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
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!!!