JTK – Notes and Ramblings Things we have found …


Weather Radio Part 3

Filed under: General,Home Automation,RTL-SDR — taing @ 10:19 am

The weather radio scripts from before had issues. The live stream from the SDR was working but the alerts were never being triggered so further work was needed.

There are now at least two other forks of the original dsame project. From nivex we have some reworking of the main dispatch routine. And from bwarden we have a reworking of the parser.

I have cloned bwarden as the new starting point and merged a portion of the nivex changes. A copy of this version of dsame.py can be found here. Or you can look at my fork on github.

Step 1 was to get the output into a json format without the text. Fortunately, this is pretty much built it. For a test using the sample txt file:

python dsame.py --no-text --json /dev/stdout <sample\ alert/WXR-RWT.txt

This has the added bonus of writing to standard out immediately and not waiting/buffering until process end.

With this working lets try to update dsame.py to output to MQTT. I’m working from a machine that already has Mosquito installed along with the Python paho library.

Let’s try adding a bit to the dsame code. The big piece looks like:

            if mqtthost:
                    import paho.mqtt.publish as mqtt
                    import json
                    data=kwdict(ORG=ORG, EEE=EEE, TTTT=TTTT, JJJHHMM=JJJHHMM, STATION=STATION, TYPE=TYPE, LLLLLLLL=LLLLLLLL, COUNTRY=COUNTRY, LANG=lang, event=get_event(EEE), type=get_indicator(EEE), end=fn_dt(alert_end(JJJHHMM,TTTT)), $
                    mqtt.single('raw/weatherAlert',json.dumps(data), hostname=mqtthost)
                except Exception as detail:

Hopefully he output looks something like this(extra linefeeds added for clarity):

{"LANG": "EN", 
 "organization": "National Weather Service", 
 "end": "07:30 PM", 
 "JJJHHMM": "3650000", 
 "COUNTRY": "US", 
 "PSSCCC": "020103-020209-020091-020121-029047-029165-029095-029037", 
 "seconds": 1800, 
 "PSSCCC_list": ["020091", "020103", "020121", "020209", "029037", "029047", "029095", "029165"], 
 "start": "07:00 PM", 
 "length": "30 minutes", 
 "TTTT": "0030", 
 "location": "Pleasant Hill, Missouri", 
 "date": "Thu Apr  2 20:44:27 2020", 
 "type": "T", 
 "EEE": "RWT", 
 "ORG": "WXR", 
 "MESSAGE": null, 
 "TYPE": "NWS", 
 "event": "Required Weekly Test"}

The new command line to stream and send mqtt looks like:

rtl_fm -f 162550000 -s 22050 -p 14 | tee >(lame --bitwidth 16 --signed -s 22050 --lowpass 3500 --abr 64 --scale 8 -r -m m - - |ezstream -c ezstream.xml) | multimon-ng -t raw -a EAS /dev/stdin | python ~/tg-dsame/dsame.py --no-text --mqtt hostname_here --json output.json
  1. receive from the SDR dongle
  2. split stdin – tee redirects to
    1. lame
    2. ezstream
  3. tee pipes to
    1. multimon-ng
    2. dsame script – sends to
      1. mqtt
      2. json appends to output.json file

A different option to multimon-ng might be minimodem. I claims to convert SAME audio to text and back again.

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