Engineering Notebook


Naval Research Lab


NRL was building a closed-loop missile guidance test set and range simulator. Two realtime computers were being used: One to control an actual missile guidance head, and one to control transmitters that simulated the radar characteristics of various target ships. They needed a way to visualize the numeric results in real time.


A separate Silicon Graphics Workstation was chosen to host the realtime display system. 3-D models of various missiles and target ships were displayed using Open-GL. sample display Multiple viewpoints were simultaneously displayed, including ship, missile, and gods-eye (overhead) views. This was easily able to keep up with the 15 frames-per-second minimum refresh requirement. All coding was done using the C++ language.

The position, orientation, and velocity of the missile and the ship were sent to the display system using TCP/IP messages sent over a 100base-TX ethernet, with the display system acting as a server. This design allowed for preliminary remote integration of the display system over the Internet, well before physical delivery, and proved invaluable in finding and correcting interface problems. The payoff came at delivery, when the full-up integration took less than a day.