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Update v0.2



consists of two parts:

, which scans the RF spectrum with rtl_power and records what it finds in a database table


, and a modified rtl_fm that outputs to database table


. The modified rtl_fm, like the regular rtl_fm, supports scanning multiple frequencies with squelch.

Combined, these two tools let you keep tabs on

and document

the airwaves. Here's the configuration file. Notice it's configured to use three rtl-sdr sticks as scanners:

You can look at the output by connecting to the sql server:

Or by using something like Splunk. Splunk can be used to find trends in the data and let you know when something changes, for example. You could get a baseline for a general area, then move on to a target of interest's location and see what pops up that wasn't there before... will run until you interrupt it, your database fills up, or something bad happens.

The modified rtl_fm works like the regular rtl_fm, except that it outputs to the database you specified in freqwatch.conf. All the cool features of rtl_fm are available to help you sort out the data you want.


Extract data from the intercept database to a file, so you can process (e.g. listen to) it: select data from intercepts where freq=95955000 order by date, time into outfile "dbout" fields escaped by ''; This method has problems.

Instead, use the

program that comes with freqwatch to get data from the monitor table.

Here's how you might play it if it's WBFM audio:

cat file | play -t raw -r 32k -e signed-integer -b 16 -c 1 -V1 -


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