I had posted a couple weeks ago and I guess it fell in the bit bucket.

I'm looking for info on DFT or similar approaches to detect very weak CW si=
gnals buried in noise.
I'm only interested in a 200Hz window, and I can control where it falls fre=
quency wise, between 150Hz (center) and several kHz.
I need as much frequency detail as possible, sub 1Hz definitely, but the "d=
ot" is pretty short. At 20WPM that works out to well below.
https://www.w8ji.com/cw_bandwidth_described.htm

This will get implemented on an AVR or similar, with input from the on-boar=
d ADC.

I expect I will need a rather long array of samples, but I am starting to t=
hink of a circular buffer there and sending chunks of to the DSP process.

I have looked in Smith's DSP book, but I haven't found what I'm looking for=
..

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