Transcript System Engineering

Systems Engineering
Bob Goeke
Cosmic RAy Telescope for the Effects of Radiation
27 June 2005
System Engineering
System Block Diagram
Cosmic RAy Telescope for the Effects of Radiation
27 June 2005
System Engineering
Configuration Management and Peer Review
Process
•
Process documented in 32-01201 Rev A
•
We maintain reference, Bookmark, and Controlled documentation
– Reference: GSFC project documents, vendor data sheets
– Bookmark: what most folks call DRAFT
– Controlled: must go through Configuration Management Board
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All revisions of all documentation are maintained on public web
site http://snebulos.mit.edu/projects/crater/
•
Peer reviews are an incremental process run in parallel with the
ECO process
– Peer review validate the proposed initial or changed design
– ECO process controls the documentation
– Review board meets in public every Wednesday
Cosmic RAy Telescope for the Effects of Radiation
27 June 2005
System Engineering
ICD Status
Data ICD
At Rev. B awaiting GSFC Sign-off
Electrical ICD
Draft returned to GSFC with comments
Mechanical ICD
Draft 2 returned to GSFC with comments
Thermal ICD
Draft returned to GSFC with comments
(We owe s/c model inputs)
Cosmic RAy Telescope for the Effects of Radiation
27 June 2005
System Engineering
Miscellaneous Requirements
•
Contamination Control (32-01203 Rev 06)
– Our internal requirements are modest; waiting to see Project requirements
– Detectors could develop surface leakage if particulates accumulate on
surface
– Exposed electrical connections to detectors could lose conductivity if
attacked by (primarily) salt atmosphere
•
Purge
– This is a precaution against air borne contamination, esp. during I&T
•
Handling
– At 5Kg total mass, we are in the “pick up and carry” class
Cosmic RAy Telescope for the Effects of Radiation
27 June 2005
System Engineering
System Resources
Mass
Power
Data Rate
4.3 Kg
4.6 watts
200/2K/200Kbps
Peak
6 Kg
12 watts
1K/100Kbps
CBE
5.0 Kg
5.1 watts
515/86.6Kbps
Allocation
5.6 Kg
6.0/9.0 watts
86.6Kbps
12%
18%/76%
n/a
Proposal
Margin
Request add. Allocation
0.4 Kg
Cosmic RAy Telescope for the Effects of Radiation
27 June 2005
System Engineering
Power Calculations & Margins & Stuff
Standard Contingency
1.3
+5VDC
Single Analog Chain (ma)
Front End
Video Chain
Sum of 6 Chains
Support (ma)
Bias supply
Sum of 2 supplies
Amptek PH300
Sum of 6 peak stretchers
Maxim 145AEUA
Sum of 3 A/D
Digital (ma)
DDC 63705X3 (25% active)
FPGA
16MHz plus buffers
Sum of Power (watts)
Coverters (watts)
AdvancedAnalog 2805S
Standby power
Conversion loss (80%/70%)
AdvancedAnalog 2806D
Standby power
Conversion loss (80%/70%)
Totals (watts)
Per Power Supply
Grand
Calculated Contingency
0.20
1.2
0
0.1
0.6
2
6
220
40
10
1.39
Worst case from manufacturer
Nominal
+6VDC
-6VDC
4.50
10.30
88.8
7.00
42
20
40
2.4
14.4
20
40
2.4
14.4
0
0.86
115.44
54.6
0
52
52
0.78
18.72
18.72
0
7.8
0
0
0.58
345
52
13
2.10
1.12
0.75
0.56
0.35
1.40
0.90
0.98
0.36
2.30
-6VDC
1.56
2.78
1.68
0.80
4.40
5.07
72%
Cosmic RAy Telescope for the Effects of Radiation
27 June 2005
Maximum
+6VDC
+5VDC
System Engineering
4.35
8.75