Scripts, Python modules and GNU Radio companion examples for measuring the reception power of an antenna during rotation, and for doing the necessary off-line analysis to produce antenna diagrams.
The code here is described in a blog post, https://www.la1k.no/2018/05/16/using-gnu-radio-and-hamlib-to-calculate-antenna-diagrams/.
Use measure.py in measurement subdirectory to sample IQ data while
simultaneously logging antenna angles to file. See README.md in that folder
for more details. Let the script run continuously while turning the rotor.
Use combine_samples_and_angles.py to combine samples/power estimates produced
using GNU Radio with the above angle measurements. See docstring of
combine_samples_and_angles.py for more details.
For time-varying, periodic morse signals, see docstring of cw_extraction.py for extracting of the high signal levels only.
Its behavior is described in:
- https://www.la1k.no/2018/06/27/extracting-the-antenna-pattern-from-a-beacon-signal-pt-i-initial-investigations-using-autocorrelation/
- https://www.la1k.no/2018/07/04/extracting-the-antenna-pattern-from-a-beacon-signal-pt-ii-measurements-of-la2shf/
- https://www.la1k.no/2018/08/01/extracting-the-antenna-pattern-from-a-beacon-signal-pt-iii-frequency-analysis-and-code/
See also probabilistic_signal_extraction.py for a basic probabilistic approach. Its behavior is described in https://www.la1k.no/2018/08/08/extracting-the-antenna-pattern-from-a-beacon-signal-pt-iv-probabilistic-approach/.