[Savonet-users] Detection of 18Hz Signal in Stream to remote control Jingle

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Hello everyone,

i want to have a solution to detect a 2 second 18Hz Signal in a livestream to play out a Jingle over the input signal.
I tried since das to get a solution. Someone told me that it is possible with liquidsoap. 
This is my current siple code (just for testing):

#!/usr/bin/liquidsoap

set("log.file.path", "/var/log/liquidsoap/radio.log")
playlist = playlist("/media/USB/Musik/")
jingle1= single("/media/USB/Musik/jingle.mp3")

url = "https://stream.antenne.de/antenne/stream/mp3"
interlude = mksafe(input.http(url))
security = single("/media/USB/Musik/emergency.mp3")
radio = playlist

radio = fallback(track_sensitive = false, [radio, security])

radio = fallback(track_sensitive=false, [blank.strip(max_blank=1., radio), interlude])

output.icecast(%mp3(bitrate=256,id3v2=true,samplerate=48000),  
  host = "XXXXX", port = 8000,
  password = "XXXX", mount = "radio", 
  radio)

The current url is just for testing the fallback to an other stream if something went wrong. 
How is it possible to detect the 18Hz and play the jingle1.mp if a two second long 18Hz signal is detected (For safety it will be 180degree phase shifted between the Channels). If that would be possible, i would like to have more frequecies ( maybe 20Hz and 22Hz) for jingle2 and jingle3. Is there anybode who can help me?

Best regards

Franz