PA3GUO Radio Aurora Explorer (RAX) Experiments
Telemetry decoding software
The objective of the RAX mission is to understand the microphysics that lead to the formation of magnetic field-aligned plasma irregularities (FAI), an anomaly known to disrupt communications with orbiting spacecraft.
RAX is a space weather science mission carrying an amateur radio transceiver. This enables the amateur radio community to be part of the RAX mission by assisting with satellite tracking.
The University of Michigan is coordinating the research and systems control efforts.
Freq: 437.505 MHz FM
Rate: 9600 baud
Transmit Interval: Every 20 seconds
RF Power Output: 750 mW
Ant Polarization: RHCP (FM)
November 26, 2010
Telemetry reception experiment
"Analyze the effectiveness of a Radio Amateur Satellite Station to serve as a Ground Station (GS) for RAX"
In order to measure the telemetry reception & decoding effectiveness of my Ground Station a 24 hours experiment has been done. During these 24 hours all passes have been tracked.
During 24 hours the GS monitors independent and fully automated (computer controlled) the RAX downlink. RAX sends each 20 seconds a data packet. Based on the amount of successfully decoded telemetry packets an indication for the “RAX decoding effectiveness” can be derived.
12 elements directional yagi (PE1ITR)
Satellite tracking in steps of <5 degrees (azimuth & elevation)
UHF (437MHz) SSB Electronics pre-amp used for improved SNR
Kenwood TS-2000x, multi-mode transceiver
Frequency control (Doppler compensation) via HamRadioDeluxe
PK96 TNC to decode the 9600 GMSK downlink of RAX
Alogger to initialize the TNC into KISS mode & 9600 baud
RAX GS Client to decode and store & forward the telemetry
1. Radio Amateur satellite ground stations can contribute to space research and science missions
2. Ground Stations (GS) can be made with relative simple, 12 elements, directional antennas
3. In 24 hours 80 telemetry data packets were downloaded
4. During medium and high elevation passes a ground station can achieve >85% ‘RAX decoding effectiveness’
The full report of the RAX Telemetry Reception Experiment is downloadable here as PDF.
November 24, 2010
My Cushcraft 416 antenna was not functioning and Rob, PE1ITR, offered me to borrow his 12 elements antenna:
November 20, 2010
Decoded RAX telemetry during its second day in space:
14:51:08 !CQ*>RAX-1:kgo8Km|eI'bUUD}9`\/ $ L\ ,$ (((X D8#
November 19, 2010
RAX was launched on November 19th, 2010 by a Minotaur 4 / STP-S26 from Kodiak Launch Complex, Kodiak Island, Alaska.