Hi

I am not an experienced Q(w)t user, but learning. I did write a software defined radio for a simple card, under Linux (Slackware) with Qt > 4, Qwt > 5.
Until now I used a spectrumdisplay for displaying the spectrum of a range of 48k around the selected frequency (depending on the chosen samplerate).

Using spectrogram stuff I managed to create a waterfall display, showing the spectrum evolving in time. However, I need some help for setting up the appropriate X axis frequencies for this display.
a. on a 512 element display (power of two handy for the FFT) it shows a block of 512 wide, but the screen is 600 wide
b. the x axis labels are 0 .. 512 (or -256 .. 256). I need to be able to map these labels
onto something like 14010 .. 14070, depending on the samplerate chosen.
anyone can help me?