Re: [Discuss-gnuradio] Just wondering why?

[Adrian Hodgson]

On Thursday, 2 November 2017 04:52:29 GMT Kevin Reid wrote:
> 
> This is true about the hardware, but gr-osmosdr, which is being used here
> according to the original post's screenshot, expresses all gain stage
> settings in dB. The RF amplifier is represented as a gain control with a
> numeric value that can be either 0 or 14 but no other values — it cannot be
> entered as a boolean through the gr-osmosdr API, and if you try, 1 dB will
> be rounded to the nearest valid value of 0 dB (amplifier off).
> 
> If one is interested in the relevant code, see:
>     hackrf_source_c::get_gain_range
>     hackrf_source_c::set_gain
>   Kevin Reid

I basically turned the RF and IF gains up to full, that was all I was doing 
there, just to see how sensitive the unit would be,   The stage gains are not 
an issue for me.

> Okay, I think I know what you're doing - I didn't look inside the
> resampler block the last time.
> 
> If you scale the interpolation in the resampler block, you change the
> output sampling rate of the resampler block - which no longer matches
> the quadrature rate - or the input sampling rate of the nbfm block.
> 
> In short, the plumbing is screwed up.
> 
> You need to scale the quadrature rate - or the input sampling rate of
> the nbfm block so it matches the output sampling rate of the resampler
> block after you re-scale the interpolation.
> 
> -- Cinaed

I am changing both the lowpass filter decimation and the resampler integration, 
so that it keeps the same rate/quadrature rate at the input to the QT 
frequency plot. and for the input to the audio stage, they do not change.
At least I believe not.

Adrian