TXs Phase offset in single USRP

[NafJ]

Hello,

I have recently started a project  with USRP 2945R. I write the same signal to both TX channels but whether by using internal/external clock source there exists a phase offset between the transmitted signals that I can see on the oscilloscope. This offset changes randomly each time I do the measurements. I wanted to know if there is a way to calibrate the LOs to compensate this phase offset?

Thanks

[Case_in_Point]

Ni NafJ,

There is some amount of random phase offset that will occur every time you tune the LOs. From Ettus' documentation: "After tuning the RF front-ends, each local oscillator may have a random phase offset due to the dividers in the VCO/PLL chains. This offset will remain constant after the device has been initialized, and will remain constant until the device is closed or re-tuned. This phase offset is typically removed by the user in MIMO applications, using a training sequence to estimate the offset. It will be necessary to re-align the LOs after each tune command."

Cason

NI Applications Engr.

[Bimx]

Is there any way to measure the phase offset between the LO's in Labview VI?