Talk:Receiving LRO and LCROSS

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LRO Transponder Info

NASA Solicitation: Lunar Reconnaissance Orbiter Mission Communication System

Source: http://www.spaceref.com/news/viewsr.html?pid=16926

General Information

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

Description

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


Logbook

2009.08.24

  • Project kick-off

2009.08.25

  • Found some unofficial info about LRO and LCROSS transmitters and antennas
  • Created preliminary link budget to the point of Signal strength at receiver antenna.

2009.08.26

2009.08.27

  • Analytical assessment of the system noise temperature available: 65 K

2009.08.28

  • LNA and Bias-T have arrived!

2009.09.02

  • Ordered cables and connectors from Wimo

2009.09.03

2009.09.04

  • 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

2009.09.05

  • 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.

2009.09.08

  • The cables and adaptors from Wimo have arrived

2009.09.12

  • Assembled antenna and mounted it on camera tripod for mechanical tests. Will work all right

2009.09.14

  • 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

2009.09.15

  • 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.

2009.09.19

2009.09.26

Potential observation day.

Time (UTC) Moon RA/DEC (J2000) Moon Az/Alt Event Notes
14:10:00 LRO AOS Lon/Lat: -70.4° / -87°
14:19:30 18h36m38.5s / -25° 42'27.1" +131° 14'00" / +0° 0'00" Moonrise
time
15:00:00 LRO LOS Lunar coordinates TBD
15:57:56 18h39m24.7s / -25° 39'47.1" +150° 27'51" / +10° 0'01" Sun Az/Alt: +248° 54'15" / +15° 35'18"
time
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"
time
18:13:36 18h42m50.9s / -25° 31'47.6 +180° 31'36" / +15° 37'07" Moon @ max Alt
time
22:07:18 18h49m1.8s / -25° 5'29.6" +229° 53'10" / +0° 0'02" Moonset