# Freq Xlating FIR Filter Question

**URL:** <https://www.ruby-forum.com/t/freq-xlating-fir-filter-question/240445>\
**Category:** GNU Radio\
**Created:** [April 14, 2014, 7:59pm UTC](https://www.ruby-forum.com/t/freq-xlating-fir-filter-question/240445 "2014-04-14T19:59:04Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\
**Post date:** [April 14, 2014, 7:59pm UTC](https://www.ruby-forum.com/t/freq-xlating-fir-filter-question/240445/1 "2014-04-14T19:59:04Z")

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When using a Freq. Xlating FIR filter with decimation and taps  
both set to 1, what determines the practical lower limit  
for the resolution of the freq change?

@(^.^)@ Ed

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**Author:** ![Ed\_Criscuolo](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/ac8455/32.png) [@Ed\_Criscuolo](https://www.ruby-forum.com/u/Ed_Criscuolo)\
**Post date:** [April 14, 2014, 11:05pm UTC](https://www.ruby-forum.com/t/freq-xlating-fir-filter-question/240445/2 "2014-04-14T23:05:29Z")

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Hi Ed!

Numerical accuracy of the exp(jN)\*tap operation.  
Usually, this accuracy is sufficient by far – why the question?

Greetings,  
Marcus

On 14.04.2014 19:57, Ed Criscuolo wrote:

> When using a Freq. Xlating FIR filter with decimation and taps both  
> set to 1, what determines the practical lower limit for the  
> resolution of the freq change?
> 
> @(^.^)@ Ed
> 
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