This is a proof of principle project to decode wireless weather sensors with simple modules and Raspberry Pi. Currently it only supports the Alecto WS 1200. As the reciver decodes the frequency, it should work with 868Mhz as well as 433Mhz depending on the reciver used. The Raspberry Pi does not handle any high frequency decoding and just reads the signal on one pin 10000 times a second. In principle it could work for any frequency if decoders are available and the output signal is digital. Cheap modules supporting on/off keying (OOK) modulation are available. The code only requires the WiringPi library. It consumes low energy and creates low processor load.
The transmitter can be used to send an identical signal, which can be recorded with an SDR:
rtl_fm -M am -f 433.9M -s 10k > rtl.dat
And visualized with audacity (import raw data, Signed 16 bit PCM, Little-endian and Mono). The station displays do not respond to the signal yet, probably due to the low amplitude.
The whole idea and the basic source code were inspired by the TempHygroRX868 project from Martin Kompf. I also really enjoy his web page.
The hardware setup is identical to rpi-rf, I also use the same sensors and wireing of the sensors and Raspberry Pi, but no code was used. It inspired the idea to send data back to the display.
A great project to deal with weather sensors is rtl_433.
Many thanks to Benjamin Larsson and especially to Christian W. Zuckschwerdt for their support decoding the Alecto WS-1200 signals.
Now I am still left with SDR for the TFA KLIMALOGG...pro sensors.
Copyright 2018 Andreas Untergasser
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
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