Abstract: The RF input of a radio receiver is converted to IF including received signal, noise and interference and fed to an interference detector and to an interference canceler of an interference suppressor. A fast Fourier transform (FFT) at the front end of the interference detector detects samples of all the interferences in the frequency domain. The frequency domain samples are scaled for gain control and detection of interferences above a predetermined threshold. The interference detector suppresses interferences to the predetermined threshold level. The scaled frequency domain interference samples are phase rotated and fed to an inverse fast Fourier transform to obtain a time domain replica of the interferences which are phase shifted replicas of the detected interferences.

Abstract: A four frequency laser gyroscope system having a rugged and compact output structure for producing output signals representing the frequency differences between counter-circulating wave pairs circulating as two beams within the gyroscope cavity. A partially transmitting dielectric mirror forms both one of the cavity reflectors and the means for extracting a small portion of each beam. The two extracted beams are combined on a beam splitter. Both the transmitted and reflected beams from the output of the beam splitter, each containing waves of all four frequencies, are utilized. Each resultant beam is then polarization discriminated to extract the desired signal content. The entire structure is adapted for rigid mechanical coupling and may be constructed to have a small size.

Abstract: A very high resolution laser gyroscope system having a phased-locked loop operatively coupled to one or more frequency difference outputs from a laser gyroscope cavity. Waves of at least four frequencies propagate around the gyroscope cavity, with output signals being formed having a frequency equal to the difference between the frequencies of wave pairs. In one set of embodiments of the invention, the frequency difference signal for one wave pair is phase-locked to an external reference source. A signal applied to a Faraday rotator bias coil provides the frequency shifting of the wave pairs necessary to achieve phase lock. The amplitude of the signal applied to the Faraday bias coil provides a highly precise measure of the rate of rotation. In another set of embodiments of the invention, one or more of the wave pair frequency difference signals are coupled as inputs to an external phase-locked loop in which a voltage controlled oscillator is followed by a frequency divider of the feedback circuit.

Abstract: A very high resolution laser gyroscope system having a phase-locked loop operatively coupled to the output of a laser gyroscope cavity. A difference frequency signal is formed between two output beams from the gyroscope cavity. The phase of the difference signal is compared with that of a reference clock to produce a signal representative of the phase difference between the reference clock and difference signal. The latter signal is amplified and coupled to a coil which produces a field within a Faraday rotator body disposed in the wave propagation path within the laser gyroscope cavity. The phase of the difference signal is thus phase-locked to that of the reference clock signal so that the frequency difference between the two beams in the cavity is maintained constant over a wide range of rates of rotation.

Abstract: A ring laser gyroscope having a self-compensating discharge path between a single anode and cathode which comprises equal segments in the laser path in series with a channel that interconnects the laser path and allows a single current to flow within the equal segments in opposite directions with respect to the laser beam thereby cancelling the Fresnel-Fizeau drag effect. This design is applicable also to laser gyroscopes having two or more rings in a single gyro block structure.