too noisy signal on frequency between 2k-7kHz

[pixtop]

Hello, I'm trying to use amodem, but I'm encountering issues with the calibration process.

It appears that the calibration fails to achieve a value above 0.99 for frequencies between 2kHz and 7kHz, whereas frequencies above 7kHz (i.e., 8kHz, 9kHz, and 10kHz) calibrate successfully. I have tested this across different bitrates.

I'm running amodem through an audio cable between two machines on Ubuntu 22.04.

Below, you’ll find the output of the calibration command as well as a recording of the calibration signal:

audio.raw