose                     Indicates IF system is ready
   Pin numbers                 SC+ pin 3, SC- pin 8

 Shield Ground                 none




                                                                                  6
  IF System Interfaces
ACSIS                                           ACSIS Hardware and Software Interfaces

IF Software Inputs and Outputs
IF S/W Data I/Os
Monitor and Status Outputs

   Purpose              Used for monitoring Total Power and other Data
   Protocol             SDS and DRAMA

Data Item Name          Type           Range              Description

“IF_MONITOR_DATA”       structure
                                           32
 “SEQ_NUM”              ulong          0-2 - 1            current sequence number. Zero means not valid

 “STATUS”               char[16]       [“Not Ready”       System not ready
                                       “Fault”            System has a serious fault
                                       “Ready” |          System is ready
                                       “Testing” |        System is running a test
                                       “Observing” ]      System is observing

 “SEQ_STATE”            char[16]       [“Idle”|           Not executing a sequence command
                                       “Waiting” |        Waiting to start a sequence
                                       “Integrating”]     Executing a sequence command

 “INLET_TEMP”           float[2]       nominally 25C      The inlet air temp of chassis in racks 1 and 2

 “EXHAUST_TEMP”         float[2]       nominally 30C      The exhaust air temp of chassis in racks 1 and 2

 “CASS_SW”              ubyte[2]       1 to 6             Setting of Cass switches 1 and 2

 “NSMYTH_SW”            ubyte[4]       1 to 6             Setting of Nasmyth switches 1 and 4

 “2ND_LO_FREQS”         double[4]      6.3 to 10.3 GHz    Frequency in GHz of LOs 1-4, modulo 976.5625
                                                          kHz

 “DCM_STATUS”           char[32]       0{[‘I’ | ‘A’]31    32 character mask array of active DCMs, 1 to 32

 “DCM_DET_NAME”         char[32][10]   ASCII Text         The detector name assigned to each DCM

 “DCM_TP_IN”            float[32]      0 to 1             input power level in mW of each DCM (1-32)

 “DCM_TP_OUT”           float[32]      0 to 1             power level in mW of each DCM output before
                                                          ALC

 “DCM_CFREQ”            float[32]      3.3 to 7.8 GHz     The centre frequency of each DCM signal (1-32)

 “DCM_BW”               ulong          [850 to 950 |      The nominal output bandwidth of the DCMs (1-32)
                                       245 to 255] MHz

 “DCM_TEMP”             float[32]      -20C to 70C        Nominally 25C to 50C of each DCM (1-32)

 “DCM_SN”               ubyte[32]      0 to 256           serial number of DCM (1-32)




                                                                                                       7
  IF System Interfaces
ACSIS                                        ACSIS Hardware and Software Interfaces

IF S/W Control I/Os
Configuration Input Parameters

   Purpose             Used to configure the IF system in response to a CONFIGURE
   Protocol            command
                       XML (eXtented Markup Language)

Data Item Name         Internal Type     Range              Description

 “IF_DPATH”             char[40]         “TASK_NAME@INET”   DRAMA path to IF system

 “CASS_SW”              ubyte[2]         0 to 6             Setting of Cass switches 1 and 2.
                                                            Zero means not selected.

 “NSMYTH_SW”            ubyte[4]         0 to 6             Setting of Nasmyth switch 1 to 4.
                                                            Zero means not selected.

 “2ND_LO_FREQS”         double[4]        6.3 to 10.3 GHz    Frequency in GHz of 2nd LOs 1 to 4

 “RUN_TYPE”             char[10]         [“Test” |          Indicates a test run
                                         “Observation” |    Indicates an observation
                                         “Other”]           Indicates run type not specified

 “3RD_LO_FREQ”          double           [2.0 GHz]          3rd LO frequency (fixed)

 “NUM_SUBANDS”          ubyte            1 to 4             used to determine how to split inputs
                                                            into subbands

 “DCM_CFREQS”           double[4]        3.3 to 7.8 GHz     The centre freq. of each of subbands
                                                            1 to 4: modulo 976.5625 kHz
                                                            Zero means inactive.

 “DCM_BW”               ulong            [850 to 950 |      The nominal output bandwidth of the
                                          245 to 255] MHz   DCMs (1-32)

 “CASS_SW_DET”          char[2][6][15]   ASCII text         Names of detectors assigned to
                                                            the six inputs on Cass Switches 1
                                                            and 2.

 “NSYMTH_SW_DET”        char[4][6][15]   ASCII text         Names of the detectors assigned to
                                                            the six inputs on Nasmyth Switches
                                                            1 and 4.

 “ARRAY_DET”            char[4][7][15]   ASCII text         Names of detectors assigned to
                                                            the 7 inputs on Quadrants 1 and 4.

 “BITE_MODE”            char[16]         [“Off” |           The mode of the built in test unit
                                         “Noise” |
                                         “Line” |
                                         “Noise + Line”]

 “TIMING_MODE”          char[40]         [“RTS” |           synchronise timing to RTS
                                         “Internal” |       run asynchronously
                                         “TASK_NAME@INET”   get timing events from this DRAMA
                                                            task

 “INT_INTERVAL”         float            50 to 5000 ms      integration interval


                                                                                                    8
  IF System Interfaces
ACSIS                                     ACSIS Hardware and Software Interfaces



Command Inputs and Parameters

   Purpose         Used to control IF system from a host computer program, like the TODD
   Protocol

Command Name       Parameter(s)     Range              Description

“INITIALISE”        none                               Forces the IF system to reset and
                                                       initialise itself to an idle state. The system
                                                       will also reconfigure itself to a default
                                                       configuration. This action is normally done
                                                       at the start of a series of observations or
                                                       after an error.

“CONFIGURE”         “FILE_SPEC” |   a legal file       If the system status is ready, it causes the
                    (Parameter)     specification or   IF system to read the XML file indicated
                                    XML Parameter      by file_spec and configure itself. Any
                                    Name               optional parameters override the XML file
                                                       parameters. If file spec is not given then
                                                       the currently stored configuration is used.
                                                       This command is normally done at the
                                                       beginning of an observation.
                                         32
“SEQUENCE”          “START_SEQ”     1 to 2 -2          Causes the IF system to perform
                    “END_SEQ”       START_SEQ < and    sequences, or integrations, from
                                        32
                                    < 2 -1             START_SEQ to END_SEQ using the
                                                       TIMING_MODE configuration parameter.

“FINISH”            none                               Signals the end of an observation, or test,
                                                       and causes the IF system status to go to
                                                       the READY state. This command is used
                                                       at the end of an observation.

“ABORT”             none                               Aborts a SEQUENCE command and
                                                       forces the system into the idle Sequence
                                                       State

“CHECK_HEALTH”      none                               Cause the system to perform a self-check




                                                                                                     9
  IF System Interfaces
ACSIS                                          ACSIS Hardware and Software Interfaces

IF Configuration File Elements
The IF configuration is specified by the if-config element in the observation configuration file. Listed
blow is an example of the contents of that element.

<if-config>
       <cass-sw>        3,3                                                     </cass-sw>
       <nasmyth-sw>     1,1,1,1                                                 </nasmyth-sw>
       <2nd-lo-freqs> 6347656250, 6347656250, 6347656250, 6347656250 </2nd-lo-freqs1>
       <3rd-lo-freqs> 2000000000, 2000000000, 2000000000, 2000000000 </3rd-lo-freqs>
       <num-subands>    2                                                       </num-subands>
       <dcm-cfreqs>     6310000000,6315000000,0,0                               <dcm-cfreqs>
       <dcm-bw>         900000000, 900000000                                    </dcm-bw>
       <cass-sw-det>    RXA3,RXB3M1,RXWCM1,RXWDM1,NOISE,BLANK,
                        RXA3,RXB3M2,RXWCM2,RXWDM2,NOISE,BLANK                   </cass-sw-det>
       <nasmyth-sw-det>                                                         </nasmyth-sw-det>
       <array-det>                                                              </array-det>
       <bite-mode>      off                                                     </bite-mode>
       <timing-mode>    rts                                                     </timing-mode>
       <interval>       50.0                                                    </interval>
</if-config>




1
    Note: 2nd-lo-freqs is modulo 4000/4096 = 976.5625 kHz


                                                                                                       10
     IF System Interfaces
ACSIS                                           ACSIS Hardware and Software Interfaces


Correlator System Interfaces
The Correlator System computes the auto-correlation function of up to 32 inputs. The system is housed in
two side-by-side cabinets and is controlled by eight microprocessors. Each microprocessor controls and
outputs the data from four correlation modules, and communicates with other computers using DRAMA,
via TCP/IP on either of its two 100 Base-T Ethernet interfaces. The system outputs correlator and auxiliary
data to the ACSIS reduction system and any other DRAMA task that requests it. Configuration parameters
for the system are contained in XML formatted text files, which are read (from an NFS mounted disk)
when commanded by a DRAMA control task such as the TODD. The operation of the system can be
synchronised externally, using RTS control signals, or alternatively, run asynchronously for test and other
purposes.

Corr. Hardware Inputs and Outputs
Corr. H/W Data I/Os

Sampler RF Inputs

    Quantity                        32
    Max bandwidth per input         1.0 GHz
    Power level                     +13 dBm
    Connector type                  SMA



Corr. H/W Control I/Os

RTS Control Signals

    Signal Levels                    Differential TTL
    Type                             isolated RS-422
    Connector                        RJ-45 Receptacle
    Cable                            Cat 5

  Sequence Control (SC) Input

    Purpose                          Advances sequence number of IF system
    Pin numbers                      SC+ pin 2, SC- pin7

  Data Valid (DV) Input

    Purpose                          Controls Total Power Detector integration period
    Pin numbers                      SC+ pin 4, SC- pin 9

  System Ready (SR) Output

    Purpose                          Indicates IF system is ready
    Pin numbers                      SC+ pin 3, SC- pin 8

  Shield Ground                      none




                                                                                                         11
   Correlator System Interfaces
ACSIS                                        ACSIS Hardware and Software Interfaces

Corr. Software Inputs and Outputs
Corr. S/W Data I/Os
Monitor and Status Outputs

   Purpose            Used to send spectra, and correlator system monitor and status data
   Protocol           SDS and DRAMA

Data Item Name        Type        Range                Description

“CM_DATA”             structure                        The output from a correlator module
                                     32
 “SEQ_NUM”             ulong      0-2 - 1              Current sequence number. Zero means not
                                                       valid

 "CM_ID"               ubyte      1 - 32               The correlator module ID.

 “DCM_ID”              ubyte      1 - 32               The DCM ID connected to the correlator
                                                       Module.

 “SUBBAND_ID”          ubyte      1–4                  The DCM sub-band ID being processed by
                                                       the correlator.

 "DET_NAME"            char[16]   ASCII TEXT           The detector name assigned to the module

 “CORR_SN”             ubyte      0 – 255              The correlator module serial number

 “SAMPLER_SN”          ubyte      0-255                The sampler serial number

 “STATUS”              char[16]   [“Not Ready”         System not ready
                                  “Fault”              System has a serious fault
                                  “Ready” |            System is ready
                                  “Testing” |          System is running a test
                                  “Observing” ]        System is observing

 “SEQ_STATE”           char[16]   [“Idle”|             Not executing a sequence commands
                                  “Waiting” |          Waiting to start a sequence
                                  “Integrating”]       Executing a sequence command

 “INLET_TEMP”          float      nominally 25C        The inlet air temp of the correlator crate

 “EXHAUST_TEMP”        float      nominally 30C        The exhaust air temp of correlator crate

 "CM_TEMP              float[3]   nominally 25C        The air temp on the front, middle and rear of
                                                       the Correlator Module (CM).

 "CM_+5V"              float[2]   5 VDC                The voltage on VME P1&P2, and P3.

 "CM_+3V"              float      3.3 VDC              the output voltage of the on board regulator

 "CM_+3A"              float      12 A                 the 3.3 V supply current.

 "CM_BW_MODE"          char[16]   [“Inactive”          The sample bandwidth mode of the
                                  “250 MHz x 4096”     correlator module. Zero means inactive
                                  “250 MHz x 8192”
                                  “1 GHz x 1024”
                                  “1 GHz x 2048”]


                                                                                                    12
  Correlator System Interfaces
ACSIS                                                  ACSIS Hardware and Software Interfaces

   Purpose            Used to send spectra, and correlator system monitor and status data
   Protocol           SDS and DRAMA

Data Item Name        Type          Range                        Description

 "CM_N_LAGS"          ulong         [1024 | 2048 | 4096 |        The number of the correlator lags
                                    8192]
                                             32
 "CM_N_SAMPLES"       ulong         0 to 2        -1             number of correlator samples in integration

 "CM_LAGS"            float[]       -1 to 1                      normalised auto-correlation function vector
                                                                 CM_N_LAGS long



Corr. S/W Control I/Os
Configuration Input Parameter

   Purpose            Used to configure the correlator system
   Protocol           eXtended Markup Language ASCII Text files

Data Item Name        Type            Range                          Description

 “CORRX_DPATH”        char[8][40]     “TASK_NAME@INET”               DRAMA path to correlator tasks 1 to 8.

 "CM_BW_MODE"         char[16]        [“Inactive”                    The sample bandwidth mode of the
                                      “250 MHz x 4096”               correlator module. Zero means inactive
                                      “250 MHz x 8192”
                                      “1 GHz x 1024”
                                      “1 GHz x 2048”]

 “DCM_ID”            ubyte[32]        1 - 32                         The DCM ID connected to each
                                                                     correlator Module 1 to 32.

 “SUBBAND_ID”        ubyte[32]        1–4                            The DCM sub-band ID to be processed
                                                                     by correlator module ID 1 to 32.

 "DET_NAME"          char[32][10]     ASCII TEXT                     The detector name assigned to each
                                                                     correlator module ID 1 to 32

 “TIMING_MODE”        char[40]        [“RTS” |                      synchronise timing to RTS
                                      “Internal” |                  run asynchronously
                                      “TASK_NAME@INET”              get timing events from this DRAMA task

 “INT_INTERVAL”      float            50 to 5000 ms                 integration interval




                                                                                                               13
  Correlator System Interfaces
ACSIS                                            ACSIS Hardware and Software Interfaces

Command Inputs and Parameters
Purpose            Used to control the correlator from a host computer program, like the TODD
Protocol           SDS and DRAMA
Command            Parameter(s)       Range                           Description
Name
                                                                      Forces the correlator system to reset
 “INITIALISE”       none
                                                                      and initialise itself to an idle state. The
                                                                      system will also reconfigure itself to a
                                                                      default configuration. This action is
                                                                      normally done at the start of a series
                                                                      of observation or after an error.
                                      a legal file specification or   If the system status is READY it causes
 “CONFIGURE”        “FILE_SPEC” |
                                      XML Parameter Name              the IF system to read the XML file
                    (Parameter)
                                                                      indicated by file_spec and configure
                                                                      itself. Any optional parameters
                                                                      override the XML file parameters. If
                                                                      file spec is not given then the
                                                                      currently stored configuration is used.
                                                                      This command is normally done at the
                                                                      beginning of an observation.
                                            32
                                      1 to 2 -2                       Causes the correlator system to
 “SEQUENCE”         “START_SEQ”
                                      START_SEQ< and                  perform sequences, or integrations,
                    “END_SEQ”             32
                                      < 2 -1                          from START_SEQ to END_SEQ
                                                                      using the TIMING_MODE
                                                                      configuration parameter.
                                                                      Signals the end of an observation, or
 “FINISH”           none
                                                                      test, and causes the correlator system
                                                                      status to go to the READY state. This
                                                                      command is used at the end of an
                                                                      observation.
                                                                      Aborts a SEQUENCE command and
 “ABORT”            none
                                                                      force the system into the IDLE
                                                                      Sequence State
                                                                      Cause the system to perform a self-
 “CHECK_            none
                                                                      check
 HEALTH”



Corr. Configuration File Elements
The correlator configuration is specified by the corr-config element in the observation configuration
file. Listed low is an example of the contents of that element.

<corr-config>
  <cm-bw-mode>         250MHz*4096,250MHz*4096,..                                   </cm-bw-mode>
  <dcm-id>             1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,
                       10,10,11,11,12,12,13,13,14,14,15,15,16,16                    </dcm-id>
 <subband-id>          1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,
                       1,2,1,2,1,2,1,2,1,2,1,2,1,2                                  </subband-id>
  <timing-mode>        RTS                                                          </timing-mode>
  <interval>           50.0                                                         </interval>
</corr-config>


                                                                                                               14
   Correlator System Interfaces
ACSIS                                            ACSIS Hardware and Software Interfaces


Reduction System Interfaces
The reduction system hardware is a 16-node Beowulf computer-cluster. Each node communicates with a
partner module in the correlator using DRAMA, via TCP/IP on a 100 base-T Ethernet. The nodes
communicate with each other and the outside world using Glish or DRAMA, also via TCP/IP and 100
Base-T Ethernet.

During an observation the system is a collection of tasks distributed across the Beowulf. Control commands
are routed to the collective through a ‘reduction_controller’ task. Data from the correlator modules travel
across Ethernet directly to tasks in their partner nodes. Data from other sub-systems are routed through the
Beowulf ‘master’ to the nodes.

Raw archive data and reduce cubes are written by each Beowulf node onto its own disk. These disks are
visible to the outside world via NFS.

The layout, function and connections between tasks on Beowulf are set when the system is configured at
the beginning of an observation. This ‘configuration’ is described by elements in an XML formatted text
file read (from an NFS mounted disk) when commanded by a DRAMA control task such as the TODD.
Once configured the system is driven by the arrival of data from the correlator modules, telescope, front-
end and IF sub-systems.




                                                                                                             15
   Reduction System Interfaces
ACSIS                                            ACSIS Hardware and Software Interfaces

Red. Sys. Software Inputs and Outputs
Red. Sys. S/W Data I/Os
Data Inputs
Purpose
                               Used to control reduction system from a host computer program,
Protocol
                               like the TODD

Command Name                   Parameter(s)          Range     Description

“IF_MONITOR_DATA”                  structure                   The SDS data structure output by the IF
                                                               system.

“ANT_MONITOR_DATA”                 structure                   The SDS data structure output by the
                                                               antenna system.

“FE_MONITOR_DATA”                  structure                   The SDS data structure output by the front-
                                                               end(s), if any).

“CM_DATA”                          structure                   The SDS data structure output by the
                                                               correlator task.




Data Outputs
Raw Data Archive
The raw spectrum data will be archived as an AIPS++ MeasurementSet (version 2,
http://www.aips2.nrao.edu/docs/notes/229/229.html) with some extensions. The reduction stage at which
data are archived can be specified as part of the reduction recipe, though it is expected that data will
normally be archived before any reduction has been performed on it. The archived spectrum data will form
the basis of any re-reduction of an observation, which may be performed using the DR system during
daytime or by using the AIPS++ ‘Dish’ package at the user’s home institution. It is to facilitate the use of
either method that the save format conforms to the standard MeasurementSet format.

The MS is implemented as a directory structure on disk with the name of the MS being given to the top
level directory. The format of the MS filename will be ‘yyyymmdd_nnnnn_ss.ms’, where yyyymmdd is the
date, nnnnn is the data reduction ‘observation number’ and ss is a section number for this part of the virtual
MS. In high data-rate modes each Beowulf node will write out to its own disk the data it receives, in which
case the MS would be broken up into 16 sections. The ‘observation number’ used in the MS name is
generated by the reduction system itself rather than provided by the JCMT OCS. The system will ensure
that duplicate numbers are not generated even after a system crash and will make the number available to
the OCS for display.

A Measurement Set (MS) is an AIPS++ ‘Table’ with a specified layout. The MS contains a number of sub-
Tables, whose names and minimum content are described by the standard. The components of the MS are:

  MAIN. The main data Table, containing coordinates, data, and flags.

     The Table is made up of rows of Records, each containing the ‘minimum’ set of fields needed to both
     conform to the MS standard and hold the necessary ACSIS-specific information. The shape of the data
     Record arriving at the Archiver object writing the MS is defined by an XML element in the
     observation configuration file. We expect that the standard ACSIS MS Record will contain the
     following fields.


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ACSIS                                                ACSIS Hardware and Software Interfaces



Field Name          MS or     Type                     Description         Units   Measure   Default     Data Manager
                    ACSIS

MS_VERSION          MS        Float                    MS format                             2.0         N/A
                    keyword                            version

CONFIGURATION       MS        String                   XML file                                          N/A
                    keyword                            describing
                                                       configuration of
                                                       instrument

TIME                MS key    Double                   Time at             s       EPOCH                 StManAipsIO
                                                       midpoint of
                                                       nominal
                                                       sampling
                                                       interval.

ANTENNA1            MS key    Int                      Index of                              0           IncrementalStM
                                                       ANTENNA1.                                         an

ANTENNA2            MS key    Int                      Index of                              0           IncrementalStM
                                                       ANTENNA2.                                         an

FEED1               MS key    Int                      Feed ID on                                        StManAips|IO
                                                       ANTENNA1.

FEED2               MS key    Int                      Feed ID on                            FEED2 =     StManAipsIO
                                                       ANTENNA2.                             FEED1

DATA_DESC_ID        MS key    Int                      Data descriptor                                   StManAipsIO
                                                       ID

PROCESSOR_ID        MS key    Int                      Processor ID                                      StManAipsIO

PHASE_ID            MS key    Int                      Switching phase                                   StManAipsIO
                                                       ID

FIELD_ID            MS key    Int                      Index of field in                                 StManAipsIO
                                                       FIELD sub-
                                                       Table

INTERVAL            MS        Double                   Sampling            s                             StManAipsIO
                                                       interval.

EXPOSURE            MS        Double                   Effective           s                             StManAipsIO
                                                       integration time.

TIME_CENTROID       MS        Double                   Time at             s       EPOCH                 StManAipsIO
                                                       midpoint of
                                                       effective
                                                       integration

SCAN_NUMBER         MS        Int                      Unique data ID                                    StManAipsIO
                                                       number.

ARRAY_ID            MS        Int                      Not used.                             -12         StManAipsIO

OBSERVATION_ID      MS        Int                      Index of                                          IncrementalStM
                                                       observation in                                    an
                                                       OBSERVATIO



2
 This column contains an index to a row entry in another Table of the MS. The value of -1 indicates that the index is
not being used.


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ACSIS                                              ACSIS Hardware and Software Interfaces

                                                     N sub-Table.

STATE_ID             MS        Int                   Index into                                   StManAipsIO
                                                     STATE sub-
                                                     table.

UVW                  MS        Double[3]             Not used.           m     UVW   [0,0,0]      StManAipsIO

FLOAT_DATA           MS        Float [NUM_CORR,      Lag/spectrum                                 TiledShapeStMa
                               NUM_CHAN]             data.                                        n

SIGMA                MS        Float [NUM_CORR]      Estimated rms                   0.0          StManAipsIO
                                                     noise on single
                                                     channel.

WEIGHT               MS        Float                 Weight for                                   StManAipsIO
                                                     whole data
                                                     matrix.

FLAG                 MS flag   Bool [NUM_CORR,       Cumulative data                 False        StManAipsIO
                               NUM_CHAN]             flags.

FLAG_CATEGORY        MS flag   Bool [NUM_CORR,       Flag categories.                False        StManAipsIO
                               NUM_CHAN,
                               NUM_CAT]

FLAG_ROW             MS flag   Bool                  The row flag.                   False        StManAipsIO

NS_JCMT_TLOAD1       ACSIS     Float                 Physical temp of    K                        StManAipsIO
                                                     FE load 1.

NS_JCMT_TLOAD2       ACSIS     Float                 Physical temp.      K                        StManAipsIO
                                                     of FE load 2.

NS_JCMT_GI3          ACSIS     Float                 Normalised gain                              StManAipsIO
                                                     in image
                                                     sideband of FE.

NS_JCMT_GS           ACSIS     Float                 Normalised gain                              StManAipsIO
                                                     in signal
                                                     sideband of FE

NS_JCMT_ETA_TE       ACSIS     Float                 Telescope                                    StManAipsIO
L                                                    throughput.

SIDEBAND             ACSIS     Int                   FE sideband         +-1                      IncrementalStM
                                                                                                  an

NS_JCMT_LO1          ACSIS     Double                FE LO               Hz                       IncrementalStM
                                                     frequency.                                   an

TTEL                 ACSIS     Float                 Physical            K                        StManAipsIO
                                                     temperature of
                                                     telescope.

NS_JCMT_TOTAL_       ACSIS     Float                 IF total power in                            StManAipsIO
POWER                                                this spectrum.

LO2                  ACSIS     Double                IF LO2              Hz                       StManAipsIO
                                                     frequency.

LO3                  ACSIS     Double                IF LO3              Hz                       StManAipsIO
                                                     frequency.



3
    Non-standard column names must conform to a naming standard, in our case beginning with NS_JCMT_.


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ACSIS                                                            ACSIS Hardware and Software Interfaces

NS_JCMT_SAMPLE     ACSIS         Int                                The sampler                                                 StManAipsIO
R                                                                   number that
                                                                    produced this
                                                                    spectrum.

NS_JCMT_SEQUEN     ACSIS         Int                                The sequence                                                StManAipsIO
CE                                                                  number of the
                                                                    integration.

NS_JCMT_TCS_RE     ACSIS         Bool                               True if the                                                 StManAipsIO
F                                                                   telescope is at
                                                                    the reference
                                                                    position.

NS_JCMT_FE_REF     ACSIS         Bool                               True if the front-                                          StManAipsIO
                                                                    end is at the
                                                                    reference
                                                                    frequency.

NS_JCMT_OBS_CO     ACSIS         Int                                Bits set if ‘last-                                          StManAipsIO
NTROL                                                               in-sequence’ or
                                                                    ‘last-in-
                                                                    observation’.




  ANTENNA. A sub-Table containing the antenna characteristics.

Field Name        MS or ACSIS          Type           Description                               Units        Measure     Default

NAME              MS                   String         Antenna name                                                       JCMT

STATION           MS                   String         Station name                                                       JCMT

TYPE              MS                   String         Antenna type                                                       GROUND--BASED

MOUNT             MS                   String         Type of mount                                                      az-alt

POSITION          MS                   Double(3)      Antenna x,y,z phase reference position    m            POSITION    TBD

OFFSET            MS                   Double(3)      Offset of mount to feed reference point   m            POSITION    (0,0,0)

DISH_DIAMETR      MS                   Double                                                   m                        15.0

FLAG_ROW          MS flag              Bool           Row flag                                                           False




  DATA DESCRIPTION. A sub-Table containing information on the shape of the data in MAIN and on
    its spectral window and polarization.

Field Name                  MS or ACSIS         Type      Description                                            Units   Measure      Default

SPECTRAL_WINDOW_ID          MS                  Int       Index into SPECTRAL_WINDOW sub-Table

POLARIZATION_ID             MS                  Int       Index into POLARIZATION sub-Table

FLAG_ROW                    MS                  Bool      Row flag; True if the row does not contain valid                            False
                                                          data.


  DOPPLER. A sub-Table containing information on the transition being Doppler tracked.

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ACSIS                                                         ACSIS Hardware and Software Interfaces

Field Name          MS or ACSIS    Type         Description                                                   Units     Measure        Default

DOPPLER_ID          MS key         Int          Doppler tracking ID

SOURCE_ID           MS key         Int          Index into SOURCE sub-Table.

TRANSITION_ID       MS             Int          Index of transition to be used from list of such in SOURCE
                                                sub-Table.




     FEED. A sub-Table containing information on the feed characteristics.

Field Name               MS or ACSIS      Type                         Description                  Units     Measure             Default

ANTENNA_ID               MS key           Int                          Antenna ID                                                 0

FEED_ID                  MS key           Int                          ID of feed horn

SPECTRAL_WINDOW          MS key           Int                          Index into                                                 -1
_ID                                                                    SPECTRAL_WINDOW
                                                                       sub-Table.

TIME                     MS key           Double                       Centre of time interval      s         EPOCH
                                                                       for which info valid

INTERVAL4                MS key           Double                       Time period for which        s                             DBL_MAX
                                                                       info are valid

NUM_RECEPTORS            MS               Int                          # of receptors on this
                                                                       feed

BEAM_ID                  MS               Int                          Not used                                                   -1

BEAM_OFFSET              MS               Double(2,NUM_RECEP           Beam position offset         radians   DIRECTION
                                          TORS)                        relative to antenna
                                                                       reference position

POLARIZATION_TYP         MS               String                       Type of polarization to
E                                         (NUM_RECEPTORS)              which receptor responds

POL_RESPONSE             MS               Complex(NUM_RECEP            Not used.
                                          TORS,NUM_RECEPTO
                                          RS)

POSITION                 MS               Double(3)                    Not used.                    m         POSITION

RECEPTOR_ANGLE           MS               Double                       The reference angle for      radians
                                          (NUM_RECEPTORS)              polarization.




     FIELD. Field positions for each source. The FIELD table defines a field position on the sky. For single-
       dish telescopes this is the nominal pointing direction.


4
    An INTERVAL entry of 0 implies the associated values to have no time dependence, i.e. constant.


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ACSIS                                                    ACSIS Hardware and Software Interfaces

Field Name            MS or ACSIS      Type            Description                                     Units     Measure     Default

NAME                  MS               String          Name of field                                                         Blank

CODE                  MS               String          Type of field.                                                        Blank

TIME                  MS               Double          Time origin for direction and rates             s         EPOCH

NUM_POLY              MS               Int             Series order                                                          0

DELAY_DIR             MS               Double(2,1)     Telescope longitude and latitude.               radians   DIRECTION

NS_JCMT_ROTATION      ACSIS            Double          Angle between up in ‘centre’ frame and          radians
                                                       detector frame.

PHASE_DIR             MS               Double(2,1)     Not used                                                              0,0

REFERENCE_DIR         MS               Double(2,1)     Not used                                                              0,0

SOURCE_ID             MS               Int             Index in SOURCE Table                                                 0

FLAG_ROW              MS flag          Bool            Row flag; True if row contains invalid                                False
                                                       info.




  FLAG_CMD. A sub-Table that defines global flagging commands which are to apply to the data in
    MAIN. Presumably this is intended for use by post-observing applications and will be created and left
    empty by the DR system.

Field Name   MS or ACSIS      Type     Description                    Units   Measure        Default

TIME         MS key           Double   Mid point of interval          s       EPOCH

INTERVAL     MS key           Double   Time interval                  s

TYPE         MS               String   FLAG or UNFLAG

REASON       MS               String   Flag reason

LEVEL        MS               Int      Flag level

SEVERITY     MS               Int      Flag severity code

APPLIED      MS               Bool     True if applied to MAIN

COMMAND      MS               String   Flag command




                                                                                                                                     21
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ACSIS                                                            ACSIS Hardware and Software Interfaces

     HISTORY. A sub-Table containing history information for the MS. During an observation this will
      store logging information.

Field Name          MS or ACSIS        Type              Description                                   Units    Measure     Default

TIME                MS key             Double            Time stamp for message.                       s        EPOCH

OBSERVATION_ID      MS key             Int               Index into OBSERVATION table

MESSAGE             MS                 String            Log message

PRIORITY            MS                 String            Message priority

ORIGIN              MS                 String            Source code origin of message

OBJECT_ID           MS                 String            Originating object ID, if available

APPLICATION         MS                 String            Application name

CLI_COMMAND         MS                 String(*)         CLI command that invoked the application

APP_PARMS           MS                 String(*)         Application parameter values




  OBSERVATION. A sub-Table containing observation information. It specifies the observing
    instrument etc.

Field Name               MS or ACSIS         Type             Description                                       Units     Measure     Default

TELESCOPE_NAME           MS                  String           Telescope name                                                          JCMT

TIME_RANGE               MS                  Double(2)        Start, end times of observation.                  s         EPOCH

OBSERVER                 MS                  String           Name of observer

LOG                      MS                  String(*)        Observing log

SCHEDULE_TYPE            MS                  String           Schedule type                                                           JCMT

SCHEDULE                 MS                  String(*)        Unmodified schedule file, as used by instrument
                                                              (the configuration file).

PROJECT                  MS                  String           PATT ID number

RELEASE_DATE             MS                  Double           The release date for the data.                    s         EPOCH

FLAG_ROW                 MS flag             Bool             True if row contains invalid data.

NS_JCMT_OPERATOR         ACSIS               String           Name of operator




                                                                                                                                          22
    Reduction System Interfaces
ACSIS                                                        ACSIS Hardware and Software Interfaces

  POINTING. This is a sub-table containing pointing info on individual antennas. As such it sounds to be
    a more appropriate place than FIELD for storing the pointing directions associated with each
    integration. However, the data are referenced from MAIN just by ANTENNA_ID and TIME, there is
    no direct index akin to FIELD_ID. This would make determining the position of an integration
    inefficient so we will use FIELD and not this table.

Field Name     MS or ACSIS     Type              Description      Units      Measure     Default

ANTENNA_ID     MS key          Int               Not used.

TIME           MS key          Double            Not used.

INTERVAL       MS key          Double            Not used.

NAME           MS              String            Not used.

NUM_POLY       MS              Int               Not used.

TIME_ORIGIN    MS              Double            Not used.

DIRECTION      MS              Double(2,1)       Not used.

TARGET         MS              Double(2,1)       Not used.

TRACKING       MS              Bool              Not used.




  POLARIZATION. This sub-Table defines the polarization labeling of the data array in MAIN. It is
    directly indexed from the DATA_DESCRIPTION sub-Table via POLARIZATION_ID.

Field Name       MS or ACSIS         Type       Description                                                 Units   Measure   Default

NUM_CORR         MS                  Int        The number of correlation products.                                           1

CORR_TYPE        MS                  Int(1)     An integer for each correlation product from the Stokes
                                                class enumeration.

CORR_PRODUCT     MS                  Int(2,1)   Pair of integers for each correlation product, specifying
                                                the receptors from which the signal originated.

FLAG_ROW         MS flag             Bool       True if data in this row is invalid.                                          False




                                                                                                                                      23
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ACSIS                                                           ACSIS Hardware and Software Interfaces

  PROCESSOR. A sub-Table that holds summary information for the back-end processing device used
    to generate the basic data in MAIN.

Field Name   MS or ACSIS        Type       Description                                                 Units    Measure    Default

TYPE         MS                 String     Type of processor                                                               SPECTROMETER

SUB_TYPE     MS                 String     Processor sub-type                                                              ACSIS

TYPE_ID      MS                 Int        Index into specialised sub-Table of processor info.                             -1
                                           Not used.

MODE_ID      MS                 Int        Another index into an unused sub-Table.                                         -1

FLAG_ROW     MS flag            Bool       True if data in this row is invalid.                                            False




  SOURCE. A sub-Table containing source information.

Field Name             MS or ACSIS       Type                        Description                 Units         Measure               Default

SOURCE_ID              MS key            Int                         Source ID in this
                                                                     observation

TIME                   MS key            Double                      Midpoint of time for        s             EPOCH
                                                                     which the data are
                                                                     accurate

INTERVAL               MS key            Double                      Time period for which       s                                   0
                                                                     source info is valid.

SPECTRAL_WINDO         MS key            Int                         Spectral Window ID                                              -1
W_ID



NUM_LINES              MS                Int                         Number of spectral
                                                                     lines.

NAME                   MS                String                      Name of source.

CALIBRATION_GRO        MS                Int                         Not used.                                                       -1
UP

CODE                   MS                String                      Special characteristics
                                                                     of source.

DIRECTION              MS                Double(2)                   Direction of source         radians       DIRECTION

POSITION               MS                Double(3)                   Position, e.g. of Solar     m             POSITION              (0,0,0)
                                                                     system objects.

PROPER_MOTION          MS                Double(2)                   Proper motion.              radians/s

TRANSITION             MS                String(NUM_LINES)           Name of transition.

REST_FREQUENCY         MS                Double(NUM_LINES)           Line rest frequency.        Hz            FREQUENCY

SYSVEL                 MS                Double                      Radial velocity             m/s           RADIAL_VELOCITY

NS_JCMT_DR_GRO         ACSIS             Int                         ORAC-DR reduction
UP                                                                   group number.




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   Reduction System Interfaces
ACSIS                                        ACSIS Hardware and Software Interfaces

  SPECTRAL_WINDOW. This sub-Table describes the properties of each spectral window.

Field Name         MS or ACSIS   Type               Description                       Units   Measure     Default

NUM_CHAN           MS            Int                Number of spectral channels.

NAME               MS            String             Name of sp.w.

REF_FREQUENCY      MS            Double.            The reference frequency?          Hz      FREQUENCY

CHAN_FREQ          MS            Double(NUM_CHAN)   Centre frequencies for each       Hz      FREQUENCY
                                                    channel.

CHAN_WIDTH         MS            Double(NUM_CHAN)   Nominal width of each             Hz
                                                    channel.

MEAS_FREQ_REF      MS            Int                Frequency Measure reference
                                                    for CHAN_FREQ

EFFECTIVE_BW       MS            Double(NUM_CHAN)   Effective noise bandwidth for     Hz
                                                    each channel.

RESOLUTION         MS            Double(NUM_CHAN)   Effective spectral resolution     Hz
                                                    of each channel.

TOTAL_BANDWIDTH    MS            Double             Total bandwidth for this sp.w.    Hz

NET_SIDEBAND       MS            Int                Net sideband for this sp.w.

IF_CONV_CHAIN      MS            Int                Not used.                                             -1

FREQ_GROUP         MS            Int                Not used.                                             -1

FREQ_GROUP_NAME                  String             Not used.                                             Blank

DOPPLER_ID         MS            Int                Index into DOPPLER sub-
                                                    Table defining frame info.

ASSOC_SPW_ID       MS            Int(*)             Associated Sp.w.

ASSOC_NATURE       MS            String(*)          Nature of association;
                                                    SUBBAND or SUBSYSTEM

FLAG_ROW           MS flag       Bool               True if data in row are invalid                       False




                                                                                                                  25
   Reduction System Interfaces
ACSIS                                                      ACSIS Hardware and Software Interfaces

  STATE. A sub-Table that defines the external system state for a data record in MAIN.

Field Name   MS or ACSIS        Type     Description                                                         Units   Measure   Default

SIG          MS                 Bool     True if source signal is being observed.

REF          MS                 Bool     True if reference signal is being observed.

CAL          MS                 Double   Noise calibrator temperature. Not used.                             K                 0

LOAD         MS                 Double   Load temperature; 0 if no load.                                     K

SUB_SCAN     MS                 Int      Sub-scan number. Indexed relative to SCAN in MAIN. Used to
                                         identify observing sequences.

OBS_MODE     MS                 String   Observing mode.

FLAG_ROW     MS flag            Bool     True if row holds invalid data.




  SYSCAL. A sub-Table containing time-variable system calibration information, indexed on FEED and
    SPECTRAL_WINDOW.

Field Name                 MS or ACSIS     Type                             Description                      Units   Measure   Default

ANTENNA_ID                 MS key          Int                              Antenna ID                       0                 0

FEED_ID                    MS key          Int                              Feed ID

SPECTRAL_WINDOW_ID         MS key          Int                              ID of spectral window of
                                                                            spectrum

TIME                       MS key          Double                           Centre time for which            s       EPOCH
                                                                            calibration is valid.

INTERVAL                   MS key          Double                           Time period for which            s                 -1
                                                                            calibration is valid. Negative
                                                                            value implies valid until
                                                                            redefined.

TRX_SPECTRUM               MS              Float[NUM_RECEPTORS,             Receiver temperature.                    K
                                           NUM_CHAN]

TSYS_SPECTRUM              MS              Float[NUM_RECEPTORS,             System temperature.                      K
                                           NUM_CHAN]

TRX_FLAG                   MS              Bool                             True if TRX data invalid.                          False.

TSYS_FLAG                  MS              Bool                             True if TSYS data invalid.                         False.

NS_JCMT_TLOAD0             ACSIS           Float[NUM_RECEPTORS,             Temperature of LOAD0.                    K
                                           NUM_CHAN]

NS_JCMT_TLOAD1             ACSIS           Float[NUM_RECEPTORS,             Temperature of LOAD1.                    K
                                           NUM_CHAN]




                                                                                                                                    26
      Reduction System Interfaces
ACSIS                                            ACSIS Hardware and Software Interfaces

  WEATHER. A sub-Table containing weather station information.

         This Table contains a number of rows, each a Record describing some weather parameters on a
         particular ANTENNA at a specific TIME. For ACSIS these data will arrive with the data record
         from the correlator. The design has such data being stored in this table rather than in MAIN. Using
         the Incremental Storage Manager on these will ensure that data are only stored if they change.

Field Name               MS or ACSIS   Type     Description                                     Units     Measure   Default

ANTENNA_ID               MS key        Int      Antenna ID                                      0                   0

TIME                     MS key        Double   Centre time for which data are valid.           s         EPOCH

INTERVAL                 MS key        Double   Time period for which calibration is valid.     s                   -1
                                                Negative value implies valid until redefined.

PRESSURE                 MS            Float    Atmospheric pressure.                           hPa

REL_HUMIDITY             MS            Float    Ambient humidity

TEMPERATURE              MS            Float    Ambient temperature                             K

WIND_DIRECTION           MS            Float                                                    radians

WIND_SPEED               MS            Float                                                    m/s

PRESSURE_FLAG            MS flag       Bool     True means PRESSURE invalid                                         False

REL_HUMIDITY_FLAG        MS flag       Bool     True means REL_HUMIDITY invalid                                     False

TEMPERATURE_FLAG         MS flag       Bool     True means TEMPERATURE invalid                                      False

WIND_DIRECTION_FLAG      MS flag       Bool     True means WIND_DIRECTION invalid                                   False

WIND_SPEED_FLAG          MS flag       Bool     True means WIND_SPEED invalid                                       False




                                                                                                                            27
   Reduction System Interfaces
ACSIS                                             ACSIS Hardware and Software Interfaces

Spectral Data Cube output file


The format of the FITS filename will be ‘yyyymmdd_nnnnn_ss.FITS’, where yyyymmdd is the date, nnnnn
is the data reduction ‘observation number’ and ss is a section number for this part of the virtual FITS file.
In high data-rate modes each Beowulf node will write out to its own disk the data it cubes, in which case
the FITS file will be broken up into up to 16 sections. The ‘observation number’ used in the MS name is
generated by the reduction system itself rather than provided by the JCMT OCS. The system will ensure
that duplicate numbers are not generated even after a system crash and will make the number available to
the OCS for display.

Purpose:                  Gridded output spectral data cube
Protocol:                 FITS

Record Field Name         Parameter(s)       Range            Description

SIMPLE                    Char                T               parameter must be set as T for a FITS file

BITPIX                    long                -32             number of floating point bits per data pixel

NAXIS                     long                3               number of data axes: 3 for a data cube

NAXIS1                    long                ?               length of data axis 1

NAXIS2                    long                ?               length of data axis 2

NAXIS3                    long                <=8192          length of data axis 3

BSCALE                    float               1               Floating output = FITSvalue * BSCALE +
                                                              BZERO

BZERO                     float               0               image offset for conversion

EPOCH                     float               ?               epoch of coordinate system - nominally
                                                              2000.0?

BUNIT                     string              ?               Units of pixel data

CTYPE1                    string              RA,GLONG        Axis type for dim 1

CTYPE2                    string              DEC,GLAT        Axis type for dim 2

CTYPE3                    string              FREQ,CHAN       Axis type for dim 3

CRPIX1                    float               ?               reference pixel for dim 1

CRPIX2                    float               ?               reference pixel for dim 2

CRPIX3                    float               0<=8192         reference pixel for dim 3

CRVAL1                    float               0<=360          Sky coord of 1st axis (deg)

CRVAL2                    float               TRUE            Sky coord of 2nd axis (deg)

CRVAL3                    float               ?               Sky coord of 3nd axis (GHz)



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   Reduction System Interfaces
ACSIS                                     ACSIS Hardware and Software Interfaces

Purpose:            Gridded output spectral data cube
Protocol:           FITS

Record Field Name   Parameter(s)    Range          Description

CDELT1              float            ?              dim 1 degrees per pixel

CDELT2              float            ?              dim 2 degrees per pixel

CDELT3              float            ?              dim 3 frequency increment (GHz) per
                                                    channel

OBJECT              string           ?              observed source

PROJECT             string           ?              PATT number

DRRECIPE            string           ?              recipe for external pipeline

DRGROUP             string           ?              identifier for the group

BMAJ                float            ?              Beam major axis in deg (?)

BMIN                float            ?              Beam minor axis in deg (?)

BPA                 float            0<=360         Beam position angle in deg

VELREF              float            ?              Barycentric velocity; radio convention

RESTFREQ            float            ?=             rest frequency in GHz

HISTORY             string




                                                                                             29
  Reduction System Interfaces
ACSIS                                      ACSIS Hardware and Software Interfaces

Red. Sys. Control I/Os
Control Inputs and Parameters
Purpose
                      Used to control reduction system from a host computer program, like
Protocol
                      the TODD

Command Name          Parameter(s)           Range                Description

“INITIALISE”           none                                       Forces the reduction system to
                                                                  reset and initialise itself to an
                                                                  idle state. The system will also
                                                                  reconfigure itself to a default
                                                                  configuration. This action is
                                                                  normally done at the start of a
                                                                  series of observation or after
                                                                  an error.

“CONFIGURE”            “FILE_SPEC” |         a legal file         If the system status is ready it
                       (Parameter)           specification or     causes the reduction system
                                             XML Parameter        to read the XML file indicated
                                             Name                 by file_spec and configure
                                                                  itself. Any optional parameters
                                                                  overide the XML file
                                                                  parameters. If file spec is not
                                                                  given then the currently stored
                                                                  configuration is used. This
                                                                  command is normally done at
                                                                  the beginning of an
                                                                  observation.
                                                   32
“SEQUENCE”             “START_SEQ”           1 to 2 -2            Causes the DR system (in
                       “END_SEQ”             START_SEQ<           particular the Sync tasks) to
                                                     32
                                             and < 2 -1           tag the data flow with ‘start’
                                                                  and ‘end’ sequence
                                                                  information by setting bits in
                                                                  the CONTROL field of data
                                                                  Records.

“SET_FIELD_VAL”        “FIELD”               field name           Causes the Sync tasks in the
                       “DATA_TYPE”           B”|“I”|”F”|”D”|”S”   DR system to set the specified
                       “VALUE”               legal type           field in the data Records to the
                                                    32
                       “START_SEQ”           1 to 2 -2            given value within the
                       “END_SEQ”             START_SEQ<           sequence range.
                                                       32
                                             and < 2 -1

“MASK”                 “TASK”                DRAMA task           Causes the DR system (in
                                                   32
                       “START_SEQ”           1 to 2 -2            particular the Sync tasks) not
                       “END_SEQ”             START_SEQ<           to wait for information from the
                                                      32
                                             and < 2 -1           named task in the given
                                                                  sequence range before
                                                                  declaring a data Record
                                                                  complete. It is needed to
                                                                  handle correctly parts of an
                                                                  observation where not all sub-
                                                                  systems are taking part. An
                                                                  example would be a calibration
                                                                  taken while the telescope is
                                                                  slewing, where the telescope

                                                                                                      30
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                                                                    is not under RTS control and
                                                                    will not broadcast any
                                                                    positional information.

“FINISH”                none                                        Signals the end of an
                                                                    observation, or test, and
                                                                    causes the IF system status to
                                                                    go to the READY state. This
                                                                    command is used at the end of
                                                                    an observation.

“ABORT”                 none                                        Stop the system as quickly as
                                                                    possible. There are no safety
                                                                    issues so the shutdown will be
                                                                    neat.

“CHECK_HEALTH”          none                                        Cause the system to perform a
                                                                    self-check




Red. Sys. Configuration File
The RT reduction system configuration is specified by the rtr-config element in the observation
configuration file. Listed below is an example of the contents of that element.

<rtr-config>

<!--The first element specifies how the Sync objects in the RT reduction system
are to compose their data Records. These tasks receive data from the
correlator, IF, front-end and telescope sub-systems and assemble them into
Records that are sent to other objects for reduction.-->

        <sync-config>

               <sync-item field="main.TIME" type="scalar" source="tel"
               param="tel.TIME"/>
               <sync-item field="main.RA" type="scalar" source="tel"
               param="tel.LONG"/>
               <sync-item field="main.DEC" type="scalar" source="tel"
               param="tel.LAT"/>
               <sync-item field="main.IMAGE_ROTATOR" type="scalar" source="tel"
               param="tel.IMAGE_ROT"/>
               <sync-item field="main.ON_SOURCE" type="scalar" source="tel"
               param="tel.ON_SOURCE"/>
               <sync-item field="main.LOAD" type="string" source="fe1"
               param="LOAD"/>
               <sync-item field="main.THOT" type="scalar" source="fe1"
               param="THOT"/>
               <sync-item field="main.TCOLD" type="scalar" source="fe1"
               param="TCOLD"/>
               <sync-item field="main.TOTAL_POWER" type="scalar"
               source="if1"param="IFDATA1"/>
               <sync-item field="main.EXPOSURE" type="scalar" source="if1"
               param="IFDATA2"/>
               <sync-item field="main.INTERVAL" type="scalar" source="if1"
               param="IFDATA3"/>



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              <sync-item field="main.RA" type="scalar" source="tel"
              param="something"/>
              <sync-item field="main.SAMPLER" type="scalar" source="correlator"
              param="something"/>
              <sync-item field="main.FLOAT_DATA" type="scalar"
              source="correlator" param="something"/>
        </sync-config>

        <rtr-recipe>

<!--This element specifies the types of ReducerProcess objects that will be
instantiated in the RT reduction system. Each type of ReducerProcess contains a
number of Reducer, Archiver or Gridder objects. The names of these objects and
their function are specified in a set of “red-object” elements.-->

              <rt-process name="REDUCER">

<!--The description of one particular ReducerProcess object type, called
“REDUCER”.-->

                       <red-object name="ON" type="reducer">

<!--This red-object element describes a Reducer object whose name will be ON.
The purpose of this object is to receive data and if it fulfills the criteria
for an on-source measurement to reduce it and pass it on to other objects that
need the results.-->

                             <red-object-recipe>

<!--The red-object-recipe element lists the reduction steps that need to be
performed on on-source data by this object.-->

                                   <string>    corr_data.FLOAT_DATA</string>
                                   <function> rvalue             </function>
                                   <function> linearise          </function>
                                   <string>    SPECTRAL_WINDOW_ID</string>
                                   <function> rvalue             </function>
                                   <function> window             </function>
                                   <function> fft                </function>
                                   <string>    if_data.TOTAL_POWER</string>
                                   <function> rvalue             </function>
                                   <function> multiply           </function>
                                   <string     corr_data.FLOAT_DATA</string>
                                   <function> lvalue             </function>
                             </red-object-recipe>
                             <red-object-source-list>

<!--The red-object-source-list element describes the type of data that this
object requires. In this case it wants any data from a SYNC object where the
LOAD field is “SKY” and the ON_SOURCE field is True.-->

                                   <string>    SELECT FROM SYNC WHERE LOAD=="SKY"
                                   andand ON_SOURCE </string>
                             </red-object-source-list>
                       </red-object>

                       <red-object name="OFF" type="reducer">

<!--This red-object element describes a Reducer object whose name will be OFF.
The purpose of this object is to receive off-source data and, reduce it and
pass it on.-->

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                                    .
                                    .
                                    .
                  </red-object>

                  <red-object name="COLD" type="reducer">

<!--Likewise red-object elements describing Reducers for reducing HOT and COLD
load measurements.-->
                                    .
                                    .
                  </red-object>

                  <red-object name="HOT" type="reducer">
                                    .
                                    .
                  </red-object>

                  <red-object name="TREC" type="reducer">
                        <red-object-recipe>
                              <string>    corr_data.FLOAT_DATA </string>
                              <string>    ant_data.TIME     </string>
                              <string>    corr_data.SAMPLER </string>
                              <string>    COLD              </string>
                              <function> previous           </function>
                              <string>    corr_data.FLOAT_DATA</string>
                              <function> rvalue             </function>
                              <function> subtract           </function>
                              <string>    fe_data.TCOLD     </string>
                              <string>    ant_data.TIME     </string>
                              <string>    corr_data.SAMPLER </string>
                              <string>    COLD              </string>
                              <function> previous           </function>
                              <string>    corr_data.FLOAT_DATA</string>
                              <function> rvalue             </function>
                              <function> multiply           </function>
                              <string>    corr_data.FLOAT_DATA</string>
                              <string>    ant_data.TIME     </string>
                              <string>    corr_data.SAMPLER </string>
                              <string>    COLD              </string>
                              <function> previous           </function>
                              <string>    fe_data.THOT      </string>
                              <function> rvalue             </function>
                              <function> multiply           </function>
                              <function> subtract           </function>
                              <function> divide             </function>
                              <string>    corr_data.FLOAT_DATA</string>
                              <function> lvalue             </function>
                        </red-object-recipe>
                        <red-object-source-list>
                              <string>    SELECT FROM HOT   </string>
                              <string>    SELECT FROM COLD </string>
                        </red-object-source-list>
                  </red-object>

                  <red-object name="CALIBRATED" type="reducer">
                        <red-object-recipe>
                              <string>    corr_data.FLOAT_DATA</string>
                              <string>    ant_data.TIME     </string>
                              <string>    corr_data.SAMPLER </string>
                              <string>    OFF               </string>

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                                <function> interpolate        </function>
                                <function> enter              </function>
                                <string>    corr_data.FLOAT_DATA</string>
                                <function> rvalue             </function>
                                <function> subtract           </function>
                                <function> divide             </function>
                                <string>    if_data.TOTAL_POWER</string>
                                <function> rvalue             </function>
                                <function> subtract           </function>
                                <function> enter              </function>
                                <function> subtract           </function>
                                <string>    corr_data.FLOAT_DATA</string>
                                <string>    ant_fata.TIME     </string>
                                <string>    corr_data.SAMPLER </string>
                                <string>    TREC              </string>
                                <function> previous           </function>
                                <function> multiply           </function>
                                <string>    corr_data.FLOAT_DATA</string>
                                <function> lvalue             </function>
                          </red-object-recipe>
                          <red-object-source-list>
                                <string>    SELECT FROM ON    </string>
                                <string>    SELECT FROM OFF   </string>
                                <string>    SELECT FROM TREC </string>
                          </red-object-source-list>
                    </red-object>

                    <red-object name="RAW_ARCHIVER" type="archiver">
                          <red-object-recipe>
                                <filename> /tmp/johnl/raw.ms </filename>
                          </red-object-recipe>
                          <red-object-source-list>
                                <string>    SELECT FROM SYNC </string>
                          </red-object-source-list>
                    </red-object>

              </rt-process>

              <rt-process name="GRIDDER">

                    <red-object name="GRIDDER" type="gridder">
                          <red-object-recipe>
                                <file-format type="FITS"/>
                          </red-object-recipe>
                          <red-object-source-list>
                                <string> SELECT
                                SEQ,CONTROL,CONTROLONLY,SENDER,SOURCERO,
                                SPECTRAL_WINDOW_ID,ant_data.TIME,
                                ant_data.RA,ant_data.DEC FROM CALIBRATED
                                </string>
                          </red-object-source-list>
                    </red-object>

              </rt-process>

        </rtr-recipe>


        <process-config>

              <process name="if_monitor" exe="if_monitor" machine="slave1">

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                    <params>    /tmp/johnl iftask1 slave8     </params>
              </process>

              <process name="ant_monitor" exe="ant_monitor" machine="slave1">
                    <params>    /tmp/johnl anttask1 slave8    </params>
              </process>

              <process name="sync1" exe="sync_task" machine="slave1">
                    <params>    /tmp/johnl corrtask1 slave8   </params>
              </process>

              <process name="sync2" exe="sync_task" machine="slave2">
                    <params>    /tmp/johnl corrtask2 slave9   </params>
              </process>

<!--Another 14 sync tasks defined here.-->
                        .
                        .

        </process-config>



 <gridder-config>

  <gridder process-name="gridder1" object-name="GRIDDER">
   <selector>          SPECTRAL_WINDOW_ID==1           </selector>
   <data>              corr_data.FLOAT_DATA            </data>
  </gridder>

  <gridder process-name="gridder2" object-name="GRIDDER">
   <selector>          SPECTRAL_WINDOW_ID==1           </selector>
   <data>              corr_data.FLOAT_DATA            </data>
  </gridder>

  <gridder process-name="gridder3" object-name="GRIDDER">
   <selector>          SPECTRAL_WINDOW_ID==1           </selector>
   <data>              corr_data.FLOAT_DATA            </data>
  </gridder>

  <gridder process-name="gridder4" object-name="GRIDDER">
   <selector>          SPECTRAL_WINDOW_ID==1           </selector>
   <data>              corr_data.FLOAT_DATA            </data>
  </gridder>

  <gridder process-name="gridder5" object-name="GRIDDER">
   <selector>          SPECTRAL_WINDOW_ID==1           </selector>
   <data>              corr_data.FLOAT_DATA            </data>
  </gridder>

  <gridder process-name="gridder6" object-name="GRIDDER">
   <selector>          SPECTRAL_WINDOW_ID==1           </selector>
   <data>              corr_data.FLOAT_DATA            </data>
  </gridder>

  <gridder process-name="gridder7" object-name="GRIDDER">
   <selector>          SPECTRAL_WINDOW_ID==1           </selector>
   <data>              corr_data.FLOAT_DATA            </data>
  </gridder>

  <gridder process-name="gridder8" object-name="GRIDDER">

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    <selector>             SPECTRAL_WINDOW_ID==1          </selector>
    <data>                 corr_data.FLOAT_DATA           </data>
   </gridder>

  </gridder-config>

</rtr-config>


 <rtd-config>

  <rtd-beam-list>
    <rtd-beam name="1"/>
    <rtd-beam name="2"/>
    <rtd-beam name="3"/>
    <rtd-beam name="4"/>
    <rtd-beam name="5"/>
    <rtd-beam name="6"/>
    <rtd-beam name="7"/>
    <rtd-beam name="8"/>

  </rtd-beam-list>

  <rtd-object-list>

   <rtd-object name="OFF">
    <rtd-object-field name="corr_data.FLOAT_DATA" type="array"/>
    <rtd-object-field name="if_data.TOTAL_POWER" type="scalar"/>
   </rtd-object>

   <rtd-object name="ON">
    <rtd-object-field name="corr_data.FLOAT_DATA" type="array"/>
    <rtd-object-field name="if_data.TOTAL_POWER" type="scalar"/>
   </rtd-object>

   <rtd-object name="COLD">
    <rtd-object-field name="corr_data.FLOAT_DATA" type="array"/>
    <rtd-object-field name="if_data.TOTAL_POWER" type="scalar"/>
   </rtd-object>

   <rtd-object name="HOT">
    <rtd-object-field name="corr_data.FLOAT_DATA" type="array"/>
    <rtd-object-field name="if_data.TOTAL_POWER" type="scalar"/>
   </rtd-object>

   <rtd-object name="TREC">
    <rtd-object-field name="corr_data.FLOAT_DATA" type="array"/>
    <rtd-object-field name="if_data.TOTAL_POWER" type="scalar"/>
   </rtd-object>

   <rtd-object name="CALIBRATED">
    <rtd-object-field name="corr_data.FLOAT_DATA" type="array"/>
    <rtd-object-field name="if_data.TOTAL_POWER" type="scalar"/>
   </rtd-object>

  </rtd-object-list>

 </rtd-config>

</ACSISconfig>


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Red. Sys. Control Output
Purpose                    Used to provide feedback from the reduction system to a host computer
                           program, like the TODD.
Protocol                   DRAMA

Command Name               Parameter(s)         Range          Description

   “FINISHED”                 none                             Signals that the DR system has
                                                               completed work on the current
                                                               observation.

   “WARNING”                  “MESSAGE”                        Signals a warning from the DR
                                                               system. The associated MESSAGE
                                                               String will contain a description of the
                                                               problem.

   “ERROR”                    “MESSAGE”                        Signals that a serious error has
                                                               occurred in the DR system. The
                                                               controlling program should shut down
                                                               the observation immediately.




                                                                                                          37
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The Real-Time Display
The RT Display is an object that displays data being processed by the reduction system. It is designed so
that instantiations of the RT Display can attach themselves to the reduction system at any time during an
observing run. They can request a list of the data objects that can be displayed, request to be sent some of
those objects as they become available, then display them. Once attached to the reduction system the RT
display will automatically display data objects specified in the configuration file for the observation with
user interaction (though the user can modify the selection afterward).

RTD Software Inputs and Outputs
RTD Data I/Os
Data is sent to the RT Display by objects in the reduction system as GlishRecords of varying format. The
RT Display will have asked for that data by sending out ‘attach’ events to the ‘reduction_controller’. When
the data arrive the display will see which request the data Record fits and handle it accordingly.

RTD Control I/Os
Command Inputs and Parameters

Purpose              Used to control the RT Display system. All commands are Glish events.
Protocol

Command Name         Parameter(s)        Range                        Description
  “INITIALISE”         none                                           Forces the RT Display to reset and
                                                                      initialise itself to an idle state. The system
                                                                      will also reconfigure itself to a default
                                                                      configuration. This action is normally done
                                                                      at the start of a series of observation or
                                                                      after an error.
  “CONFIGURE”          “CONFIGURA        A GlishRecord containing     It causes the RTD system to configure
                       TION”             the rtr-config and rtd-      itself according to the information in the
                                         config elements of the       configuration record. The rtr-config
                                         parsed XML configuration     element tells the system the data objects
                                         file.                        that can be displayed. The rtd-config
                                                                      element tells the system the data objects
                                                                      that should be displayed automatically.
  “ABORT”              none                                           Does nothing, only there to satisfy the
                                                                      need for standard JCMT interface.

  “CHECK_              none                                           Does nothing.
  HEALTH”

“EXIT”
                         none                                         Tells the task to delete itself.
“HELP”
                         none                                         Send documentation on the task actions to
                                                                      the process that invoked the action.
“PING”
                         none                                         This action does nothing but by responding
                                                                      to the command the task lets the outside
                                                                      world know that it is alive.
“REPORT”
                         none                                         Send a report on task status to the process
                                                                      that invoked the action.


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Control Output
Purpose               Used to provide feedback from the reduction system to a host computer program, like the
Protocol              TODD.

Command Name          Parameter(s)            Range                            Description

“ATTACH”                   dataRequest        A GlishRecord containing         To any object in the DR system
                                              information on the requesting    that receives it this requests that
                                              process and a TaQL request       data be sent back as they
                                              for the type of data required.   become available if they satisfy
                                                                               the TaQL request criteria.

“DETACH”                   dataRequest        A GlishRecord containing         This cancels the request made
                                              information on the requesting    by a previous ‘attach’.
                                              process and a TaQL request
                                              for the type of data required.

“OBJECTS”                  none                                                Sent to the reduction_controller
                                                                               this askes the reduction system
                                                                               to reply with a list of data object
                                                                               names and types and Reducer
                                                                               object names.




RTD Configuration Element
The RT reduction system configuration is specified by the rtd-config element in the observation
configuration file. Listed low is an example of the contents of that element. The example asks for several
types of data to be displayed:

1. Calibrated data from feed 5 to be displayed every 5th sequence number. As a vector data object this will
   be displayed as a graph.
2. The receiver temperatures TREC to be displayed for all feeds every time they are calculated.
3. The total power for all on-source measurements. As a scalar data object this will be displayed in strip-
   chart fashion.


<rtd-config>

        <display data=”corr_data.FLOAT_DATA” source=”CALIBRATED”
        selection=”FEED==5 && SEQ%5==0”/>
        <display data=”corr_data.FLOAT_DATA” source=”TREC”/>
        <display data=”if_data.TOTAL_POWER” source=”ON”/>

</rtd-config>




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Appendix A: The System Configuration File
The configuration of the entire ACSIS system for a given observation is described in an XML passed to the
TODD at observation start. The name of the file is passed to the various sub-systems that need it, they then
parse it and extract the required information from their specific XML element.

Though the configuration file as passed to Todd must contain a complete description of the observation
configuration and methods, it will have passed through several stages to reach this level of completeness.

1. The Observation Preparation Tool (OPT) is used by the prospective observer to build a configuration
   file describing the general type and instrumental configuration for the observation. Elements filled in at
   this stage will be:

        ACSISconfig.general

        ACSISconfig.source

        ACSISconfig.field

        ACSISconfig.observation

        ACSISconfig.spw-config

2. The skeleton configuration file is written to a database of such files, available for use by the JCMT
   Observation Control System.

3. At the telescope, at the start of an observation, the file is read from the database and the empty sections
   filled in. It is at this point that the ‘dynamic’ information, known only at the telescope, is added to the
   configuration. Elements filled out at this stage would be:

        ACSISconfig.todd

        ACSISconfig.symbols

        ACSISconfig.if-config

        ACSISconfig.corr-config

        ACSISconfig.rtr-config

4. During the configuration phase of the observation the TODD sends ‘configure’ commands to the IF,
   correlator and reduction_controller tasks, giving them the name of the configuration file. Each task then
   parses the file using a standard XML parser, finds the XML element pertaining to it, then configures
   itself according to the information therein.




                                                                                                           A-1
ACSIS                                         ACSIS Hardware and Software Interfaces

System Configuration File Format
The configuration file is in XML. The design is most easily described by giving a commented example.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE ACSISconfig SYSTEM "ACSISconfigv3.dtd" >

<!--This is is an ACSIS configuration file describing the system for taking and reducing a raster map observation.-
->

<!--XML is an extensible language, the extended part of which is described by rules in the DTD file cited at the
top of the file. It is a hierarchical system wherein the file contains a number of ‘elements’, which may themselves
be made up of further elements, etc.-->

<!--The main element of the file is ‘ACSISconfig’, whose contents will describe the configuration of the entire
system.-->

<ACSISconfig>

<!--An element containing general information about this observation.-->

  <general>
    <observer>    hab </observer>
    <operator> moby </operator>
    <pattname> m00u34 </pattname>
    <front-end> HARPB </front-end>
    <back-end> ACSIS </back-end>
  </general>

<!--An element containing general info about the source.-->

  <source>
    <name> OMC1 </name>
    <centre-coords> RJ </centre-coords>
    <centre-long> 12.45 </centre-long>
    <centre-lat> -5.12 </centre-lat>
    <velocity> 245648.1 </velocity>
    <vel-defn> LSR </vel-defn>
  </source>

<!--An element containing information about this particular field.-->




                                                                                                                  A-2
ACSIS                                    ACSIS Hardware and Software Interfaces


 <field>
   <name> OMC1a </name>
   <centre-coords> RJ </centre-coords>
   <centre-long> 12.15 </centre-long>
   <centre-lat> -5.20 </centre-lat>
   <ref-long> 12.00 </ref-long>
   <ref-lat> -5.2 </ref-lat>
 </field>

<!--An element specifying the type and shape of the observation.-->

 <observation>
   <mode> raster </mode>
   <row-reversal> True </row-reversal>
   <row-coords> RJ </row-coords>
   <row-length> 600.0 </row-length>
   <num-rows> 20 </num-rows>
   <inter-row-spacing> 30.0 </inter-row-spacing>
   <row-sample> 3.0 </row-sample>
   <switch-mode> REFPOS </switch-mode>
 </observation>

<!--An element containing the TODD recipe to be used for this observation.-->

 <todd>
   <recipe-name> harp_acsis_raster.v12 </recipe-name>
   <recipe-value>
     ... this would contain the saved TODD recipe ...
   </recipe-value>
 </todd>

        <symbols>
              <symbol   name=”MASTER”   value=”master.jcmt.hawaii.edu”/>
              <symbol   name=”SLAVE1”   value=”slave1.jcmt.hawaii.edu”/>
              <symbol   name=”SLAVE2”   value=”slave2.jcmt.hawaii.edu”/>
              <symbol   name=”SLAVE3”   value=”slave3.jcmt.hawaii.edu”/>
              <symbol   name=”SLAVE4”   value=”slave4.jcmt.hawaii.edu”/>
              <symbol   name=”SLAVE5”   value=”slave5.jcmt.hawaii.edu”/>
              <symbol   name=”SLAVE6”   value=”slave6.jcmt.hawaii.edu”/>
              <symbol   name=”SLAVE7”   value=”slave7.jcmt.hawaii.edu”/>




                                                                                  A-3
ACSIS                                  ACSIS Hardware and Software Interfaces

              <symbol   name=”SLAVE8” value=”slave8.jcmt.hawaii.edu”/>
              <symbol   name=”SLAVE9” value=”slave9.jcmt.hawaii.edu”/>
              <symbol   name=”SLAVE10” value=”slave10.jcmt.hawaii.edu”/>
              <symbol   name=”SLAVE11” value=”slave11.jcmt.hawaii.edu”/>
              <symbol   name=”SLAVE12” value=”slave12.jcmt.hawaii.edu”/>
              <symbol   name=”SLAVE13” value=”slave13.jcmt.hawaii.edu”/>
              <symbol   name=”SLAVE14” value=”slave14.jcmt.hawaii.edu”/>
              <symbol   name=”SLAVE15” value=”slave15.jcmt.hawaii.edu”/>
              <symbol   name=”TCS” value=”tcs@luu.jcmt.hawaii.edu”/>
              <symbol   name=”WS” value=”ws@luu.jcmt.hawaii.edu”/>
              <symbol   name=”FE_TASK” value=”harp@ulu.jcmt.hawaii.edu”/>
              <symbol   name=”IF_TASK” value=”if@iiwi.jcmt.hawaii.edu”/>
              <symbol   name=”CORR_TASK” value=”corr@iiwi.jcmt.hawaii.edu”/>
              <symbol   name=”RT_CONTROL” value=”reduction_controller@master.jcmt.hawaii.edu”/>
              <symbol   name=”REST_FREQUENCY” value=”3457590000.0”/>
              <symbol   name=”VELOCITY” value=”45648.1” />
              <symbol   name=”VEL_DEFN” value=”LSR”/>
              <symbol   name=”CENTRE_COORDS” value=”RJ”/>
              <symbol   name=”CENTRE_LONG” value=”12.15”/>
              <symbol   name=”CENTRE_LAT” value=”-5.20”/>
              <symbol   name=”LOAD1” value=”HOT”/>
              <symbol   name=”LOAD2” value=”AMB”/>
              <symbol   name=”REF_LONG” value=”12.0”/>
              <symbol   name=”REF_LAT” value=”-5.2”/>
              <symbol   name=”INTEGRATION_TIME” value=”0.05”/>
              <symbol   name=”NROWS” value=”20”/>
              <symbol   name=”ROW_LENGTH” value=”600.0”/>
              <symbol   name=”ROW_SAMPLE” value=”3.0”/>
              <symbol   name=”ROW_Y_STEP” value=”30.0”/>
        </symbols>


<!--An element specifying the setup of the IF system, described earlier so left blank here.-->

 <if-config>
     .
     .
     .
 </if-config>

<!--An element specifying the setup of the correlator system, described earlier so left blank here.-->




                                                                                                         A-4
ACSIS                               ACSIS Hardware and Software Interfaces


  <corr-config>
      .
      .
      .
  </corr-config>

<!--An element describing the Spectral Windows that will be used in this configuration and how the reduction system
is to treat them; ‘window’ function to be applied, truncation, merging, baseline fitting -->

  <spw-config>

<!--An element describing one Spectral Window.

    <spectral-window name =”0”>
      <subband-id>      1                 </subband-id>
      <name>                              </name>
      <receiver>        HARPB             </receiver>
      <rest-frequency> 345796000000.0     </rest-frequency>
      <if-centre-frequency>   5000000000.0</if-centre-frequency>
      <sw-centre-frequency>   4600000000.0</sw-centre-frquency>
      <sideband>        1                 </sideband>
      <num-chan>        4096              </num-chan>
      <bandwidth>       1000000000.0      </bandwidth>
      <assoc-spw-id name=”2” />
      <assoc-nature type=PARENT />
      <window type="TRUNCATE" length="2048" />
      <baseline-fit/>
      <archive-selection> 0,346,1         </archive-selection>
    </spectral-window>

    <spectral-window name=”1”>
      <name>                               </name>
      <receiver>        HARPB              </receiver>
      <rest-frequency> 345796000000.0      </rest-frequency>
      <if-centre-frequency>    5000000000.0</if-centre-frequency>
      <sw-centre-frequency>    5400000000.0</sw-centre-frequency>
      <sideband>        1                  </sideband>
      <num-chan>        4096               </num-chan>
      <bandwidth>       1000000000.0       </bandwidth>
      <assoc-spw-id name=”2”/>




                                                                                                                A-5
ACSIS                             ACSIS Hardware and Software Interfaces

     <assoc-nature type=PARENT />
     <window type="TRUNCATE" length="2048" />
     <baseline-fit/>
     <archive-selection> 0,346,1         </archive-selection>
   </spectral-window>

   <spectral_window name=”2”>
     <name> CO 1-0 </name>
     <receiver>        HARPB             </receiver>
     <rest-frequency> 345796000000.0 </rest-frequency>
     <if-centre-frequency/>
     <sw-centre-frequency/>
     <sideband/>
     <num-chan/>
     <bandwidth/>
     <assoc-spw-id name=”0,1”/>
     <assoc-nature type=”CHILD” />
     <window/>
     <resolution> set this if you want smoothing </resolution>
     <baseline-fit>
       <polynomial degree="2"/>
       <baseline-region>
         <range>
           <start> 1.2 </start>
           <end> 100.5 </end>
         </range>
         <range>
           <start> 200.5 </start>
           <end> 554.2 </end>
         </range>
         <range>
           <start> 3000.1 </start>
           <end> 4001.9 </end>
         </range>
       </baseline-region>
     </baseline-fit>
     <archive_selection> </archive_selection>
   </spectral_window>

 </spw_config>




                                                                           A-6

				
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