Getting the max amplitude of an FFT plot (FFT sink)

Hi,

I am trying to write a simple program that changes the TX frequency in
response to some RX stimulus. I want the TX frequency to change if any
part
of the RX signal in a band I am monitoring exceeds a threshold
amplitude.

My problem is I don’t know how to get the amplitude of the RX signal in
the
FFT plot. The “peak hold” option saves the max amplitude at every
frequency
across the band you are monitoring, so if you could access the amplitude
values of these saved peaks, you could find the max amplitude and test
if it
exceeds the threshold amplitude. But I don’t know where (what variables
or
what function) the peaks are saved. Could somebody point me in the
right
direction?

Best regards,
Anthony

Anthony Hsu wrote:

FFT plot. The “peak hold” option saves the max amplitude at every
Anthony


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Hi Anthony,

I’m working on a similar project, and with some minor alterations to
usrp_spectrum_sense.py you should be able to get peaks from the fft
sink.
For more info on the coding, please see Firas excellent explanation:
http://www.nabble.com/Some-usrp_spectrum_sense.py-code-Explanation-td21209623.html#a21209623

Regards,
Dan


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