Lock-In Amplifier Technology in Laser Gyroscope North Finder of Constant Rate Biasing.

This paper presents a newtype of strapdown north finder. A simplified configuration is proposed, including three parts: a pendulous force-feedback accelerometer, a ring laser gyroscope, and a single-axis rotating platform. The dynamic northfinding scheme of continuous rotation is adopted to eliminate the lock-in region of the laser gyroscope and to modulate the weak attitude signals; meanwhile the complex leveling process is avoided in this proposed configuration. To suppress the drift noises of the accelerometer and gyroscope, two digital lock-in amplifiers are used to extract the weak attitude signals. Simulation results show that the north finder can determine the heading angle in 72 s, when the rotating rate is 10°/s with the maximum heading error less than 1.0'; meanwhile the horizontal attitude angles as well as the constant drift noises of the inertial components could also be obtained. [ABSTRACT FROM AUTHOR]