ROBUST TRIGGERING OF MULTIPLE SUBSYSTEMS FOR A TERRAIN MEASUREMENT SYSTEM

One primary system integration challenge for a terrain measurement system is the triggering and time synchronization of all subsystems. Since individual measurement systems vary in their triggering requirements, both in terms of voltage levels and response times, a comprehensive triggering architecture is difficult to implement. Examples of triggering signal inputs include: a transistor-transistor logic (TTL) compliant signal, an RS-232 compliant signal, and an open/close switch circuit. Pulse-triggering signals are also present, and enable continuous time synchronization between instruments. Therefore, a triggering scheme is proposed capable of accurately initiating, synchronizing, and concluding data collection from multiple sensors and subsystems. Simulation of complete circuit designs show that the trigger circuit is capable of properly processing a single physical switch input signal into a TTL-compliant trigger signal. Synchronization pulse signals are likewise amplified to TTL logic levels and broadcast. The high level system design is presented with discussion about the design considerations. A proof of concept demonstrates the approach is valid for the Vehicle Terrain Measurement System (VTMS). Finally, the benefits of this approach and future development to this system are presented.