I am unable to solve the x-axis issue.
Briefly stated, my problem is as follwos:
a I create a spectrogram (basically according to the example), with width 512 elements
b. app 10 times a second I generate an update where the topline in the matrix representing
the spectrogramdata is replaced, with as result a waterfall plot.

c. I am unable to create an appropriate X axis. My requirements are
1. the 512 elements represent 96 kHz, so I need to scale. One thought is to
instruct the spectrogram that it has a matrix of 96000 x 50 by implementing
a suitable value function
2. the middle element of my 512 elements has a known (though in time varying)
frequency attached to it. I have been experimenting with drawscale etc using
material from the examples and ( as far as I could understand it) the references
however, in those cases that I had more or less an x-axis to my taste, the spectrogram
would display all blanks. This makes sense because I need to be able to create a
mapping from my frequencyrange (e.g. 14000 +/- 48) to the interval 0 .. 512 (the
implied x-axis from my raster)
it is a pity that I could not find an introductory text, but I really need help here

all the best
jan