Just a quick answer - I hope I understood your problem correctly this time.
On Fri, Aug 17, 2007 at 05:23:06PM -0600, Bahn William L Civ USAFA/DFCS wrote: > > I'm asking the question for several reasons - some theoretical and others > practical. The basic driving force is as follows: > > I have the following processing chain: > > BBC -> FILE -> GR -> USRP -> RF -> USRP -> GR -> FILE -> BBC > [file format of input and output should be equal] > This raises the following questions: > > Q1) One of the formats in which I can send data to the USRP is as IQ data. > What does the USRP do with IQ data pairs? In the USRP documentation there is > a block diagram of the Digital Down Converter, but there is no diagram of the > Digital Up Converter. It is exactly the opposite of the DDC. The fundamental concept here is that sine and cosine are orthogonal, i.e., one can transmit a ("real") valued signal modulated by a sine and, at the same time, transmit another ("real") signal modulated by a cosine. Just add them up and seperate them by demodulation (and filtering) in the receiver. This should answer your question: if you're just concerned with transmission of the data, you can divide your input stream into 2 streams and transmit one over I and the other over the Q branch. You might want to preprocess your signal and transmit it digitally, though (to add channel coding, synch frame etc.). If you're looking at a radar/sonar application or simple AM, you probably just want one carrier. Leave the I or Q branch blank. Regards, Jens _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio