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Sensor System Engineering Plan by pmv64896

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									UNIVERSITY OF ILLINOIS AT URBANA- CHAMPAIGN




               PROJECT PROPOSAL
                   ECE-345


    TEST NANOSAT UI PHOTOMETER TEAM




              PROF. GARY SWENSON

       RODRIGO MARTINEZ DUARTE drmartnz
          AHMAD MOATESIM moatesim
          MOBEEN CHAUDHRY mobeen



          CHAMPAIGN IL, SEPTEMBER 17, 2003
I. INTRODUCTION

     We’ve chosen this project to get a more real approach to work life after we finish our
studies. This project is carried out in a way that is similar to the way projects are made in
companies. It has limited resources, clear objectives and a lot of people involved from
different fields of engineering which gives us the sense of belonging to something really
big. We also get the chance to work with parts and devices that we wouldn’t be able to
work with in a regular project. That’s what it excite us, we were given the chance to work
with a lot of interesting people in a challenging project that could turn out to be really
great . So we’ll do our best to make it real.

      Our objective is to build and test the photometer module for the satellite including all
its support circuitry. The purpose of this module is to monitor the intensity of the O2
Hertzberg bands in the 260-290 nm wavelength range to improve our understanding of
the airglow layers in the atmosphere. The main goal is to be able to count the photons
hitting the Photomultiplier tubes (PMT’s), process this count and communicate with the
satellite’s main computer (Taylor’s computer).

     The main beneficiaries of this project would be students of Illinois and faculty. This
satellite is built to study upper atmosphere; its air glow at different ionosphere layers.
Students from different discipline (Aerospace and ECE) are working on this project and
they will gain hand on knowledge by this project. Prof. Gary Swenson and Prof.
Kamalabadi of ECE department, who has specialties in Aeronomy and remote sensing,
respectively, would be able to gather real data for further conclusion.

     The advantages of this module will be:

           Provide an accurate reading of the photons of desired wavelength since we
            subtract the background noise that could be present in space.
           Filtering of desired wavelength.
           Protect the PMT’s for burn out during high-light exposure times.
           Modular design with just one line as an output.
II. DESIGN


BLOCK DIAGRAM:


  TO TAYLOR’S COMPUTER                                                       HERTZBERG
   (RS-485)                         AMPLIFIER                               PHOTOMETER
                                      AND
                                  DISCRIMINATOR
                                                                            BACKGROUND
                                                                            PHOTOMETER


                                  COUNTER
       Z- WORLD                                                          SHUTDOWN
       PROCESSOR                                                          CIRCUIT


                                              TEMPERATURE
                                                SENSORS


   A brief description of each device is shown below:

      SHUTDOWN CIRCUITRY:
          This module will serve to protect the photometers from burning off during high-
          light intensity periods. It basically consists in a photodiode which voltage is
          compared against a reference voltage made with a voltage divider. The output
          will serve as the control signal to a transistor functioning as a switch to either
          give or cut the power to the photometers.

    TEMPERATURE SENSORS:
        Sensors will be located at different parts of the system to serve as noise tracer.
        When we get certain temperature the amplifier will cause too much noise. Also
        they will serve as a reference to interpret information for the photometers
        readings.

    AMPLIFIER AND DISCRIMINATOR:
       The amplifier module will allow us to get a square pulse with the appropriate
       voltage levels for each photon hitting the photometers. We need this voltage
       levels in order to be interfaced with the counter, since the output of the PMT’s
       are in the order of microvolts. The amplifier will also require a filter to
       discriminate those square pulses corresponding to electrons hitting the PMT’s
       due to dark current.
     COUNTER :
          This module will count the square pulses corresponding to each photon gathered
          by the two photometers and the imager. It will work as a multiplexer to the
          processor giving him the number of photons received by each device in
          response to the control signal sent by the processor.

   PHOTOMETERS:
       This devices will be composed of a lens, a filter and a photomultiplier tube.
       The lens is for focusing the light coming in and it will determine the field of
       view of the design. The filter will serve us to gather only photons of the
       desired wavelength, in the case of the Hertzberg photometer, and to obtain the
       background noise in the case of the Background Photometer. Then we will
       subtract the two and get only the information desired. The photomultiplier tube
       is the device that gathers the photons and amplifies it by chemical means,
       giving out a square pulse for each photon gathered. Due to the voltage level of
       this square pulse it is necessary to amplify it before we can interface with the
       counter.

   Z-WORLD PROCESSOR :
       The processor will be used to process the information gathered from the three
       photometers. It also will be used to communicate with the CCD Camera
       processor and Taylor’s computer. Information to the processor will be feed
       through a counter. There has to be some data compression done, as word size of
       the counter is 6 bits and photometer yields 8 bits information.


PERFORMANCE REQUIREMENTS:

         Amplifier’s Gain ~ 10^6
         Bandwidth of Amplifier > 200 KHz
         Hertzberg Photometer wavelength: 275 nm.
         Tolerable Bandwidth of Hertzberg Photometer: 30 nm
         Background Photometer wavelength: 245 nm.
         Tolerable Bandwidth of Background Photometer: 30 nm.
         Reference voltage for shutdown circuit ~ 3V.
         Required bits for counting: 16 bits.
         Data inputs of processor: 8
         Temperature operative range: 0 to 5 degrees celsius
         Lightweight and compact design
III. VERIFICATION

TESTING PROCEDURES:

Processor: To test the functionality and to understand Z-processor, we will write test
codes to check if the data is being transmitted properly. Since the output of the
temperature sensors are proportional to the temperature we will be first simulating them
with a function generator to test the reading of the processor. We will also use function
generators to test A/D arrays, attached on the processor. Since the real testing of the
processor depends heavily on other modules, we will be using function generators before
other modules are working properly such as the counter and the temperature sensors. We
will also test interfacing and communication of the processor with a computer, simulating
Taylor’s computer, determine protocol and make sure information is transferred securely
and correctly in both ways.

Photometers: the main testing of the photometers is positional. The lenses we are using
are very accurate and they have to be exactly positioned in order to get a good image, the
image will be blurred with just millimeters of displacement. The focal point will be tested
with different images. Also the PMT’s will be tested in a dark room to see their behavior
in order to prevent bad readings due to dark current. Different materials to cover the tube
will be tested in order to get the darkest environment possible. Different baffle sizes will
be tested in order to enhance the field of view, this will be done basing the work on the
number of photons that hit the PMT. A test has to be carried out to make sure the
wavelength of the filters is the desired one.

Counter: Based on the information gathered from the PMT we will know how many
photons in average will be hitting the PMT in certain period of time. With this
information we will have to make sure the counter will handle this number. Also test its
behavior when it resets and when information is uploaded. Test the interface with the
amplifier, see what happens if the amplifier doesn’t give the right voltage levels. Test the
counter’s behavior when noise is present. Timing interface with the processor, do
extensive testing on control signals and information transmission between the processor
and the counter.

Amplifier: Since we’ll be testing our circuits at room temperature and under normal
condition, our SNR will be pretty low to what we really need and the reason is increase
in temperature due to very high amplification. We’ll be checking differing circuits for the
Amplifiers and will be observing their temperature, weight, performance and SNR value
at required gain. After all the testing we’ll pick the optimal Amplifier circuit. Similar
testing procedure will be used for shut down circuit.

Shut down circuit: Do extensive test on the reference voltage under various situations,
making sure it doesn’t change much. Test behavior of photodiode in this same situations
and how it responds to light in different positions. Test the position of the photodiode in
the satellite making sure is the optimal position to protect the PMT’s and in this position
the light gathered is maximum. Test functionality in the same temperature range as the
sensors. Test behavior in all the above situations of the power-off switch, either transistor
or relay. Test sensitivity of the photodiode near the voltage reference. Make sure the
response time of the whole circuit (photodiode, comparator, transistor or relay) is small
enough to shut down the PMT’s before damage is caused.

Temperature Sensors: Test them in different temperatures and make sure they work in
the range they are supposed to. Test them in both extremes of the range. Test interface
with the processor and timing. Test time exposure on both extremes of the working range.

TOLERANCE ANALYSIS:

        In the processor module we can’t process data in less than a minute, this has to be
considered with information transmission from the devices as well as interfacing with
Taylor’s computer. The reference voltage of the shutdown circuit can’t have much
tolerance since the PMT’s could be burned out with just a little more light. Other issue
concerning tolerance would be the speed of the clock and amplification. Clock speed
should be kept in such a way that it is in sync with other photometer.

        Due to high amplification requirement (10^6) of amplifiers, they will be getting
hot and causing a lot of noise which is not good in order to get accurate data. To avoid all
this we need to keep the temperature really low ~ 0-5 Degree Celsius so we get the least
noise from the amplifiers circuitry. The other way to decrease this noise is the usage of
Discriminator (anti noise filter) right after each amplifier. There is minor effect of noise
due to electrons falling off the surface of PMT and got amplified by the amplifier, and the
only way to decrease that effect is to keep the temperature really low ~ -30 to -5 Degree
Celsius. This low value of temperatures is very important for the tolerance of amplifiers
and also shut down circuit.
IV. TEAM MEMBERS, COST AND SCHEDULE.

TEAM MEMBERS:

Rodrigo Martinez Duarte. drmartnz@uiuc.edu

       Electronics and Communications Engineer Student.

       Part of the U of I Team on the TEST Nanosat Project, under the leadership of
Matt Maple. Responsible of the counter and photometers blocks. The design and
assembly of the photometers once the parts are received. Auxiliary on the machining and
building of the actual satellite, such as the housing compartment for all the circuits and
pieces mentioned above.

        Background: Hardware design and implementation of laboratory security system.
Sensor design and implementation for a robotic base-scout autonomous system, included
optical, tactile and power monitoring sensors. Sensor system and power interface design
and implemented for a robotic crane waitress, consisted of the use of modulated signals
to differentiate tables to be served, transmitters and detector built. Power interface
designed and built in order to activate an electromagnet to pick up trays.

       COST:

       COST PER HOUR: $100 * 2.5 = $250
       TOTAL HOURS: 11 WEEKS WITH 15 HOURS EACH= 165

       TOTAL……………………………… $ 41,250

       SCHEDULE:

WEEK                              PROJECTED WORK
 9/8  Information gathering about the NANOSAT Project, focusing on the Photometer
      performance and design. Datasheets gathering. PMT’s and filters already
      ordered.
 9/15 Breaking of the module in blocks. Counter and Photometer block assigned.
      AUTOCAD learning. Work closely with team leader Matt Maple. Lenses
      received.
 9/22 Start design of the photometer. Sketch ideas and possible designs. Consider field
      of view, wavelength desired, lightweight requirement, filter size and handling,
      PMT positioning, I/O ports. AUTOCAD learning. Work closely with team leader
      Matt Maple.
 9/29 Middle of week- start design of photometer in AUTOCAD.
 10/6 AUTOCAD design
10/13 Design turned in to the Machine Shop for building. Start design of counter block.
10/20 Building of Counter Block. Hopefully PMT’s and filters were received by this
      time. Prepare the assembly of the PMT’s and filters to the photometer
           considering position and handling.
 10/27     TESTING
  11/3     Assembly of the PMT’s to the photometer. TESTING
 11/10     TESTING
 11/17     TESTING
 11/24     Thanksgiving
  12/1     Final Presentation
  12/8     Lab Notebook turned in. Checkout.

Ahmad Moatesim moatesim@uiuc.edu

         Undergraduate in Electrical Engineering

        As a part of auxiliary engineering team, which is working on design of Hertzberg
photometer, I will be guy who will be working with Z-processor. This Z-processor will
also interface with Matt Maple’s processor, which he will be using for his CCD camera.
Number of photons hitting the photometer will be converted to square wave pulse, which
will be amplified first by Mobeen’s Circuit and then it will be feed into a counter. Once
all the reading from photometers has been taken, this processor will convey that
information to Matt’s computer and also to Taylor University Processor. This counter has
three-bit control line and 32 bit overall storage capacity (each word is 6 bit). When all the
readings have been taken (from three photometer), this processor will reset the least
significant readings. This processor has built in A/D array, which is going to be used to
obtain data from temperature sensors.

        In the past, I have programmed x86 family processor. This will be the first time
when I will be working with micro-controller family processor. I look forward to this
project and I hope I do learn a lot.

         COST:

         COST PER HOUR: $50 * 2.5 = $125
         TOTAL HOURS: 11 WEEKS WITH 10      HOURS EACH= 110

         TOTAL……………………………… $ 13,750

         SCHEDULE:

WEEK                              PROJECTED WORK
 9/8  Focusing on understanding the Z-processor architecture, dynamic C language
      (used to program Z-Processor), and interfacing/communicating with other
      processors.
 9/15 Understand Z-Processor, bit more, and I will start taking simple data like
      temperature sensor inputs. Have simple text/files transferring between Z-
      processor and other processor (this is not a major task for this week though).
 9/22 Learn how files/data transfer between two other processors (Taylor University,
           main computer, and Matt Maple’s).
 9/29      Start working on back end photometer, which has built in amplifier. I will hard
           wire (if counter/timer/multiplexer is available, I will use that) to processor and
           record reading, so I could get a feel to how to work with other two photometer.
 10/6      Hopefully at this time the other two photometer will be available along with
           amplifier board. Output of this photometer will be passed to
           counter/timer/multiplexer and then to Z-processor. Testing will be required at this
           time to see if processor is communicating properly with photometers.
 10/13     Hopefully every part would have been built at this time and I will start
           testing/interfacing.
 10/20     INTERFACING/TESTING
 10/27     INTERFACING/TESTING
  11/3     INTERFACING/TESTING
 11/10     INTERFACING/TESTING
 11/17     INTERFACING/TESTING
 11/24     Thanksgiving
  12/1     Final Presentation
  12/8     Lab Notebook turned in. Checkout.

Mobeen Chaudhry: mobeen@uiuc.edu

         Senior in Electrical Engineering

          I’ll be working on Shut Down circuit and Amplifiers. The amplifiers need to have
a very high gain of approximately 10^6 so it could make pulse even for a very small
light. I’ll be making it on a Porto board using similar techniques that are used in cube-set
built in amplifier. One of the biggest challenges I’ll be facing in the making of these
amplifiers is to achieve gain that is good enough to create a pulse even for a tiny photon
that hits the sensor.
          My second goal is to get shut down circuit working for a case when excess of
light is detected by the sensors. For this case, shut down circuit shuts down the photon
amplification doing its essential purpose of protecting photometer from burning out
incase of abundant light. I’m planning to build this voltage divider circuit on proto board.
It’ll compare the voltage with the reference voltage value and if the input voltage exceeds
this value it’ll shut down the circuit to protect the photometer. It works other way if input
light is with in the range. So shut down circuit serve as a switch for the incoming light.
           I have worked on proto board in my previous courses like ECE 110 and ECE
249. Working on shut down circuit and amplifiers will be challenging and fun experience
for me.
         COST:

         COST PER HOUR: $75 * 2.5 = $187.5
         TOTAL HOURS: 11 WEEKS WITH 12 HOURS EACH= 132

         TOTAL……………………………… $ 24,750
             SCHEDULE:

WEEK                                PROJECTED WORK
 9/8  Getting information about the project and my responsibilities
 9/15 Finding out the optimal way for making Amplifier and Shut Down circuit on the
      web and from other resources
 9/22 Started designing shut down circuit and amplifier on Pspice, while still finding
      the optimal design
 9/29 Started designing the Shut down circuit (on proto board) after getting the optimal
      design from Pspice.
 10/6 After getting all the information and Pspice work, start designing Amplifiers
10/13 Continue designing to Amplifier and also on anti noise filter for each amplifier
10/20 Finalizing the design for both amplifier and shut down circuit and start putting
      them together
10/27 TESTING: both the amplifier and shutdown circuit
 11/3 Putting both the circuits with photometer and sensor tubes
11/10 TESTING
11/17 TESTING
11/24 Thanksgiving
 12/1 Final Presentation
 12/8 Lab Notebook turned in. Checkout.

         TOTAL COST:

         RODRIGO…………………………… $ 41,250
         AHMAD…………………………….. $ 13,750
         MOBEEN…………………………… $ 24,750

         LABOR TOTAL……………………... $ 79,750


         PARTS COST:

  PROJECT BLOCKS         US $   PARTS DESCRIPTION

Hertzberg
Photometer

Filter                   720    (Barr Associates): 275nm, 30nm FWHM, 25% trans
                                01LQF123 (Melles Griot): 75mm diameter, 100mm fl,
Lens                     395    ~ 90% trans?, Opitcal Quality Fused Silica, est mass
                                R7154 (Hamamatsu): Quantum Efficiency of 65% to
Photomultiplier Tube     418    30% in 260 to 290nm range
                                E717-63 (Hamamatsu): verify compatibility with PMT,
Socket                   55     mass est
                               C4900-51 (Hamamatsu): 12V input, 15mA to 95mA
Power Supply           128     current, 0V to 1250V output
Instrument Structure
(Parts & Labor)        300     Mass est includes tube only
                               Mass est includes cables, mounts, sockets, insulation,
Miscellaneous          200     etc; potentially heater

Amplifier and
Discriminator           100    Design TBD

Background
Photometer

Filter                 720     (Barr Associates): 240nm, 30nm FWHM, 15% trans
                               01LQF123 (Melles Griot): 75mm diameter, 100mm fl,
Lens                   395     ~ 60% trans?, Opitcal Quality Fused Silica, est mass
                               R7154 (Hamamatsu): 2 units (1 backup), Quantum
Photomultiplier Tube   418     Efficiency of 65% in 260 to 290nm range
                               E717-63 (Hamamatsu): verify compatibility with PMT,
Socket                 55      mass est
                               C4900-51 (Hamamatsu): 12V input, 15mA to 95mA
Power Supply           128     current, 0V to 1250V output
Instrument Structure
(Parts & Labor)        300     Mass est includes tube only
                               Mass est includes cables, mounts, sockets, insulation,
Miscellaneous          200     etc; potentially heater

                               LP3500 Fox: 7.4MHz, up to 512k SRAM & Flash, 26
                               Digital I/O, 8 11-bit A/D, 1 Relay, 3 PWM, 1 RS-485,
Z-World Processor      400     3 RS-232, Real time clock, 10 timers,

Shutdown Circuit       10      Photodiode, resistors, comparator, transistor.
                               CTS82C54-50 (Celeritous Technical Services): 3
Counter                10      channel, 16 bit counter/timer
                               DS18S20 (Dallas):10 sensors, -55C to +125C, 0.5C
Temperature                    accuracy from -10C to +85C, 9 bit digital output,
Circuits               30      shared bus
                               Mass est includes Counter, startup/protection circuits,
PC Boards              300     temp circuits
Structural Housing
(Parts and Labor)      500     Includes frame, instrument mounting rails, & shielding
                               Mass est includes cables, mounts, sockets, insulation;
Miscellaneous          300     potentially heater

TOTAL PART COSTS       6,084
GRAND TOTAL:

    PARTS COST…………………………… $ 6,084
    LABOR COST…………………………... $ 79,750

    GRAND TOTAL………………………… $ 85,834

								
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