1. GLAST Large Area Telescope:
Gamma-ray Large Area Space Telescope
GLAST Large Area Telescope:
G. Haller
SLAC
(650)
DOE Review DAQ

2. Contents Overview - Production & Testing - Schedule
TEM/TPS Flight Units
PDU Flight Units
GASU Flight Units
SIU/EPU Flight Units
Testbed
Installation & Test Support
Budget

3. LAT Electronics TKR Front-End Electronics (MCM)
ACD Front-End Electronics (FREE)
CAL Front-End Electronics (AFEE)
TKR
16 Tower Electronics Modules & Tower Power Supplies
CAL
Global-Trigger/ACD-EM/Signal-Distribution Unit*
3 Event-Processor Units (EPU) (2 + 1 spare)
Event processing CPU
LAT Communication Board
SIB
Spacecraft Interface Units (SIU)*
Storage Interface Board (SIB): Spacecraft interface, control & telemetry
LAT control CPU
LAT Communication Board (LCB): LAT command and data interface
Power-Distribution Unit (PDU)*
Spacecraft interface, power
LAT power distribution
LAT health monitoring
* Primary & Secondary Units shown in one chassis

4. TEM/TPS Mounted to CAL TKR not shown
LAT GRID with 16 CAL/TEM/TPS Modules
CAL
TEM
TPS

5. Tower Electronics Module/Tower Power Supply
Tower Electronics Module: Main DAQ module, one on each tower
Controls and reads out data from TKR MCM and CAL AFEE front-end electronics
Assembles CAL and TKR event fragments to tower event
Tower Power Supply module, one on each tower
Input 28V
Generates low-noise voltages for
TKR (2.65V analog, 2.65V Digital)
CAL (3.3V analog, 3.3V digital)
TEM (3.3V and 2.5V digital)
TKR Bias (20V-140V programmable)
CAL (20V to 90V programmable)
Tower Electronics Module (TEM) before coating/staking
TEM
Tower Power Supply (TPS) before coating/staking
Shown upside-down
TPS

6. TEM/TPS Status & Schedule
Three Flight Tower-Electronics Modules/Tower Power Supplies received
Fully assembled
Thermal-cycled
Vibration tested (one of them to qualification levels)
One unit finished thermal-vacuum testing
One unit in thermal-vacuum testing
Both units finished EMI/EMC testing
No issues/problems
Balance of 19 TEM/TPS in surface-mount assembly at vendor
Schedule
2/17/05 First TEM/TPS to I&T
2/25/05 Second TEM/TPS to I&T
4/1/05 Third TEM/TPS to I&T
4/22/05 Fourth TEM/TPS to I&T
One week lag between delivery of consecutive assemblies
7/26/05 Last TEM/TPS to I&T

7. PDU & GASU Mounted on LAT

8. Power Distribution Module (PDU)
EM PDU enclosure with primary/redundant PDU circuit cards, no coating/staking
Primary and Redundant Circuits in one Enclosure
Receives Primary and Redundant 28-V from spacecraft
Each, primary and redundant PDU can select between primary and redundant spacecraft power
Filters 28V
Turns on/off 28V to 16 towers and 3 EPU’s under program control
Protects PDU and down-stream circuits from over-current and under-voltage
Over-current via poly-switches
Under-voltage via custom circuit in each power-on branch
Receives command/clock from GASU
Digitizes voltages/temperatures from > 150 sources
Includes temperatures from radiators, GRID; used for thermal control
Reads back data to SIU via GASU
Provides PDU DAQ voltage and temperature analog data to spacecraft for monitoring

9. PDU Status and Schedule
Design/documentation complete
Enclosures fabricated
All parts received (except recalled International Rectifier regulator, due end of February)
Assembly contract awarded
All parts kitted and audited by assembly vendor
Assembly started
Schedule for Flight Unit
5/15/05 Precoat PDU assembly ready for electrical test
5/30/05 Complete assembly ready for environmental test
7/1/05 Flight PDU to I&T

10. GASU
PDU enclosure with primary/redundant PDU circuit cards, no coating/staking
Primary and Redundant Circuits in one Enclosure
Contains two types of circuit card assemblies
GASU Power Supply CCA
GASU DAQ Board CCA
GASU Power Supply
Receives 28-V supply voltages for
Primary and redundant DAQ board, generates 3.3V and 2.5v
ACD FREE cards
Filtering for 28-V
3.3V regulation
GASU DAQ Board
Contains 9 FPGA’s
Includes Command Response Unit, Fan-out and fan-in of commanding to 16 TEMs, PDU, EPU’s, ACD
Includes Global Trigger Logic
Includes LAT Event-Builder Logic
Includes command/control/read-back for ACD sub-system
Includes power-control for ACD FREE Boards

11. GASU Status and Schedule
Design/documentation complete
Enclosures fabricated
All components/parts received
Assembly contract awarded
Parts being kitted
Flight assembly to start 3/10/05
Schedule for Flight Unit
5/20/05 Precoat GASU assembly ready for electrical test
6/10/05 Complete assembly ready for environmental test
7/13/05 Flight GASU to I&T

12. SIU/EPU Spacecraft Interface Unit (SIU) Event Processor Unit (EPU)
Difference is boot code loaded into RAD750 CPU
LCB
Enclosure
Backplane
SIB
Power-Supply
CPU

13. SIU/EPU Status and Schedule
Design/documentation complete
Enclosures fabricated
All components/parts received except BAE RAD750 CPU
Uses recalled International Rectifier regulator
Boards to be sent back to BAE
Reworked boards expected 3 weeks after they receive components; June 05
Assembly contract out for RFP
Schedule
6/1/05 Precoat cCPI boards ready for electrical test
7/28/05 Complete assembly ready for environmental test
8/19/05 First Flight SIU/EPU to I&T
8/24/05 Second flight SIU/EPU to I&T
8/27/05 Third flight SIU/EPU to I&T
8/30/05 Fourth flight SIU/EPU to I&T
9/2/05 Last flight SIU/EPU to I&T

14. Testbed and I&T Support
Upgrade of engineering modules to reflect flight designs
Scheduled over next 6 months
Labor to support upgrade
Labor to support testing of electronics and flight software using data generated via front-end simulator boards
Labor to support test-stands for flight electronics qualification and acceptance testing
I&T Support
Design/fabrication/testing of virtual spacecraft simulator for I&T
Support for integration and testing of DAQ modules on instrument

15. Management & EGSE Management Sub-system manager Technical writer
Support for environmental test
Travel
Computer for test-stations (HW & SW) maintenance
Shipping charges for flight hardware
EGSE (Electrical Ground Support Equipment)
Maintenance/repair of test-stations supplied to sub-systems

16. Costs & Commits Explanation:
Dataflow Electronics = TEM/TPS Flight Units
ACD GASU FU & GLT FU = GASU
Power Conditioning = PDU
SIU & LAT Communication Card = SIU