enkitec@... wrote: > I want to build a FM radio squelch using an ATMEGA8. > The ADC will be sampling the FM radio audio output > ... What is the best way of doing this in software? Mark, you don't need to do this with analog hardware unless the microcontroller has other time-critical stuff to do. Sample the audio with the A-to-D as you already said, pass the samples through filters to separate high and low bands, compute the filter output magnitudes, smooth them and watch their levels over time. Others have advised you on the filters. Personally, I would put the corner frequencies at about 250 Hz and 1000 Hz to start with and just see what I get. A big advantage of using digital filters is that they are so easy to change! I would use second-order IIR filters. FIR filters take more computation for any given cut-off rate and you don't need their linear phase response. There are plenty of filter design tools on the Web. Does this answer your question? Graham.
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Re: White noise detection?
2012-06-25 by bayramdavies