Abstract: A radar apparatus includes a PN code generator for generating a PN code, a variable delay device for delaying the PN code, an oscillator for generating a high-frequency signal, a transmission frequency multiplier for multiplying a frequency of a transmission differential signal obtained by being divided from the high-frequency signal by 3, a reception frequency multiplier for multiplying a frequency of a reception differential signal obtained by being divided from the high-frequency by 3, a transmitter for generating a radar wave by using the differential signal obtained through the multiplication by the transmission frequency multiplier and the PN code generated by the PN code generator, and a receiver for generating an in-phase signal and a quadrature signal from a reflected wave by using the differential signal obtained through the multiplication by the reception frequency multiplier and the PN code delayed by the delay device.

Abstract: An RF front-end includes an input configured to receive an oscillator signal, and an antenna port configured to transmit a transmission signal and receive a reception signal from an antenna. The RF front-end further includes a mixer having an RF-input configured to receive the reception signal, an oscillator input configured to receive a modified oscillator signal, and an output. The mixer is configured to mix the received signal into an intermediate frequency band or a base band using the oscillator signal. Also included is a directional coupler connected to the antenna port, the input for the oscillator signal, and the mixer. The coupler is configured to couple the oscillator signal as a transmission signal to the antenna via the antenna port, and couple the reception signal from the antenna to the RF-input of the mixer. Also included is a first phase shifter or a second phase shifter.

Abstract: In accordance with one embodiment of the present invention, a millimeter or sub-millimeter wave portal system is provided. Generally, the portal system comprises an electrooptic source and one or more millimeter or sub-millimeter wave detectors. The electrooptic source comprises an optical signal generator, optical switching and encoding circuitry, and one or more optical/electrical converters. Additional embodiments are disclosed and claimed.

Abstract: The subject invention pertains to a frequency modulation continuous wave (FMCW) radar system. Embodiments relate to methods of improving the performance of such a FMCW system and improving the value of the information provided by such a FMCW system. In an embodiment of the subject invention, the IF level can be monitored while sweeping the frequency of the system through at least a portion of the frequency range of the system. In a specific embodiment, the system is then set to the frequency that produces the minimum IF level, which is the frequency that produces the minimum AM signal level. Embodiments of the invention pertain to techniques for expediting the adaptation of the comb filter to the signal when the system is turned on. In an embodiment, in order to reduce the number of detection calculations a processor performs every frame, a method of quickly determining the largest peaks in the RDM is implemented.

Abstract: An oscillator and a radar apparatus that includes a resonator electro-magnetically connected to a micro strip line and a rotor connected to the resonator by capacitance. The bottom surface of the rotor has a changing height in the circumferential direction of the rotor. As the rotor is rotated, an actual oscillation frequency is recognized from the rotating angle of the rotor when an output of a detector has a peak. A modulation voltage supplied to a VCO is corrected in accordance with the result.

Abstract: In an optical modulation device (10) having an electrical/optical interaction region (11), an electrical signal line (3) is connected to an electrical signal input terminal (2a), another electrical signal line (4a) is connected to an electrical signal output terminal (2b), and a reflection control circuit (5) is connected to the other electrical signal line (4a). This reflection control circuit (5) is an impedance element which positively reflects an output electrical signal from the interaction region (11) of the optical modulation device (10). This makes it possible to raise the upper-limiting frequency at which the E/O (Electrical-to-Optical) response characteristic can be improved, and improve the flatness of the frequency characteristic of the E/O response without deteriorating the absolute value of the E/O response.

Abstract: A radar system having a transmit signal path and a receive signal path and an event generator which is responsive to command signals provided by a digital signal processor (DSP) is described. The DSP generates command signals and provides the command signals to the event generator. In response to the command signals, the event generator generates event signals in the radar system. The event signals include but are not limited to ramp control signals provided to a controllable signal source which provide RF signals to the transmit path of the radar.

Abstract: A speech recognition unit (2) performs speech recognition on a speech of an utterer input by a speech input unit (1), specifies possible words which are represented by the speech, and the scores thereof, and a natural language analyzer (3) specifies parts of speech of the words and supplies word data representing the words to an agent processing unit (7). The agent processing unit (7) stores process item data which defines a data acquisition process to acquire word data or the like, a discrimination process, and an input/output process, and wires or data defining transition from one process to another and giving a weighting factor to the transition, and executes a flow represented generally by the process item data and the wires to thereby control devices belonging to an input/output target device group (6) in such a way as to adequately grasp a demand of the utterer and meet the demand.

Abstract: Provided is a radar system capable of appropriate detection even if a difference of a free space path loss due to a frequency in a range of occupied bandwidth is large. Based on a modulation signal, an amplitude control circuit amplifies amplitude of a modulated signal more significantly as the frequency in the occupied bandwidth is increased. Thus a transmission signal is generated such that the power is increased as the frequency is increased. The transmission signal is transmitted as a radio wave from the transmission antenna. As a result, a received signal obtained on the receiver side has a small level difference (i.e., having a frequency spectrum with a flat shape) between the high frequency signal components and low frequency signal components. Accurate detection is easily achieved based on the received signal.

Abstract: A radar is provided with transmitting means for transmitting a signal and with receiving means for receiving a reflection of the transmitted signal. The inventive radar is characterized in that the transmitting means is provided with a transmitting oscillator and the receiving means is provided with an evaluation oscillator. The transmitting oscillator is excited by the evaluation oscillator and/or the evaluation oscillator is excited by the transmitting oscillator in a quasi-phase coherent manner.

Abstract: Techniques for analog processing of high time-bandwidth-product (TBP) signals use a material with an inhomogeneously broadened absorption spectrum including multiple homogeneously broadened absorption lines. A first set of signals on optical carriers interact in the material during a time on the order of a phase coherence time of the homogeneously broadened absorption lines to record an analog interaction absorption spectrum. Within a time on the order of a population recovery time for a population of optical absorbers it the material, the interaction absorption spectrum in the material is read to produce a digital readout signal. The readout signal represents a temporal map of the interaction absorption spectrum, and includes frequency components that relate to a processing result of processing the first set of signals. The techniques allow processing of RADAR signals for improved range resolution to a target, as well as speed of the target, among other uses.

Abstract: The present invention provides a radar altimeter system with a closed loop modulation for generating more accurate radar altimeter values. The system includes an antenna, a circulator, a receiver, and a transmitter. The circulator receives or sends a radar signal from/to the antenna. The receiver receives the received radar signal via the circulator. The transmitter generates a radar signal and includes a phase-locked loop circuit for generating the radar signal based on a pre-defined phase signal. The transmitter includes a direct digital synthesizer that generates the phase signal based on a pre-defined clock signal and a control signal. The system includes a digital signal processor and a tail strike warning processor that determine position of a tail of the aircraft relative to ground and present an alert if a warning condition exists based on the determined position of the tail of the aircraft and a predefined threshold.

Abstract: In an FM-CW radar system, a frequency modulating said modulating wave output from said modulating signal generator has a frequency variation skew with respect to a time axis (modulation skew), and the radar system includes a means for varying the modulation skew by controlling the modulation frequency amplitude or modulation period of the modulating signal. The radar system further includes a means for discriminating a signal component varying in response to the variation of the modulation skew, thereby discriminating a signal related to a target object from other signals. In the case of an FM-CW radar system that performs transmission and/or reception by time division ON-OFF control the radar system includes a means for discriminating a signal which, when the frequency used to perform the ON OFF control is varied, varies in response to the variation of the frequency, thereby discriminating a signal related to a target object from other signals.

Abstract: A modulation circuit for a traffic surveillance Doppler radar system is disclosed. In one embodiment, the modulation circuit is utilized in a vehicular traffic surveillance Doppler radar system that processes a reflected double-modulated FM signal to determine a target range based upon a phase angle signal differential associated with the target. The modulation circuit may include a digital-to-analog (D/A) converter/voltage regulator/oscillator arrangement or a D/A converter/varactor device/oscillator arrangement. The modulation circuit generates a double-modulated FM signal based upon a frequency versus voltage characteristic associated with the oscillator.

Abstract: In an FM-CW radar system, a frequency modulating wave output from said modulating signal generator has a frequency variation skew with respect to a time axis (modulation skew), and the radar system includes a means for varying the modulation skew by controlling the modulation frequency amplitude or modulation period of the modulating signal. The radar system further includes a means for discriminating a signal component varying in response to the variation of the modulation skew, thereby discriminating a signal related to a target object from other signals. In the case of an FM-CW radar system that performs transmission and/or reception by time division ON-OFF control, the radar system includes a means for discriminating a signal which, when the frequency used to perform the ON-OFF control is varied, varies in response to the variation of the frequency, thereby discriminating a signal related to a target object from other signals.

Abstract: Methods and apparatus are provided for radar systems using multiple pulses that are shorter than the expected range delay extent of the target to be imaged. In one implementation, a method for performing radar includes the steps of: transmitting a plurality of pulses, each pulse having a different center frequency and a time duration shorter than an expected range delay extent of a target, wherein a total bandwidth is defined by a bandwidth occupied by the plurality of pulses; receiving reflections of the plurality of pulses; and performing pulse compression on the received pulse reflections to generate a detection signal having a radar resolution approximately equivalent to the transmission and reception of a single pulse having the total bandwidth. In preferred form, the pulses comprise ultrawideband (UWB) pulses each occupying a sub-band of the overall system bandwidth.

Abstract: A stepped-frequency chirped waveform improves SAR groundmapping for the following reasons. Range resolution in SAR image is inversely proportional to the transmitted signal bandwidth in nominal SAR systems. Since there is a limit in the transmitted bandwidth that can be supported by the radar hardware, there is a limit in range resolution that can be achieved by processing SAR data in conventional manner. However, if the frequency band of the transmitted signal is skipped within a group of sub-pulses and received signal is properly combined, the composite signal has effectively increased bandwidth and hence improvement in range resolution can be achieved. The proposed new and practical approach can effectively extend the limit in range resolution beyond the level that is set by the radar hardware units when conventional method is used.

Abstract: The invention relates to a pulse-modulated source with adjustable parameters and to its use in an IFF or secondary radar emitting assembly. The architecture of currently used IFF emitting assemblies is such that there is a limit to the possible reduction in the space requirement of such equipment, and this limit is soon reached. Furthermore, the precision in terms of frequency remains coarse and the number of IFF emitting modes is very small. A programmable source of pulse trains on an intermediate frequency is disclosed.

Abstract: A method used to increase the ambiguity distance of FSK radars implements a waveform made up of patterns consisting of frequency plateaux whose frequencies are alternately shifted by plus or minus a value ?f?. With this waveform, the method associates processing operations to eliminate ambiguous echoes and image signals. This method has the advantage of not modifying the repetition period of the radar to which it is applied. The method according to the invention can be applied especially to radars in automobiles and especially to anti-collision radars.

Abstract: A down-converter for processing frequency signals, preferably received, particularly digital, television signals, comprising two, preferably identical mixer stages (10a, 10b) for down-converting the signal, a local oscillator (12) controlling the mixer stages by a 90° phase shift, a complex filter (14) which couples the output signals of the mixer stages (10a, 10b) by means of a complex filtering method in such a way that the signal components outside a predetermined useful band are substantially suppressed, an adjusting device (13) for adjusting the frequency of the local oscillator (12) and a subsequent low-pass filter.

Abstract: An object of the present invention is to facilitate positioning of a metal member for mounting a high-frequency diode and of a dielectric strip, thereby remarkably improving control of oscillation characteristics and workability in production.

Abstract: A radar transmitter includes a digital ramp generator circuit for generating a VCO control signal. The ramp generator includes a digital signal processor and a digital-to-analog converter. In one embodiment, the VCO output signal is up-converted to provide the transmit signal and in another embodiment, the VCO operates over the transmit frequency. Also described is a VCO comprising a DR and a phase shifter. A temperature compensation feature includes detecting the transmit frequency and comparing the DSP output generating the detected frequency to a DSP output stored in association with the detected frequency. Also described is a technique for compensating for non-linear VCO operation in which the DSP output words are adjusted to provide a waveform complementary in shape to the non-linear VCO characteristic. Susceptibility of the radar to interference is reduced by randomly varying at least one parameter of the ramp signal, such as offset interval or voltage range, in at least one ramp signal cycle.

Abstract: A doppler radar device having comparing means 142 for comparing the level of pulse signal to be transmitted, sampled through a burst gate, with a predetermined threshold value and search means 143 for changing a set position of the gate, wherein a timing of oscillating the pulse signal is monitored and tracked to fix “range 0” by shifting a timing for triggering transmission of the pulse signal in consideration of a deviation of the timing of oscillating the pulse signal and a jitter value.

Abstract: A doppler radar device having comparing means 142 for comparing the level of pulse signal to be transmitted, sampled through a burst gate, with a predetermined threshold value and search means 143 for changing a set position of the gate, wherein a timing of oscillating the pulse signal is monitored and tracked to fix “range 0” by shifting a timing for triggering transmission of the pulse signal in consideration of a deviation of the timing of oscillating the pulse signal and a jitter value.

Abstract: The invention relates to a device for emitting high-frequency signals, comprising a signal generation unit (6), a signalling line (12), an emission cable (16) and an antenna configured as a circular waveguide (10), said antenna being sealed in an end section by a rear wall (15). According to the invention, the signal generation unit (6) creates the high-frequency signals, the signalling line (12) conducts the high-frequency signals along the emission cable (16) and said emission cable (16) projects into the interior of the antenna (10) and is positioned approximately parallel to the rear wall (15). The invention aims to provide a device for emitting electromagnetic waves, which is characterized by optimized emission characteristics. To achieve this, the distance (Z) between the emission cable (16) and the rear wall (15) of the antenna (10) is approximately &lgr;/6, whereby &lgr; is the wavelength of the high-frequency signals borne by the antenna (10).

Abstract: A compact millimeter wave radar transceiver at low cost is provided wherein a direct current voltage applying circuit is coupled to a high frequency line to apply a fast pulse wave without losing a sharp input pulse pattern. A voltage is applied to a negative resistance diode, such as a Gunn diode, which is variably controlled to vary the diode oscillating frequency signal, which signal is outputted as a transmitting wave. The transmitted wave is reflected by a target and received by the negative resistance diode. The received wave is detected as a heterodyne detection utilizing a non-linear property of the negative resistance diode. A frequency difference between the transmitted wave and the received reflected wave is outputted via a low-pass filter and processed to detect the target.

Abstract: In an FM-CW radar system, a frequency modulating wave output from said modulating signal generator has a frequency variation skew with respect to a time axis (modulation skew), and the radar system includes a means for varying the modulation skew by controlling the modulation frequency amplitude or modulation period of the modulating signal. The radar system further includes a means for discriminating a signal component varying in response to the variation of the modulation skew, thereby discriminating a signal related to a target object from other signals. In the case of an FM-CW radar system that performs transmission and/or reception by time division ON-OFF control, the radar system includes a means for discriminating a signal which, when the frequency used to perform the ON-OFF control is varied, varies in response to the variation of the frequency, thereby discriminating a signal related to a target object from other signals.

Abstract: A mixer used in a millimeter-wave band and a microwave band capable of achieving loss reduction, a radar module, and a communication apparatus incorporating the mixer and having high efficiency. The mixer includes two electrodes formed on one main surface of a dielectric substrate and another electrode formed on another main surface thereof such that non-electrode portions on both main surfaces are opposed to each other via the dielectric substrate. Additionally, a diode is connected bridging a slit between the two electrodes on one main surface to constitute a circuit board. The circuit board and a dielectric strip are arranged between upper and lower conductive plates.

Abstract: In a method and device for the encoding/decoding of the power distribution at the outputs of a system, the distribution encoder comprises an element that receives a signal s(t) and a piece of distribution information i(t), and that superposes said piece of distribution information i(t) received on said signal s(t) received. The piece of information i(t) is used for the subsequent distribution of the total power Ps of said signal s(t) at said output or outputs {S&Ggr;} of a system &Ggr;. The distribution decoder comprises one or more inputs on which there is received an encoded signal c(t) or an encoded signal divided into several signal (cj(t))j&egr;[1,2N] comprising the useful signal s(t) and the piece of distribution information i(t). It also comprises one or more outputs connected to the outputs {S&Ggr;} of said system &Ggr; to which said signal s(t) is transmitted by distributing the total power received Ps according to said piece of distribution information i(t).

Abstract: A neural network radar processor (10) comprises a multilayer perceptron neural network (100.1) comprising an input layer (102), a second layer (122), and at least a third layer (124), wherein each layer has a plurality of nodes (108), and respective subsets of nodes (108) of the second (122) and third (124) layers are interconnected so as to form mutually exclusive subnetworks (120). In-phase and quadrature phase time series from a sampled down-converted FMCW radar signal (19) are applied to the input layer, and the neural network (100) is trained so that the nodes of the output layer (106) are responsive to targets in corresponding range cells, and different subnetworks (120) are responsive to respectively different non-overlapping sets of target ranges. The neural network is trained with signals that are germane to an FMCW radar, including a wide range of target scenarios as well as leakage signals, DC bias signals, and background clutter signals.

Abstract: An FMCW sensor in which a transmission signal is generated from a high frequency of a fixed frequency oscillator and a modulated, low frequency of a second oscillator. The modulated frequency is processed in a delay line with a surface wave component to form a reference signal. A transmission mixer with a hybrid coupler having a 90° phase difference and terminated by diodes is employed in a transmission/reception means. A measured signal from the transmission mixer together with the reference signal is interpreted in an evaluation means.

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

Abstract: 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: FMCW doppler radar, in which a reference signal is generated from the transmit signal via a delay line and a mixer. A measuring signal which is received and mixed with the transmit signal is detected and digitized at the times of the zero crossings of the reference signal. In this way, the measuring signal can be evaluated at time intervals of equal phase of the reference signal. A downstream algorithm enables the generation of a strictly linearly frequency-modulated transmit signal. With this mechanism, phase errors of conventional radar systems are eliminated.

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: The present invention relates to methods and devices for such control and supervision of an oscillator signal from a controllable oscillator that is done mainly to control the frequency variation of the oscillator signal. According to the invention, the controllable oscillator is controlled by a controlling voltage, which in turn is modified by a correction signal, generated in a control loop. A time discrete representation of a secondary phase is generated in the control loop, the secondary phase corresponding to a frequency being the difference between the frequency of the oscillator signal and a constant frequency. A time discrete approximation signal is generated in dependence of the time discrete representation of the secondary phase. A time discrete error signal is generated in dependence of the time discrete approximation signal, the time discrete error signal indicating the difference between the actual frequency slope of the oscillator signal and a desired frequency slope.

Abstract: A system and method for generating a linear frequency sweep while also improving the phase noise characteristics of a microwave or millimeter wave signal source. The invention uses two phase lock loops. The first phase lock loop uses a linear frequency source to linearize a relatively low frequency VCO (typically around 100 MHz). The first phase lock loop has a bandwidth that is only wide enough to pass the radar modulation waveform with minimal distortion. The first phase lock loop includes a phase detector, narrow band loop filter, low noise HF VCO and a divide by M counter. The second phase lock loop is used to lock a millimeter wave VCO to the lower frequency of the low frequency VCO in the first loop. The low phase noise characteristics of this low frequency VCO are effectively impressed upon a microwave or millimeter wave, low noise high frequency VCO.

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 radar exciter including a direct digital synthesis (DDS) wideband waveform generator which performs the frequency synthesis function heretofore performed by a direct analog synthesizer. This is achieved by deriving the DDS frequencies, the exciter RF frequencies, the radar synchronizer clock frequency and receiver analog/digital (A/D) converter clock frequency from a common signal source generating a master frequency. The present invention eliminates the direct analog synthesizer and relies solely on the digital generation of waveforms by a DDS wideband waveform generator which performs a discrete sampling process so as to provide coherent frequency and timing relationships.

Abstract: A space-fed phased array radar utilizes a network of improved Mach-Zehnder nterferometers to provide a space-fed, optically controlled millimeter wave/microwave antenna array that is capable of either one-way or two-way transmission. In the two-way communication relay mode, both ends of the relay link can remotely switch from a transmit to a receive mode and vice versa while, at the same time, steering the outgoing radiation beams on both sides of the relay so as to achieve maximum signal-to-noise ratio between the two terminals (i.e. signal stations) of the communication link. The improvements include receiving antenna with beam-scanning capability to receive millimeter or microwave signals from a first signal station, amplifiers to amplify outgoing signals prior to being radiated outwardly by transmitting antenna and a means to render the same antenna array capable of being used in a two-way transmit and receive mode.

Abstract: A method and apparatus for frequency modulating a continuous wave signal is shown to comprise a voltage-controlled oscillator (VCO) having a first and a second control loop to maintain the carrier frequency of such VCO at a frequency determined by a crystal-controlled oscillator and to maintain the peak deviation of the FM modulation on such carrier frequency at a value equal to the deviation of the first Bessel null from the carrier frequency.

Abstract: A radar data processing method of switching a continuous wave consisting of up phase and down phase into a transmission signal and a local signal in an interrupted manner and using a beat signal between the local signal and a reception signal. The method comprises the steps of setting a range of beat frequencies in up phase used for making a search for a combination and a range of beat frequencies in down phase used for making a search for a combination from beat frequencies corresponding to a distance range to be measured and a predetermined measurement speed range, and making a search for a combination for the same target for the beat frequencies in the up phase and the beat frequencies in the down phase only in the range.

Abstract: A system to perform real time temporal correlation on pulsed and periodic signals. Application is to systems which perform PRI analysis of signals and provide signal gain as part of the correlation process. Correlation is performed in two stages, the first conditioning the signals for correlation using the zero mean, PW matched filter and the second performing temporal correlation using the difference minimization PRI correlator. The primary purpose of the filter is to minimize any DC signals before they reach the correlator. If DC signals reach the correlator, they correlate up at every PRI setting and on every temporal point, resulting in false detections and can block actual signals from detection. The filter also provides some gain for signals with pulse widths greater than one temporal cell. After conditioning with the filter, the data is correlated using a difference minimization correlator.

Abstract: A combined duplexer/mixer (2) for use with FMCW radar systems has a waveguide section (12,13) containing a fin-line structure (17,18) for responding to the linearly polarized radar return signal while permitting passage of the orthogonally polarized transmitted signal (T). A portion of the transmitted signal is extracted by a patch antenna (22), this extracted signal forming a local oscillator signal for mixing with the return.

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: 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: Systems and methods for optically controlled phase shifters are described.

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.