ADSBee: ADS-B and UAT Reception and Decoding On an RP2040 Microcontroller
ADSBee is an open-source project that has implemented a 1090 MHz ADS-B decoder on a Raspberry Pi RP2040 microcontroller using a programmable I/O (PIO) pin.
PIO pins cannot handle RF signals, so the ADSBee front end is a critical analog circuit that enables this to work. It consists of a 1090 MHz SAW filter to remove other signals, a low-noise amplifier, and, critically, a log-power detector, which essentially converts the pulse-position-modulated 1090 MHz ADS-B signal to baseband, which the PIO can handle.
However, this same trick does not work for 978 MHz UAT, as UAT signals are not pulse position modulation like ADS-B. Instead, for UAT support, the ADSBee design takes a more traditional approach, using a CC1312 sub-GHz transceiver chip connected to the RP2040.
Finally, an ESP32 S3 is added to the stack to enable networking via WiFi, allowing for received and decoded data to be used.
The project is entirely open source on their GitHub, apart from some of their commercial PCB designs. They also have a store, where they sell pre-made kits. A kit consisting of the ADSBee, 1090 MHz Antenna, and 978 MHz costs US$152in total. They are also selling an industrial model for $995, which includes PoE power.
