The perl scanning script required Net::Telnet, which we realized when we finally specified the command. We defined a csv file with the frequencies we want to scan–then by specifying the path to the file and running the code below, the gqrx scan script finds the frequency with the most activity and records when the signal strength surpasses a certain level. We allowed more noise in gqrx than we defined in gqrx-scan (so a recording is harder to trigger). Still, we noticed that we occasionally just get recordings of static. Also, moving the SDR seems to affect the levels.
$ perl gqrx-scan –type file –pause 2 –delaylevel=-34 –delaytime 5 –record –monitor
Used the virtualenv instructions from surveillance & society class last semester. I think Twilio’s documentation might be out of date. I started following their instructions at the requirements.txt section.
Started sample code for simply sending an SMS and experimented with triggers that Twilio already had examples for (sends administrators a text when you hit an error page). To demonstrate how our app would function, we want to try to send a text when a file is saved (to the pi, or to the server, for example).
We think a fully working prototype will incorporate all of these elements:
SDR with Raspberry pi -> scan with gqrx scan -> digital speech decoder -> output file -> incron job -> if new file, then trigger twilio
We are working to get as many of these components working on Raspberry Pi as possible, to be able to demonstrate how it would work.