ADC sampling window

GNU Radio
1

Hello,

The maximum sampling window of USRP2’s ADC is 50MHz or 100MHz?
Because of Nyquist Theorem the straight answer is 50MHz, once the ADC
runs at 100MHz. However if we use the complex samples (quadrature
sampling) the answer is 100MHz.
So, which is right??

Thank you,

Roberto de Matos

2

On Wed, Jun 9, 2010 at 8:27 PM, Roberto de Matos [email protected]
wrote:

Hello,

The maximum sampling window of USRP2’s ADC is 50MHz or 100MHz?
Because of Nyquist Theorem the straight answer is 50MHz, once the ADC runs at 100MHz. However if we use the complex samples (quadrature sampling) the answer is 100MHz.
So, which is right??

Nyquist states you need a sampling frequency of 2x the bandwidth of
the signal you are sampling.

When you do real sampling, you are able to accurately sample a
bandwidth of [0,Fs/2]. With baseband IQ sampling, you are accurately
able to sample a bandwidth of [-Fs/2,Fs/2]. Note you did not gain any
positive frequency content, and only negative frequency content due to
knowing the phase of your signal now.

Hopefully this clears up your confusion.

Thank you,

Roberto de Matos

Brian