[Discuss-gnuradio] [SOLVED] Re: multi usrp, 1 odd channel, HW problem?

[Steven Clark]

On Thu, Oct 14, 2010 at 12:13 PM, Steven Clark <address@hidden> wrote:

Hi all-

I have a multi-usrp setup with 2 USRP 1s and 4 WBX daughtercards. I have performed the clock synching described here: http://gnuradio.org/redmine/wiki/1/MultiUsrp

I'm doing 4-channel receive, using a power splitter to send the same CW signal into all 4 d'cards, and tuning them all identically.

3 of the 4 channels are nicely phase-locked. The 4th seems a little...off.

ClockMasterUSRP (Serial #5821): Side A: "red" channel
ClockMasterUSRP (Serial #5821): Side B: "green" channel
ClockSlaveUSRP (Serial #2087): Side A: "blue" channel
ClockSlaveUSRP (Serial #2087): Side B: "black" channel      <--- problem with this guy

Please see these 3 images to see the problem: http://picasaweb.google.com/steven.p.clark/MultiUsrpGlitches?feat=directlink

You can see the problem in both the frequency domain, and in the time domain.

I tried swapping daughtercards around, and the problem is not tied to any one daughtercard, but rather to slave USRP side B.

Any idea what could be causing this? Shouldn't the same clock be going to both sides of the USRP? (why does blue look fine, but black does not?)

-Steven

Solved....see if you can spot the problem:

self.usrp_master.tune(0, self.wbx0_subdev, freq)

self.usrp_master.tune(1, self.wbx1_subdev, freq)

self.usrp_slave.tune(0, self.wbx2_subdev, freq)

self.usrp_slave.tune(0, self.wbx3_subdev, freq)

/facepalm

(The final line's 0 should be a 1. the daughtercards were getting tuned properly, but the 4th DDC was not). Everything looks fine now. Sorry for suspecting the hardware, Matt!

-Steven