Abstract: A radar system achieves adjustment of a time-change characteristic of a frequency-modulating voltage signal to a voltage-controlled oscillator for determining a transmitting signal such that the time-change characteristic of the frequency-modulating voltage signal is changed by a minute amount and the frequency spectrum of a beat signal is determined. The adjustment is performed so that the shape of a bulge in signal intensity included in the frequency spectrum is the sharpest.

Abstract: A code generating device operates for generating a pseudo random noise code having a sequence of a predetermined number of chips each being in one of first and second logic states different from one another. A code monitoring device operates for detecting at least a preset number of successive chips in the first logic state in the pseudo random noise, and for changing at least one among the detected preset number of successive chips to the second logic state to convert the pseudo random noise code into a transmission signal. A driving device operates for activating and deactivating an electromagnetic wave generating device in response to the transmission signal. A receiving device operates for receiving an echo wave caused by reflection of an electromagnetic wave generated by the electromagnetic wave generating device at an object. A distance to the object is detected on the basis of the received echo wave.

Abstract: A sensor array with a pulse echo radar system with which a carrier signal of a microwave transmitter oscillator is transmitted in the form of pulses with a specified pulse repetition frequency in a transmission window. This radar signal is reflected from a target object and the position of the target object is calculated in a mixer from the times of transmission of the pulse to the arrival of the reflected radiation. An array of several transmitter and receiver units with switches are constructed in which the stochastic pulse sequences of each transmission window in each receiver branch are known and the transmitter and receiver units are linked to one another so that in each of the receiver branches the stochastic pulse sequences of each transmission window are detected separately and thereby the cross echoes may also be analyzed.

Abstract: In a method for HPRF-radar measurement of the range and Doppler frequency of at least one target, a transmit signal is generated which consists of two pulse sequences that are interleaved on a pulse to pulse basis, and have the same pulse repetition frequency PRF and the same transmit frequency. The pulses of a first one of the two pulse sequences have a linearly increasing phase value with a fixed phase difference &phgr;1n (greater than zero) from pulse to pulse with &phgr;1n≧0, while the pulses of the second pulse sequence have a linear increasing phase value with a fixed phase difference &phgr;2n which differs from &phgr;1n. The two received base band signals of each individual pulse sequence are Fourier transformed, and the amplitude peaks of the resulting two Fourier spectra are determined.

Abstract: The present invention relates to a radar system having means (12) for producing a code, means (18) for modulating a transmission signal in a transmit branch, using the code, means (32) for delaying the code, means (20) for modulating a signal in a receive branch, using the delayed code, and means (26) for mixing a reference signal with a receiving signal, the modulation of one of the signals being performed by an amplitude modulation (ASK; “amplitude shift keying”) and the modulation of the other signal by a phase modulation (PSK; “phase shift keying”). Furthermore, a radar system is proposed in which blanking of phase transitions is provided. The present invention also relates to methods which may advantageously be carried out, using the radar systems according to the present invention.

Abstract: A pulse radar device includes a transmitting unit, a receiving unit, a first integrating unit for sampling a reception signal at predetermined time intervals from transmission and integrating results of a predetermined number of times of the sampling at each sampling timing, a differential operating unit for, each time a predetermined time period has passed, reading results of the integrating at each sampling timing and differentiating the read results of the integrating in a sampling direction, a second integrating unit for integrating absolute values of a predetermined number of outputs from the differential operating unit at each sampling timing, a peak detecting unit for detecting the peak of an output from the second integrating unit, a distance measuring and detecting unit for calculating a distance to an object and judging presence or absence of an object based on an output from the peak detecting unit and the like.

Abstract: A radar system includes a transmitting/receiving unit, having a voltage controlled oscillator, for repeatedly transmitting a triangular transmission signal including a frequency-gradually-rising up-modulation interval and a frequency-gradually-dropping down-modulation interval and for receiving a reception signal including a reflected signal from a target, a frequency analysis unit, a data storing unit for storing time-varying characteristics of input values to a D/A converter that monotonically change an oscillation frequency of the voltage controlled oscillator with time, in the form of data concerning an expression representing the time-varying characteristics, and a data processing unit for determining the input values to the D/A converter with reference to the data. At least one of the relative distance to the target and the relative speed of the target is detected based on a beat signal during the up-modulation interval and the beat signal during the down-modulation interval.

Abstract: A radar device precisely detects a target in short time intervals by detecting a true peak frequency with high accuracy via a calculation which does not require a large amount of computation. A discrete frequency spectrum of a beat signal multiplied by a window function is determined, and values of signal strength at two discrete frequencies which are, respectively, higher and lower than a peak frequency of the discrete frequency spectrum of the beat signal and which are adjacent to the peak frequency. The frequency difference between the discrete peak frequency of the beat signal and the peak frequency of the window function is then determined from the ratio between the values of signal strength at those two discrete frequencies adjacent to the peak frequency. Thus, the true peak frequency of the beat signal is determined with a high frequency resolution.

Abstract: A radar fill level measurement sensor for measuring the level of material in a container, includes a transmit/receive circuit that transmits an electromagnetic pulse, and detects reflected electromagnetic pulses and provides an intermediate frequency signal indicative of the reflected electromagnetic pulses. A logarithm detector circuit receives the intermediate frequency signal and provides a logarithmic output signal indicative of the logarithm of the intermediate frequency signal. An evaluation unit receives and processes the logarithmic output signal, to determine the fill level of the material within the container, and provides a fill level measurement signal indicative thereof.

Abstract: A sensor front end is disclosed that is able to discriminate objects based on their range from the sensor. The sensor includes an antenna that transmits a sensor signal and, if an object is present receives a reflected signal therefrom. A pulsed oscillator provides a pulsed first signal having a first frequency and phase, and wherein the pulsed oscillator provides the pulsed first signal for a predetermined pulse duration and with a predetermined pulse repetition frequency. The pulsed oscillator provides the pulsed first signal to a first input port of a dual mode mixer that is further coupled to the antenna via a second port. The dual mode mixer transmits a portion of the pulsed first signal from the first input port to the second port and thus to the antenna to be transmitted as the sensor signal. In addition, the dual mode mixer uses a portion of the first signal to mix with the received reflected signal. The dual mode mixer then provides a mixed signal as an output at a third port.

Abstract: A pulse radar device, which includes a timing control unit that controls a transmit interval of a pulse signal, a transmitting unit that transmits the pulse signal, a receiving unit that receives a receive signal including a reflection signal component from a target object and a noise component, a receive signal change detecting unit that detects a change in the assembly of the receive signals of the assembly of the pulse signals which are transmitted during a first transmit interval and the assembly of the pulse signals which are transmitted during a second transmit interval, a reflection signal rising detecting unit that detects a rising time point of the reflection signal component, and a ranging/detecting unit that obtains a distance value on the basis of the rising time point of the reflection signal and judges the presence of the target object.

Abstract: A method and apparatus of measuring a distance to a reflection object is disclosed. A sensitivity time control (STC) process is applied to a received signal from the reflection object to provide an STC-processed signal. The radar apparatus includes a controller. The controller obtains a quantity corresponding to the distance from a transmission time of the transmission signal and a detection time of the STC-processed signal. The quantity is corrected by using a first correction value associated with the intensity of the STC-processed reflection signal to provide a corrected quantity. The corrected quantity is further corrected by using a second correction value associated with the corrected quantity and the intensity of the STC-processed reflection signal to correct the error regardless of the intensity of the STC-processed reflection signal.

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 scan type radar device capable of detecting a lateral position of a target even if a peak showing the lateral position of the target irregularly fluctuates in the lateral direction as well as reducing the mis-pairing. The former is achievable by changing a reference value of the lateral fluctuation of the target when all the past and present target data fluctuate to an extent exceeding the reference value. The latter is achievable by forecasting a representative peak position at this time in both of up-beat and down-beat from the peak position data at the preceding time and carrying out the past-correspondence grouping of the up-beat and the down-beat at this time in the vicinity of the position of the representative peak forecast this time; the pairing being carried out by using the representative peak calculated by the past-correspondence grouping.

Abstract: A pulse radar device, which includes a timing control unit that controls a transmit interval of a pulse signal, a transmitting unit that transmits the pulse signal, a receiving unit that receives a receive signal including a reflection signal component from a target object and a noise component, a receive signal change detecting unit that detects a change in the assembly of the receive signals of the assembly of the pulse signals which are transmitted during a first transmit interval and the assembly of the pulse signals which are transmitted during a second transmit interval, a reflection signal rising detecting unit that detects a rising time point of the reflection signal component, and a ranging/detecting unit that obtains a distance value on the basis of the rising time point of the reflection signal and judges the presence of the target object.

Abstract: A method for detecting and correcting non-linearities in radio-frequency, voltage controlled oscillators provides for digitization of the frequency signal by feeding the undelayed frequency signal and a delayed frequency signal generated therefrom into EXOR gates. The digital pulses produced thereform are converted using a low pass filter into a proportional DC voltage value which is proportional to the oscillator frequency and is used as a basis for producing a correction value for the frequency control of the oscillator.

Abstract: In a homodyne-receiver radar system used for ranging and/or target detection, the frequency-modulated (FM) transmit phase are removed from the received signal. Removal of the known FM transmit phase from the received signal reduces the bandwidth of the received signal to half that of a system that does not remove the transmit phase. This allows the sampling rate, and thus the processor throughput, to be cut in half. With the FM transmit phase removed, the phase sequence of the processed signal is akin to a delayed version of the transmit signal phase history. This allows the range processing to use segments of a single phase sequence for processing all range gates, resulting in a large reduction in the amount of coefficient storage used for the matched-phase sequences required to process the set of range gates.

Abstract: First-arriving-pulse detector (FAP) circuitry includes a correlator circuitry and a threshold circuitry. The correlator circuitry correlates a received signal with a template signal to provide an output signal. The threshold circuitry provides a first-arriving-pulse signal depending on the relative values of the output signal of the correlator circuitry and a threshold signal.

Abstract: In a homodyne-receiver radar system used for ranging and/or target detection, the frequency-modulated (FM) transmit phase are removed from the received signal. Removal of the known FM transmit phase from the received signal reduces the bandwidth of the received signal to half that of a system that does not remove the transmit phase. This allows the sampling rate, and thus the processor throughput, to be cut in half. With the FM transmit phase removed, the phase sequence of the processed signal is akin to a delayed version of the transmit signal phase history. This allows the range processing to use segments of a single phase sequence for processing all range gates, resulting in a large reduction in the amount of coefficient storage used for the matched-phase sequences required to process the set of range gates.

Abstract: A method and apparatus for measuring the parameters of atmospheric turbulent flows utilizes the Doppler shifted frequencies of received radar signals backscattered from sound generated aerodynamically by atmospheric turbulent flows. Doppler frequency bandwidths of the received backscattered signals are used to estimate the atmospheric flow turbulence and the mean frequency within a bandwidth is processed to estimate its radial flow velocity. Total flow velocity and the flow velocity angle with respect to the antenna boresight of the atmospheric turbulent flow may be estimated by estimating the radial flow velocity at two radial positions and processing these radial velocities. Processing of the Doppler data is initiated when the total signal power within the Doppler frequency band exceeds a predetermined power level.

Abstract: Systems and methods that may be used to determine the distance between an orbiting satellite and a ground station. A master clock divider circuit generates clock signals derived from a master clock. A transmit code generation circuit generates pseudo-random number codes and processes the pseudo-random number codes to produce a composite signal having positive and negative correlation peaks that is transmitted to the satellite as an analog signal. A digitizing circuit receives the analog signal transmitted from the satellite, and digitizes the analog signal. A frequency domain matched filter match filters the digitized analog signal to produce correlation peaks contained in the digitized analog signal.

Abstract: A method for the processing of a frequency signal especially for utilization in the evaluation of a distance measurement by means of pulsed electromagnetic waves or of frequency-modulated continuous waves on the basis of the radar principle. The frequency signal is divided into at least two frequency ranges corresponding to two main components of the frequency signal, the frequency signal in each of the two frequency ranges is then subjected to a separate Fourier transform, the Fourier transform applied to the frequency signal in the first frequency range resulting in a corresponding first complex time signal and the Fourier transform applied to the frequency signal in the other frequency range resulting in a second complex time signal. The second time signal is complex-divided by the first time signal which produces a third time signal, and the third time signal is then subjected to a Fourier transfer, the result being a processed frequency signal.

Abstract: In a radar, a frequency-modulated transmission signal whose frequency varies in time is generated. The gain-frequency characteristics of an IF signal which represents a beat signal between the transmission signal and a reception signal has its peak at or below one half of the sampling frequency of an AD converter. The gain-frequency characteristics of an IF amplifier circuit is determined so that the gain increases as the frequency increases at or below the frequency corresponding to the peak, the ratio of change in the gain relative to change in the frequency becomes smaller at short distances for which a saturation of a mixer is caused, and the gain is reduced at DC and in the vicinity of DC.

Abstract: The invention relates to a method for determining the perpendicular distance between an object and a device whose position varies, in particular a motor vehicle, in the case of which device a first sensor which is arranged on this device emits a signal which is reflected by the object, and this reflected signal is received by this first sensor, in which case the delay time of the signal from transmission to reception is used by the first sensor to determine the distance between the first sensor and the object.

Abstract: The invention relates to a device for the linearization of a frequency modulation ramp comprising a voltage controlled oscillator associated with a phase locked-loop. The device comprises a digitally controlled oscillator of which only the most heavily weighted bit is used, and a digital phase comparator receiving, on the one hand, said most heavily weighted bit and, on the other hand, a signal supplied by the voltage controlled oscillator. Application to very high linearity and very high accuracy radio altimeters.

Abstract: The invention relates to a radar distance measuring device. An especially linear frequency-modulated high frequency signal is emitted via an antenna and mixed with an echo signal reflected by a target object whose distance is to be determined. The distance of said target object can then be calculated by analyzing the frequency of the mix result. The aim of the invention is to improve the distance resolution or increase the accuracy of measurement. To this end, a first frequency analysis is first carried out to obtain a rough analysis result. Said rough analysis result is used to control a filtering device which then restricts the mix result in its time range to a segment around the frequency of the target object. A discrete Fourier transformation is then carried out for this segment in order to produce an analysis result with a more refined scanning step than the first frequency analysis.

Abstract: System and method for detection and tracking of targets, which in a preferred embodiment is based on the use of fractional Fourier transformation of time-domain signals to compute projections of the auto and cross ambiguity functions along arbitrary line segments. The efficient computational algorithms of the preferred embodiment are used to detect the position and estimate the velocity of signals, such as those encountered by active or passive sensor systems. Various applications of the proposed algorithm in the analysis of time-frequency domain signals are also disclosed.

Abstract: Disclosed is a radar system capable of obviating a problem that a sufficient improvement of an S/N ratio could not be obtained in the prior art, and comprising a transmitter/receiver for detecting a phase of a receiving signal reflected from an observation target, an A/D converter for converting the receiving signal into a digital signal, a range gate for extracting the receiving signal having a time corresponding to the predetermined pulse width, a data dividing unit for dividing the receiving signals in to two groups of data, an FFT unit for fast-Fourier-transforming one group of data of the two groups of data, an FFT unit for fast-Fourier-transforming the other group of data, a complex conjugating unit for taking a complex conjugate of an output of the FFT unit, a complex multiplying unit for performing a complex multiplication for the every same Doppler frequency component with respect to an output of the former FFT unit and an output of the complex conjugating unit, and a complex adder for executing a co

Abstract: FM-CW radar equipment to solve a conventional problem of failure detection caused by the carrier level of amplitude modulation dispersing too largely to adjust to a constant level within a criterion range. A novel method is applied based on that a noise level greatly varies on occurrence of a failure in radio-frequency circuit. A failure can be detected by comparing the varied noise level with a noise level in normal condition. Using this method, FM-CW radar equipment can be configured with a simple structure for detecting a failure in transmission/reception circuit. The equipment provides with a noise-level extraction circuit in radio-frequency circuit, and a comparator for comparing an output of the noise-level extraction circuit with a predetermined criterion value. An alarm is output when the comparator detects the output of the noise-level extraction circuit decreases to less than the predetermined criterion value.

Abstract: A lightwave distance measuring apparatus having a coaxial light-transmitting/receiving type optical system is provided with light-transmitting means for transmitting pulsed light toward an object, light-receiving means for receiving reflected pulsed light reflected by the object, a time measuring section for measuring a period of time from when the pulsed light is transmitted until the light is received, a distance measuring section for determining a distance to the object from the measured period of time, and a pulse number detecting section for detecting whether the number of received pulses of reflected light in response to one transmitting pulsed light is one or more; while the value measured when only one pulse of the reflected light is detected by the pulse number detecting section in response to the transmission of pulsed light is made effective.

Abstract: A timing and control method and apparatus (111) for performing precise range rate aiding includes a range gate delay means (114) for generating an estimate of the range gate delay (135) each pulse repetition interval as a function of the initial range (134) and velocity (133) provided by a processor (104). The range gate delay (135) is converted into a coarse delay (138) defining the integral number of clock cycles preceding the range gate, and a fine delay (139) for positioning a range gate to within a fraction of a clock cycle. Fine temporal control is achieved using programmable delay lines (117) and (118), which retard various control signals, including the system clock signal (131), in accordance with the fine delay (139). A modified signal (126) then drives a counter means (119) which outputs a signal (128) that defines an analog-to-digital sampling window beginning at the elapse of the range gate delay (135).

Abstract: A method in which a sensor system with a frequency-modulated signal source an a delay line for generating a time-delay reference signal is implemented. Phase errors are compensated by correcting the modulation (pre-equalization derived from the reference signal. Signals with a long running time are measured and additionally compensated by a computational, subsequent elimination (post-equalization). A high-pass filter is provided to that end.

Abstract: A process for determining the distance (D) between a distance sensor and an object. A transmitter sends wave pulses with a predetermined first frequency fb 1 and the wave pulses reflected by the object are received by a receiver and are directed in the form of an analog electrical incoming signal to an A-D converter. The latter scans the incoming signal with a second frequency f2 with f2>f1 and converts it into a digital signal Z(t) which is evaluated for determining a distance value (D) in the following manner: a) Evaluation of the digital signal Z(t) for determining a first wave pulse propagation time (T1); b) k-fold repetition of the step a) for determining the total k wave pulse propagation times (T1, T2, . . . , Tk); c) Calculation of a mean wave pulse propagation time (T=(T1+T2+ . . . +Tk)/k); and d) Calculation of the distance value (D) in accordance with D−v=T/2.

Abstract: An electronic circuit for the processing of an analog electrical signal is provided with a receiver for receiving the signal reflected by an object. The amplitude of the signal received is a function of the distance of the object from the receiver. A circuit is provided for the adaptation of the signal to a reference signal.

Abstract: A radar apparatus is provided with signal converting means for FFT-transforming an output signal of reception means for detecting a reception electromagnetic wave; amplitude peak value detecting means for detecting a peak value of an amplitude level from a spectrum made by data converted by this signal converting means; beam scanning means for changing a beam direction of a transmission electromagnetic wave and also a beam direction of the reception electromagnetic wave; and measured-angle processing means operated in such a manner that when the same target object can be detected along a plurality of beam directions which are changed by the beam scanning means, an angle of the target object is calculated by employing the peak value of the amplitude levels along the respective directions, acquired by the amplitude detecting means, whereas when the target object is detectable only along a single beam direction, the angle of the target object is judged as preset angles D1, E1, F1.

Abstract: A highly sensitive, high-speed dual tunnel diode detector is described for use in Ultra Wideband (UWB) object detection systems, such as a radar. The extended capability of the detector to both extremely short (sub-foot) and long distance (tens of thousands of feet) ranges is unique and permits the application of low power UWB radar to a wide variety of applications including high resolution radar altimetry at altitudes exceeding 10,000 feet and for autonomous on-deck landing operations (e.g., one-foot altitudes), the detection of extremely low radar cross section (RCS) targets for such applications as suspended wire detection for helicopters and other manned and unmanned craft, etc. High noise and interference immunity of the detector permits co-location of a UWB radar sensor with other active systems. The invention has immediate and significant application to all areas, both military and commercial, of precision distance measurement, intrusion detection, targeting, etc. over a wide range of distances.

Abstract: A heterodyned double side band diplex radar system determines the range of targets as a function of the amplitude variation of reflected target Doppler signals. The present invention includes a real radar system that accurately determines the range of fading targets and the magnitude of the velocity of the targets. The present invention also includes a complex radar system that determines the relative velocity of targets in addition to the range of targets. In either embodiment, the transmitted signal may be modulated with a pseudo-random number (“PN”) sequence to attenuate or decorrelate signals reflected from targets beyond some maximum range. The modulation of the pseudo-random sequence may also attenuate or decorrelate signals reflected from targets closer than some minimum range. The present invention also includes a real radar system having BPSK modulation with PN coding. The selection of BPSK modulation enables or facilitates the implementation of a portion of the system in digital form.

Abstract: The invention particularly relates to the detection of fast-flying targets by means of an HPRF radar system that operates with a plurality of switchable pulse-repetition frequencies (PRFs). In the method, a high velocity resolution is attained, which permits a reliable detection of a multiple-target situation. At the same time, a precise range determination is attained with a high range resolution by means of a pure transit-time measurement of the pulses. The length of the used range gates is selected to correspond to the anticipated target length.

Abstract: The location of underground objects such as pipes and conduits are located by detecting electrical signals emitted by the underground objects where the radiated signals include spread spectrum modulated RF signals. The system can operate in a passive or active mode, and in the active mode pseudo-noise (PN) generators can be employed or frequency-hopping can be employed. The use of spread spectrum minimizes or eliminates conflicting signals radiated from a plurality of underground objects and can improve signal to noise ratio of the detected signals.

Abstract: The method includes radiating an RF signal within a time Tt, receiving a reflected signal within a fixed time Tr equal in duration to the fixed time Tt of the radiated signal plus a delay &tgr;d between the end of the signal radiation and the beginning of the reflected signal reception. Once a modulated component is detected, a level of the component is measured and the reception time of the reflected signal is modified. This is carried out until the level of the modulated component decreases relative to that of the initially reflected RF signal and until the signal stops coming in. A distance is further determined from the reception time of the reflected signal with the modulated component. The method can be implemented using a microwave locator comprising a modulator and a transmitter which includes an oscillator, a power splitter and a transmitting antenna. A receiver comprises a receiving antenna, a microwave receiver, a preamplifier/demodulator and a signal processing unit. The modulator is tunable.

Abstract: Harmonic techniques are employed to leverage low-cost, ordinary surface mount technology (SMT) to high microwave frequencies where tight beamforming with a small antenna makes reliable, high-accuracy pulse-echo radar systems possible. The implementation comprises a 24 GHz short-pulse transceiver comprised of a pulsed harmonic oscillator employed as a transmitter and an integrating, pulsed harmonic sampler employed as a receiver. The transmit oscillator generates a very short (0.5 ns) phase-coherent harmonic-rich oscillation at a sub-multiple of the actual transmitter frequency. A receiver local oscillator operates at a sub-multiple of the transmit frequency and is triggered with controlled timing to provide a very short (0.5 ns), phase-coherent local oscillator burst. The local oscillator burst is coupled to an integrating harmonic sampler to produce an integrated, equivalent-time replica of the received RF.

Abstract: A radar ice sounder which employs parallel Doppler processing obtains more reliable and accurate radar ice sounding. The invention uses both incoherent and coherent techniques, in the same paradigm, to achieve simultaneously high Signal-to-Noise Ratio, high Signal-to-Speckle standard deviation Ratio, and high Signal-to-Clutter Ratio.

Abstract: Microwave radar: an additional modulation of the microwave signal (s (t)) provided for the emission or of the reception signal (e (t)) makes it possible to separate the payload signal from the noise signal parts in a following demodulation and filter unit (HP, MI2, TP). To this end, a modulation unit (MO, RG) for suitably modulating the signal to be emitted is provided preceding the antenna (A). The undesired noise signals produced by the components of the radar sensor itself are not modulated and can therefore be separated from the payload signal by filtering. This separation ensues after a raw measured signal (mess' (t)) has been generated by mixing transmission and reception signal (MI). A renewed demodulation with the modulation signal (r t)) of the modulation unit supplies the final measured signal (mess2 (t)) determinant for the determination of the distance, whereby the noise signals are previously removed by high-pass filtering and/or are subsequently removed by low-pass filtering.

Abstract: An equivalent time pulse-echo radar or other pulse-echo system employs a transmit reference sampler collocated with the transmitter to provide a transmit reference pulse, which initiates a pulse width modulated (PWM) pulse. A receive sampler connected to a receive antenna provides an echo-detection pulse that terminates the PWM pulse, such that the width of the PWM pulse indicates target range. The transmit reference sampler and the receive sampler are driven from a common clock such that transmit-receive timing offset drift precisely cancels on a picosecond scale, thereby enabling sub-mm range accuracy with common, low-cost circuit elements. The radar further includes automatically referenced pulse detectors that are responsive to either the magnitude or the phase of the sampler outputs. The radar can be used for precision tank level measurements, robotics, or automotive ranging applications.

Abstract: The present invention relates to radars and sonars, and more particularly to a synthetic-band technique of pulse compression making it possible to reach a very high distance resolution. Synthetic band consists in transmitting a waveform pattern consisting of a string of N coherent elementary pulses, linearly frequency-modulated, following one another at a recurrence frequency F.sub.r, of rectangular frequency spectra of elementary band B and of stepped carrier frequencies such that their frequency spectra will link up exactly one ahead of another to form a global spectrum of width N.times.B. On reception, the frequency spectra of the signals received in return for the N elementary pulses of a pattern are extracted by calculation, translated and juxtaposed so as to reconstruct a global frequency spectrum of width N.times.B and then compressed. Pulse compression is thus obtained which is equivalent to that which would result from the transmission of a waveform having a single pulse of frequency band N.times.

Abstract: A level measuring device suitable for highly accurate measurements. A transmission pulse generator generates microwave pulses at a transmission repetition rate and transmits them through an antenna towards a material whose level is to be measured. Echo signal from the surface of the material are received by the antenna. A reference pulse generator generates reference pulses similar to the transmission pulses but at a reference repetition rate which differs from the transmission repetition rate by a small frequency difference. The echo signal and reference pulse are input to a first mixer which generates an intermediate frequency signal that, with respect to the echo signal, is slowed by a time dilation factor equal to the quotient of the transmission repetition rate and the frequency difference. A first subcircuit samples the intermediate frequency signal, the time interval between two successive samplings equaling a time unit.

Abstract: The invention concerns a method of synthesizing a replica used in the compression filter of pulse compression radar.The replica is calculated from the spectrum of a required impulse response.The required impulse response is preferably obtained from an analytical function, such as a sinc function or a weighted sinc function, and a template.It is preferable to use calibration signals of the instrument to calculate the replica.The invention also applies to synthetic aperture radar.

Abstract: For measuring the level of a material in a vessel by a radar-based method an antenna arranged above the highest level anticipated radiates electromagnetic waves to the surface of the material contained in the vessel and receives reflected echo waves. The transit time of the wanted echo waves reflected by the material surface is measured from which the level is computed. Since this transit time corresponds to the group delay, for determining the reduction factor by which the group velocity of the electromagnetic waves differs from the velocity of propagation in the free space due to the geometry of the propagation space the phase difference of the wanted echo waves relative to a reference oscillation and the group delay are measured for various levels and the reduction factor is determined on the basis of the changes in the phase difference as a function of the group delay.

Abstract: A bi-static spread spectrum digital radar including a transmitting antenna and a receiving antenna array separate from and positioned at a distance from the transmitting antenna. The transmitting antenna transmits a pseudo random digital signal as produced by a pseudo random digital signal generator. The receiving antenna array receives signals simultaneously and parallely as reflected from a target by the transmitting antenna. A plurality of analog-to-digital converters are connected respectively to each element of the receiving antenna array so as to convert the received analog signal into a digital signal. Digital beams are produced and directed to a set of digital receivers. A processor is provided so as to produce a digital output from the set of digital receivers.

Abstract: An automotive radar incorporates a repetitive randomized equivalent LFM sequence of frequencies for improved immunity to jamming from other automotive radars. Each frequency in the sequence is of sufficient duration to travel round trip over the detection range of the radar. The Doppler shift in the received signal is estimated by performing a spectral analysis on similar frequency components of the received signal, and is then removed from the entire received signal. The received signal is then reordered so as to form an equivalent LFM received signal, and is compared with a similarly reordered image of the transmitted signal so as to estimate the range to the target. The randomization sequence, initial start frequency, or initial start time of the repetitive sequence are varied to minimize the effects of jamming by other radars, and this variation can be directionally dependent.