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High level architecture of transceiver. Core components are:
Microcontroller: Receives/sends data to rest of system via I2C, CAN, UART or SPI using CSP (CubeSat Space Protocol) or whatever system CDH wants to use.
Transceiver/Receiver or Transceiver for modulating or demodulating data. Most likely operating in the UHF Amateur (430 - 440 MHz) band.
Power Amplifier to boost signal from transmit. Usually around 1-3W for CubeSats. Probably needs heat sinking.
30% efficiency (the higher the better)
Low Noise Amplifier is used to boost the received signal.
The RF switch is used to switch between transmit and receive modes. This configuration means that our system will be half-duplex (either receive or transmit, but not both at the same time).
Some kind of PI filter is is common on the Tx side, along with band-pass filtering on the Rx side.
Extra circuitry can include an SD card or QSPI Flash to store data, a temperature sensor to monitor power amplifier temps, etc.
Shielding is necessary especially over high speed signals. Typically the entire transceiver is enclosed in an aluminum box, alternatively just sensitive equipment can be enclosed. A sufficiently thick aluminum shield/heatsink can be used to help cool the power amplifier and minimize damage from radiation.
Challenges:
Software: I don't know what software would look like. I'm assuming data is communicated between chip and MCU over SPI or similar. Modulation scheme, data rate, etc also configured via spi or similar. I don't think software will be too challenging, if we can write the software to control a COTS transceiver, I don't think a custom one will be too much worse.
Radiation/Redundancy: Aluminum shielding should protect against TID, but not sure what if any additional redundancy can be included?
Complexity: It's a moderately challenging board, mainly because of all the RF stuff. Definitely not something for a beginner to work on.
References: Alberta Sat: https://github.com/AlbertaSat/ex2_apollo_uhf_transciever_hardware https://albertasat.ca/open-source-designs/open-source-designs-currently-in-development/
Research Articlehttps://downloads.hindawi.com/journals/ijae/2019/8174158.pdf
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