For your amusement, here are two boards from my buoy project: A controller board and a power amplifier. The controller contains the GPS, SAMD processor, Si5351 clock chip, and power-control circuits. It sends 10 MHz (+/-) digital to the "power" amplifier (1W Class-E).
What exactly does the bouy project do? I know what a bouy is and that your transmitting a signal, but for what purpose? Are you wanting to track a bouy let go in the ocean? I tried searching on the forum under your name for "bouy" and it returned nothing ( but I suppose for this forum software that shouldn't be a great surprise ).
The buoy does whatever strikes my fancy if I ever finish it. I retired about 20 years ago, but still spend hours most days playing with electronics and related stuff. I like solving problems. I live on an island in the Salish Sea (between Vancouver Island and the Washington State mainland, and I occasionally sail to Hawaii and back, so designing a telemetry / beacon buoy sounded like a fun problem.
And it was! It lead me along many paths and ratholes, led me to upgrade my tools, design new measurement gear, get my hands dirty with stuff I'd only known in theory. I decided to include multiple communications modes within the 30 meter ham band (10.xxx MHz) so I got to lean the protocols (usually a combination of reviewing the source code, and the published specs).
At the moment the buoy will measure position via GPS, temperature, and some internal voltages. I *may* add a 3-axis accelerometer, gyroscope, and magnetometer to try to measure seastate and wind, but that's a big problem that may drag on longer that I have patience for -- I have given myself permission to put down any project if I lose interest (one of the joys of it being a hobby rather than a job).
There are "rules" issues regarding telemetry on the HF ham bands, but if I call it a propagation study beacon, keep the power and the transmit duty-cycle low, and don't trespass in the more popular sections of the bands I figure I can avoid serious prison-time. The whole buoy fits into a short section of 2" PVC pipe, with a very short (and inefficient, perhaps -20dB) antenna. Two small 1W solar panels will provide plenty of power.
Here's a PDF presentation I gave to the local ham club that mentions the buoy:
http://wb6cxc.com/?attachment_id=86I also discuss it a bit in a presentation I gave at the 2021 MicroHAMS conference (I'm Paul Elliott, WB6CXC):
https://www.mhdc.live/presentation-archive/2021-conference Warning: I do go on and on...