I have done that a long time ago. The application was used to detect tone pulses on mains and from the pulse sequences decode a message. A tone burst pulses of 216 Hz were added to mains voltage of 50 Hz. The amplitude of tone bursts which I needed to detect was about 1% (2Veff). I have used Philips P87C749 controller with 64 bytes of RAM and 2 KBytes of code ROM. The sampling rate of AD converter was 5200/sec. The AD sampling and Goertzel calculation was implemented in assembly and optimized for speed. For this reason a custom Fixed point arithmetic was used optimized for speed and code size. You may build a table of coefficients to select different detection frequencies.


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