GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
GLAST Large Area Telescope:
LAT System Engineering
Pat Hascall
SLAC
System Engineering Manager
hascallp@slac.stanford.edu
650-926-4266
LAT System Engineering
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GLAST LAT Project
Topics
•
Meeting goals
– Review action items
– Discuss TEM and TEM/PS subsystem testing
– Define tests to be performed on the TEM and TEM/PS tests during
LAT integration and acceptance testing
– Gain a common understanding of “calibration”
•
Team Goals
– Define test requirements necessary through December
• Tracker and Cal post delivery tests
• Cal tests post integration with TEM and TEM/PS
• Tower integration tests
• Multi tower tests (without ‘final’ flight software)
• Third layer boxes tests as necessary
– Testing with next delivery of flight software, all third layer boxes and ACD
will be defined in the next phases
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GLAST LAT Project
TEM Power Supply Testing
•
•
•
This note summarizes the testing done on the TEM power supply to verify
performance against it’s specification. The goal of the meeting Monday will be to
define the testing that will be done on the TEM power supply during various phases
of the Integration and Test sequence.
There will be no attempt to measure lower level performance parameters (such as
noise spikes) at the LAT level – the assumption is that the TEM power supply comes
tested and certified to meet those requirements
The expectation is that many of the LAT level TEM/PS tests will be covered as part
of other planned LAT level tests.
– Command functional test will include
• Turn on tower power supplies one at a time. Verify the telemetry from the
TEM/PS shows expected voltages and currents based on subsystem test.
Verify that the LAT current consumption delta matches expected values.
Turn on the calorimeter and verify the expected change in current both
through telemetry and at the power source. Turn on the tracker and verify
the expected change in current through the telemetry and at the power
source. (other calorimeter and tracker telemetry will also be verified
separately)
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TEM/PS Subsystem Test Summary
• Based on From Tower Power Supply Extended Test Procedures,
LAT-TD-01652-01, Draft dated 12/17/03
• The following parameters are measured for the 1.5 VDC, 2.5 VDC,
3.3 VDC and variable bias voltages:
– Accuracy
– RMS noise
– Bandwidth
– noise spikes
– line regulation
– load regulation
– power up output voltage rise time
– power down voltage fall times
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GLAST LAT Project
TEM/PS Subsystem Test Summary
(continued)
• The specific voltages that are measured are:
– CAL3_3V Dg
– CAL3_3V An
– CAL_Bias
– TKR2_5 Dg
– TKR1_5 An
– TKR2_5 An
– TKR_Bias
– TEM2_5 Dg
– TEM3_3V Dg
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GLAST LAT Project
TEM/PS Subsystem Test Summary
(continued)
• The two temperature sensors are monitored but not otherwise
tested.
• The TEM/PS includes the capability to turn on or off the Calorimeter
power conversion and to turn on or off the Tracker power
conversion. That capability is not explicitly tested.
• The CAL bias and tracker bias both have an analog control signal
(0-2V) that come from the TEMs. The bias circuits have a current
monitor capability. The current test procedure does not explicitly test
either capability.
• Voltage levels are routed to the TEM for telemetry purposes. (higher
level spec says that these telemetry points will be calibrated)
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GLAST LAT Project
LAT Level Tests on the TEM/PS
• Temperature sensors verified during thermal vac, sanity check
performed during integration
• Calorimeter and Tracker turn-on and turn-off capability tested as
part of command functional testing
• What are recommended tests for the Cal and tracker bias?
• Will the TEM and TEM/PS be tested as a pair and the telemetry
calibrated as a pair?
• What is recommended receiving test at I&T?
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GLAST LAT Project
TEM Testing
• TEM subsystem testing (From Tower Electronics Module (TEM)
Extended Performance Test Procedures, LAT-TD-01645-01, Draft
dated 11/25/03)
– Summary in table on next slide. Tests primarily focus on register
testing
• Interface tests to the GASU are not yet defined
• Telemetry calibration and checkout are not yet defined
• Power consumption tests are not defined
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TEM Subsystem Test Summary
Test
Description
TEM Configuration
Tests all fields in the GTIU configuration register by setting field and
observing response
TEM Communication
Checks communications with the common controller registers.
Registers tested are Configuration, Data_masks, TKR_Trgseq,
Cal_Trgseq. Registers are loaded with various values, which are
read back
The status register fields are each checked by setting up the
condition that sets the status. Few of these conditions can be set for
LAT testing
Verifies each cable controller (cal and tracker) can be masked by
setting mask, triggering an event and checking cal and tracker FIFOs
TEM Status
TEM Data Masks
TEM Command Response
Packet counts are verified by sending a known number of packets.
Parity errors are forced
GTIU Tracker Trigger
Sequencing Register Test
Measures delay to CalStrobe command and the transmission of the
TACK command
GTIU Calorimeter Trigger
Sequencing Register Test
Measures delay to CalStrobe command and the transmission of the
TACK command
TEM Address
Verify the TEM responds to the correct TEM ID
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GLAST LAT Project
Questions:
• What are recommended tests when TEM and TEM/PS are
integrated
• What are recommended tests when TEM and TEM/PS are
integrated to the calorimeter?
• What are recommended tests when the Tracker is integrated?
• What are recommended tests when the tower is integrated into the
grid, and for later comprehensive tests?
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