Abstract: In a laser rangefinder receiver, a return signal from a light-sensitive detector is passed through a high-pass filter, and is then processed in two separate circuit paths, a “signal” path and a “noise” path. The “signal” path employs a time-variable offset scheme to control receiver sensitivity. The “noise” path measures noise in the return signal, and maintain a noise-based threshold independent of the time-variable sensitivity of the “signal” path. No interstage coupling capacitors are employed, which contributes greatly to the receiver's quick saturation recovery.

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 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 radar based sensor detection system comprises a microwave source operative to provide a continuous wave signal at an output. A pulse-former is coupled to the output of the source and is operative to provide at an output a variable length pulse that increases the transmitted energy of the radar system according to the range of object detection. A modulator is coupled to the output of the pulse-former for providing a modulated pulse signal. A transmit receive switch coupled to the output of the modulator is selectively operative between a first transmit position and a second receive position. A transmit channel coupled to the transmit receive switch transmits the pulse signal when the switch is operated in the transmit position. A receiving channel coupled to the transmit receive switch receives the modulator signal when the switch is operated in the receive position.

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: 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-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 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 pulse doppler radar system simultaneously operating monostatically and bistatically. A pair of radar unit operate monostatically transmitting a radio frequency (RF) energy signal and receiving a RF return from the RF energy signal. In addition, simultaneously, one unit operates as a receiver receiving a bistatic return from the other. Information from the bistatic return is combined with information from monostatic returns to locate individual targets.

Abstract: A pulse-echo radar measures non-contact range while powered from a two-wire process control loop. A key improvement over prior loop-powered pulse-echo radar is the use of carrier-based emissions rather than carrier-free ultrawideband impulses, which are prohibited by FCC regulations. The radar is based on a swept range-gate homodyne transceiver having a single RF transistor and a single antenna separated from the radar transceiver by a transmission line. The transmission line offers operational flexibility while imparting a reflection, or timing fiducial, at the antenna plane. Time-of-flight measurements are based on the time difference between a reflected fiducial pulse and an echo pulse, thereby eliminating accuracy-degrading propagation delays in the transmitters and receivers of prior radars. The loop-powered rangefinder further incorporates a current regulator for improved signaling accuracy, a simplified sensitivity-time-control (STC) based on a variable transconductance element, and a jam detector.

Abstract: The invention relates to a distance measuring device. A transmitting part (E) for electromagnetic radiation especially radar radiation, emits measuring pulses (A, B) which are controlled by a pulse generator (1), and a receiving part (8) is switched to a ready-to-receive mode after a certain, adjustable delay (TDELAY, before a next measuring pulse is emitted, for receiving a reflected pulse during a time gate (18). The aim of the invention is to provide a calibration process taking into account all practical defects. To this end, the pulse generator (1) produces pulses with a multiple of the frequency with which the measuring pulses are repeated and a calibrating cycle in which calibrating pulses (&tgr;0 to &tgr;9) are produced with pulses generated by the pulse generator (1), controlled by the transmitting part (5), is carried out at longer intervals in time.

Abstract: A laser radar-proximity fuse with a laser-range measuring device and mask or camouflage discrimination, wherein for the initiation of the fuse, is no longer triggered at the beginning rather but at the end of an echo pulse configuration, even though its comparatively flat descending or falling pulse flank is or is not adapted for the determination of a clear, reproducible or controllable triggering point-in-time. By applying a Constant-Fraction-Trigger-Principle, which has heretofore been applied primarily to the rising or ascending flank of a pulse, there can be also derived a good controllable range or distance-dependent triggering pulse for the thereby optimized initiation of the fuse from the flatter rear flank of the echo pulse configuration, whereby the attacking of the target will not take place prematurely, but will be better directed toward the target center.

Abstract: A dual channel microwave sensor employs single sideband Doppler techniques in innumerable vibration, motion, and displacement applications. When combined with an active reflector, the sensor provides accurate range and material thickness measurements even in cluttered environments. The active reflector can also be used to transmit multi-channel data to the sensor. The sensor is a homodyne pulse Doppler radar with phasing-type Doppler sideband demodulation having a 4-decade baseband frequency range. Ranging is accomplished by comparing the phase of the Doppler sidebands when phase modulated by an active reflector. The active reflector employs a switch or modulator connected to an antenna or other reflector. In one mode, the active reflector is quadrature modulated to provide SSB reflections.

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: Radar apparatus in which output RF signals are modulated on an optical signal prior to transmission. Incoming optical echo signals are converted into RF signals using a detector. The original functionality of the radar apparatus is to a large extend retained, including the Doppler processing. The target radar cross section is determined by the wavelength of the optical signal.

Abstract: A dither oscillator randomly modulates the instantaneous phase of a precision radar PRF oscillator. Radar spectral emission lines occurring at multiples of a transmit PRF oscillator are spread by the phase modulation, resulting in a continuous noise-like spectrum for reduced interference. The dither oscillator is based on a CMOS logic inverter and has adjustable coherence. The transition times of the PRF clock are decreased to 100 ps using negative resistance in an emitter follower to help injection-lock an RF oscillator to the PRF clock. Applications include spread-spectrum radar sensors operating in the crowded ISM bands, such as robotic and automotive pulse-echo rangefinders.

Abstract: A method and apparatus is described for signal processing to identify an object in an environment. A precursor associated with an electromagnetic wave interacting with the object is received and a property of the object identified using precursor characteristics. The electromagnetic wave is transmitted with a characteristic including a pulse having a sharp rise time so as to generate the precursor. The pulse is generated using a circuit including capacitive discharge and a semiconductor device such as a Drift Step Recovery Diode. Alternatively the pulse may be generated using a microwave diode switch and a broadband semiconductor amplifier or a traveling wave tube amplifier. The characteristic may also includes a signal with a phase reversal generated by dividing the electromagnetic signal and phase modulating the first electromagnetic signal with the divided signal to generate the phase reversal so as to generate the precursor.

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: AN FM pulse Doppler radar apparatus performs pulse modulation of modulating waves having repeatedly increasing and decreasing frequency, transmits thus modulated waves, receives at each range gate having an interval equivalent to a pulse width, reflected waves reflected from an object, determines a distance according to the range gate, and calculates the distance to the object and the relative velocity of the object based on the difference between frequencies of the transmission waves and the received waves. The apparatus includes a velocity determining unit for determining velocity of the radar-mounted vehicle and a comparison-and-detection unit for comparing the detected distance according to the range gate and the distance calculated based on the difference between the frequencies of the transmission waves and the received waves.

Abstract: A radar (300) comprises a transceiver (302) for transmitting pulses directed to a subsurface area of interest (102) and for receiving a reflected wave (210) from the subsurface area of interest. The pulses have a pulse duration and amplitude constrained by the equation, d2|E|e/m≦1 Angstrom, where d is the pulse duration in seconds, E is the pulse amplitude in volts/meter, e equals the charge of an electron in Coulombs, and m equals the mass of an electron in Kg. A processing device (304), in communication with the transceiver, processes the reflected wave and displays an image of the subsurface area of interest and identifies the material composition of subsurface objects that have known properties that vary as a function of the pulse duration and amplitude.

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: The duty cycle of a pulse train from a pulse radar antenna is increased by dividing the antenna aperture into sub-apertures (1-5), generating separate pulse trains from said sub-apertures (1-5), and time shifting the separate pulse trains between themselves to produce a resulting pulse train having shorter pulse spacing or wider pulses.

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 radar device for use in backing up a vehicle is disclosed herein. A plurality of wave sensors is installed on a rear portion of a vehicle for detecting an obstacle therebehind. A master controller has a plurality of transceiver circuits and a microprocessor connected to the plurality of transceiver circuits. Each transceiver circuit corresponds to one of the plurality of wave sensors. The microprocessor activates the plurality of transceiver circuits to drive the plurality of wave sensors for transmitting and receiving ultrasound wave signals thereby determining the location of the obstacle. A location display device is connected to the master controller for receiving and decoding data related to the location of the obstacle thereby indicating the direction of the obstacle and displaying in numerical form the distance between the obstacle and the vehicle.

Abstract: The actual value of a parameter from a laser range finder to a target is determined by adjusting the measured parameter by a measurement error. The error adjustment is based on the relationship between the intensity of the detected pulse and the expected parameter error. The laser range finder has a laser diode for emitting a laser pulse to a target to produce a reflected pulse, and a detector for receiving the reflected pulse. A measurement circuit is coupled to the detector for determining a measured parameter based on the reflected pulse. An integrator is coupled to the detector for determining the pulse area, and therefore, the intensity of the reflected pulse. A processor is coupled to the measurement circuit and the integrator for adjusting the measured parameter based on the pulse area of the reflected pulse, to provide the actual value of the parameter.

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 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: Characteristics of a target are measured by a radar or sonar. Pulses (101, 102, 103) are transmitted and in between (X) the transmissions of pulses a signal is received which depends on the transmitted pulses and on the distribution of the characteristics measured at different ranges. The distribution at different ranges of the characteristics measured is determined by representing it by means of a substantially linear system of equations in which the variables are the values of the characteristics measured at desired ranges, and by solving the system of equations for the variables. The transmitted pulses form a cyclically repeated pulse code or a continuously changing pulse train.

Abstract: A radar system is described for use in vehicular applications. The radar system is particularly suited to backup warning systems and lane-change warning systems. The radar minimizes many of the problems found in the prior art by providing programmable delays and programmable gain. The radar uses a range search algorithm to detect and sort targets at various ranges within the field of view of the radar. Each target range corresponds to a particular delay and gain setting. The radar searches for targets at the various ranges by running a target search algorithm. For each target range, the search algorithm causes the proper time delay and gain setting. Targets within the selected range are detected and catalogued. Speed of the targets is obtained through Doppler processing. A display is used to warn the driver of the vehicle of the presence of targets at the various ranges. The warning may be visual and/or audible.

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: A pulse radar system includes a frequency-agile magnetron comprising an input for giving a feeding voltage of a magnetron tuner. A modulator connected to said magnetron forms pulses of a feeding voltage for the magnetron. A low power signal source also connected to said magnetron generates microwave frequency signals which are given to the magnetron in pauses between pulses. These signals have the frequencies differing from the frequencies of the signals generated by the magnetron and fixed during each period of magnetron pulse repetition. This radar system also includes a signal converter receiving the low power signals reflected by the magnetron. These signals are converted into the signals connected in time to the moments, when the frequencies of the low power source and the frequencies of the magnetron oscillating system coincide with each other. Further, said signals are used for triggering the modulator connected to said converter.

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: 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: Method and device for determining an azimuth angle and/or an elevation angle, based on a multibeam radar system, in which the echo signals of each radar target are recorded over at least two beams. The amplitude of an echo signal recorded in each receiving beam is normalized. For each receiving beam, the normalized amplitude is compared to the pattern values of an antenna pattern stored and normalized for this beam in order to determine the angle of a radar target. The comparison results from at least two receiving beams are combined to form an angle-dependent analysis quantity, and the angle whose angle-dependent analysis quantity meets a minimum and maximum criterion is determined to be the angle of the radar target. Included in the angle-dependent analysis quantity is a phase angle of at least two recorded echo signals. This operation can also be performed on the basis of a complex normalization operation.

Abstract: Method for reducing false target echo indications in a pulse Doppler radar having at least two different pulse repetition frequencies during the period in which the main beam of the radar illuminates a target. A target which is detected gives rise to a number of primary detections in each PRF. The method includes use of at least one variable criterion and a final criterion, which are both of the M/N type. The factor M in the variable criterion is initially greater than the factor M in the final criterion. The method also includes the feature that primary detections which are all to be found in the same range gate in a number of PRF's, which number is equal to the factor M in the variable criterion, are approved as targets in this range gate.

Abstract: A method provides for contactless measurement of the range between a transceiver unit for microwaves in the frequency band from 1 to 100 GHz and an object to be investigated using a pulse principle. The microwaves are focused onto the surface by an antenna to detect the contour of the object. In particular, the surface of a bolt produced using a spray compacting method can be detected.

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: A method for resolving range ambiguities and separating overlaid signals in a Doppler weather radar is proposed. For uniform PRT transmission, it consists of a special deterministic code for phases of the transmitted pulsed, and associated decoding and processing of return signals. In the decoding process when the signal from one range interval is made coherent, the signal from the other range interval has a multiple split spectrum. The multiple spectra have the same shape but are offset from each other. Processing steps to separate the overlaid signals and a procedure to estimate the spectral moments are given. One crucial aspect in this procedure is the magnitude domain deconvolution. The magnitude domain deconvolution is also applied to a staggered PRT transmission scheme whereby it enables the estimation of spectral parameters with much lower standard error than the known methods.

Abstract: A low-cost, high-resolution radar based detection system has a pulse repetition frequency generator connected to first and second narrow pulse modulators. A transmit channel is connected to the first narrow pulse modulator and emits pulse modulated carrier based transmit signals having a prescribed carrier frequency and a prescribed duration. A receive channel is connected to the second narrow pulse modulator. A time delay circuit delays the output of the second pulse modulator to the receive channel and a mixer mixes a portion of one of the pulse modulated carrier based transmit signals reflected from an object with the output of the second narrow pulse modulator.

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: The present invention provides a covert radar system in which radar signals emitted are capable to search receiver thermal noise and, therefore, are substantially undetectable in the normal radar operating range.

Abstract: A notched-chirp generator (20), utilizing first and second chirp generators (28, 30), a functional conversion element (40), an antichirp generator (42), a summing element (64), and a translation element (66), generates a notched-chirp signal (24). The second chirp generator (30) generates a second chirp phase signal (.phi..sub.C1), is translated by the functional conversion element (40) into an oscillating antichirp signal (A.sub.O1). The antichirp generator (42) generates an antichirp signal (A.sub.1) by scaling, weighting, and cyclically positioning the oscillating antichirp signal (A.sub.O1). The summing element (64) sums the antichirp signal (A.sub.1) with a first chirp phase signal (.phi..sub.C0), generated by the first chirp generator (28), to produce a notched-chirp phase signal (.phi..sub.N), which is converted by the translation element (66) into a notched-chirp signal (24) having a notch (26) positioned at a specific frequency (f.sub.N) determined by the antichirp signal (A.sub.

Abstract: Disclosed herein is a distance measuring apparatus comprising an irradiation unit for generating an electromagnetic wave, a receiving unit for receiving a reflected wave of the electromagnetic wave reflected by an object of measurement and generating a reception signal, and a propagation delay time measuring unit for measuring a propagation delay time by counting the number of pulses of a pulse train having a predetermined frequency. The propagation delay time is the time between the time that the irradiation unit irradiates the electromagnetic wave and the time that the reflected wave is received by the receiving unit.

Abstract: A highly precise range measurement instrument is made possible through the use of a novel and efficient precision timing circuit which makes use of the instrument's internal central processing unit crystal oscillator. A multi-point calibration function includes the determination of a "zero" value and a "cal" value through the addition of a known calibrated pulse width thereby providing the origin and scale for determining distance with the constant linear discharge of capacitor.

Abstract: In accordance with the teachings of the present invention, a radar system (20) and method of determining the range (R) to a remote target (14) is provided. The method includes computing a plurality of simulated M-dimensional points (x.sub.o (t)) as a function of return pulse arrival times over a range of expected return pulse arrival times (t.sub.1 through t.sub.2). The computed simulated points (x.sub.o (t)) are stored as function of return pulse arrival times in a memory (42) of the system (20). An antenna (10) is aligned in the direction of the remote target (14) and transmits at least one electromagnetic pulse (12) in the direction of the remote target (14) such that the pulse (12) reflects off the remote target (14) as a return pulse (16). The return pulse (16) is sampled at M different times representing a M-dimensional measured point (x). The measured point (x) is compared with each of the simulated points (x.sub.o (t)) stored in the memory (42) for determining which of the simulated points (x.sub.