On Sun, Jul 12, 2009 at 2:55 PM, Timur Alperovich<timur...@umich.edu> wrote: >> On Sunday 12 July 2009 08:09:24 Timur Alperovich wrote: >>> Hey guys, >>> >>> I've been trying to read from the USRP by simply doing u->read(buf, >>> 512, overrun). I used the usrp_inband_usb_packet class to extract the >>> payload size and the payload from each USB packet received. As I >>> understand, the USB packets contain pairs of I and Q for each (I >>> didn't change the format from the default). I was expecting the >>> payload size then to be a multiple of 4, since it is 2 shorts. I >>> frequently see payload sizes such as 7, 13, etc. What is going on >>> here? Are there examples of getting the data from a dbsrx using this >>> method and processing it? I found the test_standard_rx example, but it >>> doesn't do any processing and just reads. >> >> If you want to use the inband code, of course you have to use the inband >> firmware as well. Most probably, you use the standard firmware, and the >> "payload size" you see is a normal sample. > > Thank you Stefan. That definitely explains it! What is the > advantage/reason for using the inband firmware? I was working on > adapting some of the OpenBTS code for what I'm trying to do and I > didn't realize they're using the inband firmware and didn't realize > the differences in the data returned by the different firmware. > Searching gnuradio.org, I couldn't find anything on the wiki about it.
Ok, I found the information about in-band signaling, which render my other questions moot: http://gnuradio.org/trac/wiki/InBandSignaling. Thanks for the help again. >> USB packets produced by the standard firmware always contain 512 bytes/128 >> complex samples (as long as you stick to standard sample resolution of 16 bit >> per component). >> >> The inband firmware will produce packets containing 504 bytes of payload (126 >> samples), and it will accept shorter packets. >> >> Regards, >> >> Stefan -- Cheers, Timur _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
