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?
on 2007-07-21 00:03
on 2007-07-21 02:14
On Fri, Jul 20, 2007 at 05:02:55PM -0500, Ketan Mandke wrote: > mux value to 0x0098). In the single antenna case I can just reset the mux > chains, right? > > -- > Ketan Mandke Are you running one of our standard fpga images, or are you using one that you have modified? That is, are you writing verilog code? If you are compiling your own verilog, are all timing constraints being met? Did you start with our project file? It's seriously unlikely that the contents of the mux register is getting randomly disturbed. Eric