[Discuss-gnuradio] Getting the max amplitude of an FFT plot (FFT sink)

[Anthony Hsu]

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