# Ofdm\_benchmark\_tx.py on E100 results in sequence error in burst

**URL:** <https://www.ruby-forum.com/t/ofdm-benchmark-tx-py-on-e100-results-in-sequence-error-in-burst/211033>\
**Category:** GNU Radio\
**Created:** [August 24, 2011, 2:54am UTC](https://www.ruby-forum.com/t/ofdm-benchmark-tx-py-on-e100-results-in-sequence-error-in-burst/211033 "2011-08-24T02:54:56Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![dubstep](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/cdc98d/32.png) [@dubstep](https://www.ruby-forum.com/u/dubstep)\
**Post date:** [August 24, 2011, 2:54am UTC](https://www.ruby-forum.com/t/ofdm-benchmark-tx-py-on-e100-results-in-sequence-error-in-burst/211033/1 "2011-08-24T02:54:56Z")

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Hi everyone,

I updated the ofdm\_benchmark\_tx.py script to use UHD and I’m running it  
on  
my E100. If I run it at a high enough sample rate, I get a lot of “S”  
characters printed to the screen. Some googling shows that this means  
there’s packet loss within a burst. What causes this? Is there any way  
to  
avoid it?

Thanks,  
Morgan

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**Author:** ![redfieldm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/c0e974/32.png) [@redfieldm](https://www.ruby-forum.com/u/redfieldm)\
**Post date:** [August 24, 2011, 2:58am UTC](https://www.ruby-forum.com/t/ofdm-benchmark-tx-py-on-e100-results-in-sequence-error-in-burst/211033/2 "2011-08-24T02:58:03Z")

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On 08/23/2011 05:15 PM, Morgan R. wrote:

> Hi everyone,
> 
> I updated the ofdm\_benchmark\_tx.py script to use UHD and I’m running it on  
> my E100. If I run it at a high enough sample rate, I get a lot of “S”  
> characters printed to the screen. Some googling shows that this means  
> there’s packet loss within a burst. What causes this? Is there any way to  
> avoid it?

What is the exact sample rate? Can you post the updated flowgraph?

Have you tried using the NEON optimized fftw mentioned earlier?

Philip

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<div class="post-metadata">

**Author:** ![redfieldm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/c0e974/32.png) [@redfieldm](https://www.ruby-forum.com/u/redfieldm)\
**Post date:** [August 24, 2011, 2:59am UTC](https://www.ruby-forum.com/t/ofdm-benchmark-tx-py-on-e100-results-in-sequence-error-in-burst/211033/3 "2011-08-24T02:59:17Z")

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On 08/23/2011 05:15 PM, Morgan R. wrote:

> Hi everyone,
> 
> I updated the ofdm\_benchmark\_tx.py script to use UHD and I’m running it on  
> my E100. If I run it at a high enough sample rate, I get a lot of “S”  
> characters printed to the screen. Some googling shows that this means  
> there’s packet loss within a burst. What causes this? Is there any way to  
> avoid it?

Also, what kernel version are you running? Have you updated the boot  
files and root file?

Philip

---

<div class="post-metadata">

**Author:** ![redfieldm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/c0e974/32.png) [@redfieldm](https://www.ruby-forum.com/u/redfieldm)\
**Post date:** [August 24, 2011, 3:36am UTC](https://www.ruby-forum.com/t/ofdm-benchmark-tx-py-on-e100-results-in-sequence-error-in-burst/211033/4 "2011-08-24T03:36:55Z")

</div>

On Tue, Aug 23, 2011 at 5:58 PM, Philip B.  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)wrote:

> Also, what kernel version are you running? Have you updated the boot files  
> and root file?
> 
> Philip

The updated flowgraph is here:

> <https://github.com/mogar/uhd_ofdm/blob/master/benchmark_ofdm_tx.py>

I’m trying to run it with an fft-length of 1024 and 700 occupied tones.  
I’m  
using a sample rate of 4Msps.

My E100 has a kernel version of 2.6.38. I’m using fftw optimized for  
NEON  
from Vesperix, which was posted to this list a month or so ago. I  
haven’t  
updated any of the boot or root files for a couple of months, I don’t  
think  
I’m on the most recent version.

The usrp\_e module has the following version information:  
version: 0.2  
srcversion: C95640F14A5715ACE28E715

Thanks,  
Morgan