Honeywell G.m.b.h.

Harris Corporation

Information Storage, Inc.

Harris Corporation of Cleveland, Ohio

George S Moore

James Harold Lauffenburger

An improved method and circuitry for processing high-impedance (current mode) input signals for use in translinear and other mode circuits in a manner that avoids the signal dependent bandwidth variations that occur in the prior art. A non-linear feedback structure using a transconductance gain element is employed to extend the bandwidth and/or suppress bandwidth variations encountered in the prior art. One application of this invention is the extension of Gilbert amplifier topologies, with their attendant normalization and integrated circuit implementation advantages, for operation with very low input signal levels to high bandwidth applications. A further extension in this invention allow this transconductance to be electrically adjusted to allow active bandwidth control or to compensate for signal sources with different input capacitances. The invention is particularly suitable for use as a preamplifier for pairs of sensed photodetector current signals.

Fixed and adjustable bandwidth translinear input amplifier

An improved method of configuring digital information in a recording storage media so as to significantly increase the information storage capacity of the media, and the media containing such configured digital information are disclosed. Information containing markers are arranged and configured along tracks in the media in a manner such that markers of adjacent tracks are offset relative to one another. Inter-track spacings of arcuately shaped tracks on a storage media are progressively reduced as a function of the radial spacing of the tracks from their center of curvature, further increasing the marker packing density. Return to zero pulsed modulation schemes are employed to maximize the amount of information recorded in a given number of marker locations. Drive means for reading digital information configured on storage media according to the principles of this invention are provided.

Apparatus and method for increasing storage capacity of recording media

Outputs of a linear phased array antenna can be employed for emitter field sorting, i.e., providing an indication of the frequency and angle of arrival of signals from a plurality of radiation sources, through the use of a two-dimensional optical processor that does not require a mechanism for correcting for acoustic spreading in a multi-channel Bragg cell. In effect, the multi-channel array of transducers of a Bragg cell forms a composite N-channel transducer the width of which is N times the spacing between channels. For a CW radiation source, the signal received by each array element undergoes an incremental phase shift associated with the tilt of the phase front across the array. When these signals are used to drive respectively adjacent transducers of a multi-channel Bragg cell, the acoustic effect within the bulk is equivalent to that of driving a large composite transducer with a constant frequency signal. This larger size of the effective composite transducer provides significantly reduced divergence of the composite acoustic wave, while the linear phase shift across the transducer results in a tilting of the composite acoustic wave. The two-dimensional acoustic wave modulation of a light beam passing through the Bragg cell is then imaged in the transform plane of a downstream Fourier transform lens, so as to produce a two-dimensional Fourier transform of the Bragg cell. In the transform plane there is provided a frequency display in the horizontal (parallel to the direction of travel of acoustic waves in the Bragg cell) direction and an angle of arrival (azimuth angle) display in the vertical direction. Multiple radiation sources at different locations may be processed independently through superposition.

Acousto-optic two-dimensional coherent optical modulator

Linearization of a closed-loop acousto-optic modulation system is maintained over a uniform closed-loop bandwidth that is independent of the output light intensity level through the use of a compensating square-root function generator which employs the third quadrant characteristic of a MOSFET. The MOSFET may be connected as the feedback impedance of an operational amplifier which provides the square-root gain control function for complementing the non-linearity of the acousto-optic modulator. By utilizing the third quadrant characteristics of the source-to-drain voltage relative to the drain current of the MOSFET, the square-root function generator has a transfer function which insures that a linear relationship between modulator output light intensity and input signal current can be obtained irrespective of light intensity. In accordance with a preferred embodiment of the present invention, the operational amplifier of the square-root function generator may be supplied with an offset voltage in order to insure that the desired square-root transfer function can be attained regardless of differences in the manufactured characteristics of the field effect transistors that may be used. Temperature compensation circuitry may also be adopted as part of the square-root gain control component of the system to counteract the temperature sensitivity of the MOSFET's square-root current-voltage characteristic.

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Colorado Springs, CO, United States of America

George S Moore