On Tue, Aug 12, 2008 at 7:33 AM, kaleem ahmad <[EMAIL PROTECTED]> wrote: > > Hello Everyone, > > If you run following code on your machine (I am using gnradio3.1.1 and this > code is also available in this version with a name 'fsk_loopback.py' > although it is removed in gnuradio3.1.2) then you will see that it will > transfer a file send.txt (Please create file named as "send.txt" in your > current folder) to another file "rcv.txt" (It will create that file by > itself). > > But the problem is it will never transfer the complete file but some data at > the end is always missing and the amount of data missing depends on > "payload_size = ?" at line 38 in the following: > > payload_size = 64 # bytes > > If the file is larger than 64 bytes let say 64 x 10 bytes then last two > blocks will be lost, and first 8 blocks will be received (You can run the > code given at the end without and USRP hardware, because it only tests the > GNURadio and dont need any hardware). > > In short> > > 1-If the file is larger than the payload_size then last two blocks of data > (2 x payload_size) are not received. > > 2-If the file is smaller than the payload_size then data is not transferred > at all. > > For your convinience I have also attached send.txt and python code file > which you can directly download and run on your PC. > > Can some one give me some clue why this data is lost???????????
Just taking a stab in the dark here, but in your program there are a couple of low pass filters. There is a finite group delay with those filters. Do you know the length of your filters? How large have you made your payload size? I have a feeling that if you make your payload size relatively large, then you won't see the last few blocks missing, but instead a piece of the last block. To alleviate, you may want to flush the filters out with all 0's for at least the length of 1/2 the taps, but it might be better to clear the whole thing just so if you decide to start a new burst, the filter doesn't have anything left over to cause some weird transients at the beginning of the burst. Hope that helps. Brian _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
