[time-nuts] decimation versus decimation

[Anders Wallin]

Some of the confusion might come from different measurement systems dealing
with different data, either phase (in seconds), or frequency (fractional).

Sub-sampling works for phase-data, just throw away the in-between samples
and look at phase samples that are tau-distance apart.

Decimation works for frequency-data, if you collect with 1s gate-time and
want to look at tau=10s, then bin together 10 samples and create a new
time-series that is 10-fold shorter, and compute adev from that.

FWIW IIRC all the allantools examples/tests that (successfully) compare
results against Stable32, using frequency input data, just use simple
non-overlapping 'boxcar' decimation - nothing more fancy or elaborate.

AW


On Tue, Feb 25, 2020 at 7:10 PM Dana Whitlow via time-nuts <
time-nuts at lists.febo.com> wrote:

> Let's see if I have this correct, then:
>
> "Decimation" refers to the two-step procedure (filtering followed by
> picking every nth sample),   and
> "Sub-sampling" (or "downsampling") properly refers to taking every nth
> sample and discarding the rest.
>
> Is this correct?
>
> And thanks for all the responses.
>
> Dana
>
>
> On Tue, Feb 25, 2020 at 10:09 AM George Watson via time-nuts <
> time-nuts at lists.febo.com> wrote:
>
> >
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