# Resampling, filters, and CPU Usage

**URL:** <https://www.ruby-forum.com/t/resampling-filters-and-cpu-usage/240405>\
**Category:** GNU Radio\
**Created:** [April 12, 2014, 5:24am UTC](https://www.ruby-forum.com/t/resampling-filters-and-cpu-usage/240405 "2014-04-12T05:24:58Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Detlef\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/58f4c7/32.png) [@Detlef\_R](https://www.ruby-forum.com/u/Detlef_R)\
**Post date:** [April 12, 2014, 5:24am UTC](https://www.ruby-forum.com/t/resampling-filters-and-cpu-usage/240405/1 "2014-04-12T05:24:58Z")

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As most of you likely have seen, I’ve been working on a flowhraph for  
quite  
some time. Using gr-drm and an external FM processor, I have made a sort  
of  
open alternative to HD Radio…because fun.

Anyway, the DRM signals are sampled at 48khz and the FM portion at 192.  
The  
remainder of the graph is 384k due to filters. 2 bandpass filters, 4  
band  
reject filters.

To help you help me, I have uploaded the flow graph to Google Drive. It  
require gr-drm and for your audio to be set to Jack. (Or just use null  
sinks).I’m still rather new to GNURadio so…I’m sure there’s some  
rookie  
mistakes in there:

IBOC.grc -  
[https://drive.google.com/file/d/0B9lYGe4c92PnTDlVbkprVFRybnM/edit?usp=sharing](https://drive.google.com/file/d/0B9lYGe4c92PnTDlVbkprVFRybnM/edit?usp=sharing)

gr-drm - [GitHub - kit-cel/gr-drm: DRM transmitter using GNU Radio](https://github.com/kit-cel/gr-drm)

Stereo Tool (FM processor) - [Download Stereo Tool](http://www.stereotool.com/download/)

So, what is it supposed to do?

Two DRM signals are to sit on the outside of the FM envelope. There  
should  
only be two, but as they are interpolated, they make a mess and that’s  
why  
I put the filters there.