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RTTY Decoding with the SI4732 Mini Radio

Shortwave listening is enjoying a revival thanks to affordable DSP radios like the SI4732 Mini Radio. With a single-wire modification and specialized firmware, even weather reports broadcast in RTTY by the German DWD can be decoded on the device's display. The hardware mod simply connects the ESP32's ADC pin to the audio amplifier output, optionally improved with a basic low-pass filter.
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Advanced firmware by H. J. Berndt adds multi-line RTTY display and Morse code decoding, making full use of the ESP32's resources. Installation is straightforward using a web-based flashing tool, and detailed instructions are available. To decode DWD reports on 147.3 kHz (DDH47), set the radio to LSB, bandwidth 2.2 kHz, and select the RTTY decoder mode—fine-tuning helps lock onto the RY test signals. Additional frequencies for maritime weather reports are programmed with the presets.

The SI4732 Miniradio, widely available for under €35, continues to benefit from community-inspired hardware and software improvements. More information, practical tips, and documentation for firmware and modifications are provided in the original blog post:

Read the original post: 
https://peterneufeld.wordpress.com/2025/09/19/the-one-wire-wireless-weather-report/

The firmware
https://translate.google.com/translate?sl=de&tl=en&u=http://www.hjberndt.de/dvb/pocketSI4735DualCoreDecoder.html