This implementation uses only a few pieces of open source programs. OpenHAB, mqtt mosquitto, and rtl_sdr . I originally planned to use GNU Radio but when I tried to run it on my RPi it kept throwing segment faults. So then I tried SoapySDR, PothosSDR, liquid-dsp, and probably a few others. I found I just couldn't get them to do what I needed. I estimate I spent over 100 hours grinding myself into the ground. I even had some very knowledgeable advice from a few people but I couldn't make all the right things happen. So I decided to do everything myself.
The program 345MHz sends a command to the RTL-SDR dongle,
rtl_sdr -f345000000 -s250000 -g49.0 /dev/shm/stream
which tunes it to 345MHz, sampling at 250k/s and writing to the file /dev/shm/stream. I hope this file is in RAM and not on the SD card. I don't want to beat the tar out of my SD card.
bytes2mag.c does the filtering. I designed a 61 tap FIR filter and read the tap weights from TapsFIR.flt at startup. bytes2mag.c then applies the filter to the contents of stream continuously and creates the filtered "mag" samples.
mag2word.c then takes the mag samples and processes them to synchronize with the manchester data stream. It forms the WORD (see message structure) sent by the sensors and detectors.
word2sensor.c attempts to associate the WORD with a sensor (or detector) by searching the file WORD2Action.csv.
publish.c will publish the device and action as designated by WORD2Action.csv