gnuradiotips
Differences
This shows you the differences between two versions of the page.
| Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
| gnuradiotips [2021/09/13 21:53] – [Working with bits and bytes] mm3iig | gnuradiotips [2021/09/13 22:27] (current) – [Using Baseband I/Q Recordings] mm3iig | ||
|---|---|---|---|
| Line 11: | Line 11: | ||
| Depending on the specifics of your recording you may need to change bits of this. You’ll want to use a WAV file sync, set the channels to two, and then immediately convert from float to complex to do useful things with the data. Then you’ll want a throttle block to set your desired sample rate. If you have recordings in a format other than RIFF 16-bit stereo you may need to add extra conversion steps into your flowgraph, or convert your input file first with other software. | Depending on the specifics of your recording you may need to change bits of this. You’ll want to use a WAV file sync, set the channels to two, and then immediately convert from float to complex to do useful things with the data. Then you’ll want a throttle block to set your desired sample rate. If you have recordings in a format other than RIFF 16-bit stereo you may need to add extra conversion steps into your flowgraph, or convert your input file first with other software. | ||
| - | If your chosen signal is in the middle of the baseband, you’re done! If it isn’t, you will need to “tune in” to the signal with a Frequency Xlating FIR or FFT Filter first. | + | One thing you will have to look out for is the 4 GB wav file size limit in GNU Radio. WAV File Source blocks use the metadata of the file which can only store a maximum value of of 4 GB in its 32-bit size variable. Other apps can store more in a WAV container by reading file size information directly |
| - | + | ||
| - | One thing you will have to look out for us the 4 GB wav file size limit in GNU Radio. WAV File Source blocks use the metadata of the file which can only store a maximum value of of 4 GB in its 32-bit size variable. Other apps can store more in a WAV container by reading file size information directly | + | |
| To get around this you can use a tool such as sox to chop up your file into smaller chunks. You can estimate using different times and see if you get the chunk sizes you want - the following command will continue to make chunks of the chosen mm:ss length until there’s no more data and iterate a number after the outfile name: | To get around this you can use a tool such as sox to chop up your file into smaller chunks. You can estimate using different times and see if you get the chunk sizes you want - the following command will continue to make chunks of the chosen mm:ss length until there’s no more data and iterate a number after the outfile name: | ||
| Line 20: | Line 18: | ||
| For RF64 WAV files you can use a File Source followed by an iShort to Complex to effectively skip the header and send out valid data. | For RF64 WAV files you can use a File Source followed by an iShort to Complex to effectively skip the header and send out valid data. | ||
| + | |||
| + | If you’ve got the opposite issue - a bunch of smaller basebands that need joining together, you can try: | ||
| + | |||
| + | **sox --ignore-length infile1.wav ... infile[n].wav outfile.wav** | ||
| + | |||
| + | After all of that: if your chosen signal is in the middle of the baseband, you’re done! If it isn’t, you will need to “tune in” to the signal with a Frequency Xlating FIR or FFT Filter first. | ||
| ===== Adding, Subtracting, | ===== Adding, Subtracting, | ||
| Line 34: | Line 38: | ||
| ===== Useful Flowgraphs ===== | ===== Useful Flowgraphs ===== | ||
| - | Add a list of useful GRCs with explanatory text here. You can build your own projects off these. | + | Add a list of useful GRCs with explanatory text here. You can build your own projects off these basic ideas. |
| To be added: | To be added: | ||
| Line 42: | Line 46: | ||
| * NFM Modulation | * NFM Modulation | ||
| * NFM Demodulation | * NFM Demodulation | ||
| - | * Broadcast | + | * WFM Stereo Modulation |
| + | * WFM Stereo | ||
| * QPSK Modulation | * QPSK Modulation | ||
| * QPSK Demodulation | * QPSK Demodulation | ||
| * BPSK Modulation | * BPSK Modulation | ||
| * BPSK Demodulation | * BPSK Demodulation | ||
gnuradiotips.1631569986.txt.gz · Last modified: by mm3iig