Transcript STEREO Data System

MAXIM Data Systems
Command & Data Handling
Space - Ground Link
Ground System
19 August 1999
MAXIM Data Systems Topics
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Data System Recommendations
Options and Trades
Spectrum Utilization
Ground Antenna Capabilities
Data System Drivers
Data System Block Diagram
Mass/Power Summary
Operations Concept
Link Margin Summary
Cost Data
Suggested Study Areas
Recommendations for MAXIM
 Detector satellite will transmit science data using S-Band to Optics
Spacecraft for combined transmission to ground stations
 Store data continuously & dump daily for 12 min using DSN 34M
using X-Band
 Total downlink data rate: 300 Kbps
 Use 2:1 data compression
 Use S-band for Optics/Detector transmissions
 Use S-band for backup comm from DSN for both Optics & Detector
Options/Trades
 Detector spacecraft to transmit telemetry to Optics spacecraft
for combined relay to ground station ( vs separate links)
 Less ground station time required
 Smaller antenna required for Detector Spacecraft & much simpler
communication system
 Optics spacecraft sends recorded data vs real time
 Ground costs significantly less
 Allows good availability on DSN 34M system
Options/Trades
 DSN 34M recommended (vs 13M commercial)
 Allows hi-rate playback
 Reduces contact time
 Much lower cost
 Proven deep space operation
 13 M commercial has unproven ranging capability at 40 million Km
Spectrum Utilization
 X-band Space to Ground Link
(+)
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(-)
Uplink and downlink frequency assignments available
More efficient than S-Band (approx 11.5 dB)
S/C hardware is available
Rain attenuation (approx 2 dB)
 S-band for Optics/Detector link
(+ ) More efficient than X-Band (omni/omni)
(+) Existing hardware available with modifications of frequency Rx/Tx
(+) Allows backup to ground if needed (UHF not readily available)
 S-Band to ground link (emergency)
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(0) Future allocation in DSN band may be questionable
Ground Antenna Capabilities
DSN 34M:
 X-Band Rx/Tx
G/T = 52.4 dBi/K
EIRP = 103 dBw max(can go to 110 dBw)
 S-Band Rx/Tx
G/T = 42.1 dBi/K
EIRP = 98 dBw
13M commercial:
 X-Band Rx/Tx (uplink and ranging need to be added)
G/T = 37 dBi/K
EIRP = 90 dBw
 S-Band Rx/Tx
G/T = 24.5 dBi/K
EIRP = 68 dBw
MAXIM Data System Drivers
 Maximum Range: 40 million KM
 Daily Data Volume: 432 Mbits
MAXIM Data Systems Block Diagram
X-band
1.5 m HGAs
Diplexer
Switch
Commands a 2 Kbps
X-band
Xponder
&
Pwr Amp
Playback @ 300 Kbps
C&DH
BC
Diplexer
To/From Detector
Diplexer
S-band
XCVR
Tlm @ 100 bps
Cmd @ 12 bps
X-band Cmd/Tlm S-band Emergency
& Ranging
Cmd/Tlm
Hybrid
X
Commands
Satellite dish
34M Prime
70M Backup
DSN
Stations
Telemetry
Maxim
MOC
HSKP
Maxim
Science
S-band Omni
Antennas
X
Antennas
Optics
S-band
XCVR
ACS
SSR
X
X
S-band Omni
Hybrid
S/C 1553B BUS
RF Communications Mass/ Power
Optics Spacecraft
X-band Transponder (2)
6 Kg
Rx
3 watt
Cont.
RxTx
32 watts
for 1 hr/day
S-band XCVR &
Diplexers (4)
14 Kg
Rx
10 watts
RxTx
25 watts
1-2 hours/day
C&DH
4.5 Kg
30 watts
X-Band Antenna & ACU (2)
15 Kg
5 watts moving
S-Band OMNI (4)
2 Kg
RF Communications Mass/ Power
Detector Spacecraft
S-band XCVR &
Diplexers (2)
7 Kg
S-Band OMNI (2)
1 Kg
25 watts continuous
MAXIM Operations Concept Diagram
S-band command and
telemetry @ 4 Kbps
X-band Command @ 2
Kbps/Telemetry@ 300 Kbps and
Ranging
S-band
Emergency Command @ 12
bps/Telemetry @ 100 bps
S-band Emergency Command
@ 12 bps and telemetry @ 100 bps
Commands
MAXIM
Science
MAXIM
Science Data
MAXIM
MOC
DSN 34 M BWG
Telemetry (Housekeeping/Science)
(Stations at Canberra,
Madrid, Goldstone)
MAXIM Operations Concept
 Detector spacecraft will continuously transmit @ S-Band to Optics
spacecraft @ 4 Kbps (3 Kbps science, 1 Kbps housekeeping,
uncompressed)
 Optics spacecraft will compress 2:1 all Detector data and 1 Kbps
Optics housekeeping data
 Optics spacecraft will continuously record all compressed data for
playback 1/day for 12 min @ 300 Kbps to DSN 34M @ X-Band through
1 of 2 HGA antennas
 Nominal commanding/ranging to Optics spacecraft will be done via
X-Band through DSN 34M BWG
 Both Optics & Detector will have S-Band low-rate command/telemetry
through DSN 34M for emergency operations
 Commands throughput from MOC, telemetry FTP’d from fileserver
MAXIM Link Margin Summary
34 M BWG
13 M Commercial
OMNI to Ground
Spacecraft to
Spacecraft
Downlink Rate
300 Kbps
7.5 Kbps
100 bits
4 Kbps
Uplink Rate
2 Kbps
2 Kbps
12 bits
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Contact Time
12 minutes
8 hours
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Margin Downlink
3.5 dB
1.5 dB
0 dB
7.2 dB
Margin Uplink
2.5 dB
1.9 dB
0 dB
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Ranging Uplink
15.9 dB
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Ranging Downlink
21.0 dB
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All links have 3 dB required performance margins
All links have rate 1/2 convolutional encoding
Cost
Ground systems:
 DSN 34M @ 1hr/day = $365k/yr x 3= $1.1M
 13M commercial @ 8 hr/day = $7M
Optics Spacecraft:
 X Band
XPDRs(2) =$2M
HGA antennas(2)= $2M
 S-band
XCVR(4) = $2.8M
omni antennas(4) = $300K
 C&DH = $2M
Cost(cont’d)
 Detector Spacecraft:
 S-band XCVR(2)= 1.4M
 omni antennas(2) = $150K
Suggested Study Areas
 Use of new coding schemes (e.g. Turbo Codes)
 Modified frequency scheme for S-band XCVR
Acronym List
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ACS - Attitude Control System
ACU - Antenna Control Unit
BC - Bus Controller
BWG - Beam Wave Guide
DSN - Deep Space Network
FTP - File Transfer Protocol
HGA - High Gain Antenna
HSKP - housekeeping
I/F - Interface
MOC - Mission Operations Center
RF - Radio Frequency
SSR - Solid State Recorder
XCVR - Transceiver
XPDR - Transponder