Is it a coincidence I wonder, that the 'standard' Soundcard / CD
sampling rate is a multiple of the squares of the small prime numbers.
ie:
44100 = 2 * 2 * 3 * 3 * 5 * 5 * 7 * 7
Spooky !
Certainly simplifies decimation to a wide variey of lower rates. For
a CW tone centred on 800Hz, 11025 / 5 = 2205Hz would be ideal, letting a
CW filter of up to 400Hz bandwidth handle removal of the aliasing
products above 1102Hz. or 44100 / 5 = 8820 for a more accurate value
for voice bandwidth signals.
Andy G4JNT
2.) Also stay away from all sample rates except 11025, 22050 or 44100
samples
per second.
If you need lower sample rates, decimate the input signal by two or
three. If
the input spectrum does not contain frequencies above half of the
*decimated*
sample rate, you don't even need a proper software-based anti-alias
filter>
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