07-18-2021, 09:07 AM
I got side tracked for a while and wasn't able to work on this for a while. I just flashed the very latest modem firmware to make sure that it is the newest and ran the tests again.
This time, I upgraded the analysis and plotting code to make a fourth subplot that zooms in on the first peak of the frequency comb and increased the default number of samples per segment by 16 times to better resolve the peak. The code also lets one see the plot in a matplotlib gui, which makes it easier for anyone wanting to inspect it closely. The spectrogram is below
![[Image: Freja_Nordsiek_2021_07_18_2G_call_latest...rmware.png]](https://raw.githubusercontent.com/frejanordsiek/pinephone_call_noise_investigation/main/plots/Freja_Nordsiek_2021_07_18_2G_call_latest_modem_firmware.png)
The frequency comb is still there, unfortunately.
With the new subplot and the higher frequency resolution, the frequency comb's base frequency appears to be about 216.65 Hz and is about 0.5-1.0 Hz wide.
This time, I upgraded the analysis and plotting code to make a fourth subplot that zooms in on the first peak of the frequency comb and increased the default number of samples per segment by 16 times to better resolve the peak. The code also lets one see the plot in a matplotlib gui, which makes it easier for anyone wanting to inspect it closely. The spectrogram is below
The frequency comb is still there, unfortunately.
With the new subplot and the higher frequency resolution, the frequency comb's base frequency appears to be about 216.65 Hz and is about 0.5-1.0 Hz wide.
