[USRP-users] Unable to get samples above 14Msps with the B2x0 and USB3.0

Ron Economos w6rz at comcast.net
Thu Jul 16 19:02:58 EDT 2015


Increasing the buffering with num_recv_frames usually does the trick. 
Like so:

benchmark_rate --rx_otw sc16 --rx_rate 28000000 
--args="master_clock_rate=56000000,num_recv_frames=128"

Ron

On 07/16/2015 02:03 PM, Paul Andrews via USRP-users wrote:
> Dear USRP users,
>
> I am trying to stream data from the USRP-B200, and I've noticed that I 
> start getting overflows if I exceed a IQ sample rate around 16Msps.
> I am using Window 8.1 Pro computer (Intel i7-4700Q @ 2.4GHz), and 
> USB3.0 (with the Intel Series 8 C220 controller).
>
> According to the information at: 
> http://www.ettus.com/kb/detail/usrp-b200-and-b210-usb-30-streaming-rate-benchmarks 
>
> I would expect to be able to data at 56Msps.   But,  I am getting much 
> less than that.  Below are the results of the benchmark_rate at 
> 28Msps, which results in overflows.
> The maximum rate I can operate at is around 14Msps.
>
> Any ideas how to resolve this issue?
>
> Paul
> ------------------------------------
> C:\Program Files\UHD\lib\uhd\examples> benchmark_rate --rx_otw sc16 
> --rx_rate 28000000 --args="master_clock_rate=56000000"
> Win32; Microsoft Visual C++ version 12.0; Boost_105600; 
> UHD_003.008.003-release
>
>
> Creating the usrp device with: master_clock_rate=56000000...
> -- Operating over USB 3.
> -- Initialize CODEC control...
> -- Initialize Radio control...
> -- Performing register loopback test... pass
> -- Performing CODEC loopback test... pass
> -- Asking for clock rate 56.000000 MHz
> -- Actually got clock rate 56.000000 MHz
> -- Performing timer loopback test... pass
> Using Device: Single USRP:
>   Device: B-Series Device
>   Mboard 0: B200
>   RX Channel: 0
>     RX DSP: 0
>     RX Dboard: A
>     RX Subdev: FE-RX2
>   TX Channel: 0
>     TX DSP: 0
>     TX Dboard: A
>     TX Subdev: FE-TX2
>
> Testing receive rate 28.000000 Msps on 1 channels
> OO
> Benchmark rate summary:
>   Num received samples:    279460546
>   Num dropped samples:     201560
>   Num overflows detected:  2
>   Num transmitted samples: 0
>   Num sequence errors:     0
>   Num underflows detected: 0
>
>
> Done!
>
>
> _______________________________________________
> USRP-users mailing list
> USRP-users at lists.ettus.com
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

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