Re: [Discuss-gnuradio] USB2, 32 MByte/s or 480MBit/s?

[David Carr]

As a point of reference the SSRP was used in a radio astronomy application
where maximum bandwidth was important and we were able to squeeze a little
more than 40MB/s out of the bus.

I think this says that there is a little more to be had but that the USRP
is doing a pretty good job at 32MB/s...

-David Carr

>
>>> Hi,
>>>
>>> I was wondering why can the USRP "only" achieve 32 MByte/s, i.e. 256
>>> Mbit/s whereas the USB 2.0 specifications are 480 MBit/s? The 32
>>> Mbyte/s is mentioned in several earlier posts on the gnuradio mailing
>>> list archive and in the BBN report (freebsd section).
>>
>>
>> One is 'full-speed' and the other is 'high-speed'. Different chips are
>> required.
>
> That is incorrect.  Full speed is 12 megabits per second (1.5
> megabytes/s) and the USRP doesn't do full speed, only high speed.
>
> The USRP easily does 256 megabits per second (32 megabytes/s).  The USB
> 2.0 raw signalling rate is 480 megabits per second, or 60 megabytes per
> second.  You can't get the full 480 because there is overhead from
> packet headers, time between packets, etc.  We could probably squeeze a
> little more bandwidth out of the bus, but it isn't a priority for now.
>
>
> Matt
>
>
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