Abstract: A laser gyro lifetime prediction method incorporates a memory model that stores a worst case performance parameter for a readout intensity, a laser intensity and a derived quantity known as volts per mode for a laser gyro. A microprocessor based life prediction method utilizes a predetermined failure criteria to judge a estimate of laser gyro life based on historic performance of laser gyro operating parameters. The prediction is based on a linear quadratic or higher order fit of lifetime data for critical temperatures. The performance data is stored in a memory model for each critical temperature and parameter. The laser gyro reports eminent failures to the inertial navigation system or a host controller. Routine scheduled maintenance of the laser gyro is enhanced by knowing its lifetime.

Abstract: A sampling method and apparatus for sampling a dither signal includes the step of sensing a number of peak amplitudes P.sub.1, P.sub.2, P.sub.3 . . . P.sub.n each of the number of peak amplitudes having a corresponding times t.sub.1, t.sub.2, t.sub.3 . . . t.sub.n while simultaneously sensing a number of ring laser gyro output angles at each of the corresponding times t.sub.1, t.sub.2, t.sub.3 . . . t.sub.n. A value of the gyro net output, .DELTA..phi., is calculated as .DELTA..phi.=(.phi..sub.n -.phi..sub.n-1)-(.alpha..sub.n -.alpha..sub.n-1)K, where K is a correction factor. Alternatively, the stripped gyro angle output may be calculated as .phi..sub.g =.phi..sub.n -.alpha..sub.n K. Where .phi..sub.g is substantially equivalent to the sum of all of the changes in the stripped gyro angle, that is the sum of all .DELTA..phi.'s. The correction may include corrections for gain, phase angle, nonlinearity, temperature bias and scale factors.

Abstract: A laser digital path length control method and apparatus for precisely controlling a laser path length to obtain a laser mode and change a laser mode. The invention uses a microprocessor to control a path length control circuit that continuously adjusts the position of path length control mirrors. The mirrors may be positioned in response to the microprocessor to acquire a particular mode of the laser or change the mode of the laser. While the gyro mode is changed the microprocessor increases the gyro run current to prevent loss of gyro function returning the current to its normal value following the mode change. The microprocessor adjusts the position of the two path length control mirrors such that total path length follows a predetermined or dynamic range. The invention allows the calculation of volts per mode of the laser by providing a means to monitor laser intensity as a function of voltage supplied to the laser path length controllers.

Abstract: A laser gyro configuration and control using a microprocessor. The microprocessor has a high speed peripheral transaction system which communicates through a high speed Universal Asynchronous Receiver Transmitter (UART) to a serial to parallel converter through a five Byte first in first out (FIFO) to an external system processor. The external system processor sends information in a serial fashion through a single byte parallel to serial converter to the high speed UART. Various information including gyro parameter load commands, gyro control commands, gyro status commands, and gyro calibration and diagnostic commands are sent over channels. The system provides a high speed method of controlling the laser gyro and configuring it with a processor with serial transmit and receive lines.

Abstract: A laser gyro built in test apparatus. A laser gyro includes a microprocessor which provides a high speed method of communicating test data to an external inertial navigation system. The microprocessor performs tests on the gyro including temperature sensor tests, dither drive tests, active current control tests, and reports on the expected life of the gyro. The gyro can be commanded from the external system to perform any number of the built in test functions. The built in test functions are periodically executed to evaluate the health of the laser gyro and are thereby incorporated in the monitor control loop of the laser gyro.

Abstract: A laser gyro start up apparatus and method that safely and quickly starts a laser gyro. A microprocessor sequences the mechanical and electrical systems of the laser gyro such that the gyro is started up quickly in the proper sequence. The microprocessor also executes tests on the gyro and provides a health signal in the timing sequence. The start up apparatus starts the laser block dither, laser discharge and acquires the path length controllers. Optical start up operations may be performed including the calibration of volts per mode.

Abstract: A dither stripper for laser gyro dither including a digital microcomputer which controls the stripping of the dither signal from the inertial navigation signal of the laser gyro. The dither stripper schedules internal A/D conversions using an A/D conversion arbitration scheme as well as calculates the expected system sample clock. Accurate dither stripping is achieved using a phase locked loop feedback system which compensates for real time changes in dither pickoff components while incorporating an accurate gain control mechanism.

Abstract: A direct digital dither drive for a laser gyro dither motor including a digital microcomputer which controls the dithering of a laser gyro to prevent lock in of the laser beams. The digital drive senses a dither position and schedules internal A/D conversions using an A/D conversion arbitration scheme. The period frequency and location of the minimum and maximum drive are determined using the microcontroller. Accurate dither drive is accomplished using a digital analog feedback system which compensates for real time changes in dither pickoff and dither drive components.

Abstract: Disclosed is a Reed-Solomon error correction apparatus which is programmable to perform several distinct error correction functions. The apparatus performs the following functions: encoding, error detection, syndrome generation, burst error trapping, and Chien searching.