Abstract: A device for determining the frequency range and chirp rate of chirp radars or other sources of frequency-modulated signals includes a compressive receiver (16, 22, 24) for time-compressing single-frequency signals and a discriminator (26) for generating an output that represents the instantaneous frequency of the compressive-receiver output. For narrow-band signals, the frequency-modulated components in the output of the compressive receiver do not last long enough to cause a response from the discriminator (26). When the input of the compressive receiver is a chirp signal, on the other hand, the resultant compressive-receiver output lasts long enough to cause a discriminator response, and its time of occurrence and rate of frequency change are indications of the frequency range and chirp rate of the compressive-receiver input. The discriminator (26) accordingly generates an output whose slope is an indication of the chirp rate of the compressive-receiver input.

Abstract: A stripline Doppler Radar includes at least one high-frequency oscillator, a first stripline conductor connected to the oscillator, a second stripline conductor spaced from the first stripline conductor, at least one receiving diode connected to the second stripline conductor, an antenna connected to the second stripline conductor, low frequency external electrical terminals, filters connected between the stripline conductors and the external electrical terminals for inhibiting leakage of high-frequency power through the external electrical terminals, and a dielectric resonator adjustable in position from a location between the stripline conductors to a location partially covering one of the stripline conductors for conducting power delivered by the oscillator through the stripline conductors and the dielectric resonator to the receiving diode and the antenna, and for adjusting power radiated through the antenna, power received through the antenna and power transmitted from the oscillator through the resonato

Abstract: A doppler radar arrangement that is able to reject short pulses. It does so by comparing the modulus of a difference vector with the same parameter during the preceding PRI. Information corresponding to "No short pulse" or to "Short pulse detected" is stored during each pulse repetition interval. The short pulse signal is replaced by the preceding signal in the same range gate only once by comparing the stored information relating to the current i.sup.th PRI and to the preceding i-1.sup.th and i-2.sup.th PRI.

Abstract: An electro-optic memory effect providing for storing, erasing and rewriting igital information relies upon a ferroelectric polymer, polyvinylidene fluoride. Recent development of tri-fluoroethylene copolymers of this material with Curie temperatures below the melting point provides a means of selective writing, storage and erasure. The advantage of the polyvinylidene fluoride material for optical recording is its high chemical and physical stability. This material provides a mechanism for bit-by-bit erasure and long time storage of information.

Abstract: A pulse Doppler radar system with variable pulse repetition frequency has a coherent integrator to which the reflected pulses are supplied in order to avoid deterioration of the indication of a moving target given over-the-horizon reception. The coherent integrator subjects the reflected pulses to a simplified vectorial addition by the use of a number of filters. A precondition for the modified coherent integration is a staggering of the pulse repetition periods such that their sums formed over successive pulse repetition periods are constant, and a phase reference for the signal amplitudes is obtained such that the phase difference is equal to zero after every second pulse repetition.

Abstract: A hand-held, portable, simple to use, low-cost yet accurate measurement device for measuring distances and calculating areas and volumes. The device comprises a microprocessor-controlled transmitter/receiver combination for transmitting measuring signals, and receiving reflections of those signals to provide distance or length measurements. The microprocessor operates to store sequential measurements and to calculate areas and volumes therefrom. The measurement procedure involves aiming the device and operating a simple sequence of buttons to obtain the measurements. Additional features of the device include a target and stand to reflect the measuring signals, a viewfinder, a level meter, and an indented rear portion with flush sides to place the device against a vertical surface for measuring, and a generally flat surface to place the device on a horizontal surface for measuring.

Abstract: A radar system includes a variable delay circuit coupled between the transmitter and the receiver switch. A feedback loop including a comparator and an integrator is coupled between the receiver envelope detector and a control terminal for the variable delay circuit. The feedback loop controls the amount of delay of the receiver switch to maximize sensitivity to close range targets.

Abstract: A vehicle-mounted ultrasonic velocity sensor includes an ultrasonic transmitter and receiver coupled to transmit and receive horns. In one embodiment, a phase-locked-loop signal processing circuit converts the transmitted and reflected frequencies into a signal indicative of the vehicle velocity. In another embodiment, velocity data is obtained by measuring the period of a certain number of cycles of the reflected signal using a pair of counters, one counting at a rate equal to the reflected frequency, the other counting at a fixed rate. In both embodiments, the variable magnitude reflected signal is applied to an input of a drop-out detection circuit whose output is then connected to an input or inputs of the velocity determining circuits to prevent velocity detection during dropout periods.The velocity sensor may be implemented utilizing radar components.

Abstract: A method for determining a mutual position between two objects, comprising transmitting a microwave signal from the first object towards the second object, causing the second object to receive the transmittal signal and re-transmit a signal, which is caused to be received by the first object. According to the invention the first object includes a transmitter/receiver unit (S/M-unit), which transmits the aforesaid signal (f.sub.o) from a transmitter antenna. The second object (T) is caused to re-transmit the aforesaid signal modulated with a signal (f.sub.m), the first object being caused to receive the transmitted signal through at least two antennae (M.sub.1, M.sub.2) placed symmetrically on a respective side of the transmitter antenna (S) and in an antenna plane common with the transmitter antenna (S). The angle (.theta.

Abstract: This radar system makes it possible to collect complete stereo data in a single pass by utilizing an orbiting, side looking, bi-static, synthetic aperture radar. This system utilizes at least two orbiting spacecraft in synchronous parallel orbits with each other and separated by a tether. A transmitter transmits radar signals to a planet's surface which are reflected back and received by two receivers, one carried by each spacecraft. When the signals are combined, the layover produces a three dimensional picture in which vertical height information may be determined.

Abstract: The present invention relates to a process for measuring the ambiguous distance in a pulse Doppler radar of repetition frequency (f.sub.R).The device comprises means (3) for transposing the signal received R(t) by a signal of frequency p.multidot.f.sub.R, where p is a positive integer; first and second narrow band filtering means (2,5) isolating the principal line of the signal received R(t) and of the transposed signal d(t) respectively, and means (6) for measuring the phase difference (.DELTA..phi.) which exists between the two filtered signals and which is proportional to the ambiguous distance with a coefficient g.

Abstract: A "passive interrogator label system" (PILS) comprises an interrogator for transmitting an interrogation signal, one or more "labels" or passive transponders which produce a reply signal containing coded information in response to the interrogation signal, and a receiver and decoder for receiving the reply signal and decoding the information contained in it. The frequency of the interrogation signal assumes a plurality of frequency values within a prescribed frequency range. The decoder includes a mixer (4 quadrant multiplexer) for mixing together the interrogation and reply signals (or signals derived therefrom) to produce a further signal containing frequencies which are the sum and difference of the interrogation and reply signals. A signal processor, responsive to this further signal produced by the mixer, detects at least some of the frequencies contained in this further signal and determines the informational code associted with the transponder.

Abstract: A signal acquisition circuit for a missile guidance system has a phase lock loop which is responsive to incoming signals received from a target and will lock on to the frequency of the received signal. The bandwidth of the phase lock loop is altered in dependence on the signal being received in order to distinguish between a valid target and noise.

Abstract: A radar system comprising an RF transmitter and receiver means for mounting in a moving carrier for transmitting RF energy and receiving RF energy returns and a non-rotating modulating radar reflector which has a lens means for focusing incident impinging RF energy onto a spot opposite the incident side and a plurality of solid state modulating radar reflectors positioned at the spot locations for selectively reflecting the RF energy and dissipating the RF energy for providing RF energy returns modulated with a lens identification code and frequencies for determining true ground speed, range, glide slope, and azimuth position.

Abstract: Capability is provided using coherent synthetic aperture radar (SAR) techniques for substantially extending the useful range for producing 3 scaled high resolution orthogonal image projections on a CRT of a translating ship under the influence of rotational motions arising from sea state conditions, for the purpose of ship classification and weapon delivery from an airborne platform at long stand-off ranges. This advantage is brought about by determining image coordinates on the basis of range, doppler, and doppler rate measurements of individual scatterers and from ship angular rotational velocities derived from a weighted multivariate regression solution to doppler processed interferometric azimuth and elevation angle measurements of all significant ship target scatterers. In this manner, the image degradation suffered by plotting angular measurements directly, whose location accuracies are known to deteriorate rapidly with increased range due to high signal-to-noise requirements, is circumvented.

Abstract: A device for calculating a discrete moving window Fourier transform. It comprises an assembly of circuits receiving samples of the input signal (E.sub.m+n), the output signal of this assembly (.delta..sub.m) being applied to a plurality of N identical and parallel stages (E.sub.k). The assembly of circuits comprises a shift register conferring a delay of N sampling periods on the incident signal and an adder performing the subtraction:.delta..sub.m =x.sub.m+N -X.sub.mof the input and output signals of the shift register. Each of the N stages delivers a signal in the form:x.sub.k.sup.m+1 =X.sub.k.sup.m +.sub.m .delta..e.sup.j2.pi.k/N.

Abstract: Apparatus, which first de-interleaves a signal, that comprises a plurality of interleaved pulse trains, into its constituent pulse trains and then identifies the emitter which transmitted each pulse train, is described herein. Specifically, this apparatus comprises a folded shift register which performs the de-interleaving. The folded shift register comprises a plurality of serially connected identical "active" cells, each of which detects a pulse occurring at a particular group pulse repetition interval (PRI) and, in an embodiment described herein, ascertains the inter-pulse PRI for each detected pulse for use in identifying an emitter. One or more processors analyze the group and inter-pulse PRI data, provided by the folded shift register, in order to identify each emitter.

Abstract: A mode scheduling system for selecting track or search dwells in a track-while-scan radar. Targets to be tracked are classified according to acceleration levels and then arranged into priority classes based upon the acceleration. A relative update frequency for the targets in the priority classes is established. The track and search dwells are made during a repetitive dwell period having a predetermined number of track dwell intervals. Track dwells are scheduled during these intervals to satisfy the update frequency requirements. When all of the track dwell positions are not needed, search dwells are substituted for some of the track dwells. Search dwells are also inserted between track dwells, as needed, to maintain a minimum amount of search time regardless of the number of targets being tracked.

Abstract: In a radar system comprising equipment for transmitting frequency modulated pulses and compressing the received signals in a filter for frequency-dependent weighting, the weighting is asymmetrical in a manner such that the leading sidelobes of the pulse compression signal are reduced and the lagging sidelobes are raised. The reduced leading sidelobes can easily be reduced below an amplitude threshold so that the main echo lobe within the pulse compression signal is reliably acquired for determining the closest target distance. The invention may advantageously be applied to ground tracking radars.

Abstract: Adaptive radar signal processor apt to detect the useful echo in the presence of an additive disturbance made up of clutter and noise, through which the disturbance can be cancelled and the useful signal can be enhanced by means of the synthesis of a filter, adapted to the useful signal, which rejects the disturbance spectrum frequency components by adapting itself in real time to its variations.