# Achievable Sampling Rate without Under/Overflows

**URL:** <https://www.ruby-forum.com/t/achievable-sampling-rate-without-under-overflows/234760>\
**Category:** GNU Radio\
**Created:** [March 27, 2015, 6:03pm UTC](https://www.ruby-forum.com/t/achievable-sampling-rate-without-under-overflows/234760 "2015-03-27T18:03:14Z")\
**Posts on this page:** 6\
**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:** [March 27, 2015, 6:03pm UTC](https://www.ruby-forum.com/t/achievable-sampling-rate-without-under-overflows/234760/1 "2015-03-27T18:03:14Z")

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I need some understanding of what reasonably achievable sample rates are  
using GNU Radio to implement a packet base radio.

For example, I’m running into D’s at only 430 k/samples. This is running  
a  
packet detecting radio using bpsk.

Those who have working OFDM radios, what sample rates does your system  
support without over/underflow? How about those with QPSK radios  
detecting  
packets, what samle rate can you support?

I’m not using a multi-rate approach, so I know there are gains to be had  
in  
my design. But for a BPSK radio with packet detection (and full  
synchronization), I’m surprised I’m hitting the low limits of what the  
USRP  
requires already.

Thanks,  
Rich

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**Author:** ![reback](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/b5ac83/32.png) [@reback](https://www.ruby-forum.com/u/reback)\
**Post date:** [March 27, 2015, 7:33pm UTC](https://www.ruby-forum.com/t/achievable-sampling-rate-without-under-overflows/234760/2 "2015-03-27T19:33:14Z")

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On 03/27/2015 01:01 PM, Richard B. wrote:

> I’m not using a multi-rate approach, so I know there are gains to be  
> [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
> [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio)  
> The answer is, unfortunately, “it depends”.

For example, I’m running a very simple radio astronomy “flow” on an  
Odroid XU3 at 2 x 11.5Msps,without overruns (except occasionally).

What type of computer are you using? Have you made certain that any  
filters you have in your flow don’t have horrendous filter lengths?  
That’s very often a cause of newcomers getting poor performance out  
of their signal flows. They specify a filter with far-too-aggressive  
“skirts”, which yields a filter that is 10 times longer than it  
really needs to be, for example.

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**Author:** ![reback](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/b5ac83/32.png) [@reback](https://www.ruby-forum.com/u/reback)\
**Post date:** [March 27, 2015, 8:29pm UTC](https://www.ruby-forum.com/t/achievable-sampling-rate-without-under-overflows/234760/3 "2015-03-27T20:29:49Z")

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Understood MarcusL. The question remains, what are some example sample  
rates your radio’s can support? I’m requesting a reference.

Thanks,  
Rich

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**Author:** ![reback](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/b5ac83/32.png) [@reback](https://www.ruby-forum.com/u/reback)\
**Post date:** [March 28, 2015, 2:37pm UTC](https://www.ruby-forum.com/t/achievable-sampling-rate-without-under-overflows/234760/4 "2015-03-28T14:37:39Z")

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Hi Richard,

there’s definitely people doing working real-time IEEE 802.11a/b/g  
decoding/encoding [1] at 10MHz and 20MHz bandwidths (==sampling rates).

Greetings,  
Marcus

[1] [http://dl.acm.org/citation.cfm?doid=2643230.2643240](http://dl.acm.org/citation.cfm?doid=2643230.2643240)  
[2] [http://dl.acm.org/citation.cfm?doid=2491246.2491248](http://dl.acm.org/citation.cfm?doid=2491246.2491248) Table 1

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**Author:** ![reback](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/b5ac83/32.png) [@reback](https://www.ruby-forum.com/u/reback)\
**Post date:** [March 30, 2015, 9:05am UTC](https://www.ruby-forum.com/t/achievable-sampling-rate-without-under-overflows/234760/5 "2015-03-30T09:05:46Z")

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Ah, sorry, it’s all from the WiMe project site,  
[http://www.ccs-labs.org/projects/wime/](http://www.ccs-labs.org/projects/wime/)  
where there are further papers you _can_ download for free.

Greetings,  
Marcus

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**Author:** ![reback](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/b5ac83/32.png) [@reback](https://www.ruby-forum.com/u/reback)\
**Post date:** [March 30, 2015, 5:12am UTC](https://www.ruby-forum.com/t/achievable-sampling-rate-without-under-overflows/234760/6 "2015-03-30T05:12:38Z")

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On Sat, Mar 28, 2015 at 9:35 AM, Marcus M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> 

Just an FYI…reference [1] is not available to ACM non-members  
without purchase.