# Buffer too small with fft length 1024 in OFDM Transmitter

**URL:** <https://www.ruby-forum.com/t/buffer-too-small-with-fft-length-1024-in-ofdm-transmitter/261234>\
**Category:** GNU Radio\
**Created:** [April 15, 2021, 4:51am UTC](https://www.ruby-forum.com/t/buffer-too-small-with-fft-length-1024-in-ofdm-transmitter/261234 "2021-04-15T04:51:14Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Unique\_reflection](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/u/ec9cab/32.png) [@Unique\_reflection](https://www.ruby-forum.com/u/Unique_reflection)\
**Post date:** [April 15, 2021, 4:51am UTC](https://www.ruby-forum.com/t/buffer-too-small-with-fft-length-1024-in-ofdm-transmitter/261234/1 "2021-04-15T04:51:14Z")

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Hello guys,

I am currently trying to transmit data from one SDR which is HACK RF One to another using OFDM in GNURadio. I got this to work with the default fft length of 64.

Now I am trying to do this with 1024 fft length but I am getting the following error.

_thread[thread-per-block[11]: \<block ofdm\_cyclic\_prefixer(14)\>]: Buffer too small for min\_noutput\_items_

Anyone know how to fix this?

I have played around with different lengths of the cyclic prefix but to no avail.

Also, I have seen a post from 2014, where it is suggested to increase the GR\_FIXED\_BUFFER\_SIZE from 32k to 128k. I have installed GNURadio using PyBombs. I would like to know the process of doing this as well.

Thanks.

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**Author:** ![Jacobprice808](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/e0b2c6/32.png) [@Jacobprice808](https://www.ruby-forum.com/u/Jacobprice808)\
**Post date:** [June 25, 2021, 8:02pm UTC](https://www.ruby-forum.com/t/buffer-too-small-with-fft-length-1024-in-ofdm-transmitter/261234/2 "2021-06-25T20:02:34Z")

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Hey Unique\_reflection,

I’m having the same problem. Did you ever figure out a solution?

Thanks,  
Jacob