Creating a waterfall plot with the spectrogram

[twells5]

I have gotten a waterfall plot working using the spectrogram widget thanks to a lot of help from Uwe and Xicoy above.... However, until now I have been using all positive values.....fe...x axis: 0-4096 samples, y axis: 0-250 ms, sample values between 0-40, colorbar scale 0-40. Now I need to modify it so that the x axis has +/- values (-2048 to 2048 for example), and data values from -200 to 200. Can that be done with this spectrogram widget? My attempts have yielded a colorbar which is still fine for positive values, but all negative values just remain at the color used for 0. And any negative data values default to the color for zero on the colorbar. Also values only plot on the positive side of the x axis, negative data values seem to be ignored and not plotted at all. I've tried adjusting range and axis values etc...but so far have had no success. Any thoughts or advice would be appreciated.
I am using qwt 6.0.

Thank you,
tim

[Uwe]

There is no limitation for ranges - the problem is on your side. Maybe the bounding rectangle of your data is wrong.

Uwe

[twells5]

Can the labels on the x-axis scale major ticks be changed to a different string other than the bounding rect interval values it defaults to? My data is displayed fine now thanks to your tip above, but I would like the major tick labels to show something like ...50Mhz 100Mhz 150Mhz....? I don't want to change anything about how the spectrogram data is plotted, just the label strings displayed.

tim

[Uwe]

Can the labels on the x-axis scale major ticks be changed to a different string other than the bounding rect interval values it defaults to?

Derive from QwtScaleDraw and implement "QwtText YourScaleDraw::label((double) const".
F.e. see the cpuplot example.

Uwe