Abstract: A method and apparatus are described for use during testing of air-borne ground surveillance radar installations to provide positive identification of targets and other ground features in the recorded or displayed radar returns.

Abstract: An adaptive nonlinear processor in which the desired radar signal together with an interfering signal is mixing with a voltage controlled oscillator and fed to a dispersive filter, the output thereof being detected and converted into gating pulses for enabling a gate circuit that is also fed by the same dispersive filter. The gated output is frequency inverted and fed to a second dispersive filter which produces an inverse Fourier transform. The signal is then mixed with the delayed output of the voltage control oscillator and band pass filtered.

Abstract: A missile guidance system having means for deriving from a target angle tracking loop a signal indicative of an apparent movement of a target off a missile-to-target sight line caused by a change in missile attitude, and means for feeding said apparent movement signal into a space stabilization loop to adjust the position of the aerial to compensate for said apparent movement.

Abstract: The invention relates to a microwave barrier which uses at least two aerial beams of which one forms a protected zone extending down to the ground while the other is inclined upwards relative to the horizontal. In this way by the use of a simple construction intruders can be prevented both from crawling under the barrier and jumping over it.

Abstract: A video game machine for business use for playing a long video game including a status memory for storing status data which represents the status of the game stopped, a forward conversion circuit for converting the status data to an easy-to-remember password by using a forward conversion function, a display circuit for displaying the password for the game player, a password input device into which the player inputs the password when he resumes the game, and a backward conversion circuit for converting the password inputted to the status data of the game stopped by using a backward conversion function. The initial condition of the game is set by the status data obtained by the backward conversion, and the game can be resumed from where it was stopped.

Abstract: Method for determining and using clutter estimates in a radar clutter map. The method does not require synchronization of the transmitted radar pulses with the azimuth coordinates of the map cells. Data inputs close to each map azimuth location are used to estimate the echo amplitude in the map cell which would result if the antenna beam was pointing directly at the clutter when one data sample occurred. A burst of pulses are transmitted and return echoes are processed to produce clutter signals at least twice within the time it takes for the antenna to scan one beamwidth. Clutter echoes received adjacent in azimuth to the map cell for which the value is being calculated are converted by a formula into a value for adjusting the present map cell value. The formula takes into consideration the magnitude of the values, the difference between the values, the antenna beam width, and the azimuth spacing of the samples.

Abstract: A microwave absorbing ablating material is used as the ablative covering between the transmitting and receiving antennas while a standard ablating material, allowing the transmission of signals, is placed about the antennas. This allows signals to be transmitted from and received by the object covered by RF absorbing ablating material while preventing the transmission of signals transversely through the material. The RF absorbing, ablating material is made by combining an RF absorbing material with an ablating material in sufficient quantities to absorb and dissipate any signals that may be exposed to the ablative material.

Abstract: This invention relates to a method of and a device for removing range ambiguity in a pulse Doppler radar and to a radar including such a device especially for missile guidance. On tracking operation at a high pulse repetition frequency the method consists in switching the repetition frequency f.sub.R (k) for each time interval .DELTA.t, over a new value f.sub.R (k+1) obtained in a circuit from the measured ambiguous range y(k) and from the ambiguity number n(k), as estimated in a circuit from radar information supplied by the radar, in order to remove eclipsing, to maintain the ambiguity number constant and to estimate the range with a growing accuracy in the course of the tracking operation.

Abstract: A radiometric countermeasures system installable on a military tank to det a passive millimeter wave sensor in a guidance system on an enemy missile. The system comprises an oscillator source of mm waves; a variable attenuator connected to the oscillator to adjust the power level of the oscillator output signal; a circular polarizer connected to the attenuator; an antenna connected to the polarizer to broadcast mm wave radiation to the ambient atmosphere in which the military tank is located; and means for adjusting the attenuation of the attenuator such that total mm wave emission from the tank and from the antenna is substantially equal to the naturally-occurring mm wave radiation emitted by the background scenery in the vicinity of the tank.

Abstract: An active radar jamming system using a digital radio frequency memory (DRFM) as the central subsystem in the generation and detection of specific signal characteristics. Associated systems control the operation, data processing, and loading of the DRFM. Signals generated by the jamming system are either repeated replicas of the received radar signal stored in the DRFM, or newly generated signals constructed from data loaded into the DRFM by the associated subsystems. Such associated subsystems generate appropriate data for providing carrier and noise RF signals. Systems are also provided for determining the presence of phase coding and chirp modulation in the received radar signal data contained in the DRFM, and for detecting the angle-of-arrival of the radar signal.

Abstract: A radar transceiver is disclosed which operates with circularly polarized waveforms. A single circularly polarized antenna is used to transmit and receive circularly polarized waveforms. A 3-dB directional coupler splits the signal to be transmitted into two signals 90.degree. out-of-phase for transmission by the antenna and also combines the horizontal and vertical components of any return signal.

Abstract: A multiple parameter doppler radar system transmits a radar signal which is alternated between a first and second frequency toward a target. The doppler shifted signals reflected from the target are received and processed to derive a pair of doppler signals related respectively to the first and second frequency signals. The frequency of one of the doppler signals is measured and scaled to a target speed. The phase magnitude between the two doppler signals is measured and scaled to a target range. The phase lead/lag relationship of the two doppler signals is detected to determine if the target is moving toward or away from the radar system. The components of the system are controlled by a microprocessor which is programmed to perform quality determinations on the data derived from the signals to assess the reliability of the data even in a multiple target environment prior to displaying the parameters of target motion.

Abstract: A continuous wave radar system arrangement for improving the dynamic range of the radar receiver. The transmitted carrier signal is frequency modulated by a periodic sawtooth waveform causing a predetermined peak frequency shift. The radar receiver includes a plurality of separate receiving channels each selective to a small portion of the transmitted bandwidth. As the sawtooth modulation causes the carrier signal to sweep in frequency, the received leakage and clutter signals in the selective receiving channels are blocked momentarily and individually in each channel. The outputs of the separate receiving channels are combined to form a composite signal of the echo returns. Gaussian filters with quadratic phase compensation are used to provide the selectivity of the receiving channels.

Abstract: Proper operation of a system fault monitor is verified while the monitor is coupled on-line with the system and to an alarm line. During periods when actual system signals are produced, the monitor is coupled through one of two time delay circuits to the alarm line. During periods when no actual signals are produced by the system, the monitor input is switched to an error signal generator and the monitor output is coupled through the other time delay circuit to processing circuitry which detects the presence of the alarm signal after the circuit time delay. If no alarm signal is detected, a failure of the monitor and/or delay circuit is indicated.

Abstract: A "passive interrogator label system" (PILS) is disclosed with passive, SAW transponders which are capable of receiving an interrogation signal, processing this signal and transmitting a reply signal that is derived from the interrogation signal and contains encoded information. The SAW transducers employed in the transponders are operated at their third harmonic and comprise split fingers which reduce SAW reflections. These transducers are also shaped to increase their bandwidth and to reduce their capacitance. The bus bars connecting the transducers are formed of double thickness to reduce ohmic resistance losses and these bus bars as well as the transponder phase delay pads have two levels of serrations on their edges to substantially cancel reflections. SAW reflectors in the transponder are provided with shorts between successive fingers to reduce ohmic resistance losses and to render them less susceptible to fabrication errors.

Abstract: Apparatus and a method for generating simulated target signals for testing a radar system is disclosed. The fundamental timing intervals for each pulse of the simulated target signal are generated based upon the contents of a high-speed continuously running digital counter. The resolution of the system is determined by the clock rate utilized to increment the counter. Simulated target signals are generated by utilizing an adder to add the desired range to the contents of the counter at a time interval corresponding to each pulse of the radar sync signal. The output signal of the adder corresponds to the expected output of the counter at a time corresponding to the return pulse associated with the transmit sync signal. These values are stored in a digital memory at sequential address locations. The stored values are sequentially read to produce at the output of the memory a digital signal corresponding to the value of the high-speed counter at the time that the return pulse is to be generated.

Abstract: An arrangement is disclosed for coupling electrical energy into and/or out of a surface acoustic wave (SAW) device, such as a transponder. The SAW device has two input/output terminals electrically connected to at least one transducer for converting between electrical energy and SAW energy. Such transducer presents to the terminals a prescribed capacitance in the frequency range of operation. An inductive loop, formed by at least one turn of an electrical conductor, is connected to the two input/output terminals of the SAW device. The inductance of the loop is made substantially equal to the prescribed capacitance at the frequency range of operation, thus forming a resonant circuit with the SAW device. The loop also forms a protective DC short circuit across the two terminals, preventing build-up of static electricity. The inductive loop is inductively coupled to an antenna capable of receiving and/or transmitting radiation in the frequency range of operation.

Abstract: A reflecting target device usable in space or on earth in the testing and simulation of weapons and other energy radiating space hardware. The disclosed embodiment includes an icosahedral reentrant cavity structure providing both infrared and radio-radar frequency retroreflective capability through the use of corner reflectors, conductive grid wires and coating layers. Launch-related apparatus are also described.

Abstract: A Radar Altimeter signal presence circuit which provides improved useable system sensitivity for a given false track probability by providing an improved method for detecting the adequacy of the return signal. This return signal is composed of many small, rapidly changing reflections that vary between additive and substractive combination giving the net return the characteristic of noise. A non-linear detector is used to enhance the signal presence detectors sensitivity to weak but adequate returns while (1) reducing the ability of short periods of strong returns to cause a positive signal presence indication when the overall signal is inadequate, and (2) retaining a high sensitivity to periods of signal fades that produce measurement errors. This is accomplished by using a non-linear detector that reduces the effect of strong returns when the many small reflections tend to combine additively, and increases the effect of weak returns when the many small reflections tend to combine subtractively.

Abstract: A method and a system which allows for simultaneous radar tracking and data communication. The method of the invention includes the steps of (a) encoding a radar transmit signal with message data in a transmitter; (b) receiving transmitted returns of said encoded radar signal in a first receiver; (c) decoding said received return signal to eliminate message data; (d) receiving said encoded radar signal in a second receiver; and (e) decoding said received radar signal to extract said message data. The system of the invention includes a transmitter equipped for encoding a radar transmit signal with message data; a first receiver capable of decoding returns from said transmitter signal to eliminate said message data; and a second receiver capable of decoding said radar signal to extract the message data.