[Discuss-gnuradio] 64QAM Repack Bits Misalignment

Hi everyone,

I am using the Repack Bits block to unpack bytes into 6 bits (aka. k=8 to l=6) and then repack this output back into full bytes (aka. k=6 to l=8). The input is a stream of tagged packets, say of length 5 bytes (6.667 64QAM symbols), meaning the number of bits isn't exactly divisible by 6. As such I have the block doing the unpacking aligned to the input, while the block doing the packing is aligned to the output (as per doco). What I find - both in LSB and MSB modes - is that the first packet is recovered correctly while every second one is misaligned and incorrect.

If the packet length was 7 (9.333 symbols), I can expect every 3rd packet to be correct. A similar thing occurs with 8PSK which unpacks 8bits to 3bits and vice versa.

How do I fix this alignment issue to get 64QAM/8PSK repacking working? Thanks!

Regards,

Justin