I’m a starter in using the USRP, it’s known that the bandwidth of USRP
is 8M beacause of the USB bandwidth ,my question is the 8M refers to the
Nquist Bandwith or the actual signal bandwidth?If it refers to the
Nquist Bandwith, it is mean that USRP can only process the signal with
4M bandwidth,so if a signal larger than 4M, how can USRP deals with it ?

On 11/8/11 9:29 AM, wrote:

I’m a starter in using the USRP, it’s known that the bandwidth of USRP
is 8M beacause of the USB bandwidth ,my question is the 8M refers to the
Nquist Bandwith or the actual signal bandwidth?If it refers to the
Nquist Bandwith, it is mean that USRP can only process the signal with
4M bandwidth,so if a signal larger than 4M, how can USRP deals with it ?

Because the USRP does complex samples, an 8 megasample/sec rate
is enough to resolve up to 8 MHz. This is in contrast to
magnitude-only
real samples, where an 8 megasample/sec rate would only resolve up to
4 MHz.

A qualitative way to think about it is that complex samples provide
twice the data as magnitude-only real samples, providing that
“factor of 2”.

Nyquist will not be cheated!

@(^.^)@ Ed

On 08/11/2011 9:29 AM, 弓长张 wrote:

I’m a starter in using the USRP, it’s known that the bandwidth of USRP
is 8M beacause of the USB bandwidth ,my question is the 8M refers to
the Nquist Bandwith or the actual signal bandwidth?If it refers to the
Nquist Bandwith, it is mean that USRP can only process the signal with
4M bandwidth,so if a signal larger than 4M, how can USRP deals with it ?

USRP use complex-baseband sampling, which allows you to “cheat” Nyquist.
With complex sampling, the sample-rate == bandwidth.

With the very-latest UHD updates from Josh last night, 8-bit “wire
format” samples are supported, which doubles the effective
bandwidth-to-the-host for all the USRP platforms, meaning that USRP1 and
B100 can support 16Msps maximum, and USRP2/N2XX
can support 50Msps maximum. I’d like to see someone be able to “do
something” with 50Msps into their host

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