-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Bahn William L Civ USAFA/DFCS wrote: > I have a few questions, but they mostly come down to: What is the data file > format when using a file as a signal source? >
These file_sink and file_source are direct wrappers for the C functions fwrite and fread and behave exactly as they do. A file is therefore simply a binary containing {chars,shorts,ints,floats,etc} in local-endianness. > Question #1: What is the syntax for the itemsize argument? > > Since the example doesn't use one of the data types mentioned, it is hard to > tell what the syntax is supposed to be. For instance, if I want to use > gr_complex, do I specify gr.sizeof_gr_complex? If I want to use unsigned > char, is it "gr_sizeof_unsigned_char" so as to eliminate the space? > > Question #2: What are all of the options for the itemsize argument? > > It lists "gr_complex", "float", and "unsigned char" yet the example uses one > that is not in the list. Are there others? > Itemsize is the size, in bytes, of the object to be written. Valid useful values are 1 (char), 2 (short), 4 (int/float), 8 (complex); although I suspect you could put anything fwrite/fread accepted in there and it would work. > Question #3: Does the data file format for transmitting match the data file > format when receiving? > > Can I take a file that is recorded, say using receive_file_c.py (may not have > the file name exactly correct) and use that as a source without modification? > If so, what does it mean to use IQ pairs as input data? What does the USRP do > with them? > Yes. When I'm working on building a receiver for a certain modulation scheme, for example, I transmit some data and run usrp_rx_cfile.py on the receiver, then use a gr.file_source block as input to my receiver blocks to allow for reproducible testing without polluting the airwaves. Similarly, you could if you wanted generate a file to transmit by using a file_sink instead of a usrp_sink and then send it across the USRP with a file_source -> usrp_sink. The I/Q pairs are processed by the USRP from files the same way they are from a normal GNU Radio block such as e.g. the DBPSK modulator (see dbpsk.py, tunnel.py). - -Dan -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGwhxHy9GYuuMoUJ4RAstQAKC+k5g89aTnmXZsjU9ctb6sqjtCoACgjuCz 18oDQYVVTNeDL4Tx+SV+VQk= =HBOu -----END PGP SIGNATURE----- _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio