VIOLET's radio-info

VIOLET's permanent web address (unb.ca/cubesat-radio-info) is redirected to this page which the public and SatNOGS will use to access technical information regarding the radio interface and description of the protocols.

That permanent web address was documented with the Radio Amateurs of Canada (RAC); that address was also be sent to Innovation Science and Economic Development Canada (ISED) / Government of Canada, the International Amateur Radio Union (IARU) and the International Telecommunication Union (ITU).

Project description

CubeSat VIOLET is approximately 10 cm by 10 cm by 20 cm and VIOLET is named after the purple violet, the floral emblem of the province of New Brunswick.

VIOLET was designed, built, and tested, by the students in CubeSat NB, a first-of-its-kind partnership among the New Brunswick Community College, the Université de Moncton and the University of New Brunswick. CubeSat NB is one of the 15 teams in the Canadian CubeSat Project, inspired by the Canadian Space Agency. 

CubeSat NB’s primary goal is student education and nearly 300 students have contributed to VIOLET's development.

VIOLET's mission

VIOLET's mission is to study space weather, stabilized under passive magnetic attitude control, with hysteresis rods, in low Earth orbit, near the peak of the eleven-year solar cycle, obtaining the voltage and current from its four photovoltaic panels, and two internal temperature sensors.

Radio licence type

VIOLET is planned to transmit only when it is near the Earth station at the University of New Brunswick, Fredericton, in response to an authenticated and encrypted uplink command. Scientific data is planned to be downloaded. VIOLET's radio licence is developmental/amateur radio; VIOLET is not an amateur radio sateliite.

Frequency coordination and radio licensing

• On March 9, 2021, we received a frequency coordination document from the International Amateur Radio Union (IARU) for VIOLET.
• With the International Telecommunication Union, an application was made.
  • On June 29, 2023, an Advanced Publication of Information, Notification A, API/A for VIOLET, was submitted.
  • On August 22, 2023, API/A was published.
  • On February 6, 2024, API/B was published.
• VIOLET does not presently have a NORAD catalog number, but an application is being planned.
• With Innovation Science and Economic Development Canada, radio Licenses were issued based on
• CPC-2-6-02, Development/Amateur Radio, licence number 011016827-001 and
• CPC-2-6-01, Developmental Spectrum Licence, licence number 011027277-01, with a site approval, approval number 011027974-001 and a call sign VF907.

VIOLET's hardware

VIOLET uses the following two commerically manufactured boards,

• The ISISspace TRXVU, a UHF transmitter, and a VHF receiver, and
• The ISISPace CEPS, Type C. Rev. E, compact electrical power supply.

VIOLET's on-board computer is a custom design.

Downlink physical-layer parameters

The technical downlink parameters are:

• carrier frequency of 436.830 MHz,
• 25.36 dBm EIRP,
• effectively a 2.1 dB dipole antenna gain in VIOLET, but VIOLET has passive magnetic attitude control and over its Earth station, would have similar attitudes and would rotate around the magnetic field,
• BPSK modulation at 9600 bits/second,
• 0.5 roll-off-factor with raised-cosine pulse shaping,
• emission designator 15K0G1DAN,
• 15 kHz bandwidth,
• G3RUH scrambling polynomial x¹⁷+x¹²+1,
• NRZ-I encoding, and
• AX.25 downlink packets, described next.

Downlink AX.25 packet format

• In response to one encrypted-and-authenticated uplink packet, VIOLET will transmit 25 AX.25 downlink packets.
• Each downlink AX.25 packet has:
  
  •  connectionless and UI frames,
  • a source call sign VE9VLT-1,
  • a destination call sign VE9CNB-1, and
  • 243 bytes from a
    
    • 16 byte header, and
    • 227 bytes of data.

Downlink data format

The 227 bytes of downlink data contain data from the electrical power supply and the RF transceiver.

• Counter buffer index, 2 bytes
• Counter next id, 4 bytes
• Counter next iv, 4 bytes
• Electrical power supply, 177 bytes
  • Power integrated unit (PIU) status, 1 byte
  • PIU software version number, 1 byte
  • PIU response code, 1 byte
  • PIU board identifier, 1 byte
  • PIU reserved, 1 byte
  • Voltage on board supply, 2 bytes
  • and so on.
• RF transceiver, 40 bytes
  • Uptime, in s, 4 bytes
  • Transmitter instantaneous RF reflected power, in ADC units, where it could be converted later to dBm using 20 log10(0.00767 * ADC), 2 bytes
  • and so on.

VIOLET's launch and deployment

• The launch of VIOLET was on March 21, 2024, from the Kennedy Space Center to the International Space Station (ISS).
• The docking of the SpaceX Dragon with the ISS was on March 23, 2024.
• VIOLET is part of the NRCSD27/SpX-30 Deployments, very likely on April 18, 2024, at 17:55 UTC. Three 2U CubeSats will be deployed:
  
  • KIllick-1 first,
  • QMSAT, second and
  • VIOLET would be the last one out of the deployer.
• In the first week after deployment, VIOLET's orbit will be similar to the ISS,
  
  • apogee 408 km,
  • perigee 403 km,
  • orbit inclination 51.6 degrees and
  • orbital period of 92.7 minutes.
• The orbit will decay quickly after three to six months near the peak of the eleven-year solar cycle.

CubeSat NB Earth station

At this time, the planned CubeSat NB Earth station

• is located at coordinates, WGS84:
  • 45.94994 N, -66.64249 W,
  • 45°56′59.8″ N, 66°38′33.0″ W,
• would have an azimuth-elevation rotator with a 1 degree pointing accuracy,
• a UHF right circularly polarized 15.5 dBic Yagi-Uda antenna, and
• includes SatNOGS 3044 - UNB Fredericton Canada which may use different antennas.

Uplink command and control

• cubicrypt is used for encryption and authentication, where required for communication to VIOLET and control of VIOLET.

Status of VIOLET

• VIOLET was deployed into space from the International Space Station on April 18, 2024. These were the last three CubeSats from the Canadian CubeSat Project. The first CubeSat out of the deployer was Killick 1, followed by QMsat, followed by VIOLET.
• Of the 15 teams in the Canadian CubeSat Project, 14 made it to space. Of the 14 in space, to our knowledge, only one team was successful in making regular radio communication with their CubeSat, ORCASat from the University of Victoria; we welcome further information and could provide links here.
• No radio messages were received from CubeSat VIOLET, depite transmitting millions of uplink commands. As they say, space is hard.
• Of those three Canadian CubeSats that were deployed on April 18, the last one's orbit decayed on September 17, 2024.

Acknowledgements

We thank the local amateur radio community for their support, providing equipment, and loaning equipment. including:

• three VHF cavity filters from Ron, VE1KO, 
• a solid state VHF amplifier, from Richard, VE9VHF,
• a Mirage B-2518-G VHF amplifier, from Don, VE9ZP, and 
• a Henry Tempo 2N6 VHF amplifier, from Dave, VE3KG.

Amateur radio activities at the University of New Brunswick

Some activities are documented at

• the VE9UNB amateur radio news page,
• the general UNB amateur radio website and
• a recent highlight was contact with the AO-92 amateur radio satellite, an event co-sponsored with the IEEE-UNB student branch.