Problem with packet decoder

Hi Everyone,

I want to find the BER for my experiment. I use DQPSK modulation. Packet
encoder is encoding the data and working fine. But my packet decoder is
giving an output which is much less than expected. Attached the GRC
files for transmitter and receiver side. I use the default access code
and threshold value of 12. If I check the output of packet decoder (file
sink size), it is 140 KB (each packet size is 4K, so it comes to 35
packets). The output of the unpack K- bits block is something around
190KB. But output of packet Decoder is only 12KB. It shows that I have
some problem with packet decoder block.
Any help or suggestion would be appreciated. I also checked the output
file size of throttle block on transmitter and receiver. They are same,
showing whatever information or data sent is received. I use concrete
channel between tX and RX.