Hello, everyone!
I am working on using USRP to realize mutirate transmission. I have spent these two days trying to transmit data with dqpsk modulation scheme, and the file I used is python/digital/benchmark_tx.py and benchmark_rx.py. Below is the conclusion I could reach based on the data I got:
1, I changed the tx-amplitude to different values ranging from 1000 to 12000 with two USRP 5 feet apart and the rssi values I tested at the receiver side are quite great, but no matter the tx-amplitude was the minimum value or the maximum value, the PER was CONSTANT which was arount 12%. While I was doing these experiments, the size of the packet was set to 40 which was actually too small.
2, While from the experiments I described above we know the PER was not changing with the
transmission power, after I changed the size of the packet to 100, the PER was changed to 30%, which was still a CONSTANT level. After I changed the number of samples per symbol to 4, the PER was decreased to 20%.
So, it looks like that if the transmission power is large enough, the PER of dqpsk modulaiton scheme in gnuradio is only related to the packet size and the samples per symbol, which means dqpsk modulation scheme is not functioning well in gnuradio, am I right?
Has anybody come across the same problem as me? Is the dqpsk modulation scheme in gnuradio working fine? Can we use that in our experiment? What kind of workaround I should do for the dqpsk if it is proved that dqpsk cannot work as well as dbpsk? Thanks a lot for all!!!
Bill