International Telephone and Telegraph Corporation

Itt Gilfillan, a Division of Itt Corporation

Damian F Albanese

Henry R Kennedy

David E Hammers

Albert M Klein

Richard Roland Waer

Jack W Goodwin

Frank J O'Farrell

Kanji F Sayano

A system for determining the range R of a stationary emitter on the ground from an airborne bistatic radar as a function of velocity V, direction .beta., antenna spacing d, wavelength .lambda. and rate of change of phase with respect to time .theta. is discussed herein: ##EQU1##

Radar ranging system

A compressive receiver for developing a series of time-based identifying pulses corresponding to discrete received signals having various frequencies within a predetermined band of surveillance. A multiple local oscillator function is included, effectively dividing the predetermined band of interest into small frequency increments, each of these local oscillator signals being coded by a pseudo-random coded sequence (bi-phase code) of maximal length. Each frequency increment thus developed is coded by this sequence delayed by one bit duration as compared to that applied to the local oscillator frequency immediately preceding it. A mixer receiving input signals in the band of interest, and also the multiple local oscillator signals thus generated and coded, has its output processed by a passive correlator which provides pulses at times determined by the frequencies extant in the input signal.

Digital compressive receiver

An FM-CW radar system with improved range discrimination and improved immunity to clutter, chaff, jamming and multiple target environments. The FM-CW apparatus involves a repetitive cycle including a first, constant-transmitted-frequency (monochromatic) transmission, a linear frequency upsweep as a second period and a linear frequency downsweep as a third period within each transmission frame. Pseudorandom coding is superimposed on the FM-CW waveform, a code word duration being selected to place the first Doppler ambiguity beyond the highest expected equivalent target velocity. The resulting range ambiguities are resolved by means of the unambiguous range-determining capability of the FM-CW feature.

PRC/FM CW Radar system

A system for elimination of transmitter (illuminator) leakage in a high duty cycle, pulsed, pseudonoise, semi-active missile guidance system. The missile has front and back receiving systems, and the illuminator signal extant at the rear receiver is used to develop a gating signal which turns the front receiver 'off' during the time of arrival of the leakage signals at the front receiver. The receiver gating is automatically time adjusted as a function of missile range. Alternate reversal of the bi-phase transmitted code bits is offered as a means of reducing the 'eclipsing' loss due to receiver gating out of useful signal return from the target being tracked.

Gated pseudonoise semi-active missile guidance system with improved

A range, angle, and Doppler (velocity) measuring radar in which a CW, PRC radar floodlights a volume of interest. A receiving antenna in the form of a linear array generally broadside with respect to the bisector of the volume of interest is commutated (sampled) element-by-element to provide a phase modulated received signal from which angle information may be derived. Autocorrelation of the PRC signal received against the transmitted code provides for range determination and a Doppler filter bank is provided corresponding to each discrete receiving angle, the outputs indicating range and velocity of a target at each discrete angle of reception.

Range and angle determining Doppler radar

A system primarily for industrial security; to detect intruder movement in interior areas. A Doppler detecting, bi-static system utilizing range (time-delay) areas of varying shapes. The detection containment obtained is orders of magnitude more absolute than conventional systems which depend on antenna beam shaping to obtain varying detection coverage. Range discrimination is effected by bi-phase modulating the transmitted CW radio frequency waves according to a maximal length pseudo-random code. The autocorrelation function provides the ideal range discrimination response for the application. Omni antenna coverages are provided and a lower rf band is used than in conventional systems for this use, affording lower moving clutter susceptibility and better coverage. The general pseudo-random coding techniques are available within the state of the Radar Arts.

Large area motion sensor using pseudo-random coding technique

A CW pseudo-random-coded (PRC) radar system including a triple-clock arrangement. The three slightly different clock frequencies are sequentially employed to generate the bi-phase coded RF transmissions and the received echo signals are separately bi-phase de-modulated by code bit. Clutter filtering and sampling in both I and Q channels by a commutating element are employed. Video processing, preferably of the FFT type, is provided as is range-ambiguity processing. The system provides resolution of range ambiguities over a long total range permitting the PRC word length and other system parameters to be optimized for elimination of Doppler ambiguities.

Growing community of inventors

Chatsworth, CA, United States of America

Damian F Albanese