# Preamble length

**URL:** <https://www.ruby-forum.com/t/preamble-length/232110>\
**Category:** GNU Radio\
**Created:** [September 18, 2014, 3:10pm UTC](https://www.ruby-forum.com/t/preamble-length/232110 "2014-09-18T15:10:17Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [September 18, 2014, 3:10pm UTC](https://www.ruby-forum.com/t/preamble-length/232110/1 "2014-09-18T15:10:17Z")

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Hello,

What is the length of the preamble that is used in narrowband  
benchmark\_tx.py example, given BPSK is chosen for type of modulation? Is  
there a way to modify the length?

Thanks,  
Zaher