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

[David G. McGaw]

In digital filtering, decimation is a reduction of sample rate, 
truncation is a reduction of precision.  Interpolation can refer to 
either of the opposite processes.  The terms downsampling and upsampling 
can be used to avoid confusion with regards to sample rate.  I am trying 
to come up with an adequate term for improving precision.  Averaging is 
one form, but not inclusive.

David N1HAC


On 1/10/19 7:59 AM, Magnus Danielson wrote:
> Peter,
>
> While the word derives back to the Roman times, today it is a 
> technical term for data-reduction being used in professional 
> literature, so it's meaning has already been established.
>
> For instance, in modern phase-noise measurement setups the sample-rate 
> is around 100 MS/s, and that sample-rate of multiple ADCs with 
> relatively high amounts of bits is way to high to hand over to 
> software, so it is decimated down in steps in FPGA before handing over 
> to software. Decimation is the term used in that context.
>
> Cheers,
> Magnus
>
> On 2019-01-10 13:01, Peter Vince wrote:
>> In his comment below, Mark has used the word "decimate".  There is much
>> debate about what this word means (presently, and/or in the past), but
>> common explanations refer back to Roman times when they apparently 
>> killed
>> one person in ten as a punishment, and similarly "tithes" - or taxes, 
>> where
>> one in ten was taken.  Now OK, you can argue this until the cows come 
>> home,
>> but the result is that the meaning isn't crystal clear, and 
>> particularly on
>> a technical forum where precision is paramount, and the entire reason we
>> are here, I believe accuracy and clarity of expression is also 
>> important.
>> In this instance, I believe "truncate" would be a better word.
>>
>> </rant>  :-)
>>
>>       Regards,
>>
>>            Peter Vince
>>
>> On Wed, 9 Jan 2019 at 23:56, Mark Sims <holrum at hotmail.com> wrote:
>>> ...
>>> And as far as decimating the TICC output values in firmware... please
>> don't.   Let the user decimate the values if they want to.
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