[USRP-users] Errors 0x8 and 0xf when capturing with b210.

Weaver, Tyler tweaver at lgsinnovations.com
Wed Apr 22 12:24:26 EDT 2015

This is not through a VM in either case.  All of the following tests were performed on the Dell.  

The initial messages say that it’s operating over USB3, clock rate of 32 MHz, all tests pass and the reference is internal GPSDO.  Device is connected to included external power supply.  850 band antenna is connected to RF-A RX2.

using rx_samples_to_file
output was set to /dev/null
duration was 60 seconds
frequency was set to 800 MHz

D = bad packet
O = overflow error

sc8/32e6: DO x5
sc8/16e6: DO x2
sc8/8e6: DO x2
sc8/4e6: DO
sc16/32e6: O x5
sc16/16e6: O x2
sc16/8e6: O
sc16/4e6: O 

I ran several of these multiple times and saw different numbers of errors but not more than +/- 2 of what I showed above.  I determined the bad packet occurs when the format is set to signed complex 8 bit.  Where the overflow error rate seems to happen even at very low data rates and more at high data rates.  The error printed by rx_samples_to_file relating to the overflow indicates that the medium (hard drive or ram?) has to sustain a rate of a certain amount for this to be avoided.  What’s confusing is that I’ve never seen either of these errors when running the N210 I have on the same computer at a sample rate of 40 MS/s.  It is content to a usb3-to-ethernet dongle and performs just fine.

Are there any other tests you’d suggest?  Does this tell you anything more about my configuration?  Could it have to do with the usb’s buffering?  Is there anyway to increase the size of the buffer?  Is the medium mentioned the hard drive or ram.  In either case they should be fast enough, this computer has a high end ssd that I’ve been able to stream to at 40 MS/s (sc16) off the pci buss with a different company’s radio with no problems.

thank you,

> On Apr 22, 2015, at 8:39 AM, Marcus D. Leech <mleech at ripnet.com> wrote:
> On 04/21/2015 01:41 PM, Weaver, Tyler wrote:
>> Hash: SHA512
>> Sample rates:
>> I have tried various sample rates and the errors occur at > 8 MHz.  For my application I need something > 20 MHz.  Preferably I want to sample at 30.72 MHz.
>> Hardware:
>> dell: i7-4800MQ, 16gb ram, radion 8790M, SSD hd.
>> mac: i704980HQ, 16gb ram, nvidia gt 750M, SSD hd.
>> Clock rate:
>> I’ve tried 30.72 and 61.44 MHz.  Neither have gotten rid of the errors.
> What happens if you do something super-simple, like using rx_samples_to_file, and specifying /dev/null for the output file, and then try your
>   various sample rates.  Leaving the master clock at the default 32MHz, I'd try 4, 8, and 16 msps.
> If this is through a VM, then you can expect potentially-horrible USB performance...

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