LAT Integrated Tower LVDS Interface Confidence Test



Baun, Rich

Bright, Rick

Haller, Gunther

Hascall, Pat

Horn, Dick

Johnson, Neil


Meeting held in GLAST 2 Conference Room on Thursday, January 13, 2005.


Purpose of meeting:

To determine criteria to retire risk and gain confidence in flight-like LVDS interface with TEM/TPS, Calorimeter AFEE boards, and Tracker MCM cards.


It was agreed that the desired method would be to demonstrate LVDS functionality over temperature while varying voltage and frequency to the TEM/TPS. Existing plan had first testing of the flight interface over temperature during LAT Thermal Vacuum testing at NRL. An Integrated Tower LVDS Interface Confidence Test for engineering evaluation is now being planned to be performed at SLAC in the thermal chamber that is located in building 33. The test will use the TEM/TPS Qualification unit, 8 (4 minimum) AFEE boards, 36 (18 minimum) MCM cards, and flight-like cables. Thermal chamber will be controlled to TEM/TPS qualification temperatures extremes defined in LAT-SS-00778, LAT Environmental Specification.


Current issues that need to be resolved are:

  1. TEM/TPS Qualification Unit availability
    1. Waiting for TEM/TPS Qualification unit to complete qualification program G. Haller.
  2. AFEE boards availability
    1. Waiting for AFEE boards from Calorimeter N. Johnson.
  3. MCM card availability
    1. Waiting for MCM cards from Tracker R. Johnson.
  4. TEM to MCM Cables availability
    1. Need to identify source for, and procure, cables G. Haller/R. Johnson.
  5. Test procedure or checklist to document test requirements and results.


The thermal cycle testing of each integrated flight tower as part of integrated single tower test was briefly discussed. The decision was to not implement this testing primarily due to schedule impact and potential risk to flight hardware.

The group also agreed that LVDS functional interface testing over frequency needs to be implemented at the Subsystem Level by the subsystem providers. Testing over frequency also needs to be tested at the Single Tower level by LAT at SLAC.