WX GUI FFT Sink Performance

I think the best approach is just to include every possible method in
GNURadio. This can only make the platform more versatile. I make use
of overlapping a lot because computation times are a pain. The
trade-off in resolution is acceptable to me because it has limits that I
can work around. This allows me to work with weak signals that would
otherwise go unnoticed without some heavy computation. I typically work
at resolutions of over 1 million to examine narrow-band signals.

The other method is to have a system setup to record the spectrum to a
file, then allow another computer to do the FFT at different
resolutions. SETI do the same thing with the BOINC platform, only on a
far greater scale.

Regards,

Mark McCarron

On 5/28/2013 1:28 PM, Simon IJskes wrote:

On 17-05-13 02:22, Marcus D. Leech wrote:

Again, given the fact that your display geometry is likely less than
1280 wide, you’ll simply lose information for FFTs larger than that.

I one is looking for weak CW signals, in a waterfall, wouldn’t a wide
bin, make this signal invisible in among the noise? If more bins fit in
one pixel, there could be a mode where the bin with the most power is
displayed. If this is complete non-sense, how would you implement
looking for faint cw carriers, in like EME applications?

Take a look at the “rosenfell” or “normal” detector used in spectrum
analyzers – I think it’s a way to deal with this question. There’s a
good discussion in the Agilent spectrum analysis basics app note:
http://cp.literature.agilent.com/litweb/pdf/5952-0292.pdf

John

On 05/28/2013 01:54 PM, Mark McCarron wrote:

file, then allow another computer to do the FFT at different
resolutions. SETI do the same thing with the BOINC platform, only on
a far greater scale.

Regards,

Mark McCarron
There are two distinct issues here:

o overlapped FFT processing (to improve temporal resolution)
o compression for visual display

They’re both, in essence, about the “visual presentation” of FFT data.

Anyone is welcome to improve either/both of these and submit code…