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[Discuss-gnuradio] Goertzel vs FIR bandpass

From: Marcus D. Leech
Subject: [Discuss-gnuradio] Goertzel vs FIR bandpass
Date: Mon, 27 Dec 2010 22:12:50 -0500
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I tried an experiment this evening with my 6-channel VLF receiver, which uses a sound-card (sampled at 96KHz or 192KHz) to sample a VLF loop antenna and amplifier, and then do power detection (and other things) over six discrete channels, arbitrarily spaced.

The version that I've been using up until now uses a FIR bandpass filter for each channel, followed by an utterly-uninteresting
  power-detector chain.

I didn't know anything about the Goertzel transform until a couple of days ago, and decided to substitute an equivalent Goertzel transform for each channel, to see if I could save any CPU by doing so. The result was that I can save about 15% by going to the Goertzel transform, instead of an FIR filter with roughly-equivalent bandwidth.

I'm going to let it run for a couple of days to compare sensitivity.

For equally-spaced channels (which isn't the case here), an FFT might also be useful and slightly cheaper than a discrete FIR filter
  for each channel.

Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

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