# Long preambles in the Gr-ieee 802.11 a/g/p transceiver

**URL:** <https://www.ruby-forum.com/t/long-preambles-in-the-gr-ieee-802-11-a-g-p-transceiver/242190>\
**Category:** GNU Radio\
**Created:** [June 3, 2015, 3:01pm UTC](https://www.ruby-forum.com/t/long-preambles-in-the-gr-ieee-802-11-a-g-p-transceiver/242190 "2015-06-03T15:01:18Z")\
**Posts on this page:** 2\
**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:** [June 3, 2015, 3:01pm UTC](https://www.ruby-forum.com/t/long-preambles-in-the-gr-ieee-802-11-a-g-p-transceiver/242190/1 "2015-06-03T15:01:18Z")

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Hello,

I am using the gr-ieee802-11 module and want to analyse the long  
preambles  
in the 11p standard. Going through the code I am getting the feeling  
that  
the long preambles might be found in the ofdm\_sync\_long.cc(attached)  
Kindly  
point me to the place where I could find the preambles.

Thanks  
Kelvin

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**Author:** ![Kelvin\_Augustin](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/ec9cab/32.png) [@Kelvin\_Augustin](https://www.ruby-forum.com/u/Kelvin_Augustin)\
**Post date:** [June 3, 2015, 3:55pm UTC](https://www.ruby-forum.com/t/long-preambles-in-the-gr-ieee-802-11-a-g-p-transceiver/242190/2 "2015-06-03T15:55:38Z")

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Hi,

On 06/03/2015 02:59 PM, Kelvin Augustin wrote:

> Kindly point me to the place where I could  
> find the preambles.

[https://github.com/bastibl/gr-ieee802-11/blob/master/lib/ofdm\_sync\_long.cc#L245](https://github.com/bastibl/gr-ieee802-11/blob/master/lib/ofdm_sync_long.cc#L245)

is the time domain representation of the long preamble that is used in a  
matched filter.

Best,  
Bastian