I wear the Model X16-1C accelerometer at night, Velcro'ed to the top of my Quattro FX head gear. The mask head gear is conveniently made to accommodate Velcro because that is how the head gear is adjusted. I put the accelerometer on the top of my head because there's a strap there to attach to and it's out of the way of my nightly movements. The accelerometer records X, Y, and Z positions into text files from moment to moment, which I capture and record into a database.
I "calibrated" the meaning of the X, Y, and Z values by putting my head and body into known positions for a while and then looked at the values. The chart below shows last night's data with some notations about sleeping position.
In another posting later I'll show how I relate positions to my brain waves from the Zeo and my breathing and apnea events.