[Discuss-gnuradio] improper WBX transmission of tone in center of spectrum

[George Nychis]

I have a WBX, and I've noticed that no matter what I transmit, the WBX always introduces a very narrow (but full-power) tone at the center of my spectrum.  When the transmitter is disabled, the tone is not present.

This can be seen below, where I'm transmitting a stream of complex(0,0), yet it still transmits this tone in at the center (520MHz):

Has anyone experienced this before with the WBX board?  I've confirmed it's only my WBX board by using the same USRP2 board and trying my RFX2400 and XCVR2450 with the same transmit script and sample stream and neither see this problem.

I am using the latest USRP2 firmware that includes the WBX support, and the newest GR git.  It's possible that the board is defective in some way... but I thought I'd punt it to the list to see if anyone else has seen the issue.

- George