Build an automatic frequency scanner with RTL-SDR and Gqrx
Wouldn’t it be nice to have an scanner that records interesting radio signals automatically? For example you could record whenever people talk on certain frequencies.
Prerequisites:
– You have Gqrx installed (Guide for Armbian here)
– You have an RTL-SDR attached and the sdr drivers are installed (= it works with Gqrx).
Tip: If the Rtlsdr doesn’t work with Gqrx make sure that under File>I/O Devices you have selected “Realtek RTL2838…” (or whatever is your version) and not “Generic RTL2832…”
Installation of Gqrx-Scan
1. In the terminal go to a folder where you want the scanner to be installed.
2. Install Pearl prerequisites
sudo apt-get install libnet-telnet-perl
3. Download the scanner script:
git clone https://gitlab.com/khaytsus/gqrx-scan
4. Open Gqrx and set bookmarks on the frequencies you want to check. CTRL+b opens the bookmark manager.
5. Under Tools click on “Remote control” to enable it and start the reception (play symbol). Play around with the Squelch setting on the right side until you hear the audio clearly (you could start with -40.0db).
6. Now, you can go to the folder with the scanner script
7. There are several options to use it:
A) Switch between your bookmarks every two seconds
./gqrx-scan --type gqrxfile --pause 2
B) Check your bookmarks and stay on a frequency if it receives a signal above a threshold
./gqrx-scan --type gqrxfile --pause 0.2 --wait --delaytime 0.2
C) Record the audio whenever it hears something
./gqrx-scan --type gqrxfile --pause 0.2 --wait --delaytime 0.2 --record
By default it stores the .wav audio file in the home directory. If you have sox installed you can listen to it by typing:
How to Get RTL-SDR to work on Kali Linux
Kali Linux is the successor to Backtrack Linux, a popular digital forensics, security and penetration testing Linux based operating system. YouTube user NeedSec has posted a video tutorial on how he got his E4000 rtl-sdr dongle working with GNURadio and Gqrx on Kali Linux.
Related posts:
The link provided says its a private video.
Unfortunately it seems to have been removed by the uploader, as well as all of his other content.
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Packages and Binaries:
A cross platform Python frequency scanning GUI for the OsmoSDR rtl-sdr library.
The scanner attempts to overcome the tuner’s frequency response by averaging scans from both the positive and negative frequency offsets of the baseband data.
Installed size: 2.46 MB
How to install: sudo apt install rtlsdr-scanner
- python3
- python3-ipdb
- python3-matplotlib
- python3-numpy
- python3-pil
- python3-rtlsdr
- python3-serial
- python3-visvis
- python3-wxgtk4.0
rtlsdr-scanner
[email protected]:~# rtlsdr-scanner -h RTLSDR Scanner usage: rtlsdr_scan.py [-h] [-s START] [-e END] [-w SWEEPS] [-p DELAY] [-g GAIN] [-d DWELL] [-f FFT] [-l LO] [-c CONF] [-i INDEX | -r REMOTE] [file] Scan a range of frequencies and save the results to a file positional arguments: file Output file (.rfs.csv, .plt, .m or .sdb2) options: -h, --help show this help message and exit -s START, --start START Start frequency (MHz) -e END, --end END End frequency (MHz) -w SWEEPS, --sweeps SWEEPS Number of sweeps -p DELAY, --delay DELAY Delay between sweeps (s) -g GAIN, --gain GAIN Gain (dB) -d DWELL, --dwell DWELL Dwell time (seconds) -f FFT, --fft FFT FFT bins -l LO, --lo LO Local oscillator offset -c CONF, --conf CONF Load a config file -i INDEX, --index INDEX Device index (from 0) -r REMOTE, --remote REMOTE Server IP and port