# Problem to recover data DBPSK **URL:** \ **Category:** GNU Radio\ **Created:** [May 9, 2016, 3:42pm UTC](https://www.ruby-forum.com/t/problem-to-recover-data-dbpsk/244590 "2016-05-09T15:42:57Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![Sadaf\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@Sadaf\_N](https://www.ruby-forum.com/u/Sadaf_N)\ **Post date:** [May 9, 2016, 3:42pm UTC](https://www.ruby-forum.com/t/problem-to-recover-data-dbpsk/244590/1 "2016-05-09T15:42:57Z")
Hello, I am trying to demodulate DBPSK with a baud rate of 100 symbol/sec and I have a sample rate of 100000 samples/sec. To obtain my sample rate of 100 symbol/sec I realise a first decimation by 50 and then a second decimation of 10 to obtain 2 samples/symbol. On my constellation I can see properly 2 points. But when I recover my data I don’t find the same size of my payload that I transmit. I always miss 1 bit. Do I demodulate correctly ? (image in attachment) I already try to use the block DPSK demod, MPSK receiver, and PSK demod but for me the FLL band edge doesn’t work better than costa loop. And after some test, clock recovery seems to work more better than polyphase clock recovery. Thank you for your help. Sincerely, Nathan28