Abstract: A pulse-echo ranging system is described employing a microwave transducer head (100) providing an echo profile output signal which is largely compatible with receivers (204) and echo processing systems (206) designed for acoustic transducers. The transducer head employs novel microwave pulse generators (20a, 20b) each utilizing a microwave cavity (20a, 20b) excited by an avalanche discharge through a small signal diode (D2a, D2b) initiated by avalanche of a driver transistor (TR1a, TR1b) by a trigger pulse. Repeated pulse from one generator (2a) are transmitted by an antenna (12) towards a target, and return are mixed with pulses from the second generator (26) which are subject to a progressively swept delay relative to the transmitter pulses. The mixer output is applied to a tuned amplified (110) to extract components at an alias frequency related to the sweep rate of the delay relative to the transmitter frequency. The aliased signal is passed to a receiver (204) and echo processing system (206).

Abstract: A device which can accurately detect even objects in very close proximity to a vehicle and at the same time can reliably detect more distant objects has means (MM) that can execute a selection of those reception pulses (EI) whose chronological offset in comparison to the respective transmission pulses (SI) emitted is of such a magnitude that these reception signals (EI) result exclusively from reflections against objects from a selected distance range correlating to the chronological offset. Means (DG) are also provided that permit the transmission pulse power to be increased and decreased as the distance range rises and falls.

Abstract: This invention is a radar/tag system where pulses from a radar cause a tag (or transponder) to respond to the radar. The radar, along with its conventional pulse transmissions, sends a reference signal to the tag. The tag recovers the reference signal and uses it to shift the center frequency of the received radar pulse to a different frequency. This shift causes the frequencies of the tag response pulses to be disjoint from those of the transmit pulse. In this way, radar clutter can be eliminated from the tag responses. The radar predicts, to within a small Doppler offset, the center frequency of tag response pulses. The radar can create synthetic-aperture-radar-like images and moving-target-indicator-radar-like maps containing the signature of the tag against a background of thermal noise and greatly attenuated radar clutter. The radar can geolocate the tag precisely and accurately (to within better than one meter of error).

Abstract: A radar system and a characteristic adjustment method for the radar system are provided, in which a control voltage waveform of a voltage controlled oscillator for frequency-modulating a sending signal can be set in a short time without increasing the required amount of memory. In adjusting time-varying characteristics of a voltage signal for frequency modulation on a voltage controlled oscillator determining a sending frequency, the time-varying characteristics of the voltage signal for frequency modulation are adjusted to optimize a form of a protrusion in signal intensity included in a frequency spectrum of a beat signal.

Abstract: A dual port memory waveform generator system uses a clock-based system whose pulse durations and separations were set by counters that use the same fundamental clock frequency of the radar to be simulated. This pulse generator is loaded from a laptop computer. The output pulses are used to control pin switches to switch various frequencies, amplitudes, or phases as required for the particular radar being simulated. The result is a system with very good fidelity that will fit in a suitcase, and is very portable.

Abstract: A method and system to create an ultra wideband (UWB) signal are disclosed. The UWB signal comprises a carrier frequency with each cycle reversing in phase. The UWB signal is generated from a limited number of high power narrow band amplifiers. Each amplifier's output signal is combined to produce the desired UWB signal. The combination may occur in a combiner network or in free space.

Abstract: Methods and systems consistent with this invention identify a buried object using array-based ground penetrating radar having a control device, a plurality of transmit antennas, and a plurality of receive antennas. Such methods and systems receive a transmit timing input signal and a receive timing input signal. Such methods and systems comprise a first delay circuit for receiving the transmit timing input signal and generating a number of intermediate transmit timing signals delayed with respect to each other by a delay time, and transmit output switch circuit to select either the transmit timing input signal or a corresponding one of the intermediate transmit timing signals as a corresponding output transmit timing signal.

Abstract: A radar for locating and tracking objects based on the use of a pulsed waveform, each pulse of the pulsed waveform being made up of a plurality of spectral components having different frequencies, including an antenna. The radar further includes a transmitter operatively coupled to the antenna for generating the plurality of spectral components that make up each pulse of the pulsed waveform and a receiver operatively coupled to the antenna for receiving signals at the frequencies of the plurality of spectral components.

Abstract: The present invention provides a method for efficient use of the transmit power of a Traffic Alert Collision Avoidance System (TCAS) that allows enhanced surveillance range and limits radio frequency (RF) interference in crowded airspace. The method reduces power density in crowded airspace by modifying Mode S, Mode A and Mode C interrogations. During Mode S broadcasts, tracking interrogation power is reduced as a function of range. Further transmit power reduction is achieved by broadcasting a variable power density whisper-shout interrogation technique for Mode A/C aircraft when garbling is detected. If garbling is observed during a medium whisper-shout interrogation sequence, the method of the present invention attempts to clear the garbling by using focused high-density whisper-shout steps but only in the ranges where garbling was detected. Formation members can account for other formation members that are TCAS equipped using a special E-TCAS Broadcast Interrogation.

Abstract: An apparatus and method for detecting radar system blockage includes a radar system (10) having an antenna unit (14) configured to transmit radar signals and receive reflected radar signals. In one embodiment, fixed frequency continuous wave radar signals are transmitted, and corresponding reflected signals are sampled and processed to determine a mainbeam clutter signal peak in frequency bins near those corresponding to vehicle speed. If this peak is less than a power threshold, the antenna unit (14) is at least partially blocked. In another embodiment, a number of most recent reflected tracking signal amplitudes are sampled, normalized to a predefined range value and filtered to produce a smoothed tracking amplitude. If the smoothed tracking amplitude drops below an amplitude threshold, the antenna unit (14) is at least partially blocked. The two embodiments may be combined to determine a radar antenna blockage status as a function of both techniques.

Abstract: A device which can accurately detect even objects in very close proximity to a vehicle and at the same time can reliably detect more distant objects has means (MM) that can execute a selection of those reception pulses (EI) whose chronological offset in comparison to the respective transmission pulses (SI) emitted is of such a magnitude that these reception signals (EI) result exclusively from reflections against objects from a selected distance range correlating to the chronological offset. Means (DG) are also provided that permit the transmission pulse power to be increased and decreased as the distance range rises and falls.

Abstract: A method and apparatus for permitting a host automotive vehicle to avoid or mitigate the consequences of a collision between the host vehicle and a target automotive vehicle by using a combination of radar derived target information and transponder information. The host vehicle is equipped with a radar system operative detect the target vehicle and generate target data, and a computer which determines a likelihood of collision with target vehicle. If the likelihood of collision is above a certain level, the computer directs the radar system to transmit a directional interrogation system toward the target vehicle. The target vehicle is equipped with one or more transponders that receive the interrogation signal and respond by transmitting a response signal containing information indicating various dynamic and/or static characteristics of the target vehicle. The response signal is received by the host vehicle and is decoded to extract the target vehicle information.

Abstract: A silent radar system which detects a target and its position without the countermeasure operator located at the target being able to detect the presence of the radar. The silent radar operates by transmitting signals with specific characteristics which allow optimum processing by the radar while taking advantage of the limitations inherent in typical signal receiving equipment. The silent radar transmits low energy per cycle signals which are wideband, purely random noise, e.g. spread spectrum signals.

Abstract: Apparatus and method for surveying rails, in particular running rails for cranes, shelf handling units, running wheel blocks, includes a transmitter unit arranged on the rail and having a laser, which emits at least one laser beam aligned longitudinally in the direction of the rail, and a detector unit capable of traveling on the same rail longitudinally in the direction of the rail and having at least one photodetector, which confronts the laser beam and generates an electric output signal in response to the incident laser beam, for determining the local position of the laser beam in a vertical measuring surface aligned transversely to the longitudinal direction of the rail.

Abstract: A single-antenna short-range radar transceiver emits 24 GHz RF sinewave packets and samples echoes with strobed timing such that the illusion of wave propagation at the speed of sound is observed, thereby forming an ultrasound mimicking radar (UMR). A 12 GHz frequency-doubled transmit oscillator is pulsed a first time to transmit a 24 GHz harmonic burst and pulsed a second time to produce a 12 GHz local oscillator burst for a sub-harmonically pumped, coherently integrating sample-hold receiver (homodyne operation). The time between the first and second oscillator bursts is swept to form an expanded-time replica of echo bursts at the receiver output. A random phase RF marker pulse is interleaved with the coherent phase transmitted RF to aid in spectrum assessment of the radar's nearly undetectable emissions.

Abstract: The present invention provides a method for efficient use of the transmit power of a Traffic Alert Collision Avoidance System (TCAS) that allows enhanced surveillance range and limits radio frequency (RF) interference in crowded airspace. The method reduces power density in crowded airspace by modifying Mode S, Mode A and Mode C interrogations. During Mode S broadcasts, tracking interrogation power is reduced as a function of range. Further transmit power reduction is achieved by broadcasting a variable power density whisper-shout interrogation technique for Mode A/C aircraft when garbling is detected. If garbling is observed during a medium whisper-shout interrogation sequence, the method of the present invention attempts to clear the garbling by using focused high-density whisper-shout steps but only in the ranges where garbling was detected. Formation members can account for other formation members that are TCAS equipped using a special E-TCAS Broadcast Interrogation.

Abstract: Identity transform filters, such as sin(x)/x filters, are used to coherently fragment the frequency continuum of a wideband waveform, such as an ultra wideband radar signal, into a plurality of spectral segments that are capable of fitting into unoccupied spectral regions of a partially occupied electromagnetic spectrum. The wideband waveform has a bandwidth that falls within the partially occupied portion of the electromagnetic spectrum, and exceeds that of any unoccupied spectral region. The total useable bandwidth of the unoccupied regions is at least equal to that of the wideband waveform.

Abstract: Two crystal oscillators are configured as a “plug-and-play” precision transmit-receive clock system that requires no calibration during manufacture. A first crystal oscillator generates a transmit clock and a second crystal oscillator generates a receive clock that operates at a small offset frequency &Dgr; from the transmit clock. A frequency locked loop regulates &Dgr; by regulating the frequency of the detected receive pulses from a radio, radar, laser, ultrasonic, or TDR system. The clock system further includes a wrong sideband reset circuit and a phase lock injection port. Applications include a timing system for automotive backup and collision warning radars, precision radar and laser rangefinders for fluid level sensing and robotics, precision radiolocation systems, and universal object/obstacle detection and ranging.

Abstract: Faraday Rotation causes rotation of the plane of polarization of plane polarised radiation emitted by a radar e.g. a synthetic aperture radar and, if returns polarized in orthogonal planes are measured at the synthetic aperture radar in order to determine polarimetric characteristics of the ground, which could show up features of the ground such as crop patterns, the measurements made at the SAR are contaminated by the Faraday Rotation. In the invention, the transmitted plane polarized beam is pre-rotated in transmitter 9, the radar returns in receiver 13 are mathematically adjusted in signal formatting 14, 15 to compensate for just the pre-rotated angle, to produce data streams on downlink 16 uncontaminated by the Faraday Rotation.

Abstract: The digital coherent radar generates its transmitted waveform from a low intermediate frequency (IF) and a local oscillator (LO) by digitally generated waveforms after passing through digital-to-analog (D/A) converters. The LO is increased in frequency using a product multiplier. The IF representation of the transmitted waveform is upconverted using the LO. The transmitted waveform is amplified and passed through a circulator to an antenna. The echos are received through the antenna and passed through the circulator and receiver protector. The received signal is then downconverted to a digital signal and passed on to a processor. Finally, the waveform is reset and restarted by the local oscillator generator, the digital-to-analog converters, and the analog-to-digital converter at the beginning of each pulse. It must be insured that all pulses in a pulse train are identical even though there are deterministic errors in the representation of the transmitted signals desired coherent component.

Abstract: A switching interface for routing RF signals. The interface comprises a buffer decoder which receives first, second and third control signals and then decodes the signals to selectively turn on five RF switches. The decoded output signals from the buffer decoder are supplied to five pair of switch drivers for the RF switches. When a logic one is provided to a switch driver, the switch driver sets the RF switch to an ON position. When a logic zero to a switch driver, the switch driver set the RF switch to an OFF position. A window comparator monitors the outputs of the switch drivers for each of the five RF switches. Whenever one of the two output signals from the switch drivers is within a preset voltage range the window comparator provides a logic one and a logic zero which are supplied to a bit decode circuit.

Abstract: A frequency modulated continuous wave (FMCW) radar system having a voltage controlled oscillator (VCO) for transmitting a RF signal and a linearizer for linearizing the VCO. The FMCW receives the transmitted RF signal as an input and outputs a signal to a modulator, which successively sweeps the VCO frequency over a defined range. The receiver mixes a return signal with a sample of the transmitted RF signal to derive an IF signal. An adaptive frequency sample clock drives an analog to digital converter to sample and digitize the IF signal, with the clock being derived from the transmitted RF signal.

Abstract: A radar gauge adapted to sense fluid level in a tank and including a radar gauge circuit in which radar transmission and level sampling are controlled by a transmit frequency and a sample frequency respectively. A first frequency separation between first and second frequencies is controlled by a control input. The first and second frequencies can be divided to generate the transmit and sample frequencies, separated by a second frequency separation. At least one frequency difference is evaluated and the evaluation used to generate the control input, stabilizing the first frequency difference, and to correct the gauge output.

Abstract: In a method for operating a radar system, the object is to determine by simple means and at low cost the distance and/or the radial velocity of at least one target object with high resolution. For this purpose, in each measuring phase of the measurement process in the "pulse FMCW radar system", switchover between a transmission mode and a receiving mode is effected a multiple number of times and at short intervals of time. In the transmission mode, all receiving units of the radar system are switched off, while a pulse-shaped (frequency-modulated) transmission signal with time-successive transmission pulses having a specific pulse-on time and a specific carrier frequency is emitted from at least one transmitter unit of the radar system.

Abstract: A continuous wave radar system, for example a radar altimeter, comprises a memory (24) for storing an array of return signals, means for performing a time integration (25) of the array to improve its signal-to-noise ratio, means responsive to the time integrated array (26) to compare (30) the noise level (28) thereof with the peak level (27) thereof to obtain the signal-to-noise ratio of the array, and control means (31) responsive to the signal-to-noise ratio thus obtained to set either the period over which the said time integration is performed for each renewal of the time integrated array (26), or the power of the transmitted signal, of both, in accordance with predetermined criteria to the minimum necessary to ensure an adequate signal-to-noise ratio.

Abstract: A system of enhancing target detection in a polarization modulated signaling system for detecting targets through one or more given media. A polarization modulated signal is generated and transmitted in the given medium which is the complex conjugate of the polarization modulated response over time of the combined medium and target. The wave equation for transmission through the medium, reflectance from the target and transmission through the one or more given media, is solved and the polarization modulation of the polarization modulated signal is adjusted to match the polarization response over time for maximum propagation through the one or more given media and maximum reflectance from the target over time.

Abstract: The objectives of the invention are met by an improved radar tracking system and a process of radar tracking. In the improved system and process, an estimate of a target range and a range uncertainity swath from a first radar system is inputted into a second radar system along with a duty factor. The second radar system determines a set of zero eclipse intervals and respective ranges of range pulse repetition frequencies that solves a first set of equations. A usable range pulse repetition frequency is chosen from the results. Next, an estimated target Doppler frequency region and a Doppler uncertainity swath is inputted into the second radar system. The second radar system is instructed to determine a set of clear Doppler frequency region intervals, and respective ranges of Doppler frequency pulse repetition frequencies by solving a second set of equations.

Abstract: A single antenna is used so that time-division transmission and reception is carried out in a radar apparatus for obtaining a distance and a relative speed with respect to a target object based on a beat signal obtained by transmitting a frequency modulated signal and mixing a received signal reflected by said target object with the frequency modulated signal that is transmitted.

Abstract: A procedure and a device transmit information in a pulse radar device simultaneously with the ordinary radar function of the pulse radar device. The radar device includes a control unit, a radar transmitter and an antenna. The control unit controls the radar transmitter to generate radar pulses in pulse groups that are transmitted via the antenna. The pulse groups for the ordinary radar function are information coded by position coding by the control unit of the information that is to be transmitted. The pulse groups are position coded by transmitting radar pulses with time displacements relative to their nominal radar pulse positions. Pulses are received and information decoded to thereby recreate, in the form of an information copy, information that has been positions coded and transmitted by a radar device.

Abstract: A procedure and a system increase the performance of a group of radar units. The radar units are arbitrarily located in such a way that the respective antenna beam of a radar unit functioning as a normal radar at least partially coincides with the antenna beam of at least one other radar unit in the group. The radar units are synchronised to transmit alternately and in turn, preferably with an increased energy output. All the radar units in the system are synchronised to work continuously in their ordinary reception mode. In this way at each moment echo signals originating from the radar unit transmitting at that moment are received and processed.

Abstract: When a transmitted and received radio wave is scanned, even if, for example, a large vehicle is running on an adjacent lane, a preceding vehicle running on the same lane as an own vehicle can be sensed and tracked continually. An on-vehicle radar comprises a transmitter receiver 6 for transmitting and receiving a radio wave with a relatively high frequency, and a signal processor 10 calculating a relative distance to an object and a relative velocity of the object on the basis of a radio wave transmitted by the transmitter receiver, reflected from the object, and received by the transmitter receiver.

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: A continuous wave radar altimeter comprises a pulsed power control (4), operable when the signal-to-noise ratio of the received signal is likely to be too low, to pulse the transmitted power so that the power varies between a non-zero base level and a higher level. The receiver channel (13, 14) is switched off during each transmitted pulse.

Abstract: A radar system for detecting hazardous objects has a transceiver including a transmitting antenna for transmitting microwave power. For a side detection system, power transmission is available when the vehicle is moving forward. A signal processor receives a pulsed vehicle speed signal and a reverse signal and is programmed to terminate transmission when no speed pulse is received for a preset time or when the reverse signal is present. The transmission is terminated by removing power from the transceiver or by rerouting the microwave power from the antenna to an internal calibration circuit. Radar transmission is re-enabled when the vehicle begins to move forward again. For a rear detection system, radar transmissions are enabled when the reverse signal is present.

Abstract: A multichannel radar system for use on a motor vehicle has a plurality of transmission and reception channels each composed of an AM or FM signal generator for generating an AM or FM signal including a carrier which is amplitude- or frequency-modulated by a modulation signal, transmission and reception antennas for radiating the generated AM signal and receiving a return signal reflected by an obstacle, an amplifier for amplifying the received return signal, and either a detector for detecting the amplified return signal or a mixer for mixing the amplified return signal with the FM signal generated by the FM signal generator thereby to generate a beat signal. A power supply circuit supplies DC voltages respectively to the AM or FM signal generators and the amplifiers of the respective transmission and reception channels in a time-division multiplex manner at successive times.

Abstract: Apparatus and method for allowing ground vehicle identification and communication utilizing IFF equipment consisting of a multi-channel extremely high frequency transmitter for IFF and data transmissions and a receiver for multi-frequency conversions and multi-channel reception. The apparatus and method has both an IFF mode of operation in which the vehicle is able to identify itself and a communications mode in which the vehicle transmits vehicle status information to other vehicles and a command unit. The transmitter comprises a first and second oscillator means for generating a number of frequency tones and a power combiner for combining the tones prior to transmission. A controller monitors the transmitted signal and operates the first and second oscillation means. The receiver consists of a channelizer for separating a received signal into separate frequency tones and a measuring means for determining the values of the frequency tones. A controller controls the comparison or decoding of received signals.

Abstract: An efficient wideband low noise microwave signal generator for active radars. Separate transmit drive (TD) and receiver local oscillator (LO) signals are generated by use of a single programmable reference generator and two frequency synthesized signals separated in frequency by an offset precisely equal to the transmit drive offset. The frequency synthesized signals are respectively summed and subtracted in frequency with the reference generator signal to obtain signals which may be selected as the TD and LO signals.

Abstract: The signal-to-noise ratio of a received radar echo is maximized by maximizing the received energy E of the echo. The energy E is maximized when the transmitted waveform s(t) is chosen so that ##EQU1## is maximized, where y(t) is the echo signal echoing from the target.

Abstract: Subsurface target identification radar includes an antenna array, a rotary encoder, a radar controller, a polarization switching circuit, and transmitter and receiver circuits. The antenna array is constituted by dipole antennas having plane triangle elements. The antennas are disposed at angular intervals of 120.degree. with respect to a rotated symmetric point of the array. The rotary encoder generates a distance pulse every time the radar travels a presetted distance. The radar controller sequentially generates three switching pulses within one period on the basis of the distance pulse from the rotary encoder. The polarization switching circuit selects an arbitrary dipole antenna as a transmitting antenna from the antenna array, selects an arbitrary dipole antenna, other than the selected antenna, as a receiving antenna, and changes a combination of selected antennas every time the switching pulse is generated by the radar controller.

Abstract: An optimization of the monitoring range is achieved for an antenna lobe position for the search function in a multi-function radar given a prescribed power part, asa result whereof the most beneficial signal shape, the most beneficial form of signal processing and the most beneficial sampling period are also supplied. In that case in which no clutter and no shadowings are present in the monitoring area to be covered by the multi-function radar, an instruction for optimum distribution of the radar power available for the search onto a plurality of antenna lobes is established. For general cases, an instruction for optimum distribution of the power available for the search onto a plurality of antenna lobes is established, namely by optimization of the prescribed cost-benefit function with the assistance of an iteration method sequencing in the clock of the generation of elementary radar requests.

Abstract: A moving target detector (MTD) in a radar system uses corrected weighting coefficients to compensate for pulse stagger effect on transmitted pulses. Transmitted pulses are sampled when the radar is switched to a test mode for determining a correction factor which is used to calculate the corrected weighting coefficients. The radar return signals are processed in the MTD by a finite impulse response (FIR) filter using the stored corrected weighting coefficients calculated for each sequence of transmitted pulses including block stagger and pulse stagger sequences.

Abstract: A mechanism for avoiding satellite transponder TWT saturation in an ALPC communication network detects the onset of a lockup condition through an avalanche detector. In response to avalanche detection, those links which have been identified as participating in a downlink fade have their ALPC attenuator settings placed at a minimum level, so that the operating point of the transponder TWT may be reduced below the avalanche threshold. Thereafter, as the fade recedes, those units whose ALPC attenuators have minimum power settings may be restored to normal operation. Because the orderwire which couples link quality data from a received terminal monitor unit to transmitter attenuator control units through the avalanche detection and recovery scheme may itself be impacted by a downlink fade, the foregoing scheme is augmented by a lockup detection and avoidance mechanism through which recovery from an actual lockup may take place.

Abstract: An adaptive radar apparatus is provided for substantially reducing background clutter, particularly relatively time-invariant clutter, such as sea clutter, and especially at low radar grazing angles. The apparatus includes a transmitting antenna having horizontally and vertically oriented, transmitting elements and a relative phase control therebetween and a receiving antenna also with horizontally and vertically oriented receiving elements also having relative phase detection and phase shift possible therebetween. A controllable radar signal generator is provided for supplying signals to the transmitting antenna and a controllable signal processor is provided for processing return signals from the receiving antenna. Means are included for determining, from return test signals, a background mean null polarization for a number of radar range and azimuth cells and for providing null polarization control signals H.sub.o, V.sub.o and .phi..sub.

Abstract: A high PRF pulse doppler radar for tracking moving targets is described wherein the PRF of the transmitted signal is varied within predetermined PRF limits to keep the target reflected high PRF signal centered within the receive gate of the radar and wherein spurious signals incidentally generated by the action of the receive gate are reduced below the receiver noise level. In the event of temporary target reflected signal loss, the PRF of the transmitted signal is varied within predetermined PRF limits based upon the velocity and range estimate of the target to keep subsequent target reflected signals centered within the receive gate of the radar.