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					2001 University of Tokyo
CUBESAT Project




                      University of Tokyo
                       CubeSat Project
    CRITICAL DESIGN REVIEW

                         April, 6, 2001
            Intelligent Space Systems Laboratory
                     University of Tokyo
2001 University of Tokyo CUBESAT Project


  ■Contents

 •Project Overview
       –CubeSat program, Organization, Management, Schedule

 •Mission Overview
       –Design Assumption, Mission Objective, Mission Profile,
       Success Level

 •System Design
       –Design Strategy & Concepts

 •Subsystem Details
       –Electronics, Power, Communication, Structure,
       Environment, Ground Segment

 •Concerns
2001 University of Tokyo
CUBESAT Project




     Project Overview
2001 University of Tokyo CUBESAT Project


  ■CubeSat Program


     ・Proposed in University Space Systems Symposium. (Nov.
     1998, Hawaii)
     ・International educational program to improve students’
     skill of space engineering and project management.
     ・Quick and low cost development policy.
     ・10cm cubic satellite weighing less than 1kg.
2001 University of Tokyo CUBESAT Project


  ■Project Constraints


 ・10cm cubic shape, weight less than 1kg.
 ・Installed in the carrier called “P-POD”, developed by CalPoly.
 ・P-POD is to be installed in MPA (Multiple Payload Adopter),
 developed by One Stop Satellite Solutions Inc.
 ・Launched by Russian rocket “Dnepr” from Baikonur in
 November, 2001.
 ・Orbit 600-800km circular, 60 degree inclination
 ・HAM band operation
2001 University of Tokyo CUBESAT Project


  ■CubeSat Developers



・California Polytechnic State              ・Taylor University
U ・Dartmouth College                       ・Tokyo Institute of Technology
・Florida Space Institute                   ・University of Arizona
・Leland High School                        ・University of Tokyo
・Montana State University                  ・Wilcox High School
・Stanford University
・Stellar Innovations
2001 University of Tokyo CUBESAT Project


  ■CubeSat Program Organization


    Russia
   Launcher Provider                OS2 Mission Organizer
    ISC Kosmotras                     OSSS Inc.    Stanford U
                                                                    Carrier Provider
                                                                     CalPoly

    U.S.A.
                                                            Japan        Japan-side Agency
                                                                    Astro Reserch Co.

CubeSat Developers
                  U.S.A.                                Japan
                  10 Facilities                         ・U of Tokyo
                                                        ・Tokyo Inst. of Tech.
2001 University of Tokyo CUBESAT Project


  ■Payload Configuration


                                           MPA
                                           Mass      < 300kg
                                           Isogrid Spaceframe
                                           Deploys Payload Satellites
                                           Three-axis Stabilization
     Dnepr LV
     Launch weight         211 t
     Propellant      amyl + heptyl
     Number of stages 3                                P-POD
     LV diameter           3m                          Deployes 3 CubeSats
     LV length34m
     Reliability           0.97
     Payload 400kg (800km)
                1400kg (600km)
                (inclination 65deg)                           CubeSat
 2001 University of Tokyo CUBESAT Project


   ■UT’s Project Organization


                                                Program Director
・21 active members
                                               Prof. Nakasuka
・General meeting every 1-2 week(s)
・Subsystem meeting every week
                                                Project Manager

                                                    Y.Tsuda




   Electronics     Communication            Power             Structure    Environment     Ground Seg.

 Y.Arikawa        T.Ito             N.Sako                N.Miyamura      P.Seo          S.Ogasawara
 Y.Tsuda          Y.Kato            T.Eishima             T.Ito           N.Sako         Y.Tsuda
 N.Miyamura       T.Eishima         Y.Arikawa             S.Ogasawara     K.Kanairo      T.Murakami
 S.Ishikawa       S.Ukawa           S.Ukawa                               K.Muramatsu    Y.Oda
 T.Murakami       S.Ihikawa         R.Funase                                             I.Ikeda
 E.Hwan           Y.Kuwata          S.Hori
 K.Kanairo        T.Yamamoto
                  S.Ganryu
2001 University of Tokyo CUBESAT Project


  ■Development Milestone

 Development code : XI [sai] (X-factor Investigator)
                         ・Basic functional check
  XI-I                   ・Technological demonstration for USSS conference

                         ・Bread board model
  XI-II                  ・Validation of all technology to be used

 Communication test model, Mass model, CDR
                         ・Engineering model
  XI-III                 ・Served to the integration & environmental testing

                         ・Flight model & back up model
  XI-IV,V                ・One for flight, the other for operation practice etc.
2001 University of Tokyo
CUBESAT Project




     Mission Overview
2001 University of Tokyo CUBESAT Project


  ■“XI” Outlook




                                                               Solar cells are to
   Antenna Latch                                               be attached on
   Mechanism                                                   whole surface




        Antenna



           Flight Pin Hole
                 Camera Hole               photo: XI-II (BBM model)
2001 University of Tokyo CUBESAT Project


  ■Mission Description



 ■Mission Statement
 "To acquire the indispensable technology in developing super-
  small satellite system"

 ■Mission
 ・Gathering the satellite’s health information via beacon signal.
 ・Command uplink & data downlink.
 ・Telemetry data broadcasting service.
 ・On-orbit verification of the commercial-off-the-shelves (COTS)
  components.
 ・Imaging experiment as an extended mission. (TBD)
 ・Sending everyone’s message into space.
2001 University of Tokyo CUBESAT Project


  ■Success Level (1)


■Project‟s Minimum Success
--- Acquiring the important technology and knowledge through
designing and fabricating the spacecraft.
・Establishing overall work flow of the satellite development project.
・Establishing a methodology of spacecraft design.
・Raising the fabrication technique.
・Conducting several kind of testing and feeding back its results to the design.
・Keeping the project progressing smoothly so as to bring it to be the launchable condition.

■Mission Success
--- Receiving signals from the spacecraft.
・Surviving in the actual launch environment.
・Successfully verifying the function of the communication system.
・Gathering house keeping data.
2001 University of Tokyo CUBESAT Project


  ■Success Level (2)


    ■Full Success
    --- Succeeding in uplink & downlink.
    ・Successfully commanding the spacecraft by uplink.
    ・Getting downlink data as a reaction to the command uplink.


    ■Advanced Success
    --- Successfully verifying the function of the advanced
    mission components.
    ・Verifying that sensors planned to be equipped as advanced mission components
    should work normally.
2001 University of Tokyo CUBESAT Project


  ■Mission Profile (1)


                  ・Launched by Dnepr from Baikonur in Nov. 2001.
                  ・MPA is put in 600-800km circular orbit with 60 degree inclination.



                       ・MPA deploys some of its payloads & activates P-POD.
                       ・P-POD deploys CubeSats.




                          ・CubeSat starts operation after a certain elapsed time.
 2001 University of Tokyo CUBESAT Project


   ■Mission Profile (2)



  1.                                  2.                             3.




■Post Ejection Stand-by          ■Nominal Operation               ■Telemetry Transmission
Main OBC is activated            Antenna is deployed. All         This mode occurs as a reply
while the other                  components including beacon      to the uplink command from
components are off.              are activated except telemetry   ground station.
                                 transmission system.
2001 University of Tokyo
CUBESAT Project




     System Design
2001 University of Tokyo CUBESAT Project


  ■Basic Specifications


         ●Structure                        10cm cubic, 1kg, Aluminum A7075 body
         ●Main Processor
                OBC PIC16F877 4MHz(Program memory 8k, RAM 368)
                Data Recorder  EEPROM 32k + 224k
         ●Communication System
               Downlink                    437.490MHz, FSK, AX.25, 1200bps, 600mW
               Uplink                      145.835MHz, FSK, AX.25, 1200bps
               Beacon                      436.8475MHz, CW, 100mW
         ●Power System
                Battery                    Manganese type lithium-ion battery, 8 parallel
                Solar Cells                Single crystal silicon, 60 cells
                Bus Voltage                5V
         ●Attitude Control                 Passive stabilization using permanent magnet
         ●Sensors                          Voltage, Current, Temperature, Area sensor
Structure                                      PWR5V
    Power
             OBC
                                              Main                      Com1
                          DC-DC1                                                                     TX

             RX TNC                                    ROM                   TX TNC         TX
                                                                                               Analog SW
                          DC-DC2                                 TLM
                                                           TLM
             OBC

                                                                        Com2
                          DC-DC3
                                                           OBC     CMD
             uSW                                                             RX TNC         RX
             Flight Pin                                                          ACK
                                                                       TLM
         Charge                                                              CW Gen         CW
         Circuit


                                             PWR5V
               Flight Pin

Solar Cell                               Digital Sensors                              Important Analog
                                         Antenna Latch                                Sensors

                                                                                          Analog Sensors
                                   Battery
  2001 University of Tokyo CUBESAT Project


    ■Internal Function Design Strategy

■Mother board
 intervenes inter-           Structure
 subsystem signal &          Subsystem
 power flow.                                                           Camera Module



                                             Electronics Subsystem


            Battery                             Data Handling Unit
                                Mother
                                Board        Power Subsystem

                                                Power Unit
           Solar Cell
                                             Communication Subsystem

Temperature Sensors                             Communication Unit
2001 University of Tokyo
CUBESAT Project




     Structure Subsystem
2001 University of Tokyo CUBESAT Project


  ■Structure Subsystem


  1.   Body of CUBESAT                     3. Antennae Deployment
  a)   Assembly                            Mechanism
  b)   Weight and Center Of Mass           a) Magnetic Plunger
  c)   Material                            b) Folding Method
  d)   Size

  2.   Interface                           4. Strength Analysis
  a)   Flight Pin                          a) Behavior as
  b)   External Input/Output                   Cantilever Beam
  c)   Connector                           b) Ceiling panel’s vibration
  d)   Kill Switch                         c) Load Estimation
                                           d) Countermeasure
                                              for vibration(Antennae)
2001 University of Tokyo CUBESAT Project


  ■Body of CUBESAT


         a)      Assembly
         b)      Weight and Center Of Mass
         c)      Material
         d)      Size
                                               z




                                                         y


                                                   Center Of Mass
                                           x
2001 University of Tokyo CUBESAT Project


  ■Assembly of XI-II


        +z panel                                        ■First, Subsystem
Panels to put up solar array on                          Boards are attached
                                             +y panel    to Mother Board.
                                                        ■Then,that module is
                                                         attached to 4 pillars.
                                                        ■Finally,Solar Cell
                                                         panels covered
             The mainstay of XI-II
                                           +x panel      CUBESAT’s
                                                         surface.
  2001 University of Tokyo CUBESAT Project


    ■Construction of subsystem board


Electronic board                        Communication board      ■Each subsystem
                                                                  board is
                                                                  attached to
Power board                                        Transceiver    Mother Board.
                                                                 ■Battery and I/F
                                             Main motherboard     connectors are
Battery box                                                       also attached to
                                                                  Mother Board.
   I/F board                                  Sub motherboard
2001 University of Tokyo CUBESAT Project


  ■Center Of mass


                  z                            ■The difference of
                                                geometric center
                                                between center of mass
                                                is 7.8mm
                                           y    (within 20mm)
                                           ■Total mass is 990g
                               Center Of Mass
                                            (within 1kg)
 x
2001 University of Tokyo CUBESAT Project


  ■Material


             USE                           PRODUCT
             Main Structure                A7075
             PCB                           Glass Epoxy
             Battery                       Li-ion Rechargeable battery
             Solar Cell                    Si-Cell
             IC                            Plastic Packaged
            W ir in g                      Teflon coated
             Bolt,Nut                      Steel
             Antenna                       Convex tape
■A7075 is the same material of P-POD which means that
 thermal expansion is equal.
2001 University of Tokyo CUBESAT Project


  ■Front view of XI-II



                                           ■Solar cells mounted on
                                            EXTERNAL
                                            MOUNTING SURFACE
                                            do NOT exceed 6.5mm
                                           ■Antennae are also
                                            mounted on EXTERNAL
                                            MOUNTING SURFACE.
2001 University of Tokyo CUBESAT Project


  ■Bottom view of XI-II



                                           ■Antennae are mounted
                                            within 6.5mm.
                                           ■2 Kill Switches are
                                            mounted on this plane.
2001 University of Tokyo CUBESAT Project


  ■Interface


         a)      Flight Pin
         b)      External Input/Output
         c)      Connector
         d)      Kill Switch
2001 University of Tokyo CUBESAT Project


  ■Installation of CUBESAT


                                           ■3 CUBESATs can
                                            be installed in a P-
                                            POD carrier.
                                           ■We can get some
                                            experimental data
                                            from I/F hole before
                                            launch.
2001 University of Tokyo CUBESAT Project


  ■Interface System


                Micro                                     V up          Subsystem
                Switch         Switch Unit   Flight Pin
                                                          V down
      Plunger                                             Antenna Deployment Order
                                                          Charge up
                               Switch Unit
                                                          Charge down
                Flight Pin 2
                           1                              GND
                           2                              Battery V
                           3                              DCDC 5V for electronics
        External Interface 4                              DCDC 5V for communication
             RJ-45         5                              DCDC 10V
                           6                              V operate 4V
                           7                              External Tx
                           8                              External Rx
2001 University of Tokyo CUBESAT Project


  ■Mother Board




                                           ■All Subsystem Boards are
                                            attached to Green
                                            connector.
2001 University of Tokyo CUBESAT Project


  ■Interface Board

                                Before-Flight Pin




                Kill Switch                         RJ-45 Connector
     ■All External I/F is allocated to Interface Board
     ■Interface Board has some module as follows.
          • Kill Switch
          • Before-Flight Pin
          • External I/O Connector
 2001 University of Tokyo CUBESAT Project


   ■External Interface

                                            No(Ext)      Name                        Function

                                              1       GND(1 )       Grou n d

                                              2       BATT(2 )      Batte ry

                                              3       E- DC(3 )
                                                                    DCDC- Con ve rte r(for Ere c tric
                                                                    su bsyste m) ou tpu t

 8,7,6,5,4,3,2,1                              4       C- DC(4 )
                                                                    DCDC- Con ve rte r(for Commu n ic ation
                                                                    su bsyste m) ou tpu t

                                              5       Tx- DC(5 )
                                                                    DCDC- Con ve rte r(for Te le me try
                                                                    Tran smitte r) ou tpu t
RJ-45 Connector                               6       EXT Tx(3 6 ) Exte rn al se rial Tx

                                              7       EXT Rx(3 7 ) Exte rn al se rial Rx


                              RJ-45 Plug      8       VTO           CMOS Image se n sor NTSC sign al



     ■ We use RJ-45 connector.
     ■ Even if CUBESAT is installed in the P-POD , we can get the
       data witch the table shows.
2001 University of Tokyo CUBESAT Project


  ■Kill Switch




                                           OFF   ON

         Kill Switch

  ■We use 2 Kill Switches in parallel for redundancy.
  ■When one of 2 switches is ON , all system can get
   power.
2001 University of Tokyo CUBESAT Project


  ■Flight Pin




                                           Switch 1

                                                      Switch 2
■Switch1:Supplying power to the system.
■Switch2:OPEN/CLOSE battery charging circuit.
2001 University of Tokyo CUBESAT Project


  ■Antennae Deployment Mechanism




                  a) Magnetic Plunger
                  b) Folding Method
2001 University of Tokyo CUBESAT Project


  ■Antenna Deployment System


 ■Antenna is deployed using Electromagnetic Plunger


                                     fa
                                               +V is impressed   fb
                               The piece is captured
                               by the magnet              Magnetic Power decreases
                                                          And the piece is released

Electromagnetic Plunger
    fa = 3.5 [N] min.
    fb = 0.8 [N]
2001 University of Tokyo CUBESAT Project


  ■Antenna Deployment System




                               Antenna Deployment Video
2001 University of Tokyo CUBESAT Project


  ■Strength Analysis


   a)      Behavior as Cantilever Beam
   b)      Ceiling panel’s vibration
   c)      Load Estimation
   d)      Countermeasure for vibration(Antennae)
2001 University of Tokyo CUBESAT Project


  ■Behavior as Cantilever Beam[1]


                                           ■If CUBESAT experiences very
                                            strong vibration, it may behave as
                                            a cantilever beam.
                                           ■ In this case , the Harmonic
                                            Frequency is around 20[kHz]
                                            (witch is enough high, comparing
                                            to the launch vehicle’s
                                            frequency)
2001 University of Tokyo CUBESAT Project


  ■Ceiling panel’s vibration[1]


                                           ■Harmonic Frequency is around
                                             1 - 2 [kHz]
                                           ■The Harmonic Frequency
                                            largely depends on the
                                            thickness of the panel.
                                           ■The thicker the panel is
                                            designed , the higher the
                                            Harmonic Frequency becomes.
2001 University of Tokyo CUBESAT Project


        ■Ceiling panel’s vibration[2]



                                             Thickness of panel                                          ■ To avoid ceiling
                                           vs Harmonic frequency
                                                                                                           panel’s vibration we
                         3.0                                                      1100
                                                                                                           have to design it as
                                                                                  1080
                         2.5                                                                               possible as thick.
 Frequency(n=m=1)[kHz]




                                                                                  1060
                                                                                                         ■ For this design ,




                                                                                         Total Mass[g]
                         2.0                                                      1040
                                                                                                           Total Mass is large
        Harmonic




                                                                                  1020
                         1.5                                                                               problem
                                                                                  1000
                         1.0                                   Harmonic           980
                                                                                                         ■ Eventually,we have
                                                               Frequency                                   to choose around
                                                               Total Mass         960
                         0.5                                                                                1.0-1.5mm
                                                                                  940
                         0.0                                                      920
                               0.0   0.5     1.0   1.5   2.0   2.5    3.0   3.5
                                             Thickness of panel[mm]
2001 University of Tokyo CUBESAT Project


      ■Load Estimation
            P-POD
                                  ■ The 3rd CubeSat experiences maximum
                                    load while 2nd stage flight
                                           • The maximum stress is
                                             0.011kgf/mm2
7.7g(max)




                                             (enough for Aluminum use)




                                           Maximum Stress
2001 University of Tokyo CUBESAT Project


  ■Countermeasure for vibration(Antennae)


                                  ■To complete any mission , fastening
                                   and deploying antennae is very
                                   important.
                                  ■It is difficult to simulate the
                                   behavior of the antenna , so we
                                   conduct some experiments to
                                   confirm the feasibility of this design.
                                  ■Fixing antennae with several points.
2001 University of Tokyo
CUBESAT Project




     Electronics Subsystem
2001 University of Tokyo CUBESAT Project


  ■Function of Electronics


          Our Works
              • Health monitoring
              • Command & data-handling
              • Resetting DCDC
              • Antenna deployment
              • Controlling area sensors

           Our Goals
              • Satellite system management
              • Capturing images with area sensors
2001 University of Tokyo CUBESAT Project


  ■Block Diagram

                                                              Rx-EtoC
                                              CW-CtoE
                                                                           Rx-TNC
                               CW-TNC                         Rx-CtoE                      Thermometer
                                         CW-EtoC                                           0 to 7

                                                                                MPX


                               Tx-CtoE         OBC               MPX_SEL0 ~2

                Tx-TNC
                               Tx-EtoC
                                                            Reset Signal              (Power Sub Sys.)

                                                            E-DCDC 5V
                                                                                      SEL Detect

               OBC Program                              C-DCDC 5V
                    &                                                                            To Comm
              ROM Read/Write                                                                     Sub Sys.
                   Pins
                                                                        Battery Voltage
                                                                        Charge Current
                                  SCL Line
                ROM0
                ROM0                                           Battery Charger IC Reset Signal
                 ROM0
                 ROM0
                  ROM0
                  ROM0
                   ROM0
                   ROM0           SDA Line
                                                                              (Structure Mother Board)

                                                                                   Solar Cell Current
                                                           MPX                     1 to 6
2001 University of Tokyo CUBESAT Project


  ■Command & Data-Handling



CRNT /ROND /SOLA
                                                             OBC
TEMP /VOLT

                                 Fixed length = 17 bytes
                                                                 Uplink Command
                                                                 ANTD /CRNT /DCDC
                                                                 MTQC /POWR/ROMD
     Tx-TNC                           CW-TNC                     SOLA /TEMP /VOLT




                                                           Ground Station in UT
2001 University of Tokyo CUBESAT Project


  ■Command & Data-Handling(2)




                ●Antenna deployment
                ●Requesting current data
                 (Total , Solar Array , C-DCDC , E-DCDC)
                ●Resetting C-DCDC
                ●Resetting charging circuit
                ●Requesting EEPROM data
                ●Requesting temperature data
                  (Battery , Solar Array , FM-Transmit)
                ●Requesting voltage data
                  (Battery , Solar Array)
2001 University of Tokyo CUBESAT Project


  ■Command & Data-Handling(3)




     ●Current ----- 9 bytes
            (Total , Solar Array , C-DCDC , E-DCDC)
     ●EEPROM Data ----- Undecided
     ●Current & Temperature of Solar Array ----- 12 bytes
     ●Temperature ----- 8 bytes
            (Battery , Solar Array , FM-Transmit)
     ●Voltage ----- 2bytes
            (Battery , Solar Array)
2001 University of Tokyo CUBESAT Project


  ■Command & Data-Handling(4)




                     Time                    3 bytes

           Status                            1 bytes

           Picture                           1 bytes

               Voltage                       2 bytes

                                           Current     9 bytes

    Additional Data                          1 bytes
2001 University of Tokyo CUBESAT Project


  ■Components of Electronics

                For Thermometer
                                                            JumperPin For ROM
                                       ROM READ/WRITE Pin




                              For Camera
                                              ROM Module       XI-II model
2001 University of Tokyo CUBESAT Project


  ■Components of Electronics-(2)

                              OPAmp Module                Program Pin




                                             Thermometer Module   XI-II model
2001 University of Tokyo CUBESAT Project


  ■Components of Electronics-(3)


           PIC 16F877
               • Clock            :4MHz
               • Memory           :8kword
               • RAM               :368bytes
               • EEPROM            :256bytes
               • Operative Voltage:2.0~5.5V

           ROM (24LC256)
               • I2C serial EEPROM
               • Memory                :256Kbit(32Kbyte)
               • Max erase/write cycles:100,000
               • Max write-cycle time :5ms
               • Max clock frequency :400kHz
2001 University of Tokyo CUBESAT Project


  ■Thermal Monitoring


Thermal Sensor ( LM335Z )
                                                                       Thermal Sensor Calibration
・Power consumption:5mW                                      40
                                                                                    y = 99.218x - 270.29
・Measuring range :-40~100℃                                  35




                                           Temperature[]
                                                            30




                                                       
・Characteristic   :10mV/℃                                   25
                                                            20
・Precision        :±1℃                                      15
                                                            10                                        data
                                                                                                    @
                                                                                                      @
                                                             5                                      linearized
                                                                                                    \
                                                             0
                                                            -5
                                                                 2.7       2.8         2.9         3              3.1
                                                                                   Voltage[V]




     Monitoring
      ・Temperature of Battery, Solar Panel(6) and Transceiver.
      ・AD converting a data & sending it to comm subsystem.
2001 University of Tokyo CUBESAT Project


  ■Function of Reset-(1)

          P.U. = Pull Up
          P.D. = Pull Down
                                                    Pch FET          Tx-DC       Tx-TNC
                                                        e     P.U.

                        P.D.
                              c     d    P.U.                                a       b
                              Pch FET
                                                    A           E-DC             OBC
                              Nch FET

                                                        SEL Detect
                                                                                     e


             V in
                                                        SEL Detect                CW-GEN

                              Pch FET
                                                A              C-DC              Rx-TNC
                              Nch FET
                       P.D.   a     b   P.U.                                     c        d
2001 University of Tokyo CUBESAT Project


  ■Function of Reset-(2)


                                   For SEL tolerance, reset function is needed.
                                   Reset system requires high reliability so as
                   CPU             not to shut off continuously even in CPU
                                   malfunction case.



              If a=1&b=0                   Two wire AND reset system using FET

                                                        Switching Circuit

                                                      • PchMOSFET
Vin                                        DCDC       • NOT gate
2001 University of Tokyo
CUBESAT Project




     Communication Subsystem
2001 University of Tokyo CUBESAT Project


  ■Communication System Diagram

                                                OBC
           Telemetry data              Beacon data     Sensors              Up-link command
                                                     AD Convert
             Tx TNC          Negotiation                                       Rx TNC
            PIC16C622                       Morse encoder                     PIC16C711
          AX25 Coded data                    PIC16C716
                                                                        AX25 Coded command
          with Parity
PLL                                                               PLL
             Modulator                     Morse Coded data       Control   Demodulator
Control
                                             PTT Control                      MX614
              MX614
                                      PLL
       FSK modulated data             Control                         FSK modulated command

           Nishi RF Lab.                    Nishi RF Lab.                    Nishi RF Lab.
           Custom made                      Custom made                      Custom made
          FM transmitter                   CW transmitter                     FM receiver
                               switching
 Half wave length                                          Half wave length
 dipole antenna              Antenna SW                    monopole antenna
2001 University of Tokyo
CUBESAT Project




   Telemetry Transmission System
2001 University of Tokyo CUBESAT Project


  ■Tx TNC (AX.25 encoder)

     ■Tx TNC:Micro controller PIC16C622
        -program memory(EPROM) : 2 kbyte
        -data memory(RAM) : 128 byte
        -clock : 4 MHz
        -I/O port : 13 (4 AD Converters)
        -power consumption : 2.0 mA @ 5V
     ■Tx TNC receives telemetry data from OBC
     ■Puts Parity byte for error detection
     ■Encodes the telemetry data with AX.25 protocol                      PIC16C622
     ■Sends encoded data to FSK modulator
     AX.25 Protocol
     ■This protocol is mainly used for data transmission by HAM
     ■Every Amateur Radio Station all around the world can
     decode our telemetry data!!!
   Flag Destination Source Control PID         parity   data   parity   data   FCS Flag
                             AX.25 frame structure(with Parity)
2001 University of Tokyo CUBESAT Project


  ■Tx TNC Program

                                  Start & Initialization


                                                           No
                                     data from OBC ?

                                             Yes
                                Receive data from OBC


                             Packetize into AX25 format


                           Send packet to FSK modulator
2001 University of Tokyo CUBESAT Project


  ■FM Transmitter


      ■FM Transmitter is used to transmit telemetry data
      ■Nishi RF Laboratory custom made transmitter
        -frequency:          437.490MHz
        -band width:         20kHz
        -RF output power: 1W
        -input power:        under 6W
        -operative temp.: -30℃~+60℃
                                                                 FM transmitter
        -volume:             90×60×10cm
                             (including CW transmitter)




                                 FM transmitter System Diagram
2001 University of Tokyo
CUBESAT Project




     Beacon Transmission System
2001 University of Tokyo CUBESAT Project


  ■CW Generator (Morse encoder)

     ■Morse encoder:Micro controller PIC16C716
        -program memory(EPROM) : 2 kbyte
        -data memory(RAM) : 128 byte
        -clock : 4 MHz
        -4 AD Converters (8bit)
        -power consumption : 2.0 mA @ 5V
     ■CW generator receives beacon data from OBC
     ■Monitors sensor data independently from OBC
      (Countermeasure of OBC‟s hang up)                                                          PIC16C716
     ■Generates Morse code
     ■Controls the KEY of CW transmitter
     ■Data rate : human decodable speed
     Beacon data format
   "UT1"           "www.space.t.u-tokyo.ac.jp"         "UT4"          total I          tmp. battery           tmp. Panel
                                                                  tmp.       tmp.       tmp.       tmp.       tmp.       tmp.
   "UT2"      time1          time2           time3     "UT5"    battery1   battery2   battery3   battery4   battery5   battery6
                                                               tmp. Panel tmp. Panel tmp. Panel tmp. Panel tmp. Panel tmp. Panel
   "UT3"      Status     Camera status     battery V   "UT6"        1          2          3          4          5          6
2001 University of Tokyo CUBESAT Project


  ■CW Generator Program

                                 Start & Initialization

                                            OBC ready      No
                                           to send data?                      Yes
             Data Sampling
                                                    Yes         Counter < 10sec
                                Receive data from OBC
                                                                         No
                              Data sensing (AD Convert)

                           UT1 www.space.t.u-tokyo.ac.jp
                                UT2 AA BB CC
                                 UT3 DD EE FF                   Data Sending
                                 UT4 GG HH II
                                UT5 JK LM NO
                                 UT6 PQ RS TU
2001 University of Tokyo
CUBESAT Project




      Command Receiving System
2001 University of Tokyo CUBESAT Project


  ■Rx TNC (AX.25 decoder)


     ■Rx TNC:Micro controller PIC16C711
        -program memory(EPROM) : 1 kbyte
        -data memory(RAM) : 64 byte
        -clock : 4 MHz
        -4 AD Converters (8bit)
        -power consumption : 2.0 mA @ 5V
     ■Rx TNC receives AX.25 encoded command
      from FSK demodulator                            PIC16C711
     ■Decodes it and sends command to OBC

     OBC Reset System
     ■If the command is “Reset Command”, resets OBC
     ■Monitors OBC‟s current and resets OBC in case of SEL
      (Countermeasure of OBC‟s SEL)
2001 University of Tokyo CUBESAT Project


  ■Rx TNC Program

                          Main Routine
                      Start & Initialization
                                                                       Interruption Routine
                   Receive Uplink command                              A/D convert „Total I‟

                       set „Receiving‟ flag
                                                                       „Total I‟ > Threshold ?
                  Yes Command = “rset”            No
                                                                                    Yes
                           or flag_rst = 1 ?                                flag_rst = 1
                                                                 No
           Reset OBC                           OBC ready to receive?

                                                      Yes                  Wait 10 [ms]
           flag_rst = 0                Send serial data to OBC



                      clear „Receiving‟ flag
2001 University of Tokyo CUBESAT Project


  ■FM Receiver



     ■FM Receiver is used to receive up-link command
     ■Nishi RF Laboratory custom made receiver

     -frequency:                           145.835MHz
     -input power:                         under 100mW
     -receive sensitivity:                 under -16dBμ
     -receive output:                      16dBV typ.
     -operative temp.:                     -30℃~+60℃
                                                          FM receiver
     -volume:                              50×60×10cm
2001 University of Tokyo CUBESAT Project


  ■Antenna Configuration




               Antenna for Transmitters
               430MHz band Half wavelength dipole antenna




                            Antenna for Receiver
                            144MHz Half wavelength monopole antenna
2001 University of Tokyo CUBESAT Project


  ■Antenna Pattern (Transmitter)


                                        Antenna Absolute Gain
                             Transmitters' Half wavelength dipole Antenna
                                                 (dBm)
                                              5.00                           The gain which
                                              0.00
                                                                             we can decode
                                             -5.00
                                                                             the data in our
                                            -10.00
                                            -15.00
                                                                             ground station
                                            -20.00
                                            -25.00




                                                                        Gt
                                                                        Gt,req
2001 University of Tokyo CUBESAT Project


  ■Antenna Pattern (Receiver)


                                             Antenna Gain
                             Receiver's Half wavelength monopole antenna
                                                (dBm)

                                            -20.00
                                            -25.00
                                            -30.00
                                            -35.00
                                            -40.00
                                            -45.00
                                            -50.00
                                            -55.00
    2001 University of Tokyo CUBESAT Project


      ■Link Budget (Telemetry Tx)

                                               Link Budget
                                               Telemetry (TDMA)
                                                   Symbol    UnitTelemetry        Remark
              Frequency                           f         MHz    437.400
              Transmit                            P         W        0.600       Parameter
              Transmit                            P         dBW     -2.218
              Transmitter Line Loss               Ll        dB                            `
                                                                    -3.000 Usually -1dB-3dB
                                                l 
                                                  Æ
              Transmit Antenna Half-Power Beamwidth t       deg        e
                                                                   110.000      Ideal dip
              Peak Transmit Antenna Gain        l Gpt       dB       2.148
                                                                       e        Ideal dip
                                                                                                   CUBESAT
              Transmit Antenna Pointing Offset    et        deg     90.000     Uncontrolled        Comm. System
              Transmit Antenna Pointing Loss      Lpt       dB      -8.033
              Transmit Antenna Gain               Gt        dB      -5.885
              Equiv. Isotropic Radiated Power     EIRP      dBW    -11.103
              Propagation Path Length             S         km    1439.940    50kbyte/1pass
              Space Loss                          Ls        dB    -148.434
              Propagation & Polarization Loss     La        dB      -0.470 Polarization (-0.3dB)
              Peak Receive Antenna Gain           Grp       dB      12.500     GS 435HS20
                                                  Æ
                                                  
              Receive Antenna Half-Power Beamwidth r        deg     29.000     GS 435HS20          UT‟s
              Receive Antenna Pointing Error      er        deg     15.000     Assumption
              Receive Antenna Pointing Loss       Lpr       dB      -3.210                         Ground Station
              Receive Antenna Gain                Gr        dB       9.290
              System Noise Temperature            Ts        dBK     25.700
              Data Rate                           R         bps   1200.000        MX614
0         N   Eb                      0           Eb        dB      21.390
              Bit                             E
                                              r   BER                0.000
              Required Eb/N0                      Req Eb/N0dB-Hz    13.000    FSK, BER=10-5
              Implementation Loss                          dB       -5.000
              Margine                                      dB        3.390
    2001 University of Tokyo CUBESAT Project


      ■Link Budget (Command Rx)

                                               Link Budget
                                               Uplink Command
                                                 Symbol    Unit    Uplink         Remark
             Frequency                           f        MHz      145.835
             Transmit                            P        W         20.000      Parameter
             Transmit                            P        dBW       13.010
             Transmitter Line Loss               LlB      dB                             `
                                                                    -3.000 Usually -1dB-3
             Transmit Antenna Half-Power Beamwidth t
                                                 Æ
                                                         deg       33.000     GS 144HS12          UT‟s
             Peak Transmit Antenna Gain          Gpt      dB        10.000     GS 144HS12          Ground Station
                                      e
             Transmit Antenna Pointing O f       et       degt      15.000 f   Assumption
             Transmit Antenna Pointing Loss      Lpt      dB        -2.479
             Transmit Antenna Gain               Gt       dB         7.521
             Equiv. Isotropic Radiated Power     EIRP     dBW       17.531
             Propagation Path Length             S        km      1439.940
             Space Loss                          Ls       dB      -138.894
             Propagation & Polarization Loss     La       dB        -0.470 Polarization (-0.3dB)
             Peak Receive A                           e
                                                 Grp nt   dB        -2.521       Monopole
                                                 
                                                 Æ
             Receive Antenna Half-Power Beamwidth r       deg      100.000       Monopole          CUBESAT
             Receive Antenna Pointing Error      er       deg       90.000     Uncontrolled
             Receive Antenna Pointing Loss       Lpr      dB        -9.720
                                                                                                   Comm. System
             Receive Antenna Gain                Gr       dB       -12.241
             System Noise Temperature            Ts       dBK       31.100
             Data Rate                           R        bps     1200.000
0        N   Eb                      0           Eb       dB        32.634
             Bit                             E
                                             r   BER                 0.000
             Required Eb/N0                      Req Eb/N0dB-Hz     13.000    FSK, BER=10-5
             Implemention Loss                            dB        -5.000
             Margine                                      dB        14.634
2001 University of Tokyo
CUBESAT Project




     Power Subsystem
2001 University of Tokyo CUBESAT Project


  ■Power Subsystem


             Charge
             Circuit
                                    A                    A
A
A
A                                           TNC                OBC               OBC


           Batteries         Switching            Switching           DCDC
                             Regulator            Regulator          Converter




                                           Electronics       Communicati     Tx
                                           Subsystem         on Subsytem
2001 University of Tokyo CUBESAT Project


  ■Power Subsystem(CONT’D)


■Supply a continuous source of electrical power
 to loads.
      • Power source is solar panels.
      • Batteries are used for storage
      • Regulated DC power and unregulated power is
        supplied for loads.
      • Power consumption is monitored for SEL.
2001 University of Tokyo CUBESAT Project


  ■Power Regulation & Control


■Bus voltage: main 5[V]
■Regulated to 5V using
 switching regulators and
 DCDC converter
■Elect. subsystem power line
 & Comm. subsystem power
 lines are independent so that
 they monitor each other and
 shutdown in case of SEL
2001 University of Tokyo CUBESAT Project


  ■Source


■Power is supplied by body mounted solar cells.
■Cells are arranged on all 6 CubeSat surfaces.
■Average power 1228 [mW] (typ @ 80℃)
2001 University of Tokyo CUBESAT Project


  ■Solar Panel


                                                    Bass bar


                                                      ■Cell type : Si Crystal (SHARP)
                                                      ■Efficiency : 16%
                                                      ■10 cells in series / panel
                                                      ■Cell size:
                                                         +X      :28.25x13.8mm
                                                         -X,+Y,-Y:47.75x13.8mm
                                                         +Z,-Z :47.75x15.8mm




                          Photo:3 cells in series
2001 University of Tokyo CUBESAT Project


  ■Solar Array Layout (+X panel)




                                                 +X panel:

                                           4.5V x 172mA = 774mW
                                                (typ. @ 25 ℃)
                                           4.5V x 162mA = 727mW
                                                (typ. @ 80 ℃)
2001 University of Tokyo CUBESAT Project


  ■Solar Array Layout (-X,+Y,-Y panel)




                                              -X,+Y,-Y panels:

                                           4.5V x 297mA = 1336mW
                                                (typ. @ 25 ℃)
                                           4.5V x 279mA = 1256mW
                                                (typ. @ 80 ℃)
2001 University of Tokyo CUBESAT Project


  ■Solar Array Layout (+Z,-Z panel)




                                                +Z,-Z panels:

                                           4.5V x 340mA = 1530mW
                                                (typ. @ 25 ℃)
                                           4.5V x 319mA = 1438mW
                                                (typ. @ 80 ℃)
2001 University of Tokyo CUBESAT Project


  ■Energy Storage


■Batteries will be used during
 eclipse and downlink
■Liion secondary batteries are
 selected.
■8 batteries are set in parallel.
■DOD is 3%
■Batteries only lifetime is 38
 hrs
2001 University of Tokyo CUBESAT Project


  ■Liion battery




      Cathode Material                      Lithium Manganate
      Anode Material                        Carbon
      Operating Voltage                     3.8[V]
      Discharge Capacity                    780 [mAhr]

                                Single Cell Spec.
2001 University of Tokyo CUBESAT Project


  ■Battery Charger


■3 candidates for Battery Charge Circuit
    MAX1679                           MM1333                  MM1485



                                                             •Small power dissipation
•Small package (8 pins),            •Small package (8 pins), •Const. Voltage &
small power dissipation             small power dissipation Current Charge Mode
•Voltage&Temperature                •Const. Voltage &        •Pre-charge
protection                          Current Charge Mode      Temperature protection
•Pre-charge, Timeout
                                    •No pre-charge func or   •Large package (16 pins)
•Need constant reset                temperature protection   and may be difficult to
before IC‟s timeout                                          assembly
2001 University of Tokyo CUBESAT Project


  ■Energy Consumption


       Components Power[mW]                Frequency in use

        OBC                    20          All times
        sensors                20          All times
        Tx TNC                 20          During downlink
        Tx                     6000        During downlink
        CW                     300/125     All times (ON / OFF)
        CW TNC                 20          All times
        Rx                     125         All times
        Rx TNC                 20          All times
        Camera                 150         Sometimes
        Magnetic Plg.          800         Antennae deployment
2001 University of Tokyo CUBESAT Project


  ■Power Balance


■Points
      • Beacon can be sent by solar panels direct drive
      • Source and consumption must be balanced
■Solar cell average output 1228[mW] >
 Consumption at beacon use 900[mW]
                                           OK

■Maximum average supply power: 669[mW] >
 Average consumption 616[mW]
                                            OK
2001 University of Tokyo CUBESAT Project


  ■Attitude Control


■Objectives
      • To make CubeSat tumble in order to smooth thermal
        input
      • Point antennae to the ground station


■Methods
      • Use a permanent magnet and a libration damper
2001 University of Tokyo CUBESAT Project


  ■Control Mechanism


■Torque will be
 generated to align earth
 magnetic direction and                               Dipole
 CubeSat’s dipole
                                                               Ground
                                                      Moment   Station
                                           Magnetic
 moment.                                   Field


■ Libration is damped
 by energy dissipater.

                                                        Antennae
2001 University of Tokyo CUBESAT Project


  ■Torquer Sizing



  Disturbance                 Torque[Nm]
  AirDrag                      2.26E-10                 Required Torque
  Solar Pressure               1.38E-9                   1.0E-6 [Nm]
  Gravity Gradient              1.25E-8

To follow the change                                       At 800km
  of magnetic field                    1.0E-6              magnetic field


                                           Required Magnetic Dipole Moment
                                                    0.046 [Am^2]
2001 University of Tokyo CUBESAT Project


  ■Permanent Magnet


Material                                   Alnico-5
Magnetic Dipole Moment                     0.05   [Am^2]
Size                                       φ4*25 [mm]
Weight                                     2      [g]
Residual Magnetic Flux Density 1300               [mT]
2001 University of Tokyo CUBESAT Project


  ■Libration Damper


■Libration damper dissipates energy to stable
 attitude change.
      • Dissipation caused by hysteresis loss and eddy
        current loss
      • High permeability iron is used for the damper
      • 3days are expected (8 days for worst case) to damp
        oscillation
2001 University of Tokyo
CUBESAT Project




     Environment Subsystem
2001 University of Tokyo CUBESAT Project


  ■Environmental Tests (outline)



         Tried and Tested                         Future Works

■Heavy ion testing                         ■ Thermostat
(PIC16F877 F84 C622 C774)                   EM-Plunger , Li -ion battery ,
                                            C-MOS camera,Solar Panels
■Heavy ion testing
(PIC16F877 C774 C622)                      ■ SEL testing
                                             DCDCs,OP-AMPs,Tx,Rx etc
■Li -ion battery testing
        (in a vacuum)                      ■ Vibration testing
                                             Solar Panels , EM-Plunger,EM
■C-MOS Camera testing
     (in a vacuum)                         ■ Thermal Vacuum Chamber
                                             XI-II α , EM , FM1 , FM2
2001 University of Tokyo CUBESAT Project


  ■Analysis (outline)



       ■ thermal analysis
        We construct a model of heat transfer by means of the node
       point method using C-programming. We will complete building
       50nodes model and fixing the value of every parameter from XI-
       IIα testing.

       ■ SEE analysis
       We calculated SEE rate using the CRÈME software and
       provided reset functions to XI-IIα.
       ( http://crsp3.nrl.navy.mil/creme96/ )
2001 University of Tokyo CUBESAT Project


  ■Tried and Tested



      ■Heavy ion testing ( at NASDA)
      2000.09.12 source ; Calfornium (Cf252)


   Device      Number Number Irradiation Fluence SEE Cross
               of SEU of SEL time[sec]   [/cm^2]  Section[cm^2/bit]
   F877        102         0               2502   332353   7.49272E-08
   F84         101         3               1040   137956   3.57477E-07
   C622        101         0               2599   344759   1.43046E-07
   C774        101         0               2563   205669   1.19892E-07


                           (for quick look)
2001 University of Tokyo CUBESAT Project


  ■Tried and Tested


      ■Heavy ion testing ( at JAERI Takasaki)
      2000.10.09 source ; 20Ne4+, 40Ar8+, 84Kr17+
            Device          SEU(Ne)    SEU(Ar)    SEU(Kr)
                            LET=6.01    LET=15.1   LET=38.3
            F877            1.6468E-07 2.1559E-08   ----
            C622            8.4045E-10 9.6120E-09      -----
            C774            1.8376E-08 2.4405E-08 4.1931E-08


      ■Using CREME96 Results,We decided to use PIC16F877.
              Device           SEUs/device/day
              F877             2.3514E-05
              C622             1.26733E-06
              C774             2.550029E-07
                           (height 600km,incrination=60°)
                                                    cf. LET[MeV/(mg/cm^2)],SEU[cm^2/bit]
2001 University of Tokyo CUBESAT Project


  ■Tried and Tested



      ■ Vacuum chamber testing
         - Li ion battery test (2001.01.21 - 23 at UT-Arakawa Lab.)
           No deterioration observed in 10^-5 Torr evacuated
         chamber.
2001 University of Tokyo CUBESAT Project


  ■Analysis


        Quick look

    Height=600km                                                                  Temperature of 6-nodes
    incrination =60°
    6 nodes (CUBE planes)                                          10




                                           Temperature[degree C]
                                                                    8
    mass density = Al density                                       6                                              T1
    specific heat=920*9[J kg^-1K-1]                                 4                                              T2
    conductivity=240[W m^-1K^-1]                                    2                                              T3
                                                                    0                                              T4
    ε=0.825                                                        -2 0   20000    40000    60000   80000 100000   T5
    α=0.805                                                        -4                                              T6
                                                                   -6
                                                                   -8
                                                                                      time[sec]
2001 University of Tokyo CUBESAT Project


  ■Future Works


      We have a plan to execute EM-Plunger and XI-II α test with
      thermal vacuum chamber. (2001.04.10. - at ISAS Ohnishi Lab.)
                         ~
                    Wires3
           GND                                   CW
                                                 CW

            Vin(5V)                             Rx-TNC
                                                Rx-TNC                            ¨
                                                                               BNCONS



                        Battery                 Tx-TNC
                                                Tx-TNC
            GND
                                                 OBC
                                                 OBC
                Q
         flanged
         (Dsub50)                     Temperature sensor     Serial
                                                                                      Q
                                                                               flanged
                                                                               (Dsub50)

                                                             Thermocouple sensor


                                                             9-wires
                                    A/D                               P
                                                               flanged
                                Q
                         flanged
                         (Dsub50)         PIC      5V
                 SW                                        Mpx.B
2001 University of Tokyo CUBESAT Project


  ■Future Works


                                            Battery ON
                                                                 no
                                   yes


            OBC status(Serial)
                                               E5V        C5V         10V       Vop
          with checking telemetry

                yes

        Communication
         system status
      CW,Rx-TNC,Tx-TNC                                    Executing partial test.

                yes              no


                                             Running
       Long time       Running
                                           Thermometer
        running        OBC only
                                           for checking
2001 University of Tokyo CUBESAT Project


  ■Future Works


               CW                 Rx       Tx



                                   ...           Rx and Tx




                                           ...
                                                 communicate 300
                                                 times per 5 minutes
                                                 and suspend for
                                                 25 minutes .

                                                 CW speak at all times.
                                  ...




                                           ...
2001 University of Tokyo CUBESAT Project


  ■Outgas Examination

         We choose following products from out-gas point of view.


                USE                        PRODUCT
                Wiring                     Fluorocarbon wires (H itachiC able Ltd.
                                                                                 )
                RTV                        LTV rubber KE1204(AL or BL)
                Rubber                     Si rubber KE9610/C-8B
                Bonding Agent              SYLGARD184 ; FSXA-2869

                    USE                       TML      CVCM        WVR
                    Wiring                    <0.1     <0.01
                    RTV                       0.597    0.117       0.007
                    Rubber                    0.846    0.052       0.736
                    Bonding Agent             1.740    0.660       0.040

                             ※However, they are not fixed yet.
2001 University of Tokyo CUBESAT Project


  ■Work Room

                            Work Room Environment

           We will construct isolated work space to manufacture EM,FM1,FM2.
           (aiming at 1000-level clean room)
                  ※Air conditioner
                  HEPA Unit(SS-MAC) YAMATO science co.
2001 University of Tokyo
CUBESAT Project




     Ground Segment
2001 University of Tokyo CUBESAT Project


          ■When can we contact?(1)

                                      Pass time for 1 week
                 1000
                  900
                  800
Pass time[sec]




                  700
                  600
                  500
                  400
                  300
                  200
                  100
                    0



                                       Simulation passage time[hr]
2001 University of Tokyo CUBESAT Project


  ■When can we contact?(2)


                                                                           Åå } p
                                                                           

                                           90
           Maximum elevation angle (deg)




                                           80
                                           70
                                           60
                                           50
                                           40
                                           30
                                           20
                                           10
                                            0
                                                1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49
                                                                           Pass #
2001 University of Tokyo CUBESAT Project


  ■When can we contact?(3)



      •There are 49 passes.
       which means we can contact with our CubeSat
       6 or 7 times per day.
      •In those passes, 22 passes have an elevation over 20[deg].
      •The longest pass time is about 900[sec].
      •We have 1 or 2 chances to contact for 900[sec] everyday.
2001 University of Tokyo CUBESAT Project


  ■Necessary Time for Communication




 CW Beacon Downlink
 •CW Beacon is consist of 73 words.
 •If duty ratio is 0.3, it takes about 240[sec] to send 73 words.
  (60 words per minute )


 FM Packet Telemetory downlink
 •Packet length is about 80 bytes.
 •Baud rate is 1200 [bps] , so it takes 0.54[sec] to receive a packet.
2001 University of Tokyo CUBESAT Project


  ■Operation Plan


                                                  FM Packet 1200bps



                                           Uplink Command
CW Beacon


                If we can receive the CW Beacon,
                we send Uplink Command once or twice a day.
2001 University of Tokyo CUBESAT Project


  ■How to handle Downlink Data



              We expect it may be difficult for us to
              receive and decode downlink data perfectly,
              so we prepare backup system to get something of
              traces of downlink data.




      •Recording CW Beacon & Telemetry Packet to Mini Disk.
      •Original TNC skipping CRC (check sum).
2001 University of Tokyo CUBESAT Project


  ■Ground Station Equipment(1)




  144MHz/430MHz Antenna                    Transceiver, TNC, etc.
2001 University of Tokyo CUBESAT Project


  ■Ground Station Equipment(2)


    •144MHz/430MHz cross Yagi antenna [WHS32N, MASPRO]
    •430MHz cross Yagi antenna (TBD)

    •Antenna rotator & controller for azimuth
     [750FX, EMOTATOR]
    •Antenna rotator & controller for elevation
     [EV800, EMOTATOR]

    •VHF/UHF multi band all mode transceiver [IC-970J, ICOM]
    •VHF/UHF multi band all mode transceiver
     (Equipped for 9600bps packets) [IC-910D, ICOM]
2001 University of Tokyo CUBESAT Project


  ■Ground Station Equipment(3)


•TNC [TNC505,TASCO]
•TNC (With function to co-decode CW signal) [TNC555, TASCO]
•TNC (Skipping CRC)
 [handmade]

•Signal converter [I/F between PC and rotators]
•Level converter [CT17, ICOM (I/F between PC and Tranceivers]

•PC (OS:Window98)

•MDLP mode MD recorder (TBD)
 [MDS-S50, SONY]×2
2001 University of Tokyo CUBESAT Project


  ■Ground Station Configuration

                                                  Command
                                                                 TNC-505
                       144MHz uplink

                                                    Telemetory
                                        IC-970J                   TNC
           430MHz Telemetory downlink


                                                            MD recorder
                                                                                     PC
                                                            MD recorder          (Windows98)


430MHz CW downlink
                          IC-910D                                TNC-555
                                                    CW beacon


     EV-800

                           Signal
     750FX                                   CT17
                          converter                                        Frequency, Azimuth, Elevation
http://www.space.t.u-tokyo.ac.jp/cubesat
2001 University of Tokyo CUBESAT Project


  ■Message Mission


■Message from all over the world will be
 microfilmed and packed in CubeSat
■Themes are
      • Dreams for space
      • CubeSat mission proposal etc.
■Messages are accepted by postal cards.
■Details are uploaded to WebPages
2001 University of Tokyo CUBESAT Project


  ■Program Timeline


  3          4         5         6         7   8      9           10       11




                                                 FM Shipment (8/15)             Launch
           TCDR                       FM Deadline
      CDR                      Mass Model Shipment
      (3/19)          Long Range Comm. Experiment
      *postponed
                   EM Deadline



                                                          red char. : contract matter
2001 University of Tokyo CUBESAT Project


  ■Concerns (Electronics)


 ■We made a reset system for countermeasure against SEL,
  but still do not decide the SEL threshold current. How do
  we decide it and how much should we have a margin for it?

 ■For countermeasure against SEU, we will set only Watch
  Dog Timer. Is it enough? How can we detect SEU?
2001 University of Tokyo CUBESAT Project


  ■Concerns (Communication)


 ■When and by whom will our CubeSat‟s call sign be
  distributed?
 ■Only one frequency band is allocated for up-link command.
  If some developers uses the same protocol (ex. AX.25), how
  each Cubesat distinguishes its GS‟s command from other
  GS‟s command? Are there any regulations?
 ■Does our Cubesat require an impedance matching circuit
  between transceiver and antenna?
 ■Is it necessary to conduct a radiation environment test to
  FSK modulator-demodulator?
 ■Must our Cubesat equip space rated coaxial cable? Now, we
  are planning to use normal one (1.5D2V).
2001 University of Tokyo CUBESAT Project


  ■Concerns (Environment)


 ■the thermal vacuum testing regulation for Flight Model

 ■TML,CVCM limits

 ■the Vibration testing on Flight Model.
2001 University of Tokyo CUBESAT Project


  ■Concerns (Power)


■Is the use of a permanent magnet permitted?

■ When can we charge batteries last?
2001 University of Tokyo CUBESAT Project


  ■Concerns (Ground)


■How can we get the orbital information of our CubeSat?

				
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