[Discuss-gnuradio] tx/rx turnaround on usrp2/xcvr 2450

[Apurv Bhartia]

Hi All, 

I'm trying to verify the transceiver operations on USRP2 w/ XCVR 2450 (raw ethernet driver) using the OFDM tunneling script (tunnel.py). I see a strange behavior, which I'm unable to parse. 

I tried the ping-pong test between two nodes: the node that transmits the data fails to receive the next packet that is sent to it (tx->rx switch) 70% of the time. On the other hand the rx->tx switch seems to work fine, i.e. a node is able to receive data and then transmit it. I also plotted the peaks thrown by the pn correlation, and the peaks are very inconsistent - though generally missing, which explains that the packet was not seen. 

Moreover, I've limited the application rate to send a packet once every 0.5s , to ensure that too many packets are not being sent out. The CPU utilization also looks fine, its a dual core 2.33 GHz that I'm running and I've not seen the CPU utilization go above 70% on the combined cores. 

If I just enable the node as a sender or receiver only, everything seems to work fine. Any thoughts?

Thanks,
Apurv