The Rapiscan/TSA MD134 is designed to automatically scan vehicles or containers without the need for frequent calibration. The system can be stationary to scan vehicles as they drive by or it can be mounted in a vehicle and driven past items to be scanned.
When the system is powered up, it acquires an initial background count typically within 120 seconds. The TSA MD134 can be put in occupancy mode two different ways, sensor activated or constant. When occupancy is activated the system starts comparing the current count to the most recent background data. Alarm comparisons are made every 200ms. If the count exceeds the alarm level, both audible and visual alarms will be triggered. The system monitors itself and indicates low and high background conditions.