This is a GPS/radio tracker for high altitude balloons. It uses a GPS receiver to determine its position, and a LoRa transceiver to transmit that position to the ground. It is written in C for the Pi Pico microcontroller, using the official C/C++ SDK. The resulting executable code can be downloaded to the Pico using a serial programming/debug cable as described in the Pico C/C++ SDK manual. You will need a means of receiving the telemetry from your tracker. One popular option is the Pi LoRa HAB gateway.
Frequency Range: 134~174MHz
Tx/Rx frequency independent
Channel space: 12.5/25KHz
CTCSS / CDCSS codes
An electronics project for patching together a small APRS transmitter module. The project is largely obsolete and unmaintained but it's good because it talks about the DRA818V radio module, which is pretty obscure.
A general purpose radio frequency transmitter for Raspberry Pi which doesn't require any other hardware unless filter to avoid intererence. It can handle frequencies from 5 KHz up to 1500 MHz. Plug a wire into GPIO pin 4 (hardware pin 7) and it'll broadcast just about whatever you tell it to. Has an installation script. It's recommended that you use a bandpass filter to minimize noise on the air. Works with just about every RasPi (except the B). Has a text based menu to control it. Defaults to 434 MHz (international free ISM band). You can even broadcast spectrogram pictures! Can even do POCSAG to activate pagers!
Pi-based FM Number Station w/ basic Speech Synthesis.
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