Patent ID: 8547220

Claim:
A device for establishing two compliance zones within a room, the room having a back wall and two generally opposed walls, the device interacting with a dual ultrasonic transmitter, the dual ultrasonic transmitter having first and second ultrasonic transmitters located on the back wall with the first ultrasonic transmitter directed generally toward a first of the two generally opposed walls for establishing a first compliance zone and the second ultrasonic transmitter directed generally toward a second of the two generally opposed walls for establishing a second compliance zone, the first and second ultrasonic transmitters transmitting ultrasonic signals at predetermined intervals of time, the device comprising: a processor connected to a memory and an ultrasound signal receiver, the memory storing an executable program, the program instructing the processor to: receive, through the ultrasound signal receiver, a first ultrasound transmission from the first ultrasonic transmitter and record a first time at which the first ultrasound transmission is received; receive, through the ultrasound signal receiver, a second ultrasound transmission from the second ultrasonic transmitter and record a second time at which the second ultrasound transmission is received; comparing the first and second times to determine whether the device is located in the first compliance zone or the second compliance zone.