I am checking my usrp setup with benchmark_tx
and benchmark_rx scripts. The results I got were very odd, I want to ask
your opinion about it.
I have two "nodes" and each
node has 1x laptop, 1x USRP1 with 2x RFX2400 daughter cards.
The two RX/TX ports from a node are
connected to coaxial cables then combined, and the two cables from the
two nodes are connected with 45dB attenuator (miniCircuits).
1) When the modulation scheme was set
to dbpsk, there was no error, no packet was dropped.
2) However, when the modulation scheme
was set to dqpsk or d8psk, the error rate was 100% with many dropped packet.
3) When the modulation scheme was set
to gmsk, the error rate was about 86% (without dropped packet)
NOTE: error rate = number of packets
with error / total number of received packet
I did not go over the scripts, but the
script recognized the USRP as MIMO system, I assume having two daughter
boards is allowed.