[Discuss-gnuradio] weird interaction between start of burst and oscillator phase

[Arun Pillai]

Hi folks,

I am seeing a very bizarre problem. I am using the USRP2 to transmit a 
stream of packets interleaved with silence. Each USRP packet obviously 
spans multiple Ethernet packets. When I send each USRP packet as part of 
its own burst (i.e. start of burst = 1 on the first ethernet packet 
corresponding to a USRP packet, end of burst = 1 on the last ethernet 
packet corresponding to that USRP packet, immediate = 1 on all packets, 
and repeated for each USRP packet), the channel that I see at the 
receiver for each packet has a very different phase even after 
accounting for CFO. However, if I send all the USRP packets along with 
complex zeros for intervening silence as one burst, I see that the 
channel phase is as expected i.e. the change in channel phase from 
packet to packet corresponds to exactly the CFO.

Any idea why this could be happening?

Thanks,
Arun.