Super Hi-Res Spectrum?

[pauldbnut]

Hi, could anyone give me an explanation suitable for dummies please?

Some systems, like RFSPACE receivers with SpectraVue, somehow manage to create a very high resolution real time spectrum (say RBW better than 1 Hz) at a reasonable refresh rate (say at least 1 Hz). That's really handy for measuring carrier offsets from nominal frequency - and maybe tuning. What I don't understand is how it can be done in real time. Most SDR software gives much poorer resolution than that.

It's possible to get this resolution by re-processing an IQ recording - Console Analyser can do it. But my amateur attempts with Gnu Radio (lots of decimation) never worked properly.

Thanks for any help.

[Simon G4ELI]

Paul,

The magic words you're looking for are probably FFT Overlap, this is what I do when the resolution is increased.

You could have an update rate of 10 / second and a RBW of 2Hz by using this approach, it's really the only true solution.

GNU Radio is something I've never played with so can't help, sorry.

https://dsp.stackexchange.com/questions ... ap-and-fft

[pauldbnut]

Simon, Hi, and thanks for that quick response. Never heard of FFT overlap before.
Quickly checked the reference you gave me. Not sure if it's doable in GRC (or Pothos), and I don't know MatLab.
Very sure, though, I'm not going to try wading in those deep waters .
Just keep my head down and use whatever features the experts are generous enough to offer!

[Simon G4ELI]

Shout here when you have any DSP-related questions.