HYPERVELOCITY TELEMETRY SYSTEM

Abstract

This paper presents the development of a very high shock telemetry system designed to operate when subjected to acceleration forces of 50,000 g’s in a 120mm gun environment. This system consists of an RF transmitter, a ten channel FM/FM multiplexer, a very rugged power supply, a microstrip patch antenna, and a sensor module. The sensor module contains a tri-axial accelerometer designed to measure the projectile’s low in-flight radial and drag forces and two additional accelerometers to measure the projectile’s high in-bore setback and balloting forces. The sensor suite is located at the center of gravity of the projectile. The patch antenna is incorporated into a radiating structure consisting of a cylindrical metal tube and a plastic cover. To accommodate the antenna in the space available, a microstrip antenna is built on a substrate material that has a dielectric constant of e = 10. Though the cylindrical metal tube, in which the antenna is housed, acts as a cylindrical waveguide operating below its cut-off frequency, its relatively short length allows for adequate power to be radiated for proper system operation. The telemetry system uses standard off-the-shelf telemetry components that were modified and repackaged to withstand the 50,000 "g" environment. All components performed very well in preliminary high "g" (50,000 g’s) tests in a laboratory gun at the Army Research Development and Engineering Center (ARDEC).