>If you want to look at the site I could give you a URL.....

Yes, send it in PM

Note - this link I gave yesterday http://stackoverflow.com/questions/18112729/calculate-compass-heading-from-deviceorientation-event-api

They test for absolute being true, if not the reading is discarded

 if(evt.absolute === true && evt.alpha !== null) {
    heading = compassHeading(evt.alpha, evt.beta, evt.gamma);
  }