Re: Is there something similar to the zero-span of spectrum analyzers in gnuradio?

[Marcus D. Leech]

On 19/12/2022 10:50, Juan Antonio wrote:
> I think I'm not explaining myself well again.
>
> What I want to see in the time domain is a single carrier of an 8mhz 
> signal. That's why I was referring to the zero-span function of 
> spectrum analyzers.
>
> I have tried to isolate a single 1K carrier using filters but I did 
> not get good results. That is why I was looking for something simpler, 
> where simply indicating the frequency, I would have the output that 
> specific frequency in the time domain. Something like a very narrow 
> band  raw iq(or magnitude) demodulator
Isolating a 1KHz-wide signal from an 8MHz bandwidth in a single step is 
likely to create *enormous* filters.  Do you really need
  to bring in 8MHz of bandwidth?

If this were my problem, I'd use frequency-xlating-fft-filter to rotate 
the center of the desired carrier down to baseband, and
  then use a multi-stage filter-decimator chain to narrow the bandwidth.

I've said this in both this forum and others in the past.  Gnu Radio *IS 
NOT* a "radio with a lot of knobs to tweak", but a
  domain-specific software-development environment.    It's somewhat 
rare in Gnu Radio for there to be a "button I can push to
  make my answers come out".   What this means is that in order to be 
successful developing Gnu Radio flow-graphs
  to accomplish some specific task, there's usually some amount of 
background in signals, signal-processing, and software
  development required.

Another things to consider is this:  the field, loosely-described, as 
"useful and interesting things one might do at the
  intersection  between radio and computers" is likely approaching 
infinite.  Which means that no finite effort could
  ever possibly address each one of those useful and interesting 
things--some coding may be required.  This same observation
  applies to the software universe in general, even ignoring SDR and 
DSP and the like...