# RF packet length of narrowband benchmark\_tx

**URL:** <https://www.ruby-forum.com/t/rf-packet-length-of-narrowband-benchmark-tx/232156>\
**Category:** GNU Radio\
**Created:** [September 21, 2014, 2:44pm UTC](https://www.ruby-forum.com/t/rf-packet-length-of-narrowband-benchmark-tx/232156 "2014-09-21T14:44:38Z")\
**Posts on this page:** 3\
**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 21, 2014, 2:44pm UTC](https://www.ruby-forum.com/t/rf-packet-length-of-narrowband-benchmark-tx/232156/1 "2014-09-21T14:44:38Z")

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Hello,

I am using narrowband benchmark\_tx.py example to transmit packets. Each  
single packet is separated from its neighbors by a second.  
The parameters I am using:

benchmark\_tx\_modified.py -m gmsk -s 4000 -r 1000000 --tx-amplitude=1 -f  
2.402G -A TX/RX --tx-gain=25

benchmark\_rx\_modified.py -m gmsk -r 1000000 -f 2.402G -A RX2 --rx-gain=0

At the receiver side (different USRP device), I am converting the  
complex stream into magnitude\_squared then into a file sink. What I  
should receive according to parameters above is a packet of 64000  
samples. This is because sps (sample per symbol) equals to 2. (4000 \* 8

- 2 = 64000). However, using MATLAB, I am receiving extra ~31500  
samples!!! Please have a look at the attached image.  
I tried different packet sizes, modulation, etc, but there are still  
~31500 extra samples.

Thanks,  
Zaher

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<div class="post-metadata">

**Author:** ![mzaherm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/2bfe46/32.png) [@mzaherm](https://www.ruby-forum.com/u/mzaherm)\
**Post date:** [September 24, 2014, 3:22pm UTC](https://www.ruby-forum.com/t/rf-packet-length-of-narrowband-benchmark-tx/232156/2 "2014-09-24T15:22:57Z")

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Hello,

Any comment or suggestion is highly appreciated.

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<div class="post-metadata">

**Author:** ![mzaherm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/2bfe46/32.png) [@mzaherm](https://www.ruby-forum.com/u/mzaherm)\
**Post date:** [September 29, 2014, 5:28am UTC](https://www.ruby-forum.com/t/rf-packet-length-of-narrowband-benchmark-tx/232156/3 "2014-09-29T05:28:29Z")

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Hello guys,

Please I want your help in this issue.

Zaher