I have been experiencing a weird bug when transmitting packets using the
USRP. I am part of the Hydra group at UT (hydra.ece.utexas.edu). We have
been developing a multiple antenna system using the USRP. It seems to
work
quite well except for the following bug:
Since we’re using two transmit chains, I set the mux value in
usrp.sink_c to
0xBA98. I have noticed however, that at random the transmitter will flip
the
IQ channels of the transmitter. I have verified that this occurs by
analyzing the trace of the received signal. I noticed that this same bug
seems to occur when using a single antenna system as well (there I set
the
mux value to 0x0098). In the single antenna case I can just reset the
mux
value to 0x0098 everytime I send a packet in order to alleviate the
problem.
This same approach does not work in the two-antenna case.
Any thoughts on why the mux value in the transmitter might be changing
or
why the IQ channels might get flipped? Please note that I have already
verified that the EXACT same waveform is being sent to the usrp
everytime I
transmit a packet; hence, I am certain that the bug is not being caused
in
software.
I am currently using a multiple antenna system, so I set the usrp.sink_c
mux
value to 0xBA98. This should enable the USRP to support to transmit RF
chains, right?