sounds good it must work on ultra Sonics does it ?<br />we use Ultrasonic sensors in the trade and there about 900 bucks for a basic setpoint ( on off like a limilt switch) but the Analog output ( 4 20ma ) they are very pricey its seams that they work on the same lines as what you are talking about <br /><br />what would be cool would be a Radar that you could install in you house and it shows you a outline of the house and all the movments around it better that having 10 PIR sensors