Hi everyone,
This might be more of a general digital communication question, so forgive me if this is inappropriate for this list, but I'm hoping you can provide some insight w.r.t the implementation.
I'm using the architecture from the packet_tx/rx examples (
https://www.gnuradio.org/doc/doxygen-v3.7.13.4/page_packet_comms.html I am using 3.7) to send packet data wirelessly between two USRP N310s.
I'm using the repetition encoder and BPSK for both the header and the payload. The receiver is correctly detecting the packets, and the headers match exactly to what was transmitted, so I believe detection parts of the flowgraph
(amplitude, timing, phase estimation and correction)
are working properly, but there are significant bit errors in the payload. I've observed two things happening:
1. The first 8-9 bytes will be correct and then it appears to "drop" a bit, and the remaining bits will be off by one to the tx data. This "dropping" could happen a few times per message.
2. The entire rx payload will be the complement of the tx data.
These two things could happen together or independently.
For the first effect, it seems like the sample rate is not lining up with the edges of the symbols, or maybe a slight offset between the true sample rates of the tx and rx. But the header is detected and decoded perfectly consistently; it's only in the payload that these "drops" occur. I'm not sure why the second would happen.
Can you think of anything in the blocks of the packet_tx/rx examples that I can adjust to help with either of these problems? Or just in general what might be going on?
Thank you for your time,
Cameron