Talk:Receiving LRO and LCROSS
LRO Transponder Info
NASA Solicitation: Lunar Reconnaissance Orbiter Mission Communication System
Solicitation Number: LRO-NASA-GSFC-06-07-05
Posted Date: Jun 09, 2005
FedBizOpps Posted Date: Jun 09, 2005
Original Response Date: N/A
Current Response Date: N/A
Classification Code: A – Research and Development
NAICS Code: 927110 – Space Research and Technology
Contracting Office Address
NASA/Goddard Space Flight Center, Code 210.S, Greenbelt, MD 20771
LRO RF Communications Reference Baseline dated June 2, 2005
This document is intended to inform interested vendors of the current baseline architecture for the Lunar Reconnaissance Orbiter mission communication system. This document describes the current project understanding of LRO's mission communications as a result of the project's previous RFI process. This is not a request for additional RFI responses, nor is this a request for vendor proposals. No procurement action will be taken as a result of this document's release.
The LRO Project intends to initiate three separate competed procurement efforts to acquire the flight components for the LRO Spacecraft Communication System. These procurements will consist of the S-Band TT&C Transponder, the High-Rate Ka-Band Modulator, and the Ka-Band Traveling Wave Tube Amplifier (TWTA).
LRO shall provide tracking, telemetry and command functions using S-Band. LRO shall provide high rate mission data return at Ka-band. At a minimum, LRO will perform a 30 minute TT&C pass every lunar orbit (approximately every 2 hours). LRO will perform up to 4 high rate Ka-band downlinks in a 24 hour period. The high rate downlinks may be adjacent passes.
S-Band TT&C Subsystem
LRO's S-Band TT&C subsystem architecture consists of a STDN transponder and associated diplexer, switches and RF network to connect the transponder to the omnidirectional and high gain antennas. Command decryption (if required) can be accommodated internal to the transponder, or through the use of a standalone command decryptor in-line between the transponder receiver and the S-Band comm. card in the C&DH processor. The transponder shall provide the following modes:
Transponder Characteristics: Downlink data: RS-422 CLK and DATA Uplink data: RS-422 CLK and DATA Control/Status: RS-422 serial UART interface RF Output: S-Band 5W
Command Uplink (Ground to LRO) Frequency Band: 2.025 - 2.11 GHz Command Modulation: PCM/PSK/PM Command Subcarrier: 16 KHz Command Data Rate: 4 Kbps Command Link FEC: (none) Command Decryption: Caribou assumed Tracking: STDN tones, baseband modulated Simultaneous with CMD Highest ranging tone will be 500 KHz
Telemetry Downlink (Subcarrier Modulated Mode) (LRO to Ground) Frequency Band: 2.2 – 2.29 GHz Telemetry Modulation: PCM/PSK/PM Telemetry Subcarrier: 1.024 MHz Telemetry Data Rates: 16Kbps (36.64 K-symbols/sec) 32Kbps (73.28 K-symbols/sec) 64Kbps (146.56 K-symbols/sec) 128Kbps (293.12 K-symbols/sec) Downlink FEC: CCSDS Reed-Solomon & Convolutional Rate ½ Downlink Encryption: (none) Tracking: STDN tones, baseband modulated Simultaneous with TLM Highest ranging tone will be 500 KHz
Telemetry Downlink (Direct Modulated Mode) (LRO to Ground) Frequency Band: 2.2 – 2.29 GHz Telemetry Modulation: OQPSK (direct carrier) Telemetry Subcarrier: (none) Telemetry Data Rates: 300Kbps (687 K-symbols/sec) 2180Kbps (4992.2 K-symbols/sec) 5000Kbps (no FEC) Downlink FEC: CCSDS Reed-Solomon & Rate ½ (2.29x multiplier) Downlink Encryption: (none) Tracking: (none)
Ka-Band Mission Data Subsystem
LRO's Ka-band subsystem consists of a high rate Ka-band modulator, TWTA, EPC, and the RF network between the TWTA and LRO's high gain antenna.
Modulator Characteristics: Downlink Data: LVDS CLK and DATA Control/Status: RS-422 serial UART interface RF Output: +7 dBm (at the modulator output port)
TWTA/EPC Characteristics: Control/Status: Discrete RF Output: Ka-Band 20W (+13 dBW) RF Input: >0 dBm (at the TWT input port)
High Rate Data Downlink (LRO to Ground) Frequency Band: 25.5 – 27.0 GHz Telemetry Modulation: OQPSK (direct carrier) Telemetry Subcarrier: (none) Telemetry Data Rates: 25Mbps (57.25 M-symbols/sec) 50Mbps (114.5 M-symbols/sec) 100Mbps (229 M-symbols/sec) Downlink FEC: CCSDS Reed-Solomon & Rate ½ (2.29x multiplier) Downlink Encryption: (none) Tracking: (none)
Point of Contact
Name: Jason A Soloff
Title: Communication Systems Engineer
Phone: (301) 286-1368
Fax: (301) 286-1750
Name: Julie A. Janus
Title: Contracting Officer
Phone: (301) 286-4931
Fax: (301) 286-0341
- Project kick-off
- Found some unofficial info about LRO and LCROSS transmitters and antennas
- Created preliminary link budget to the point of Signal strength at receiver antenna.
- Ordered LNA and Bias-T from Kuhne Electronic
- Analytical assessment of the system noise temperature available: 65 K
- LNA and Bias-T have arrived!
- Ordered cables and connectors from Wimo
- Created a videoblog presenting the project and current status, see http://www.youtube.com/watch?v=7wIDIsu1zus
- Cables and connectors shipped from Wimo
- The project was one Evadot today: It’s inspiration Friday...
- Managed to get some hardware for mounting the antenna on the photo tripod
- The antenna support plate I got was made of something that I can not drill in (steel?). Therefore, the antenna mount has been postponed to next weekend.
- The cables and adaptors from Wimo have arrived
- Assembled antenna and mounted it on camera tripod for mechanical tests. Will work all right
- Decided to change the electric architecture to use batteries instead of bias-T
- 6V 10-12 Ah rechargeable lead battery for USRP (USRP draws 1.6 A with 2 daughter boards)
- 9V 280 mAh rechargeable Ni-MH for LNA (LNA is specified to draw 80 mA)
- Smoke test of LNA before taking it into lab: http://www.youtube.com/watch?v=Ov5_lsFi66w
- Lab measurements on the receiver and LNA:
- LNA gain and noise figure confirmed in the range 2.2 - 2.3 GHz
- LNA does not have bandpass filter
- LNA gain stays > 28 dB down to 700 MHz and up to 2.45 GHz
- LNA NF @ 1.5 GHz ~ 1 dB
- USRP+DBSRX can detect -132 dBm CW signal @ 2.25 GHz (FFT avg. α = 0.07)
- USRP+DBSRX+LNA can detect -138 dBm CW signal @ 2.25 GHz (FFT avg. α = 0.07)
- USRP+TVRX could go down to about -120 dBm FM @ 435 MHz
- Complete report on the TFN forum.
- Video tour of the antenna available on YouTube: http://www.youtube.com/watch?v=1mx1_b96uK8
There are some potential comm windows today, but the weather is teasing... It's overcast and raining from time to time. Not risking the receiver.
|Time (UTC)||Moon RA/DEC (J2000)||Moon Az/Alt||Event||Notes|
|14:10:00||LRO AOS||Lon/Lat: -87° / -70.4°|
|14:19:30||18h36m38.5s / -25° 42'27.1"||+131° 14'00" / +0° 0'00"||Moonrise|
|15:00:00||LRO LOS||-78.5° / 85.9°|
|15:57:56||18h39m24.7s / -25° 39'47.1"||+150° 27'51" / +10° 0'01"||Sun Az/Alt: +248° 54'15" / +15° 35'18"|
|17:34:58||18h41m53.5s / -25° 34'38.1"||+171° 42'09" / +15° 8'59"||Sunset||Sun Az/Alt: +267° 43'16" / -0° 0'02"|
|16:05:00||LRO AOS||-87.9° / -68.2°|
|18:13:36||18h42m50.9s / -25° 31'47.6||+180° 31'36" / +15° 37'07"||Moon @ max Alt|
|22:07:18||18h49m1.8s / -25° 5'29.6"||+229° 53'10" / +0° 0'02"||Moonset|
Perfect Moon passes but the weather was very bad this weekend. Raining most of the time. Tests cancelled until next weekend.