Abstract: A portable test system is arranged to enable testing of an aircraft-mounted radar system. Simulated radar returns are transmitted via a test antenna positioned a short distance from an aircraft parked on an airport surface. The varying amplitude of received radar pulses is analyzed as the test antenna is illuminated by the main beam and side lobes of the radar antenna pattern as the radar beam is scanned. By controlling the amplitude of the simulated radar returns in inverse relation to the amplitude of received radar pulses, simulated radar returns inserted off beam center line are interpreted by the radar system as received on the beam center line. Test system transmissions, which may incorporate windshear effect test data, are thus enabled to create simulated effects usable for testing radar system response to a variety of airborne conditions, such as windshear. Test methods are also described.

Abstract: A simple and inexpensive method for using aerial or satellite photographs of an area of terrain to form images to be used in the simulation of a series of synthetic aperture radar (SAR) images of the terrain as would be observed by a down-looking SAR mounted on an aircraft over the terrain. Scanned and digitized photographic pixels are formed and converted into radar image pixels and combined into composite images as required for SAR simulation. Terrain elevation data are assembled, correlated with the radar image pixels and converted to elevation images. These images are stored on media accessible by aircraft simulators and correlated with simulated aircraft position and altitude data to form composite images with obscured terrain features for display as darkened areas closely duplicating actual SAR images when displayed in an aircraft simulator.

Abstract: A phase measurement circuit of a phased array antenna having both transmitting and receiving functions includes a plurality of antenna elements arranged in a line or on a plain; phase shifters disposed corresponding to the antenna elements, respectively, for shifting phases of signals to form a beam in a desired direction by changing the phase value; a control circuit for controlling the phase shift quantity of the phase shifter; a test antenna for receiving electric wave of a transmission frequency band from the phased array antenna and transmitting a test signal for measuring an excitation phase to each element of the phased array antenna; and a test translator for converting a frequency of the signal of the transmission frequency band received by the test antenna to that of the signal of a reception frequency band and outputting it as a test signal to the test antenna.

Abstract: A system for simulating a moving target, having an antenna that emits a steerable propagation pattern, a receiver and a target signal generator. Analog signals representing the azimuth position of the target and the azimuth position of the antenna propagation pattern are summed yielding analog azimuth position signals. The analog azimuth position signals are then converted to digital code. Analog signals representing the elevation position of the target and the elevation position of the propagation pattern are summed yielding analog elevation position signals. The analog elevation position signals are then converted to digital code. The azimuth position digital code and digital code representing the propagation pattern direction are input into a memory unit which outputs an azimuth attenuation digital code. The elevation position digital code and the propagation pattern direction digital code are likewise input into a memory to produce an elevation attenuation digital code.

Abstract: A visual simulation system in combination with a radar simulation system may be used for generating full radar or synthetic aperture radar (SAR) radar images from a common data base that are correlated to video images of the visual system while facilitating radar image processing. The combination of visual and radar simulation systems in accordance with the present invention obviates the need for a separate stand-alone radar processor and dedicated radar data base. Simulated electronic tactical map data may also be provided.

Abstract: A programmable radar target simulator provides microwave signals for testing a missile that is otherwise controlled by such signals when it is deployed. The simulator has the capability for initiating suitable microwave signals at the proper power levels in the fully automatic, semi-automatic, or fully manual modes. A control section and an IF section accept digital commands from an external computer or manual control from switches and thumbwheels on the front panel of the simulator to provide for the automatic and manual control signals respectively. A frequency synthesizer section provides three frequency modulated IF signals and one amplitude modulated coding signal which respectively are fed to the IF section and to the control section. Doppler frequency shifts are extracted and representative signals are provided in both AC and DC forms to a microwave section.

Abstract: A portable radar simulator which when connected to a transmitting means s as a waveguide horn antenna provides a radar signal to test a radar receiver. The portable radar simulator comprises a tunable oscillator which generates a continuous wave signal in the microwave frequency range with the desired frequency of the signal being selected by an operator. The signal generated by the tunable oscillator is supplied to a microwave switch. The microwave switch receives a control signal provided by a pulse repetition frequency generating circuit and in response to the control signal turns the switch on or off controlling the transmission of the oscillator generated signal to the wave guide horn antenna. The pulse repetition frequency generating circuit which comprises an integrated circuit timer and a monostable multivibrator provides a variable frequency and variable pulse width control signal. The frequency and pulse width of the control signal are, in turn, set by the operator.

Abstract: Tracking system for monitoring aircraft position during simulated training exercises. Standard IFF transponders on the aircraft are periodically enabled by a squitter transmitter mounted on the aircraft. On the ground a plurality of receiving stations are interconnected through a communication link. The transponder replies are received at each receiving station. The time of arrival for each of the transponder replies is measured and communicated to one of the receiving stations. Using Loran techniques, accurate longitudinal and latitude coordinates are determined from the time of arrival data.

Abstract: A simulated burst echo signal (artificial target), corresponding to a deld and conditioned version of an RF burst signal from an associated radar under test, is presented to the associated radar under test by coupling a portion of the RF burst signal into a shipboard sensor exerciser apparatus in which the present invention is employed to feed an attenuated facsimile of the RF burst signal into a phase-locked loop portion thereof. The phase-locked loop locks on to the attenuated facsimile of the RF burst signal and generates an error signal in response thereto. The error signal is then digitized and stored in an error storage unit portion where it is delayed for a predetermined time associated with the desired selected range of the artificial target.

Abstract: A portable radar simulator which when connected to a transmitting means s as a magnetron generated microwave threat transmitter simulates up to 2048 pre-programmed radar signatures. The portable radar simulator comprises a replaceable Erasable Programmable Read Only Memory (EPROM) which will hold up to 2048 pre-programmed radar signatures. Selection of a particular radar threat to be simulated is entered by an operator via thumbwheel switches located on the front panel of the simulator. The portable radar simulator simulates such radar parameters as jitter, stagger, frequency hop, simple and complex scans, pulse repetition intervals and frequency pulse widths.

Abstract: A low cost simulator for training electronic warfare operators to recognize signatures of various emitters. The simulator consists of a card which can be plugged into an IBM PC or compatible computer. Through the computer, various characteristics of one, or a plurality of emitters are entered. The simulator, using an existing digital signal processing (DSP) chip generates a replica of a signal received by a radar system receiver from one, or a plurality of emitters.

Abstract: A method and apparatus for electronically simulating the transmit-receive gnal path of doppler radar during a target encounter in a simulator. It is an end-to-end fuze (radar) test from RF "in" to video "out". Target signature data is collected at a reduced relative encounter velocity from the actual target. The modified pulse doppler radar produces two orthogonal signals which define the complex received radar signal. These signals are then recorded. The missile radar to be tested is coupled to the simulator which simulates an actual missile to target encounter. During the test the PROMs are clocked into RF components in an RF Loop and clock counter is started. When the radar threshold is exceeded, a radar video output function stops the counter. By correlating the number of clock pulses counter to the distance marks traveled along the missile trajectory, missile radar function with respect to target location data is obtained and missle lethality computed.

Abstract: Faulty subarray module circuit boards are detected in a phased array antenna having many subarray module circuit boards while the antenna is fully assembled and operationally integrated with a radar system. A far field ratio frequency test source illuminates the antenna. Binary digital signals that control subarray steering bits are set to a reference setting. A particular subarray module circuit board that is under test has its 180.degree. main phase bit toggled between 0.degree. and 180.degree.. The radar selects the output of that particular subarray module by Doppler filter type of software filtering. The amplitude of the in-phase and quadrature phase signals from the radar is recorded. The binary digital signals that control subarray steering bits are set to a second setting. The 180.degree. main phase bit of the module under test is again toggled between 0.degree. and 180.degree.. The output of the module under test is again selected by Doppler filter type of software filtering.

Abstract: A portable compact target motion simulation system, adapted to generate simulated target motion for displaying, tracking, and controlling a plurality of simulated targets on a display device for training purposes. The system is operable to generate pre-programmed and dynamic exercises, for training trainees in operating tracking devices, to develop trainee skill in analyzing and responding properly to target motion.The apparatus is totally programmable, and capable of providing targets in any matrix. It includes a target display generator, adapted to store, merge, and transmit timed data signals for driving a target-display device. It further includes a dynamic target motion generator, microprocessor-based, adapted to receive input data identifying the characteristics of particular operator-controlled targets and convert such data into dynamic target motion input data for driving the target display generator.

Abstract: Both a system and a method for simulating targets for a radar system is disclosed herein which generally comprises a test target generator having an input slaved to the pulse transmit frequencies of the radar system for generating a target simulating signal, a horn antenna for emitting the target simulating signal back to the radar receiver, a laser-operated optical transmission link having a single mode fiber optic cable for transmitting the target simulating signal from the test target generator to the horn antenna via optical carrier, and an amplification and processing circuit system connected between the output of the optical transmission link and the input of the horn antenna for increasing the amplitude of the target simulating signal to a level that is detectable by the radar receiver, and for further processing the signal.

Abstract: A system is disclosed in which a direction-finding system (12) employed on an aircraft (20) receives RF transmissions from a remote signal source (16). Amplitude and phase data concerning the transmission are used for direction finding but are perturbed by the various surfaces of the aircraft. To minimize the influence of such perturbations, a database (14) including model data subject to the same perturbations is employed by the system and incoming transmissions from signal source (16) are correlated to the database data to determine the proper azimuth and elevation associated with said transmissions. Several embodiments of a database production system (18) used in creating the database are also disclosed.

Abstract: A target simulates the coincident infrared and microwave signatures of a rce being tracked by a missile whose systems are undergoing test.

Abstract: Radar signature simulator for use in electronic warfare and training intercept operators. Recorded video portions of radar signature as they appear at the point of intercept on a video tape recorder are played back to produce video signals. These signals are used to amplitude modululate an RF signal of the desired frequency. The modulated signal is amplified in a linear amplifier and fed to a broadband tansmitting antenna.

Abstract: The present invention provides a radar simulation system with at least two counters. The first counter is a coarse counter 20/30 that counts a transmit pulse interpulse periods to provide a coarse return delay at the beginning of a radar look. The second counter is a fine counter 22/36 which counts, after the coarse counter has counted down to zero, from each subsequent transmit pulse to the time for the return pulse. Once the coarse counter has finished counting, the fine counter, which can be reset and reloaded during the look responsive to each transmit pulse, can provide return targets repeating at the same distance at the pulse repetition frequency. A cyclic counter 24 can also be added that produces the return pulses by cyclically counting the interpulse period one the fine counter has timed out. If the cyclic counter is used the fine counter is not reloaded during the look.

Abstract: A software controlled generic radar display system using a microcomputer ing a high performance graphics card that drives a high resolution color monitor which displays the radar sweep, compass rose, front panel symbology and diagnostic information. A target generator provides simulated target information that is displayed on the monitor in standard PPI format.

Abstract: A test facility, especially for the seeker or search heads of intelligent guided ammunition, including a target simulator for the reflection of a target signature through the intermediary of antenna elements towards the search head which is mounted on a turntable or rotary member with a flight simulator. Arranged between the target simulator and the search head is a quasi-optical coupling which follows the beam geometry by means of an imaging system and, on the one hand, the search head, as well as, on the other hand, the target simulator are located in or proximate to the applicable focal point of the resultingly produced path of transmission.

Abstract: A null command generator test apparatus capable of operating in either the open or closed loop configuration for testing the Sarcalm system. When operating in an open loop configuration the null command generator test apparatus utilizes the normalized voltage output of the null command generator as the estimator for the beam pointing error. When operating in the closed loop configuration, the test apparatus utilizes either the voltage output of the null command generator or the angle difference between the line of sight to the target and the null direction of the antenna servo simulator to estimate the dynamic pointing errors.

Abstract: A device constructed as simple as possible shall be provided for simulating, in laboratory tests of radar seekers, the conditions of free space with a moving target emitting radar radiation. To this end, a radar anechoic chamber is formed as hollow body pivotable about the radar seeker and serving as ray trap. A radar transmitter is arranged in this hollow body.

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: 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: 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 method for computer aided simulation of complete radar systems under evaluation of the instantaneous power and frequency information comprises the steps of providing a simulation signal representing the instantaneous power spectrum of the transmitter modifying said signal in accordance with the propagation and spreading path to be simulated and in addition modifying said signal in accordance with preselected target properties, modifying the previously modified signal in accordance with particular properties characteristic of the receiver and associated components to be simulated, such as amplifier characteristics, filters, mixers, Doppler stages, analog-to-digital conversion and calculating statistical moments of the first and second order of the resulting signal such as the expectancy value and its variance and indicating the same.

Abstract: Proper operation of a beam steering unit for a phase array antenna, is verified by simulating the pattern of wave energy which would be radiated to an observation point in space when the beam steering unit is connected to phase shifters associated with elements of the antenna. The simulated pattern thus obtained may be compared with a preset pattern for the observation point during a scanning operation of the beam steering unit, and an alarm or other indication is obtained when the difference between the simulated and the preset pattern exceeds a certain limit. The simulated pattern is obtained by storing phase angle data from the beam steering unit in a memory at areas corresponding to phase shifters associated with elements of the phased array antenna.Observation angle data corresponding to the angle of the point in space relative to the antenna array is generated, the observation angle data being a function of observation angle, antenna element spacing and radiation wavelength.

Abstract: An adaptive, fail-soft digital filterbank for digitized Doppler-modulated video signals. A plurality of modules are controlled by the impulse filter weighting technique to each respond to a set of discrete Doppler frequencies. A built-in test feature is included, the module inputs being multiplexed between system digitized video and synthetic signals to continuously confirm proper operation. Module failures are recognized by the control (programming) circuitry and spare modules can be activated. Control and communications link circuitry is constructed with multiple redundancy.

Abstract: System and method for producing a pattern of radar radiation encountered by a object in the scan path of a radar, commonly referred to as "radar signature". The basic system has a memory containing at least digital amplitude information for each pulse of the signature, digital pulse width information for each pulse, digital pulse-to-pulse interval information for each pulse, scan time information and scan gap information. A digital to analog converter converts the digital amplitude information to a proportional voltage. Timers convert the pulse width information, the pulse-to-pulse interval information, scan time information and scan gap information to intervals of time in sequential fashion. During pulse width times, the output of the digital to analog converter is enabled. The output is disabled during pulse-to-pulse intervals and scan gap time. A controller controls the transfer of amplitude information from memory to the digital to analog converter and controls operation of the timers.

Abstract: A simulator for simulating radar or sonar signals returned to an observation point from a three-dimensional object of non-uniform reflectivity. An imaginary three-dimensional object is defined spatially in the form of a series of three-dimensional regularly shaped elements. Each element has allocated to it a predetermined level of uniform reflectivity.The position of boundaries of the element along an imaginary radial line extending from the observation point are calculated and the reflectivity allocated to points on the line on each side of each of the boundary positions is calculated. A sequence of signals is then generated which is representative of the allocated reflectivities occurring along the length of the line.

Abstract: The radar comprises in known manner a transmitter (1), a transmitting antenna (E.sub.1), two receiving antennas (R.sub.1,R.sub.2), mixers (6,7) and means for processing the subtractive beat signals supplied by the mixers for effecting detection of the bearing of a target (10) and of the range and/or the relative velocity of the target. According to the invention, a target simulator is provided to correct the phase errors of electrical and mechanical origins. The simulator comprises a transmission circuit including a modulator (11) and a simulated target echo transmission antenna (E.sub.2) which transmits towards the receiving antenna. The radar also includes means for processing a beat signal derived from the simulated echo and for effecting detection of the simulated target bearing and means for correcting phase errors.

Abstract: The simulation of clutter echo return signals for a radar system is accomplished using two sets of diode noise sources, a frequency synthesizer for bandwidth control, multiplexing control, two D/A converters and mixers, a 90-degree sower splitter, and a summer; the output of the summer being the simulated clutter. The two sets of noise sources each produce a digital encoded controlled bandwidth Gaussian noise signal which is strobed by the multiplexing control unit firstly to the pulse repetition interval of the radar system and secondly to the data rate of the radar system. The two strobed D/A converters convert the two digital noise signals into their analog equivalents. The two separate video channels are required to obtain the Rayleigh noise distribution characteristic of clutter. This distribution results when the analog signals from the D/A converters are multiplied with in-phase and quadrature RF reference frequencies in the two mixers, then summed in the summer.

Abstract: The testing of radar systems is enhanced with the use of clutter generator that simulates realistic terrain echo returns which are provided in real-time. A fast array processor is used in combination with a Fourier Transform processor to produce a complex digital output having time, frequency and magnitude information corresponding to the composite echos from thousands of points. A digital-to-analog converter filters the output and a single-sideband mixer converts the digital output to a radio frequency signal.

Abstract: An array of target elements having emissivity and reflectivity properties variable in accordance with a data processing simulation of the electromagnetic signature of a target and target terrain suitable for evaluating the tracking capabilities of an active/passive millimeter wave target seeker.