Some people have been wondering if the IR projector is somehow synced to the camera that does 3D estimation.
Short answer: No.
The easiest way to visualize a modulated signal is to use an oscilloscope. I got out my trusty Hameg and hooked up a photodiode to it. This photodiode has a peak response at 850nm, plenty close to the IR coming out of the projector on the Kinect.
I connected the photodiode to my ‘scope probe.
As a sanity check, hold it under a CFL bulb. You can clearly see the bulb oscillating on the ‘scope.
Holding the same photodiode in front of the Kinect IR projector gets…. flatline. As far as I could observe, the projector is never modulated — during capture, or when capture is not running but the Kinect is on.