Abstract: A radar apparatus installed on a vehicle includes a transmission section, a reception section and a processing section. The transmission section includes at least a transmission antenna, and emits a transmission wave toward a detection area in front of the vehicle. The transmission wave is reflected by a reflector to produce a reflection wave, and the detection area includes a plurality of sub-areas. The reception section includes at least a reception antenna, and receives and detects the reflection wave. The processing section detects a reflector indication data indicative of a reflector attribute based on the detecting result by the reception section, and then determines whether there is the reflector in the detection area, based on the reflector indication data. Also, the processing section manages the reflector indication data over a management area which is wider than the detection area.

Abstract: An apparatus and computer-implemented method of determining a probability that a first track and a second track represent the same physical object.

Abstract: A radar system for processing a series of radar returns to determine Doppler velocity of an object. Each one of the radar returns is produced in response the object reflecting each one of a series of transmitted radar pulses. The series of radar returns is processed in a sequence of successive dwells. Each one of the dwells has a predetermined number of radar returns. The radar system includes a system clock for producing a series of clock pulses. A range gate is provided for sampling each one of a series of radar returns produced in response to a each one of a series of transmitted radar pulse. The range gate has a time duration equal to an integer number of, N, clock pulse periods. A range gate positioning system initiates the range gate a selected time, .DELTA., after each one of the transmitted pulses. The positioning system determines the selected time, .DELTA.

Abstract: A procedure and a device for controlling, in a radar unit for the measurement of target data, the transmission of radar pulses and the reception of target echoes originating from the transmitted radar pulses, in such a way that the performance of the radar unit increases, in order thereby to gain a longer range during a period of time. The period of time is preferably repeated continually. The period of time is divided into a first and a second partial period of time where the first and the second partial periods of time are each at least twice as long as a pulse repetition interval which is used during the first partial period of time. During the first partial period of time the radar unit is controlled so that it transmits radar pulses for the measurement of target data with a higher energy content than what is possible in a steady state.

Abstract: An UWB receiver utilizing a microwave tunnel diode as a single pulse detector for short pulse, impulse, baseband or ultra wideband signals. The tunnel diode detector's bias point is set at system start-up, through an automatic calibration procedure to its highest sensitivity point relative to the desired bit error rate performance (based upon internal noise only) and remains there during the entire reception process. High noise immunity is achieved through the use of a high speed, adaptive dynamic range extension process using a high speed, Gallium Arsenide (GaAs) voltage variable attenuator (VVA) whose instantaneous attenuation level is determined by a periodic sampling of the ambient noise environment. Microprocessor-controlled detector time-gating is performed to switch the tunnel diode detector to the receiver front end circuitry for reception of an incoming UWB pulse, and alternately to ground through a resistor to discharge stored charge on the tunnel diode detector.

Abstract: A radar range finder and hidden object locator is based on ultra-wide band radar with a high resolution swept range gate. The device generates an equivalent time amplitude scan with a typical range of 4 inches to 20 feet, and an analog range resolution as limited by a jitter of on the order of 0.01 inches. A differential sampling receiver is employed to effectively eliminate ringing and other aberrations induced in the receiver by the near proximity of the transmit antenna (10), so a background subtraction is not needed, simplifying the circuitry while improving performance. Techniques are used to reduce clutter in the receive signal, such as decoupling the receive (24) and transmit cavities (22) by placing a space between them, using conductive or radiative damping elements on the cavities, and using terminating plates on the sides of the openings.

Abstract: An apparatus and method for accurately determining a target distance in adverse weather conditions utilizing both LASER and RADAR is disclosed. The radar signals are used to determine an approximate range which is then used as a gating window for the determination of which laser reflection is from the actual target as opposed to a reflection from the atmospheric interference. The method basically comprises the steps of initiating a radar pulse in the direction of a target and receiving a reflection, transmitting a laser signal and receiving a plurality of reflections, determining an approximate range based on the radar signals, and using this approximate range to ascertain which of the laser reflections is from the target. This determination is preferably made by generating a gating signal and gate width from the radar signals and passing the set of laser range signals through the gate to eliminate the false signals and select the signal that survives the gate as the accurate target range.

Abstract: A radar range finder and hidden object locator is based on ultra-wide band radar with a high resolution swept range gate. The device generates an equivalent time amplitude scan with a typical range of 4 inches to 20 feet, and an analog range resolution as limited by a jitter of on the order of 0.01 inches. A differential sampling receiver is employed to effectively eliminate ringing and other aberrations induced in the receiver by the near proximity of the transmit antenna, so a background subtraction is not needed, simplifying the circuitry while improving performance. Uses of the invention include a replacement of ultrasound devices for fluid level sensing, automotive radar, such as cruise control and parking assistance, hidden object location, such as stud and rebar finding. Also, this technology can be used when positioned over a highway lane to collect vehicle count and speed data for traffic control.

Abstract: An exclusively digital timing engine that measures extremely short time intervals for use in time of flight systems such as laser range finding systems. This exclusively digital timing engine minimizes the use of high speed, high cost components by employing a novel time multiplexing scheme to execute each of the primary time of flight functions: frequency synthesis, range gating, and time of flight interval measurement. In addition, the timing engine incorporates a random time delay scheme which enhances the resolution of the time interval measurement.

Abstract: A target detecting device having a plurality of gate circuits for detecting he presence of sea return signals and reducing the effective target detecting range to a range less than the range to the sea surface which permits the detecting of true target signals.

Abstract: In an FMCW radar system, the velocity of obstacles relative to the radar couples a Doppler frequency shift into the return signal which causes an error in the range measurement. It is known to use a radar signal having a frequency ramp that both increases and decreases to distinguish the range of an obstacle from its velocity but when multiple obstacles are present this is not practical. By using a measure of velocity from a succesion of return signals, which of the radar output signals from the upsweep and downsweep of the radar signal that relate to a particular obstacle can be identified so that the range and velocity can be determined accurately. The FMCW radar system may be provided with a frequency scanned antenna, the beamwidth determined by the processing circuitry is variable according to the size of the obstacle being detected or the range at which the radar is searching for obstacles.

Abstract: An electromagnetic detector is designed to locate an object hidden behind a separator or a cavity within a solid object. The detector includes a PRF generator for generating 2 MHz pulses, a homodyne oscillator for generating a 2 kHz square wave, and for modulating the pulses from the PRF generator. A transmit antenna transmits the modulated pulses through the separator, and a receive antenna receives the signals reflected off the object. The receiver path of the detector includes a sample and hold circuit, an AC coupled amplifier which filters out DC bias level shifts in the sample and hold circuit, and a rectifier circuit connected to the homodyne oscillator and to the AC coupled amplifier, for synchronously rectifying the modulated pulses transmitted over the transmit antenna. The homodyne oscillator modulates the signal from the PRF generator with a continuous wave (CW) signal, and the AC coupled amplifier operates with a passband centered on that CW signal.

Abstract: A target tracking system (10) comprises sensors (12) which provide data corresponding to a region of interest, the data being time dependent and consisting of amplitudes, ranges and angles. A window (202) is placed around data of interest, the size of the window being determined based on target size, assumed speed and acceleration characteristic, and the window is thereafter broken down into a plurality of smaller windows (208), thereby forming a grid having a nodal point (210) at each corner of the smaller windows. The data within the window is stored in a matrix, and background noise is thereafter minimized by filtering the data past a threshold value (215). The filtered data is analyzed to determine its distance weighted contribution at each nodal point (219), and the weighted distances are summed for each nodal point resulting in a nodal point magnitude for each of the nodal points (220).

Abstract: A laser speed detector is described which includes a laser rangefinder which determines the time-of-flight of an infrared laser pulse to a target and a microprocessor-based microcontroller. The device is small enough to be easily hand-held, and includes a trigger and a sighting scope for a user to visually select a target and to trigger operation of the device upon the selected target. The laser rangefinder includes self-calibrating interpolation circuitry, a digital logic-operated gate for reflected laser pulses in which both the "opening" and the "closing" of the gate can be selectably set by the microcontroller, and dual collimation of the outgoing laser pulse such that a minor portion of the outgoing laser pulse is sent to means for producing a timing reference signal.

Abstract: A transmitting and receiving part of a pulse Doppler radar, in which the transmitting oscillator, by frequency shifting, is at the same time used as a local (reception) oscillator, and the intermediate-frequency reference frequency is generated coherently with respect to the pulse repetition frequency. Since only one high-frequency oscillator is required, the quality of which does not have to meet very high requirements, a low-price pulse Doppler radar can be implemented.

Abstract: An optical ranging system includes optics that create a backscatter signal in response to a transmitted light pulse. The transmitted pulse is reflected from a target to provide range information. The backscatter signal is applied to trigger a threshold detector. The output of the threshold circuit is applied to a delay circuit to provide a receiver switch control signal which renders a receiver switch conductive after the backscatter signal. Accordingly, the receiver switch blanks the backscatter signal and applies the reflected signal to the receiver.

Abstract: A semi-active radar receiver for receiving a sequence of radar pulses and providing radar timing signals in response thereto. In a most general sense, the semi-active receiver of the present invention includes a receiver 10 for receiving a direct transmission of a series of pulses from a radar transmitter 2 and for providing a series of first signal pulses in response thereto. A range gate generator 42 is included for processing the series of first pulses to provide said radar timing signals. In a more specific embodiment, the receiver includes a filter 40 for processing said received pulses and deriving estimates of the timing of the receipt thereof. The estimates are then used by the range gate generator 42 to provide said radar timing signals.

Abstract: A sensor for creating images containing range depth information is disclosed. The sensor comprises a gated energy transmitter used to "illuminate" the object to be imaged, a gated integrating imaging energy receiver to produce "raw" images, a processor system to combine the raw images from the receiver to produce a output image, and a timing system to control the gate timing of the transmitter and gate timing of the receiver. In operation, two raw images are created with differing time relationships between the transmitter gating, receiver gating and integrated energy readout. One raw image is a reference image containing no range information while the second image contains range information along with unwanted information such as reflectivity variations. These raw images are processed to produce a final output image in which the unwanted information is mainly cancelled producing an output "range" image. This output image is a one or two dimensional array of data.

Abstract: The invention comprises a plurality of monostatic devices for radiating and receiving signals. The monostatic devices are disposed in a vertical spaced relationship such that signals from each device follow a direct path to an object to be detected and a reflected path to the object to be detected. The reflected path includes a path to a surface below the object and a path from the surface to the object. The signals are then reflected from the object and return through both the direct and reflected path. The monostatic devices may be radar antennas or acoustic transmitters.

Abstract: Conventionally, a shift register receives radar video return signals and es them into a signal processing and detecting means. Since continuous, large cross-section echoes such as those derived from land masses may saturate the processor, the present apparatus is set to blank such land masses. For this purpose, the shift register capacity is made coextensive with the continuous land mass echo and further, the register is provided with a series of taps spaced one from the other a distance representing selected increments of the range extent being tested. Each tap output is applied to an amplitude-thresholder to pass only higher strength echoes to a counter. Count-responsive means operating as a counter threshold control the radar signal processor to the extent that when the total count exceeds a certain number a processor "shut-off" signal is generated. When the count goes below the certain number a "turn-on" signal is generated.

Abstract: Successive MLS scanning signals are received as pulse-type analog signals and converted into corresponding digital signals. The centroid of each digital signal is determined at at least two different levels below the peak of the digital signal. The centroids for each signal are averaged, whereby the average represents the centroid of the corresponding received pulse-type signal.

Abstract: In a receiving circuit a control circuit and a direction finding circuit generate a digitally encoded "descriptor" which characterizes pulses of r.f. radiation received in a particular azimuthal direction and having a particular carrier frequency. The "descriptor" may be compared with data stored in a processing circuit representing r.f. pulses emitted by sources which have already been detected or which are known to exist. To reduce the workload on processing circuit a number of emulator circuits generate pulse patterns which simulate pulses produced by known sources of little inherent interest. If the received pulses match the simulated pulses a gate inhibits control circuit.

Abstract: Signal processing circuitry is disclosed for processing the echo signals of echo sounders to extract the leading edge of bottom echo components of the echo signals and to provide a reading of the average area under successive leading edges. Second and later bottom echo processing is additionally disclosed. Processing is achieved with a sample and hold circuit comprising an integrator (34), a first switch (33) for switching the required echo signal portion to the integrator, storage means (C2) for storing integrated values to be displayed, and a second switch (35) for selectively coupling values from the integrator to the storage means.

Abstract: A pulsed Doppler radar mounted adjacent to the tip of a helicopter rotor blade for sensing obstacles in the helicopter path. The rotor tip velocity shifts the frequency of radar echos so that, through pulsed Doppler radar techniques, the echos from obstacles can be separated from clutter.

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 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: Clutter suppressors and methods of clutter suppression for radars which employ the doppler effect for enhancing signals due to moving targets relative to signals due to clutter caused by land, sea or rain. Specifically, the disclosure concerns suppressors and methods of clutter suppression for cw doppler, pulse doppler and MTI (moving target indication) radars. The suppressors reduce the occurrence of radar output due to clutter by permitting and prohibiting radar output on the basis of the strength of signals that contain doppler frequency components of the radar echo.

Abstract: A radar system for finding the location of a second flying object from a first flying object, comprises a nondirectional antenna for radiating a first radio wave from the first flying object, a second nondirectional antenna provided on the second flying object to receive the first radio wave and to radiate a second radio wave generated by modulating the received first radio wave and an array antenna provided on the first flying object to receive the second radio wave. The respective amplitudes of the signals given by the antenna elements of the array antenna are compared individually with a specified level and an operation for determining the direction of arrival of the second radio wave is executed using the signals given by all the antenna elements when either of the amplitudes of the signals given by the antenna elements is greater than the specified level.

Abstract: A method of recognizing targets and suppressing spurious signals in radar equipment, in which the surveillance area is divided, in azimuth and range, into a plurality of radar cells. The method comprises comparing the echo signal of each radar cell with a threshold value, producing a sequence of magnitude related amplitude values of echo signals in certain neighboring cells and deriving the threshold value from a value situated in a specific position in said sequence.