Re: [Discuss-gnuradio] Support wideband(20MHz) OFDM transmitting/receiving using RawOFMD and USRP N210

[Qing Yang]

I have enabled the real-time scheduling in my PCs. And my USRPs are connected to PCs via direct link of a Gigabyte ethernet card.

I am now trying the volk.

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Yang, Qing

Information Engineering, CUHK

2012/8/7 Nathan West <address@hidden>

On Tue, Aug 7, 2012 at 10:12 AM, <address@hidden> wrote:

On 06 Aug 2012 17:59, Alex Zhang wrote:

Just state, I was using the tunnel.py instead of the rawOFDM to do the test. Seems nobody declared good bitrate within this community, although I have asked for many times.

 

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Alex,

Dreams can come true – just believe.

Nobody has answered because there is no single answer.  Your achievable performance depends on too many factors for anyone to come up with a reasonable answer.

Different computers, with very different performance levels, different OS distributions with different optimizations in different parts of the kernel.  And that's ignoring any of the path distortions that may be present between your radios.

The fact is that general-purpose operating systems aren't well-optimized for real-time, high-bandwidth, digital signal processing, even on systems where the "raw" compute power would seem to be adequate. The path lengths (in terms of number of executed instructions) between data sources and the calculations are much longer than they would be in a compute environment optimized for the job.

 

 

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Agreed, which is why there is general advice, like enabling real-time scheduling for non-root users: http://lists.gnu.org/archive/html/discuss-gnuradio/2010-07/msg00463.html

You should also run volk_profile : http://gnuradio.org/redmine/projects/gnuradio/wiki/Volk

And if you think the link between the USRP and your PC is an issue you shouldn't use any kind of hub/switch.

-Nathan