Replay

In order to clearly see my screen during the demonstrations, viewing the video in full screen mode may help. Even better: You can download this video in high resolution (720p). (torrent)

In this Lesson

• being a good neighbor on the spectrum
• QT vs. WX GUI in GNU Radio
• saving a waveform to file
• inspectrum
• transmitting
• replaying a captured radio signal
• using multiple HackRF Ones
  
  

Homework

1. Capture a radio signal and save it to a file with hackrf_transfer ( Hint: use the -r option).

2. Convert the file from unsigned 8-bit integers to 32-bit floats. This can be done with:

   sox foo.s8 foo.f32

   or:

   cat foo.s8 | csdr convert_s8_f > foo.cfile

   or with convert_s8_cfile.grc.

3. Analyze the file with GNU Radio Companion and/or inspectrum to verify that you captured your signal of interest.

4. Determine how many distinct sample values are present in your signal. (Hint: The number should be no more than 256.)

5. How many bits of dynamic range does your signal span. (Hint: take the base 2 logarithm of the number of distinct sample values.)

Resources

• inspectrum, software used to produce the spectrogram in this lesson. The latest bootable release of Pentoo Linux includes inspectrum.
• the lesson 11a flowgraph: lesson11a.grc
• the lesson 11b flowgraph: lesson11b.grc
• a flowgraph that converts complex signed integers to complex floats: convert_s8_cfile.grc

Software Defined Radio with HackRF is copyright 2014, 2015 by Michael Ossmann and is released under the CC BY license.