Raytheon Company

Hughes Aircraft Company

Edward L Arnn

Robert William Byren

Preben B Jensen

An efficient multi-emitter boresight reference source ( ). The efficient reference source ( ) includes a first mechanism ( ) for transmitting a first portion of electromagnetic energy ( ) within a first waveband. A second mechanism ( ) transmits a second portion of electromagnetic energy ( ) within a second waveband different than the first waveband. A third mechanism ( ) for combining the first portion of electromagnetic energy and the second portion of electromagnetic energy to yield a uniform reference beam ( ).

Efficient multiple emitter boresight reference source

A system and method for processing the output of a fiber-optic gyroscope. The inventive circuit ( ) includes a photodetector ( ) for detecting electromagnetic energy received from the fiber-optic gyroscope ( ) and providing an analog input signal in response thereto. An analog-to-digital converter ( ) is provided for processing the analog input signal and providing a digital signal in response thereto. A source ( ) is provided for injecting a dither signal between the photodetector ( ) and the analog-to-digital converter ( ). In the illustrative embodiment, the source ( ) supplies a triangle wave signal. The output of the photodetector ( ) is supplied to the summing input of a differential amplifier ( ) and the output of the source ( ) supplies the differencing input to the differential amplifier ( ). The output of the analog-to-digital converter ( ) is provided to a digital signal processor ( ) as per usual practice.

Method for processing the output of a fiber optic gyroscope to reduce the effects of vibration therefrom

A chirped backscatter filter 10 compares a received signal (RSIG) to a reference signal related to a transmitted signal (TSIG) and removes from RSIG the frequency component which is equal to TSIG in frequency. This removed frequency component corresponds to the frequency of the transmitter backscatter radiation. The filter of the invention adds a frequency offset (f.sub.n) to both RSIG and TSIG in mixers 12 and 14 before substracting one from the other in mixer 22. Thus, equal frequency components in both RSIG and TSIG, such as the backscatter radiation frequency component of RSIG, will equal f.sub.n. The frequencies resulting from this subtraction are thereafter passed through a notch filter 24 which is centered on f.sub.n and which passes all frequency components except f.sub.n. The output of the notch filter thus no longer has a frequency component associated with the backscatter frequency component. The loss of the RSIG phase reference due to the phase reference between the RSIG and TSIG modulation envelopes being destroyed during the backscatter filtering process is therafter compensated for by adding TSIG to the filtered difference frequency component, thereby reestablishing the phase relationship of the original RSIG frequency components minus the backscatter frequency component.

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Torrance, CA, United States of America

Edward L Arnn