GLAST LAT Project LAT System Engineering 1 GLAST Large Area Telescope: LAT System Engineering Pat Hascall SLAC System Engineering Manager Gamma-ray Large Area Space Telescope

GLAST LAT Project LAT System Engineering 2 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

GLAST LAT Project LAT System Engineering 3 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)

GLAST LAT Project LAT System Engineering 4 TEM/PS Subsystem Test Summary Based on From Tower Power Supply Extended Test Procedures, LAT-TD , 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

GLAST LAT Project LAT System Engineering 5 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

GLAST LAT Project LAT System Engineering 6 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)

GLAST LAT Project LAT System Engineering 7 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?

GLAST LAT Project LAT System Engineering 8 TEM Testing TEM subsystem testing (From Tower Electronics Module (TEM) Extended Performance Test Procedures, LAT-TD , 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

GLAST LAT Project LAT System Engineering 9 TEM Subsystem Test Summary

GLAST LAT Project LAT System Engineering 10 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?