Guide : what is the value of the IF converted before feeding the ADC in usrp/gnuradio

Hi everyone ,
I would like to know what is the actual last converted IF frequency
which
is actually fed to the ADC in usrp/gnuradio , since ADC rate is 64MS/s ,
I
hope it IF should be less than 2xSampling rate of ADC, which implies IF
could not be 70Mhz. So what is the value of IF before entering the ADC
and
what speed rate does the baseband is fed to the ADC for samping.
Thanks in advance and also i apologize for any errrormatic information
in my
post.


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On 04/12/2011 04:44 AM, ton ph wrote:

Hi everyone ,
I would like to know what is the actual last converted IF frequency
which is actually fed to the ADC in usrp/gnuradio , since ADC rate is
64MS/s , I hope it IF should be less than 2xSampling rate of ADC,
which implies IF could not be 70Mhz. So what is the value of IF before
entering the ADC and what speed rate does the baseband is fed to the
ADC for samping.
Thanks in advance and also i apologize for any errrormatic information
in my post.

It depends on the daughtercard in use, but most daughtercards
down-convert the desired center
frequency to a complex baseband, centered at 0Hz.

There are execeptions. The original TV_RX used an IF of 5.75MHz, which
was converted to complex
baseband (I and Q) in the FPGA with a DDC.


Principal Investigator
Shirleys Bay Radio Astronomy Consortium