I recorded a signal with GNU Radio using a file sink block which outputs a raw binary file that can be analyzed or used as a source of input into GNU Radio.
I want to edit this raw file so that when I use it as a source inside GNU Radio it transmits my changed file instead of the original. For example: The signal is very long and repeats a pattern, I want to edit the file to reduce the number of repeated signals and save it back to the raw format to transmit using gnuradio later.
I tried importing the file into Audacity as a raw file (selecting 32bit float with 1 channel and 48k as the sample rate). This works for me to see the signal as audio data and I can even edit it but I'm not sure if it's saving it correctly when I export it as raw data. Also, the time indices in audacity seem to be way off; the signal should only be microseconds but audacity is showing it as a total of several seconds!
Anyone have any luck with editing the raw file sink output from GNU Radio?
I was able to consistently make this work. There seemed to be 3 things preventing this from working properly.
1) I was doing it wrong! I needed to output both the Real and the Imaginary numbers to a 2 channel wav file.
2) Using a spectrum analyzer, I was able to see that audacity was doing something really weird with the wav file when you delete a section of audio, so to combat this I "silenced" the section of audio I wanted to delete.
3) There seems to be a bug with Gnuradio and the Osmocom Sink (yes, I have the latest version of both, from source). If you run your flow graph, start transmitting then stop the flow graph by clicking the red X in Gnuradio (Kill the flow graph) it keeps my device (HackRF) transmitting! If you try to transmit a new file or the same file again, it will not transmit that signal because it's already trying to transmit something. In order to stop the device from transmitting, just close the block popup window that appears when you run the flow graph.
The 3rd item might not be a bug because I might have been stopping my flow graphs incorrectly to begin with, but following Michael Ossmann's tutorial on using the HackRF with Gnuradio, he says to click the red X to properly shutdown the flow graph and clean everything up; this appears to NOT be the case.