Two types of receiver are available.
Securely mount the receiver in the car on the roll bar or in any other location with the red window facing in the direction of the transmitter. Aim the receiver directly at the transmitter. If you must mount the receiver behind a panel, mount it close to the surface and cut a 1 inch hole in the material. The infrared sensor is located 3/8 inch behind the red window. More than 15 degrees of tilt or swing can shade the sensor from the transmitter beam. Test your mounting location using the Cal (P2) feature.
The receiver is a very high gain device that just waits to see the beam. When it sees the beam for 0.002 second, it tells the display to increase the lap count and show the time elapsed since it last saw the beam. Power is sent to the receiver and the receiver sends information to the display over the telephone cable.