AD936x - TX Power depends on Sample Rate

[xdch47]

For the AD936x / FMCOMM5 gain reduction by -6dbm can be observed, when switching sample_rates > 20 MHz to < 20 MHz.

This looks like a bug of filter coefficients (Multiplication by 2) or using the other filters with an interpolation factor of 2 fixes the issue. The programmable FIR coefficients with an interpolation factor of 4 have only a gain of 0.5 per phase of 1.0 (Total gain should by 4 instead of 2

or total gain should match the Interpolation Factor

)