> 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. > 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 [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
