The goal of the gr-sql project is to bring some SQL-like SELECT capabilities to GNURadio to facilitate working with smaller portions of large recorded files. For instance if you recorded 10 minutes of data and only want to extract the first 2 minutes, or minutes 7-8.
gr-sql provides this capability as both a native GNURadio source block where the SQL syntax can be used to query the original file, as well as a command-line tool (grsql) that can be used to extract and save sub-portions to separate files. The command-line tool also provides a query option to get the total time length of a recording given the sample rate and data type.
The syntax is very straightforward: SELECT [* | I | Q | TIMELENGTH] FROM '' ASDATATYPE [COMPLEX | FLOAT | INT | SHORT | BYTE | HACKRF (alias for SIGNED8) | RTLSDR (alias for UNSIGNED8) | SIGNED8 | UNSIGNED8] SAMPLERATE [STARTTIME ENDTIME ] [SAVEAS '']
Notes:
- The sample rate can be specified in either the 6200000 or 6.2M format
- Start and end time are relative to the beginning of the recording as t=0
- If no end time is specified, the end of the file is assumed
- SELECT I and Q only apply to COMPLEX data type
- If using the command-line tool and running TIMELENGTH, SAVEAS is not required (it'll just print it to the console)
- If using the flowgraph source block, SAVEAS and TIMELENGTH are not available (didn't make sense to save or just get time from a flowgraph)
- There is an sample flowgraph under examples. You'll just need to update the SQL with an appropriate filename and sample rate.
- If you're using a hackrf and record directly with hackrf_transfer, you can use that file directly (specify hackrf or signed8 as the type). SAVEAS will automatically convert it to float32 for use with gnuradio.
- If you're using an rtlsdr and record directly with rtl_sdr, you can use that file directly (specify rtlsdr or unsigned8 as the type). SAVEAS will automatically convert it to float32 for use with gnuradio.
- For both hackrf and rtlsdr recordings, you can use the flowgraph block directly to read those files since it auto-converts to gnuradio's float32.
Command-line Examples: Get the total time length of a recording:
grsql "select TIMELENGTH FROM '/tmp/myrecording_593MHz_6.2MSPS.raw' ASDATATYPE complex SAMPLERATE 6.2M"
Select the recording sample from 45.2 to 80.0 seconds into the recording and save it in a new file:
grsql "SELECT * FROM '/tmp/myrecording_593MHz_6.2MSPS.raw' ASDATATYPE complex SAMPLERATE 6.2M STARTTIME 45.2 ENDTIME 80.0 SAVEAS '/tmp/extracted.raw'"
Select just the I channel from the entire complex stream:
grsql "SELECT I FROM '/tmp/myrecording_593MHz_6.2MSPS.raw' ASDATATYPE complex SAMPLERATE 6.2M STARTTIME 0.0 SAVEAS '/tmp/extracted.raw'"
Convert entire hackrf_transfer (signed 8-bit format) to gnuradio float IQ stream:
grsql "SELECT * FROM '/tmp/myrecording.raw' ASDATATYPE HACKRF SAMPLERATE 10M STARTTIME 0.0 SAVEAS '/tmp/extracted.raw'"
Convert entire rtl_sdr (unsigned 8-bit format) to gnuradio float IQ stream:
grsql "SELECT * FROM '/tmp/myrecording.raw' ASDATATYPE RTLSDR SAMPLERATE 2.048M STARTTIME 0.0 SAVEAS '/tmp/extracted.raw'"
Note: for hackrf/rtlsdr in the gnuradio flowgraph block you can go straight from the signed/unsigned file to output complex to save the conversion step. Also, because on hackrf/rtlsdr processing each sample needs to be processed, expect this to take some time to run through.
Building is the standard approach:
cd
mkdir build
cd build
cmake ..
make
[sudo] make install
sudo ldconfig
If each step was successful (do not overlook the "sudo ldconfig" step).