# Notch Filter on feedback

**URL:** <https://forum.deltamotion.com/t/notch-filter-on-feedback/916>\
**Category:** Programming\
**Created:** [July 16, 2021, 6:37pm UTC](https://forum.deltamotion.com/t/notch-filter-on-feedback/916 "2021-07-16T18:37:30Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![dmcnichol](https://forum.deltamotion.com/letter_avatar_proxy/v4/letter/d/ba9def/32.png) [@dmcnichol](https://forum.deltamotion.com/u/dmcnichol)\
**Post date:** [July 16, 2021, 9:30pm UTC](https://forum.deltamotion.com/t/notch-filter-on-feedback/916/2 "2021-07-16T21:30:31Z")

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Hi,

Here’s a nice little example program with a notch filter implemented.

Here’s the basic equation:  
 ![image](https://forum.deltamotion.com/uploads/default/original/1X/9e73d15823900010ee90348155448f6f79afa1a3.png)

It’s easy to change the notch center and also the width - Q with the variables in the equation.  
Here’s the project, this one is implemented and an RMC75 but will be easy to copy over to your 150.  
[NotchFilter.rmcproj](https://forum.deltamotion.com/uploads/short-url/s4WIzw0LxiTCKA6PbA1OMV0jWQv.rmcproj) (21.1 KB)

Also, here’s a quick screen shot of the filter in action, I have this one setup with a notch center at 10Hz, you can see its working very well:

 ![image](https://forum.deltamotion.com/uploads/default/original/1X/bfe81b0fea61a664b2c729ea0138c86fa951731e.png)

One last note, the filter works just as it should, but if it’s feedback you are wanting to filter, you’ll want to setup your axis as a custom feedback axis and run the actual feedback you are receiving through this filter then back into the axis as a variable. Here’s an example where this is done: [Redundant/Custom Feedback](https://forum.deltamotion.com/t/redundant-custom-feedback/205)

Don’t hesitate to reach out if you have questions, and good luck on your project!

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