Communications

The Communications Team is responsible for the communications link between the satellite and the ground station. This involves various communications components, designing the communication protocol and bit error correction algorithms, creating the link budget to ensure all information can be transmitted and received, and obtaining any licenses required to operate the link. The communications team also coordinates with the other teams to determine what type of data will be transmitted, how much, how often, etc.

The main components of the communications system will be:

  • 2 transceivers

  • 3 antenna (two for satellite, one big dish for ground station)

Transceivers

The current transceivers included in the communications system design are Microhard transceivers; one of which will be on the satellite and the other will be used on the ground station. These transceivers will operate in the S-band range and will be capable of achieving baud rates of around 1.2 Mbps.

S-band transceiver

Antenna

The satellite antennas are Antcom S Band antenna that are mounted to two sides of the satellite. These antenna can transmit and receive signals to and from the ground station.

The ground station antenna will be a high power, large dish antenna to compensate for the low-power components used on the satellites. The current ground station antenna selected will be a Hyptra Ares Series antenna and have a 1.8m dish that will hopefully be mounted to the roof of one of the buildings at the University of Waterloo. This antenna will connect with a ground station computer that will be used to issue commands and receive telemetry.

ground station antenna

Protocol and Bit Error Correction

The protocol selected to be used in the WatSat communications link will be a modified version of the AX.25 protocol used by amateur radio operators. This modified version will use a Reed-Solomon bit error correction algorithm in the place of the standard parity check field in the AX.25 protocol. Given that amateur radio systems are used, communications team members are actively working towards amateur radio licences through Industry Canada.

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