1963Re: [SpectrumLabUsers] NWC signal spectrogram [3 Attachments]
- May 2, 2014Hello Edgar,
> I expect that the signal composition will be different, but can notseem to get the spectrum colours to be as smooth as those in the above
Difficult to say how the 'AWESOME' software avoids the steps in the
spectrogram colours when zooming in so deeply.
Math dictates the tradeoff between spectral and time resolution - it's
impossible to achieve a true time resolution of "fractions of a bit
time" and -at the same time- a frequency resolution of "fractions of the
frequency shift" (if MSK is considered FSK with a modulation index of 0.5).
Possible ways they do it:
A - individually interpolate the colour for each pixel in the
spectrogram, even if those pixels fall inside the same FFT frequency bin
B - use a radically different FFT windowing function (which is almost
zero within most of the FFT window) and a much longer FFT. The net
result would be similar as A : spectral smearing between neighbouring
Since there is no such FFT windowing function hard-coded in SL (yet),
the only way to achive both high resolution in the time- and frequency
domain is to use the 'reassigned spectrogram' as already suggested here
some time ago.
All the best,
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