Re: aliasing with X310 BasicRX (higher order Nyquist zone) ?

On 07/20/2020 11:29 AM, jean-michel.friedt@femto-st.fr wrote:
> Indeed second Nyquist zone before decimation.
> My thought was
> 143.05 MHz -> transpose by 100 MHz using the DDC (NCO at 100 MHz considering the
> 200 MHz sampling rate) to reach 43.05, and after transposition, decimating to reach
> 8 MS/s (I do have Epcos B3607 SAW filters 140+/-3 MHz frontend to select only the
> signal I am interested in).
> It is in the decimation process that I was thinking of being in the third
> Nyquist zone after decimation, which is incorrect because 8 MS/s is -4 to +4, so that
> 43.05 is in the 6th Nyquist zone after decimation (\in[36:44] MHz).
>
> Thanks, JM
>
The signal will be coming out of the ADC at 56.5Mhz, which you should be
able to just ask the DDC to pick off and give you your desired 8MHz
of bandwidth--I think it's as uncomplicated as that.

The BASIC_RX implementation still accepts tuning requests, and those
just direct the DDC to do the right thing. This should "just work", unless
there's breakage in the BASIC_RX implementation...