UltraSonic Presence Detector

The UltraSonic Presence Detector is a sonic mass detector that tells how far away solid objects are from the sensor. When used as a presence system for AEI, it determines whether or not a train is present. When the device detects mass, a train must be present. It can detect objects as far away as 21 feet. The detector is typically placed about twelve feet from the track and is able to send its information over a serial connection.