On Fri, Nov 03, 2006 at 06:58:41PM -0500, Dawei Shen wrote: > Hi, Guys > > I am suddenly a little bit confused about the difference between > usrp.source_s and usrp.source_c. Basically I have two questions: > > 1. Since the ADC only has 12 bits, does it mean the short integers entering > the computer have their last four bits as zeros? Or are their first four > digits are zero (the first bit should be the sign)?
The short integers entering the computer have been through the DDC and have been processed as 16-bit ints. Without looking at the verilog code I don't recall how they're adjusted before being clocked into the DDC. > 2. Is anything interesting done when the short integers converted to float > values? Or are they simply converted to a different type without changing > the values? At this point nothing besides the format conversion is done. There have been some conversations about changing the _c format to be normalized to +/- 1.0 but the details aren't worked out yet. We'll probably define a new interface so that we don't break a bunch of code. The normalization would also be a function of the kind of daughterboard that's connected, and will probably factor in some kind of two-tone IMD performance result. Eric _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
