[USRP-users] b200 Overflows

Simon Brown simon at sdr-radio.com
Sat Sep 27 14:37:13 EDT 2014


I do mean fc32, not fc21, being harassed by my dog.

 

Simon Brown G4ELI
http://v2.sdr-radio.com

 

From: USRP-users [mailto:usrp-users-bounces at lists.ettus.com] On Behalf Of
Simon Brown via USRP-users
Sent: 27 September 2014 19:31
To: usrp-users at lists.ettus.com
Subject: Re: [USRP-users] b200 Overflows

 

Hi Marcus,

 

I'll try sc12 tomorrow, possibly later this evening. I'm currently preparing
food and adding some diagnostics.

 

It's probably in the manual, but is there a way to determine the most
efficient format for a device without losing resolution, for example sc12
for b200, (maybe) sc16 or fc21 for the N210 etc.? I would like to reduce any
network / bus traffic where possible.

 

Simon Brown G4ELI
http://v2.sdr-radio.com

 

From: USRP-users [mailto:usrp-users-bounces at lists.ettus.com] On Behalf Of
Marcus D. Leech via USRP-users
Sent: 27 September 2014 19:11
To: usrp-users at lists.ettus.com
Subject: Re: [USRP-users] b200 Overflows

 

On 09/27/2014 02:00 PM, Simon Brown via USRP-users wrote: 

Thanks,

 

I've tried changing these, still get overruns with sample rates of 8MS/s or
higher.

 

Simon Brown G4ELI
http://v2.sdr-radio.com

 

Are you sure that your USB-3.0 interface is actually dealing with the device
as a USB-3.0 and not a USB-2.0 device?  

If you specify a wire-format of sc8 or sc12, do the overruns go away?  This
will help distinguish between cases involving CPU exhaustion, and interior
  bus deficiencies  (I found this on one of my embedded systems--could
sustain only 6.4Msps with full-width samples, but was perfectly happy to
  stream 12.8Msps with 8-bit samples).




From: USRP-users [mailto:usrp-users-bounces at lists.ettus.com] On Behalf Of
Marcus D. Leech via USRP-users
Sent: 26 September 2014 20:03
To: usrp-users at lists.ettus.com
Subject: Re: [USRP-users] b200 Overflows

 

On 09/26/2014 02:18 PM, Simon Brown via USRP-users wrote:

Hi,

 

Windows 64-bit: I'm streaming nicely, none of my threads indicate CPU
problems (plenty of headroom). At 8MB/s and higher I'm getting fastpath
Overrun messages every second or so even though I'm pulling data from the
b200 as fast as it's available, I am not CPU limited in any way. Using Intel
USB 3.

 

FWIW I don't see any way to tune the uhd::rx_streamer - bigger / more
buffers, also I don't see any way to flush either.

 

Interestingly if I get my CUDA card working harder (more work on the bus)
the Overrun messages appear more frequently. I7 4770k, good motherboard
(can't remember what).

 

Any suggestions?

 

Simon Brown G4ELI
http://v2.sdr-radio.com

 






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The USB transport parameters can be tweaked:

http://files.ettus.com/manual/page_transport.html#transport_usb_params



 
 
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-- 
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
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