Transcript 2/27/2004

GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
GLAST Large Area Telescope:
LAT System Engineering
Pat Hascall
SLAC
System Engineering Manager
[email protected]
650-926-4266
LAT System Engineering
1
GLAST LAT Project
Topics
• Meeting goals
– Lay out plan for completing the I&T requirements
• Mechanical Integration Details
• Electrical Integration Details
• Functional and Performance Tests (CPT, LPT, Aliveness,
other)
– Test development strategy
• Develop tests that take advantage of Subsystem
Tests/Scripts at LAT I&T
• Focus is on integration testing, will phase in
development of tests to be performed later
• Establish FSW functionality requirements
– limit to functionality required for in orbit ops, but may
include special test only version
LAT System Engineering
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GLAST LAT Project
Assumptions/Initial Conditions
• The following set of initial conditions is my understanding of
the current approach - feedback?
• Subsystems will have a thorough interface verification at the
subsystem level
– Electrical interface waveforms tested and margin
demonstrated
– No I&T electrical characterization is required
• TEM and TEM/PS are delivered with no additional tests
required
• Calorimeter, Tracker and ACD have been tested with flight
design TEM equivalents, so no pin-out verification is
necessary
• cables will be pinout verified
• If this is true, other than the use of connector savers as
defined in the assembly plan, integration begins with plugging
inLATsubsystems
and running test scripts
System Engineering
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GLAST LAT Project
I&T Requirements Strategy Overview
• Baseline tests will include
– Functions tested at Subsystems level
– Functions tested by Flight software tests
– Flight software in-orbit special processing (e.g. calibration
mode)
– Timing in Tracker layers, Tracker to Cal, between Towers
and between ACD and Towers
– Data collection required by SVAC
– LAT to spacecraft interface verification tests
– Any other source of test requirements (besides JJ) ?
• Will begin by defining earliest required tests first (based on
updated subsystem test plans)
• I will be asking for help to get clear definitions for each of the
tests
LAT System Engineering
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GLAST LAT Project
LAT Performance & Operations Test Plan
Contents
• Will focus on electrical tests
– Mechanical operations defined elsewhere
• Assembly Sequence
• Environmental Test Sequence
• Dynamics Test Plan
• Alignment Plan
• Thermal Test Plan
• Will contain a list of tests, with a test ID, test title, test
description and where possible relationship to subsystem test
• Will contain a matrix to define which test is run in which test
phase (test instance)
LAT System Engineering
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GLAST LAT Project
Test Definition Sample
• Tracker GTRC configuration register and readback
– The GTRC chips are sequentially addressed and their
configuration registers loaded with a bit pattern. Each time
the register is read back and checked for errors. The test is
repeated with the complement of the bit pattern. The test
then is repeated with a broadcast address for writing the
register, followed by sequential readback. (Based on
Tracker Test TE201)
• FSW Tracker Configuration Test
– This test shall verify the ability of the SIU to configure the
TKR subsystem as desired and read back the necessary
configuration information to completely determine the TKR
subsystem configuration (Based on FSW test nnn)
LAT System Engineering
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GLAST LAT Project
Test Instance Format Sample
ID
Test
Incoming
Tower
Two
Tower
Power Consumption
X
X
Temperature
X
X
Leakage Current
X
X
X
GTRC configuration
X
X
X
GFTE left/right configuration
X
X
X
GFTE split configuration
X
X
X
Reset
X
X
Threshold Scan
X
X
Charge Injection Scan
X
Gain and Noise
X
X
Layer Timing
X
X
Occupancy
X
X
Occupancy w/readout
X
X
Muon Scan
X
X
High Rate/ Deadtime
X
X
…
Comp.
X
…
Combined Charge Injection Scan
X
X
…
FSW Tracker Configuration Test
LAT System Engineering
X
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GLAST LAT Project
S/C Interface Verification
•
•
•
•
DC Power
– Measure total power consumption in all operational modes (including
calibration mode) and in survival mode
1553 interface
– Verify signal voltages and waveforms are compliant to beginning of life
values based on the 1553 standard (may be done at DAQ/SIU subsystem
level)
– Verify ability to receive commands from the spacecraft (SIIS) and return
telemetry to the SIIS
• Verify that all commands can be sent (not necessarily send all
commands)
• verify that all telemetry is sent to the SIIS
Science Data Stream
– Verify signal voltages and waveforms are compliant to beginning of life
values based on the LVDS standard (may be done at DAQ/EPU subsystem
level)
– Verify that the transport of the information is working correctly by successful
ingest of the science data
Analog telemetry, Control and monitor discretes
– TBD
LAT System Engineering
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GLAST LAT Project
Integration Test Configurations
Post Ship/Receiving Test
Integrated Tower Bench Test
LAT Integration Tests
Flt CAL
FLT TKR
GSE
TEM & TEM PS
FLT TKR
FLT TKR
FLT CAL
FLT CAL
FLT TEM & TEM PS
FLT TEM & TEM PS
E-GSE
E-GSE
flt TKR or CAL
FLT CAL
GSE TEM & TEM PS
FLT TEM & TEM PS
flt TKR
GSE
TEM & TEM PS
E-GSE
E-GSE
GSE SIU
FLT SIU
GSE PDU
GSE TEM & TEM PS
FLT PDU
GSE GASU
FLT GASU
E-GSE
E-GSE
LAT System Engineering
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GLAST LAT Project
Test Stand Capabilities
• Test stand functionality
– 1 - Supports testing of a tracker, calorimeter, or integrated
single tower
– 2 - Supports testing of multiple towers without SIU using
the “backdoor”
– 3 - Uses SIIS through SIU to perform testing, use of
“backdoor” access is possible
• Must use “backdoor” for early integration testing, since SIU
and flight software will not be available
LAT System Engineering
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GLAST LAT Project
Test Implementation Strategy Overview
•
•
•
Use subsystem level test scripts during integration
– Scripts should run in a multi tower environment
– I&T will have to merge some subsytem scripts for tests that must run in
parallel
For some cases, change over to tests run through flight software
– Matches the way we fly it
– Means that some algorithms imbedded in scripts will be ported to flight
software
• Need systematic approach to defining and documenting those
requirements, baseline is only the functionality needed for in-orbit
operations
– One issue is comparison of results between subsystem baselines, initial
I&T testing, and final testing using FSW
– Likely need to capture some data for off line processing to confirm flight
software processing
– Will need toolbox of offline processing, but not part of formal acceptance
testing
For some cases use the “backdoor” access
– May be faster or may provide a more direct measurement of the parameter
LAT System Engineering
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GLAST LAT Project
Implementation Plan
•
•
Hold meetings (what else?)
Goals of meetings will be to
– Define the requirements
• Test definitions for the required tests
• Gather a complete list of formal tests
– Work the implementation issues
• Define subsystems tests/scripts to be used during integration
testing
• Define which subsystem scripts are to be combined to perform
integrated tests
• Define what functionality from the subsystems and I&T LATTE
scripts is required for on-orbit operations and ensure that that
functionality is in the FSW requirements
• Define which additional tests are needed for science
verification and calibration (SVAC plan)
• Define which additional tests are needed to support interface
or other requirements that can only be observed at LAT level
(e.g. power consumption during calibration mode)
LAT System Engineering
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GLAST LAT Project
Redundancy Verification
• The tests shall use redundancy combinations that verify all
cross strapping
• During TV testing, the time on redundant units shall be spread
approximately evenly
• trending requirements
LAT System Engineering
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