Project Homathko is a mission designed to leverage the systems developed for ECOSat-II and adapt them for use in a lower-cost 1U cubesat. Essentially, Homathko operates as a stripped-down version of ECOSat-II, with the following changes:
- Primary scientific payload removed.
- Secondary payload promoted to primary payload.
- Number of battery cells reduced from 8 to 4.
- ADCS removed and replaced with passive magnetic stabilization.
The mission objective is to operate as an amateur radio relay satellite (an OSCAR, or Orbiting Satellite Carrying Amateur Radio). The secondary mission objectives are systems qualification and educational outreach. The primary OSCAR payload will operate as a mode U/V amateur radio repeater, with a 70 cm amateur band uplink and a 2m band downlink. Through use of a custom-designed software defined radio board, the 1U cubesat will be able to simultaneously operate three communications services off a single communications system:
- A narrowband FM voice repeater,
- A QPSK packet-switched mode with forward error correction, and
- A linear transponder.
Orbiting Satellite Carrying Amateur Radio (OSCAR)
ECOSat’s communications system is a highly flexible software defined radio platform developed in-house at the University of Victoria. This allows the satellite to operate as an amateur radio relay satellite in addition to a scientific satellite.
Homathkos communications system operates with a 70cm band uplink and a 2m band downlink (mode U/V). The uplink noise figure is 3 dB and the downlink transmitter power is 2W. Uplink and downlink both use a 192 kS/s quadrature baseband rate at 16 bits per sample, providing excellent dynamic range. This dynamic range allows multiple amateur radio services to operate simultaneously off of one communications system.
Planned amateur radio services are:
- Narrowband FM repeater
- Linear transponder
- 12 kBit/sec packet-switched digital mode shared with experiment data (pi/4 QPSK with soft-decision R=1/2 K=7 convolutional code).
With a combination of high transmit power, good sensitivity, and multiple services, we believe that ECOSat-II will be an extremely valuable addition to the amateur radio satellites currently on-orbit.