Abstract: A radar device capable of discriminating a person possessing metals from a person having no metals by transmitting a radio wave includes a voltage controlled oscillator for generating a radio wave, an antenna for transmitting the radio wave generated by the voltage controlled oscillator and for receiving a reflected wave from metals as an object irradiated by the radio wave transmitted by the antenna, a multiplier for detecting a beat component of the wave transmitted by the antenna and the reflected wave received by the antenna, and an FFT operator for analyzing a frequency spectrum of the beat component detected by the multiplier, a recording unit for previously storing a predetermined reference pattern, and a comparison unit for comparing the analyzed result by the FFT operator with the reference pattern stored in the recording unit.

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 radar device for detecting distances and relative speeds of obstructions such as preceding vehicles has a stationary object identifier for identifying stationary objects such as roadside guard rails and the like and a stationary object eliminator for eliminating data identified as pertaining to such stationary objects. The stationary object identifier detects peak densities in a beat spectrum detected as a difference between transmitted and received frequencies of a radar beam modulated to rise and fall in frequency periodically and identifies peak groups having peak densities above a predetermined value as stationary objects. Therefore, it is possible to detect a stationary roadside object on the basis of peak densities. The stationary object eliminator eliminates data of peak groups identified as stationary objects by the stationary object identifier and thereby removes them as objects of combination processing for pairing rise side beat frequencies with fall side beat frequencies.

Abstract: A method and apparatus for detecting the presence of objects in a vehicle operator's blind spots. The apparatus comprises a side-facing Doppler radar system using continuous wave (CW) transmission with frequency modulation (FM) operation from a frequency modulation switching technique. The radar system determines the presence, range and closing rate of detected targets. The radar system detects targets even when operated in adverse weather conditions and will not generate false warnings due to rain clutter caused by wet roads and other wet surroundings. The radar system uses ranging techniques to reject false targets that are detected outside of a predetermined target detection zone. In accordance with the present invention, the radar system indicates that a target is detected if and only if any part of the target is within the detection zone and it: (1) remains in front of the antenna for at least TH1 seconds; (2) is at a range between Range.sub.min and Range.sub.

Abstract: A radar apparatus of the present invention is a radar apparatus for detecting an object around a vehicle, which comprises a transmitter section for radiating a frequency-modulated, transmitted wave a receiver section for receiving a radio wave re-radiated from an object exposed to the transmitted wave and mixing the radio wave received with part of the transmitted wave to obtain beat signals, and a signal processing section for analyzing frequencies of the beat signals to detect the object around the vehicle. This radar apparatus is arranged to set a first threshold value and a second threshold value higher than the first threshold value as to signal levels of a frequency spectrum of the beat signals.

Abstract: In an FM-CW radar, a receive section has an array antenna in which a plurality of element antennas are arrayed as receive antennas, and a plurality of mixers for generating a beat signal of each channel from a receive signal for each element antenna, and a signal processing section comprises a first device for performing analog-to-digital conversion of the beat signal of each channel into a digital beat signal of each channel and storing it, a second device for performing a Fourier transform process for the digital beat signal of each channel to obtain Fourier transform data of each channel, a third device for performing a phase shift process according to beam direction angles for the Fourier transform data of each channel and thereafter synthesizing the Fourier transform data of each channel every beam direction angle to obtain Fourier transform data of each beam direction angle, and a fourth device for detecting a range to an object and a relative velocity of the object from the Fourier transform data of ea

Abstract: A procedure for the elimination of interferences of short duration, such as pulses, in a radar unit of the FMCW type where the transmitted and received signals are combined to form a useable signal is provided. According to the procedure, interferences in the useable signal are detected and eliminated in the time domain and the part of the useable signal with interference is reconstructed by extrapolation based on samples without interference. Thus, the occurrence of interferences is prevented in the complex Fourier Transform of the type that is generated by known methods of clipping the signal.

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: A source for a linear homodyne transceiver that generates repeated linear chirps. A YIG oscillator with a main coil and an FM coil receives a basic linear current ramp at the main coil to generate a chirp. The FM coil is coupled to receive a PLL error signal. The PLL receives a sample of the output signal from the YIG oscillator at one input and a linear chirp reference signal at the other input generated by a DDS chirp generator. Any variation between the linear chirp frequency at any instant and the actual frequency output by the YIG is corrected by an error signal to the FM coil to correct for nonlinearities of the YIG caused by variations in the chirp rate, the rate of change of frequency per second per chirp, temperature variations and microphonics.

Abstract: A signal source produces a frequency-modulated signal. The signal is supplied to a transmit/receive unit and transmitted. A surface-wave element produces a signal delayed by a delay from the frequency-modulated signal. A mixer mixes the delayed signal with the received signal and outputs the mixed signal to an evaluation device. The delay is preferably equal to the propagation time of a signal on the measurement path. The coherence length of the ranging apparatus is thereby substantially improved.

Abstract: In a radar of FM-CW system having a transmitting and a receiving unit 20 and 28 both connected to a transmitting/receiving antenna 26 via a circulator 24, a high frequency switch 22 for transmission, is inserted and turns on and off the path between the transmitting unit 20 and the circulator 24, and in the receiving operation of the receiving unit 28 the high frequency switch 22 for transmission is controlled according to a switch control signal 320a provided from a signal processing unit 30 such as to be held "off" to hold the transmission output of the transmitting unit 20 "off" for a predetermined time, thus reducing sneak noise component between the transmission and reception. Thus it makes possible to reduce sneak noise between the transmission and reception, and readily realize cost reduction without need of separate antennas for the transmission and reception.

Abstract: For improving the measuring precision, a reference unit (REF) is juxtaposed with a continuous wave radar (DSR). This reference unit (REF) comprises a surface wave element (OFW) for generating a signal delayed relative to the transmission signal. A mixed signal is formed from the delayed signal and the transmission signal with a mixer (MI2), this mixed signal being utilized in combination with the measured signal stemming from the continuous wave radar (DSR) for determining the distance.

Abstract: According to the invention, a monostatic FMCW radar sensor for a vehicle for detecting objects is proposed in which at least one antenna feed in combination with a dielectric lens is embodied for both transmitting and receiving a corresponding echo signal. At least one antenna feed is connected to a ring mixer via a ratrace ring or double ratrace ring, so that an expensive circulator can be dispensed with. The high-frequency structure is advantageously embodied in planar microstrip form. A plurality of transmission and reception antennas are focused via one common lens.

Abstract: A transmission channel selection controller intermittently energizes transmission amplifiers indicated by transmission channel information, based on a modulation signal supplied from a modulation signal generator, to modulate an FM signal. The modulated FM signal is radiated as a beam from transmission antennas. When the beam is reflected as an echo beam by an object, the echo beam is received by reception antennas which supply a reception signal to reception amplifiers. A first mixer mixes the FM signal with the amplified reception signal, producing a modulated beat signal which is a beat signal representing the distance up to the object and modulated by the frequency of the modulation signal. A second mixer mixes the modulated beat signal with the modulation signal thereby demodulating the modulated beat signal into the beat signal.

Abstract: The measurement apparatus (1) delivers both a raw measurement d(i) of the distance and a raw measurement v(i) of the relative speed of said object with respect to the apparatus (1). According to the invention, said speed measurement v(i) is integrated over a predetermined sliding time interval, the difference of the raw distance measurement d(i) and of the integral d'(i) of the speed is formed, a mean value (C.sub.dif) of said difference is calculated over said time interval and the calculated mean (Copt) is added to the integral d'(i) of the speed to form a filtered measurement (d.sub.filt) of the object/measurement apparatus distance.

Abstract: The distance to a target is determined by transmitting a radio frequency signal comprised of a plurality of pulses to a target from a transmitter at a given transmission time, receiving a plurality of return scans at a receiver, selecting a scan meeting a predetermined parameter that includes a reflected pulse; comparing the scan with a template of a reflected pulse at different locations to select the time at which the match between the scan and the template have the closest match; and calculating the distance to the target. The signal is transmitted and received through a wall of an aperture-free container that is transparent of said radio frequency pulses. The device also includes a barrier plate that is opaque to radio frequency pulses between the transmitter and receiver.

Abstract: An FM signal generator generates a frequency-swept FM signal, which is radiated as a beam from a transmission and reception antenna. The transmission and reception antenna is angularly moved by an antenna actuator to scan the beam. An echo signal reflected from a target and a signal related to the frequency-swept FM signal are mixed into a beat signal, whose frequency spectrum is analyzed by a frequency analyzer. A target detector determines the distance up to the target based on the frequency spectrum of the beat signal. A BPF processor comprises a bandpass filter which extracts a frequency component corresponding to the distance up to the target from the beat signal. A bearing calculator compares the level of a signal that has passed through the BPF processor with a threshold level to determine a bearing and a width of the target.

Abstract: The invention relates to a method for realizing a radar transmission for a high-resolution radar. According to the method, a number of groups of pulses is transmitted with incremental frequencies, each group also comprising a number of pulses with incremental frequencies, which pulses are transmitted simultaneously or substantially simultaneously.

Abstract: An onboard radar system for a vehicle using the FM-CW method is provided. The radar system includes a mode changer. The mode changer provides a first mode which is suitable to detect a target existing distant from the vehicle. The mode changer also provides a second mode which is suitable to detect a target existing nearby the vehicle. The radar system detects a pair of beat frequencies in the first mode. Further, the radar system detects another pair of beat frequencies in the second mode. The radar system detects a target based on a pair of base beat frequencies which are determined based on an analysis result of both pairs of the beat frequencies.

Abstract: An altimetric type measurement method for use on a satellite transmits a pulse towards the surface of the sea and carries out frequency transformation on the return signal resulting from the reflection of this pulse at the surface of the sea. This produces a spectral signal of samples successively comprising:(a)--a first zone with a low amplitude level,(b)--a second zone with a sharply increasing slope ending at a peak, and(c)--a third zone of decreasing slope.Samples of the spectral signal are selected within a selection zone that corresponds to the first and second zones for a predetermined maximal level of the height of the waves at the surface of the sea and maximum likelihood processing is applied only to the selected samples.

Abstract: A relative distance and relative velocity to a target object is accurately estimated even if an error in slopes of the triangular wave modulation, that is unbalanced upward and downward slopes, or error in absolute values in an FMCW radar exists. A first distance estimator estimates a distance up to the target object based on a sum of a beat wave frequency generated between the upward and downward slopes of the triangular wave and an absolute value of an average frequency modulation factor which is a mean value of frequency modulation factors for the upward and downward slopes of the triangular wave, and a first velocity estimator estimates a relative velocity to the target object based on a time difference of the calculated distance.

Abstract: An FM radar system of more simple construction, smaller size, lower cost and improved performance is provided in which circulators of any type in the prior art are eliminated by constructing a transceiver comprised of a transmitting part and a receiving part, each formed on a common dielectric plate and having a dedicated transmitting antenna and a dedicated receiving antenna respectively. The antennas comprise planar array antennas, in contrast to the solid antennas used in prior art systems. The planar array antennas are also formed on the single dielectric plate. The transmitting part comprises a plurality of transmission antennas and a plurality of frequency multipliers coupled to said transmission antennas. The receiving part comprises a plurality of receiving antennas which are coupled to a plurality of switches through a plurality of mixers, frequency multipliers, and low noise amplifiers.

Abstract: Monostatic homodyne radar system, in particular for continuous wave operation, in which one input port of a balanced mixer (2) is connected to an oscillator (1) and another input port of the mixer is connected to an antenna (3). The mixer has a directional coupler with a 90.degree. phase difference between the coupling arms. The load impedances of the coupling arms have a reflection factor greater than 0.3, so that coupling of the power supplied from the oscillator to the antenna ensues, which coupling is sufficient for the radiation.

Abstract: An apparatus and method for detecting an object and determining the range of the object is disclosed. A transmitter, coupled to an antenna, transmits a frequency-modulated probe signal at each of a number of center frequency intervals or steps. A receiver, coupled to the antenna when operating in a monostatic mode or, alternatively, to a separate antenna when operating in a bistatic mode, receives a return signal from a target object resulting from the probe signal. Magnitude and phase information corresponding to the object are measured and stored in a memory at each of the center frequency steps. The range to the object is determined using the magnitude and phase information stored in the memory. The present invention provides for high-resolution probing and object detection in short-range applications. The present invention has a wide range of applications including high-resolution probing of geophysical surfaces and ground-penetration applications.

Abstract: An FM radar system includes an amplifier for amplifying the beat signal at an amplification factor varying with the frequency, and a level correcting device for correcting a spectrum level of an amplified signal or a spectrum level of a signal generated based on the amplified signal, into a spectrum level obtained when the beat signal is amplified without involving Doppler shift caused by a velocity of the target relative to the FM radar system. By virtue of the correction performed by the level correcting device, it becomes possible to obtain a real spectrum level which is observed when the target is stationary or fixed in position relative to the radar system.

Abstract: A pulse-echo ranging system includes an improved target and a ranging device which emits pulses of electromagnetic radiation toward the target and receives pulses reflected from the target. The target is provided with a modulating mechanism for modulating the reflected pulses in a predetermined manner. The modulating mechanism allows the ranging device to distinguish pulses truly reflected from the target from noise and pulses reflected from objects other than the target. More specifically, the modulating mechanism may include a reflector which reflects the pulses at plural distances from the ranging device. The reflector may include a single reflective surface coupled to an oscillating vibrator, or plural reflective surfaces spaced at different locations from the ranging device.

Abstract: A process for measuring the relative distance and speed of an object in relation to a periodically frequency-modulated continuous wave radar includes extracting the distance and the speed by combining beat frequencies derived from a mixture of emitted and reflected signals being respectively obtained during ascending and descending alternations of a modulation. The distance and the speed of an object at each half-period are calculated from beat frequencies of two immediately preceding alternations.

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

Abstract: In a Frequency Modulated Continuous Wave (FMCW) radar, a radar return signal is mixed with a delayed frequency sweep waveform to gain a ranging signal to noise ratio (RSNR) higher than the RSNR available from mixing the return signal with a transmitted waveform.

Abstract: Apparatus for linearizing the sweep frequency output of an FMCW radar employing a voltage controlled oscillator includes means for comparing a series of reference voltages sequentially with the instantaeous oscillator drive voltge, accumulating the individual resultant error voltages throughout successive sweep cycles, sequentially converting the individual accumulated voltages to exponential form and feeding the exponential voltages back into the drive circuit for the VCO.

Abstract: A conventional radar module (1) for level measurements is designed for operation within a specific, narrowly restricted frequency range. To enable level measurements to be implemented at a substantially higher frequency without involving any change in the existing radar module (1) whatsoever, a frequency converter circuit (2) is inserted between the duplexer antenna (7) designed for said higher frequency and the antenna port (A) of the radar module (1). This frequency converter circuit (2) which can be realized at small expense converts the lower frequency into the higher frequency in the direction from the radar module (1) to the antenna (7) and the higher frequency into the lower frequency in the opposite direction.

Abstract: In an FM-CW radar system, a beat signal is frequency-analyzed for selecting ascending-side beat frequencies and descending-side beat frequencies for a plurality of targets. By pairing the ascending-side and descending-side beat frequencies one by one from each side, all possible combinations thereof are prepared. Based on these beat frequency combinations, beat frequency combinations after a given time are predicted, respectively. If an ascending-side beat frequency and a descending-side beat frequency of the predicted beat frequency combination are found in ascending-side beat frequencies and descending-side beat frequencies of a beat signal selected after the given time, respectively, or in the neighborhood of them, respectively, the predicted beat frequency combination of the found ascending-side and descending-side beat frequencies is set as a correct beat frequency combination. A further correct beat frequency combination/combinations can be set in the same manner.

Abstract: An FM radar system of more simple construction, smaller size, lower cost and improved performance is provided in which circulators of any type in the prior art are eliminated by constructing a transceiver comprised of a transmitting part and a receiving part, each formed on a common dielectric plate and having a dedicated transmitting antenna and a dedicated receiving antenna respectively. The antennas comprise planar array antennas, in contrast to the solid antennas used in prior art systems. The planar array antennas are also formed on the single dielectric plate. The transmitting part comprises a plurality of transmission antennas and a plurality of frequency multipliers coupled to said transmission antennas. The receiving part comprises a plurality of receiving antennas which are coupled to a plurality of switches through a plurality of mixers, frequency multipliers, and low noise amplifiers.

Abstract: In a high range resolution ladar, a chirp signal waveform is propagated as a divergent laser light waveform and the target reflected return is collected and converted to a current proportional to power. An undelayed chirp signal is added in a mixer to the return current and then low pass filtered to recover a mixed intermediate frequency (IF) signal having a frequency proportional to the target range. Periodically, the light circuit is interrupted and the chirp signal is processed through the mixer and low pass filter without a target return current and this output, the mixer self-clutter, is stored. This stored self-clutter signal is subsequently subtracted from the mixed IF signal on a chirp by chirp basis to cancel the self-clutter produced by the mixer. The subtracted signal is then frequency analyzed to determine target range.

Abstract: An FM radar system of more simple construction, smaller size, lower cost and improved performance is provided in which circulators of any type in the prior art are eliminated by constructing a transceiver comprised of a transmitting part and a receiving part, each formed on a common dielectric plate and having a dedicated transmitting antenna and a dedicated receiving antenna respectively. The antennas comprise planar array antennas, in contrast to the solid antennas used in prior art systems. The planar array antennas are also formed on the single dielectric plate. The transmitting part comprises a plurality of transmission antennas and a plurality of frequency multipliers coupled to said transmission antennas. The receiving part comprises a plurality of receiving antennas which are coupled to a plurality of switches through a plurality of mixers, frequency multipliers, and low noise amplifiers.

Abstract: In a method for measuring the distance and the velocity of objects employing electromagnetic waves, the frequency of an emitted signal is modulated. The signals received during one rise and one drop in the frequency of the emitted signal are mixed with the emitted signal. The intermediate-frequency signals resulting from the mixing are then spectrally analyzed. The distance and the velocity of at least one object are calculated from the frequency of the spectral lines of the intermediate-frequency signals during at least one rise and at least one drop in the frequency of the emitted signal.

Abstract: Frequency-modulated wave trains are used in target locating by means of transmitted pulses and evaluation of portions reflected by the target in relation to bearing, distance and speed, wherein the pulse length and bandwidth of the transmitted pulse are pre-selected. The received signals are evaluated in Doppler channels by calculation of the ambiguity function. To make possible an increase in accuracy of the speed determination with the same number of Doppler channels, the frequency of the wave train within the bandwidth is calculated in accordance with an irrational function, the exponent of which has a value between 0 and 1. The smaller the value, while keeping the same pulse length, the greater the Doppler sensitivity. This method for modulating the wave train in the transmitted pulse can be advantageously employed for target identification by means of sound waves and electromagnetic waves.

Abstract: A method and apparatus for identifying a remote target includes a transmitter for transmitting pulses of energy toward the target for generating echo signals, and a receiver for receiving the echo signals, and for generating received signals representing the target, noise and clutter. The received signals are applied through a plurality of cascaded channels, each including a Doppler filter cascaded with a multiplier, each also including range sidelobe suppression, for, in each of the cascaded channels, narrowband filtering the signals passing therethrough about a controllable center frequency, and for, if necessary, converting the signals passing therethrough to baseband, for thereby applying one of a plurality of Doppler filtered baseband signals to the input of each of the range sidelobe suppressors of each of the cascaded channels. The power of the Doppler filtered baseband signals in each range bin is evaluated for determining the frequency at which the spectral density is greatest.

Abstract: A microwave transceiver using a reflection pumped mixer includes an electromagnetic signal generator, a subreflector, a reflector of electromagnetic signals from the subreflector, a mixer, circulator, and processing circuitry to relate electromagnetic signal frequency differences to the range of a target from the transceiver. Such frequency differences are detected by the mixer from the captured electromagnetic signals reflected distant targets and reflected electromagnetic signals from the subreflector.

Abstract: A latent electrical charge pattern of electrical signals is produced by an electrode matrix. Apertures between the electrodes are opened and closed, respectively, to expose electric fields for the attraction of pigment particles of toner against an information carrier. The electrical charge pattern electrostatically controls the transmission of electrical fields through the apertures of the matrix to attract particles of toner against the information carrier. The apertures are opened and closed by generating electrostatic fields between the electrode layer, particle supply and backing electrode. Each electrode is arranged on a carrier to completely surround one aperture and is individually connected to a voltage source to supply the electrical signals.

Abstract: For distance measurement using the reflected beam principle a transmission wave is transmitted with a periodically frequency modulated transmission frequency. The echo wave reflected at the target has a reception frequency which is periodically frequency modulated in the same manner, there being a transit time dependent frequency difference between the transmission frequency and the reception frequency, such frequency difference being the distance frequency which is determined as measure of the distance of the target from the transmission/reception location. Using a constant reference frequency the transmission frequency and the reception frequency are converted in a common mixer to give a transmission/reception intermediate frequencies mixture, which includes a transmission intermediate frequency formed by conversion of the transmission frequency using the reference frequency, and a reception intermediate frequency formed by conversion of the reception frequency using the reference frequency.

Abstract: A homodyne radar apparatus and method for performing radar cross-section surement by maintaining the linearity and compensating for frequency drift of an FM chirp waveform produced by a YIG tuned oscillator. A digital computer uses a predetermined data look-up table of each YIG oscillator frequency characteristic in conjunction with a digital to analog converter to provide a compensating sweep signal to linearize the frequency output of the oscillator. The computer uses an analog to digital converter in conjunction with a reference circuit output to compare the actual YIG signal nulls resulting from the reference circuit to the nulls in a signal produced by a lab standard oscillator in the reference circuit to adjust start sample delay of the ADC and to correct any frequency drift evidenced by the difference in the null of the signal.

Abstract: A time-sharing FM radar system. A plurality of beam radiating and receiving means, an FM signal generating means, a transmitting unit, a receiving unit, and a direction detecting means are configured to minimize power consumption and interference between channels. The beam radiating and receiving means are arranged to radiate partially overlapping beams in space and to receive return beams. The FM signal generating means generates an FM signal. The transmitting unit includes a plurality of transmitting switching circuits each comprised of a plurality of amplifiers. Each amplifier corresponds to one of the beam radiating and receiving means, and is configured to intermittently amplify and distribute a portion of the FM signal generated by the FM signal generating means to its corresponding beam radiating and receiving means. The receiving unit includes a plurality of receiving switching circuits and a single mixer.

Abstract: The wave is modulated in frequency (or in phase) and a measurement is made of the frequency of the beat between the transmitted wave and the received wave which gives the propagation delay and hence the distance. The method provides for the superimposing, on this modulation, of a periodic over-modulation with a period that is equal to or is a multiple of the propagation delay corresponding to a pre-selected expected distance. The device comprises, at transmission, in the case of a linear modulation of frequency, a saw-tooth generator (31) and a generator of over-modulations (32), for example sinusoidal, controlled by the expected distance given by a distance selector (30). The modulation signal of the transmitter is obtained by summation (33) of the signals of the two generators (31, 32).

Abstract: A processor for an FM/CW sensor divides the sweep periods of the sensor into a number of subsweep intervals, measures the received power within a multiplicity of frequency windows during each of the subsweep intervals, and then performs a spectrum analysis of the power measurements in each frequency window to characterize the reflectors in the corresponding range bins of the FM/CW sensor footprint.

Abstract: A dynamically tunable notch filter is used within a continuously transmitting laser radar system for filtering narcissus signals generated from a continuous linear frequency modulated chirp transmission signal at the transmission aperture antenna with the filter including mixing and band pass filtering at the narcissus dynamic frequency to eliminate the unwanted narcissus signals varying over the dynamic frequency range of the narcissus signals, and to also eliminate unwanted target images, for improved resolution and detection of low level reflected target signals which are often obscured by the presence of the relatively high-level unwanted narcissus signals.

Abstract: A segmented stretch waveform for wide band high duty cycle tracking application. The waveform is divided into multiples of two spaced segments as the tracking range closes. Target returns received during spaced segments are combined to correspond to the complete waveform; and range is determined in accordance with the combined waveform. Tracking range can be varied without changing bandwidth, FM slope, duty cycle or processing time.

Abstract: A simple self-oscillating mixer circuit is provided, suitable for forming with an antenna (21) the complete front end of an inexpensive short-range FMCW radar. A modulating signal (40), e.g. from a sweep generator (44), is applied to a control terminal (14) to sweep the RF output (R) of the self-oscillating mixer SOM (10). A cancellation circuit (6 to 9) is connected between the control terminal (14) and an IF output line (13) to remove a corresponding modulation (41) which occurs on the IF line (13) and so to generate a substantially demodulated IF output signal (I). Advantageously a grounded-source MESFET in a feed-back network forms the SOM (10) and has the IF output line (13) taken from its gate. In this case the IF modulation (41) is inverted with respect to the modulating signal (40), and so the cancellation is achieved by adding the modulating signal (40) to the modulated IF output signal (41), e.g. via a resistor network 6 to 8.

Abstract: The distance between the target and the measurement means is segmented into adjacent distance compartments, the first one of which starts at the zero distance. Each distance compartment has an associated energy level obtained by the demodulation of the delay measurement signal resulting from the product of correlation between the emitted signal and the received signal reflected by the target. The disclosed method consists in creating two distinct aliasings of the spectrum of the signal measurement signal, the energy level of which corresponds to the first distance compartment, these aliasings being achieved on the part of the spectrum corresponding to negative distances. This two distinct aliasings make it possible to obtain two distinct energy levels on the totality of the first distance compartment, and thus enable the measurement of all the distances on this first distance compartment, including the very small distances, even almost zero distances, by comparisons and analyses of the two energy levels.

Abstract: A time-sharing FM radar system. A plurality of beam radiating and receiving means, an FM signal generating means, a transmitting unit, a receiving unit, and a direction detecting means are configured to minimize power consumption and interference between channels. The beam radiating and receiving means are arranged to radiate partially overlapping beams in space and to receive return beams. The FM signal generating means generates an FM signal. The transmitting unit includes a plurality of transmitting switching circuits each comprised of a plurality of amplifiers. Each amplifier corresponds to one of the beam radiating and receiving means, and is configured to intermittently amplify and distribute a portion of the FM signal generated by the FM signal generating means to its corresponding beam radiating and receiving means. The receiving unit includes a plurality of receiving switching circuits and a single mixer.