# PLL blocks parameters units

**URL:** <https://www.ruby-forum.com/t/pll-blocks-parameters-units/234727>\
**Category:** GNU Radio\
**Created:** [March 24, 2015, 10:24pm UTC](https://www.ruby-forum.com/t/pll-blocks-parameters-units/234727 "2015-03-24T22:24:42Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [March 24, 2015, 10:24pm UTC](https://www.ruby-forum.com/t/pll-blocks-parameters-units/234727/1 "2015-03-24T22:24:42Z")

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Hello,

the documentation for the PLL blocks in GNURadio says: “All settings  
max\_freq and min\_freq are in terms of radians per sample, NOT HERTZ.”

Therefore I thought that to specify a bandwidth `bw` it would have to  
converted from natural frequency units (Hz) into radians per sample with  
something like:

bw\_rad\_per\_sample = bw \* 2\*pi / sampl\_rate

where `sampl_rate` is of course the sampling rate in Hz.

However, looking at the PSD of the input and outputs to the PLL blocks,  
it looks like my understanding is wrong and that the bandwidth should be  
computed as

bw\_rad\_per\_sample = bw \* pi / sampl\_rate

with a missing factor of 2.

Is the documentation right, and my understanding of it wrong, or the  
documentation is wrong? In the former case, I think it would be better  
to clarify it a bit.

Thanks! Cheers,  
Daniele