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G'day Wolf,
I had a look at the Spectrum Lab manual and see
that when you say decimation you don't mean taking smaller records and then
averaging (which I understood was decimation). Unfortunately,
I still don't understand how this works.
If you start off with a 650Hz tone sampled at
11025Hz with a record size of 16384 you have a record length of 1.49 seconds (BW
= 0.67Hz). Averaging or skipping samples could be done
down to maybe a 2205Hz sample rate, but that would only get a record length of
about 7.5Hz (BW = 0.134Hz). The only way I can see that
5.3mHz can be achieved is if you mix down the input signal to close to zero
frequency (say 20Hz) and low-pass filter to eliminate
aliasing. This would make the 16384 record length long enough
for mHz range resolutions. Is this how it is done
?
73s Steve Olney (VK2ZTO/AXSO -
QF56IK : Lat -33 34 07, Long +150 44
40)
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