[time-nuts] Misuse of word "decimate" (was Re: Short term 10MHz source)

[Hal Murray]

k8yumdoober at gmail.com said:
> Case A:  you simply throw away samples, keeping only every nth sample,
> without regard for the frequency content of the original signal.

> Case B:  you first perform appropriate anti-aliasing filtering on the
> original signal, and only then throw away all but every nth sample

I don't think case A makes sense.  You are throwing away information.  You 
will get aliasing.

Case B can be more complicated than a traditional low pass anti-aliasing 
filter.  Consider a simple SDR (software defined radio).  The front end ADC 
captures a wide bandwidth, a filter selects a narrow chunk that you are 
interested in.  Decimation is appropriate.  The filter threw away the out of 
band signal that would get aliased on top of your signal if you didn't filter.


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