On Jan 28, 2008 10:43 AM, Richard Jaeger <[EMAIL PROTECTED]> wrote: > I have been playing with a number of the examples - FM NB and WB > receivers, AM receiver, etc. > The sample rate appears to default to 64 MSPS, but I have been unable > to find where that default rate is set. > Where is it defined? Can it be changed from the examples themselves?
The 64MHz comes from the crystal that runs both the FPGA and other digital electronics on the USRP. You cannot change the sample rate unless you change the crystal (which I suppose isn't recommended, but hack away if you're willing to!). There is a programmable decimating CIC filter (up to 128x decimation I believe) followed by a decimating halfband FIR filter (fixed 2x decimation) implemented within the FPGA before you get to the host processing. > For example, 64MPS is not a proper subsample rate for the FM broadcast > band. > It results in aliasing and should be reduced. You could always put a bandpass filter inline to suppress anything outside of the band(s) you may be interested in. Other than aliasing, what other types of issues are you worried about with regards to the high speed 64MHz sample rate? Brian _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
