SDRecord

Tool for audio recording with a SDR, tested to work with Gqrx: http://gqrx.dk

SDRecord is able to reduce network traffic, disk space needed for records and record for X specified minutes and/or for X specified MBs of data.

SDRecord drops UDP packets coming from Gqrx that do not contain any data ( data payload is 0 ) and sends in output ( on stdout or to a file and/or to a remote host ) only packets containing information.

Usage and Options

Usage:

usage: java SDRecord [options]
 -d <arg>   Remote UDP port, to use with -r option
 -f <arg>   Output file where to save the recording
 -h         Print help and exit
 -l <arg>   Bind to a specific local IP address, DEFAULT: 0.0.0.0 (all)
 -m <arg>   Minutes to record, DEFAULT: no limit
 -p <arg>   Local UDP port to use, DEFAULT: 7355
 -r <arg>   Remote IP address where to send data
 -s <arg>   MBs of data to record, DEFAULT: no limit
 -v         Print SDRecord version and exit

NOTE: When is not specified an output file or a remote host, data is written on stdout.

Windows users alert!

This tool makes use of ANSI escape characters for text color and cursor position, Microsoft Windows OSs are not compliant with this standard.

For these users I suggest to use others terminal emulators, like Cygwin.

Putting all together

Clone the repository using git or download it manually.
Unzip the repository and compile the java code (requires JDK to be installed) ignoring warning messages: andrea@Workstation:~/Downloads/SDRecord-master$javac SDRecord.java
Launch Gqrx enabling stream audio over UDP (default port 7355) setting squelch to eliminate noise.
In a terminal window, execute SDRecord (requires JRE to be installed):
andrea@Workstation:~/Downloads/SDRecord-master$java SDRecord [options]

Audio spec from Gqrx

The streamed audio has the following specifications:

Channels: 1 (left)

Sample rate: 48 kHz

Sample format: 16 bit signed, little endian (S16LE)

Examples

Recording in a file with no limit:

andrea@Workstation:~/Downloads/SDRecord-master$ java SDRecord -f audiofile
INFO: Listening /0.0.0.0 on port 7355
345.9 KB transferred	 Press Ctrl+c to terminate

Recording in a file for a max of 10 MB:

andrea@Workstation:~/Downloads/SDRecord-master$ java SDRecord -s 10 -f audiofile
INFO: Listening /0.0.0.0 on port 7355
345.9 KB / 10.00 MB transferred	 Press Ctrl+c to terminate

Recording for 30 minutes and sending max 50 MB of data to a remote host:

andrea@Workstation:~/Downloads/SDRecord-master$ java SDRecord -m 30 -s 50 -r 192.168.1.105 -d 7356
INFO: Listening /0.0.0.0 on port 7355
1782 seconds remaining
345.9 KB / 50.00 MB transferred	 Press Ctrl+c to terminate

License

Coded by Andrea Dari and licensed under GNU GPL v2.0