[USRP-users] Detecting if USRP contended via USB 2.0 or USB 3.0.

Marcus Müller marcus.mueller at ettus.com
Thu Apr 16 15:34:35 EDT 2015


Hello,

Those are Bytes/s. So your calculation is correct. I don't really know
why the USB2 limit is 32MB/s, but it's the same as for the old USRP1, so
that would make sense.
I'm still going to just playfully adjust that value, because I thought
8MS/s was the maximum for USRP1 because two things had to be fulfilled:
a) the sampling rate * 32 bit must fit through USB2, and
b) the sampling rate must be an integer fraction of the fixed USRP1
master_clock_rate, which is 64MHz

a) still applies, but I'm not so sure about b), since the B2x0 has a
variable master clock rate, so rates 44MHz/4 would actually be o.k.

Greetings,
Marcus

On 04/16/2015 09:18 PM, Weaver, Tyler via USRP-users wrote:
> Hello Marcus,
>
> Thank you for the help.  I need to access it through a UHD
> application.  Using your method I got these two results when connecting:
>
> usb 2: 3.2e+07
> usb 3: 5e+08
>
> The question I have relates to the usb 2 rate.  I’ve read that the
> greatest sample rate under usb 2 is 8 MS/s.  Are these numbers in
> bytes/s?  If so that would make sense that you need 32e6 bytes/s to
> transfer 8e6 2x16bit complex values.  Is this correct?
>
> tyler
>
>
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> USRP-users at lists.ettus.com
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