# Inverse of cyclic prefix adder

**URL:** <https://www.ruby-forum.com/t/inverse-of-cyclic-prefix-adder/243252>\
**Category:** GNU Radio\
**Created:** [September 4, 2015, 10:20am UTC](https://www.ruby-forum.com/t/inverse-of-cyclic-prefix-adder/243252 "2015-09-04T10:20:55Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Sadaf\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@Sadaf\_N](https://www.ruby-forum.com/u/Sadaf_N)\
**Post date:** [September 4, 2015, 10:20am UTC](https://www.ruby-forum.com/t/inverse-of-cyclic-prefix-adder/243252/1 "2015-09-04T10:20:55Z")

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Hii

In OFDM system, at the receiver side i want to remove initial ‘x’  
symbols  
from the every ‘x+fft\_len’ symbols. How can i do this ? Is there any  
block?  
or i need to create one…

Thanks.

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**Author:** ![monika\_bansal](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/7c8e57/32.png) [@monika\_bansal](https://www.ruby-forum.com/u/monika_bansal)\
**Post date:** [September 4, 2015, 11:31am UTC](https://www.ruby-forum.com/t/inverse-of-cyclic-prefix-adder/243252/2 "2015-09-04T11:31:36Z")

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Hi Monika,

personally, I’d use the “Keep M in N” block.

Best regards,  
Marcus

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**Author:** ![monika\_bansal](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/7c8e57/32.png) [@monika\_bansal](https://www.ruby-forum.com/u/monika_bansal)\
**Post date:** [September 4, 2015, 12:45pm UTC](https://www.ruby-forum.com/t/inverse-of-cyclic-prefix-adder/243252/3 "2015-09-04T12:45:47Z")

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Hii

Thanks 🙂

On Fri, Sep 4, 2015 at 3:00 PM, Marcus Müller [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)

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**Author:** ![monika\_bansal](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/7c8e57/32.png) [@monika\_bansal](https://www.ruby-forum.com/u/monika_bansal)\
**Post date:** [September 4, 2015, 9:37pm UTC](https://www.ruby-forum.com/t/inverse-of-cyclic-prefix-adder/243252/4 "2015-09-04T21:37:24Z")

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On 04.09.2015 01:20, monika bansal wrote:

> Hii
> 
> In OFDM system, at the receiver side i want to remove initial ‘x’  
> symbols from the every ‘x+fft\_len’ symbols. How can i do this ? Is there  
> any block? or i need to create one…

If you’re using the Header/Payload Demux, that’ll take care of the CP.

Cheers,  
Martin

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**Author:** ![monika\_bansal](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/7c8e57/32.png) [@monika\_bansal](https://www.ruby-forum.com/u/monika_bansal)\
**Post date:** [September 5, 2015, 10:18am UTC](https://www.ruby-forum.com/t/inverse-of-cyclic-prefix-adder/243252/5 "2015-09-05T10:18:37Z")

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I am not using Header/Payload Demux.