The plane watcher is our attempt at creating a hardware-based ADS-B receiver and decoder. It is a hat/cape/shield for a HelloFPGA Smart ZYNQ SL board.
The goal of the project is to make a reasonably priced yet high quality ADS-B receiver for hobbiests, that achieves high MLAT accuracy by including GPS timing and message decoding in hardware.
We are currently working on our first prototype. This is not yet ready for use. We don’t know if it works yet…
The design consists of these parts:
The signal from the antenna is amplified and filtered using two stages of LNA amplification and SAW filters centred on 1090MHz.
The amplified and filtered RF signal is fed into a log detector. This device shows the RF power level. With an oscilloscope on the output of this device, we can read the raw ADS-B pulses and decode them by hand.
The pulse output is fed into an analog to digital converter (ADC) through a differential driver. This allows digital sampling of the pulses.
The FPGA contains bytecode to perform the ADS-B decoding via discrete logic blocks. The FPGA decodes the pulses sampled by the ADC and decodes into usable ADS-B messages.
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add GPS module to board.Added in proto 1.2. -
re-spin board so RF conectors both on same side.
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check if the ADC digital supply can operate from FPGA’s 3V3 supply to further reduce noise on the LT3045-1 supply.
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check test points when prototype is returned, to ensure voltages and expected signals are correct.
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if signal is too hot on prototype, consider fitting pi pad parts.
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VNA front end to determine if additional tuning required.
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Front panel
- Use PCB for this, using silkscreem and down-firing LEDs
- LEDs: Kingbright AAA3528RBGS/08-09
- LED Driver / GPIO Extender: TCA9535
- Reverse mount button
- “1.09 GHz Mode-S Receiver Design and VHF Radar Antenna Characterization”, Senior Thesis in Electrical Engineering, Dabin Zhang.
- Project “ADS-B Receiver and Decoder” presentation by Günter Köllner, DL4MEA.
- “Dickbutt” appears courtesy of K.C. Green. RF performance gains are unverified.
Public licence: CERN-OHL-S-2.0
Commercial carve-out: Companies that want different terms can enter a separate commercial agreement.
TL;DR: If you are happy to keep your changes open, use the public licence. If you want private modifications, proprietary integration, or some other commercial arrangement, talk to us.
This repository may include third-party datasheets, application notes, and technical documentation.
Such materials remain the copyright of their respective owners and are included solely to assist development and interoperability of this project.
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