I am working with 3 people on a project involving GNU Radio and USRP1. We have tried to implement a simple point to point digital communication system in GRC involving DQPSK modulation. Using a vector source we are sending a finite stream of zeros and ones (the vector source has Repeat set to yes). On the receiver side, what we receive is really very strange: The same stream of zeros and ones, but with extra zeros in between our actual data. For example, we send three ones and three zeros, but what we receive is a one followed by seven zeros, another one followed by seven zeros, another one followed by seven zeros, and then a zero followed by seven zeros e.t.c. We tried to experiment more by using the 'KEEP 1 in N' block and the 'DECIMATING FIR FILTER', but things are not working out the way they should.
I am also attaching a snapshot of the .grc file for your reference. Please tell us the reason why these extra zeros are present between our data bits, and the way to combat this effect (remember that the decimating fir filter and keep 1 in N block are not showing the desired output). Any kind of help is appreciated in advance.