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

[Matt Ettus]

> > 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