263 results about "Impulse radar" patented technology

A millimeter wave pulsed radar system includes a radar synthesizer having a voltage controlled oscillator/phase locked loop (VCO/PLL) circuit, direct digital synthesizer (DDS) circuit and quadrature modulator circuit that are operative to generate an intermediate frequency local oscillator signal (IF/LO signal). A radar transceiver is operative with the radar synthesizer for receiving the IF/LO signal. A transmitter section has a frequency multiplier that multiplies the IF/LO signal up to a millimeter wave (MMW) radar signal and a receiver section and includes a direct conversion mixer that receives a MMW radar signal and the IF/LO signal to produce I/Q baseband signals that are later digitized and processed.

An antenna array comprising a ground plane and a plurality of elements mounted thereon, said elements being capable of emitting and receiving ultra wideband emissions. Elements are arrayed on the ground plane in two parallel rows, a transmitting row, and a receiving row, such that a given element in the receiving row is aligned in at least one direction with a corresponding element in the transmitting row. Additionally, the elements are configured on the ground plane to elicit a symmetrical product response in the azimuthal plane, and to produce horizontally polarized signals. An alternative embodiment places the elements with unique inter-element spacing within the rows. An embodiment comprises a fence structure between rows. A method for use comprises the step of transmitting a signal via an element in the transmitting row and receiving said signal through an element in the receiving row, not aligned with the transmitting element.

A radar apparatus comprises: a transmitter unit having a high-frequency oscillating unit whose oscillation frequency is variable, and a pulse amplitude modulating unit for amplitude-modulating a pulse of a transmission high-frequency signal output from the high-frequency oscillating unit with a first control pulse signal; a receiver unit having a gating unit for controlling ON/OFF of an input of a received high-frequency signal with a second control pulse signal; and a controlling and signal processing unit for controlling the transmitter unit and the receiver unit, and for switching a first operation mode for making the apparatus function as an FM-CW radar, and a second operation mode for making the apparatus function as a pulse radar.

A system and method are provided to reduce the effect of an interfering signal in a radar return signal for a frequency modulated continuous wave (FMCW) radar. Once the interfering signal is detected, an extent of the interfering signal is determined and the data that was corrupted by the interfering signal is not included in the processing of the radar return signal. This allows the radar to detect a target in the presence of the interfering signal. The system and method can benefit any FMCW radar that is within the range of an interfering radar source (e.g. another FMCW radar, a police radar gun, a pulse radar, etc.) operating in the same frequency band as the FMCW radar. An alternative arrangement provides a system and method for determining the frequency of the interfering signal and then avoiding transmitting power in that portion of the frequency spectrum where the interfering signal is present.

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 when required. 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. First and second voltage multipliers each have a local oscillator input for receiving the modulator signal in the receive position, and each have an input signal port, and an output port. A receiver channel receives a reflected transmitted signal from an object and applies the received signal to the receive signal input ports of the voltage multipliers. An autocorrelator coupled to the output ports of the voltage multipliers correlates the received signal to produce an output signal indicating the detection and position of the object.

A pulse radar is provided with a filter for eliminating a transmission waveform interfered with an answering signal from a received waveform, and a harmonic detector or a phase delay detector for detecting arrival and end of the answering signal reflected on a target.

A security system senses intrusions into a shipping container through the opening of doors, cutting an opening, or removing the doors from their hinges. Intrusion information is transmitted to a remote receiver without interrogation, thereby reducing power consumption. Sensing is accomplished by employing a range-gated micro-impulse radar (“RGR”) that generates microwave pulses that bounce around the interior of the container. The RGR includes a range gate that enables measuring reflected signals during the time gate period that is set for the time it takes a pulse to propagate a maximum distance within the container and reflect back. A direct current signal level is produced that represents the average reflected signal level within the container, and a Doppler shift measurement is made that represents motion inside the container. The signals are conveyed to the transmitter for conveyance to the remote receiver.

An apparatus and method for detecting objects buried beneath the surface of a medium. A plurality of wide-bandwidth antennas, coupled to form an array, is drawn across the surface. Each antenna radiates a plurality of pulses of electromagnetic radiation at periodic intervals of time and receives the plurality of pulses after their interaction with the medium. The return pulses are sampled by a sampling circuit disposed at the feed of each antenna so as to create an equivalent-time pulse signal, and a self-signature of each antenna is subtracted from the equivalent-time pulse signal so as to detect features of objects buried beneath the surface of the medium. A pulse former is provided at the feedpoint of the receiving antenna.

A gated peak detector produces phase-independent, magnitude-only samples of an RF signal. Gate duration can span as few as two RF cycles or thousands of RF cycles. Response is linearly proportional to RF amplitude while being independent of RF phase and frequency. A quadrature implementation is disclosed. The RF magnitude sampler can finely resolve interferometric patterns produced by narrowband holographic pulse radar.

A method for operating a radar system using at least two antennas provides an increased angular resolution for determining the angular position, radial velocity, and/or distance to a reflection object. A plurality of successive measuring phases are carried out in at least one measuring process. In each measuring phase, operation is repeatedly switched between a transmitting operation in which a transmitted signal pulse is emitted, and a receiving operation in which reflection signals are detected as received signals in the pulse pause interval between successive transmitted pulses. In at least one measuring phase, two different neighboring antennas of the radar system are used respectively as the transmitting antenna for emitting the transmitted signal and as the receiving antenna for detecting the reflected signal. In this manner, the respective receiving antenna monitors only the angular range of overlap between the emitted beam of the transmitting antenna and the field of view of the receiving antenna. The information provided by the detected signals in this overlapping angular range achieves an increased angular resolution. The method is particularly suitable for operating a separation distance warning system for a motor vehicle.

The invention discloses a phased array monopulse radar system based on the time modulation antenna array technology. The basic scheme of the invention comprises an antenna array comprising a plurality of array antenna units, a high-speed radio frequency switch controlled by a complex programmable logic device, a radar receiver, and the like; based on the basic scheme, a power-divider, a mixer, and an intermediate frequency amplifier are reasonably added in the radar receiver, and an amplitude detector, a phase detector and the like are reasonably added at a data processing terminal to form various improved schemes of the invention. With the invention, sum beams and difference beams are easily generated simultaneously, therefore, the transmission of simultaneous frequency diversity signals can be easily realized, and difference beams of higher performance (beam gain, null depth, slope of zero, and the like) can be easily obtained. The invention can be widely used in the phased array monopulse radar systems having application background adding radar reconnaissance difficulty of enemy, or used in radar systems of other target angle measurement and precision angle tracking.

A method for imaging test objects by millimeter waves, especially for checking individuals for suspicious objects is provided, whereby the test object is gradually irradiated with millimeter waves along its circumference and the scattered waves are received and evaluated in order to display an image of the test object. A viewing direction of the transmitting area and a direction of reception of the receiving area extend at an angle of 15° to 70°, preferably 20° to 35° to the longitudinal axis of the test object. For evaluation of the scattered waves in the direction of the longitudinal axis of the test object, a pulse radar or FMCW radar technology is used, and for evaluation at an angle to the longitudinal axis, SAR technology is used.

Pulsed radar detects the presence and range of very short-range objects via small perturbations in phase and/or amplitude of relatively long duration coherently related transmit pulses. In one embodiment, echoes forming a received signal waveform from a sampling baseband radar receiver are processed at audio frequency to look for perturbations of the phase of the time-stretched received radar signal while the radar is still transmitting a long-duration pulse. In a second embodiment, the time-stretched received signal is processed to look for perturbations in the amplitude of the received radar signal. Small amplitude perturbations due to constructive and destructive interference of the transmitted and reflected signals occur in the receiver when objects are very close to the radar if the receiver is not heavily saturated. These same techniques can also be used to achieve highly accurate ranging of long-distance objects and detection of overlapping echoes from multiple objects.

Pulsed or mutual interference in a pulse radar system is ameliorated by a process that includes a pulse-Doppler filter, some frequency bins of which correlate with clutter. Pulsed interference is identified, and the corresponding column vectors of a pulse-Doppler-filter-equivalent matrix are identified. The row values of the corresponding interference-affected column vectors that correlate with clutter are nulled. The vectors are orthogonalized, and then converted to measurement and correction signal vectors for application to the pulse-Doppler received signals. Vector dot products of the measurement signal vectors with the received signals are calculated, to produce pulsed interference measurements that are nominally free of clutter. The pulsed interference measurements are combined with the correction signals which are then subtracted from the received signals to produce signals that are nominally free of pulsed interference. In one embodiment, the pulsed interference-free received signals are applied to a pulse-Doppler filter to suppress the clutter signals.

The present invention provides a pulse radar device comprising a radar module that includes a transmission unit which transmits a transmitted pulse wave obtained by modulating a transmitted pulse and a reception unit receives a reflected wave of said transmitted pulse wave reflected by a measurement target and demodulates said reflected wave to thereby generate a received pulse, a switching power source which generates drive power for said radar module by switching DC power by turning a switching pulse on and off, and a control unit which controls operations of said radar module so that a process from transmission of said transmitted pulse wave to generation of said received pulse may be completed in a period during which said switching pulse is in an on-state except a predetermined period measured from rising edge of said switching pulse or a period during which said switching pulse is in an off-state except the predetermined period measured from trailing of said switching pulse.

An improvement in monopulse radar achieves nulling of a single mainlobe jammer and multiple sidelobe jammers while maintaining the angle measurement accuracy of the monopulse ratio by cascading a multiple sidelobe canceller and a mainlobe canceller, and imposing a mainlobe maintenance technique during the sidelobe jammer cancellation process so that the results of the sidelobe jammer cancellation process do not distort the subsequent mainlobe cancellation process. In this manner, the sidelobe jammers and the mainlobe jammer are cancelled sequentially in separate processes.

The invention relates to the technical field of radar jamming, and discloses an adaptive cross-polarization active jamming method and device. The device comprises a receiving antenna, a transmitting antenna, a receiving module and a jamming control module, wherein the receiving antenna which is used for receiving horizontal or vertical polarized signals is connected with the jamming control module through the receiving module; the output end of the jamming control module is connected with the transmitting antenna which is used for transmitting horizontal or vertical polarized signals; and a receiving-transmitting isolation device is arranged between the receiving antenna and the transmitting antenna. According to the jamming device, the jamming effect generated when a plurality of jammers work at the same time can be achieved by one jammer without measuring pulse description words (PDW) of a radar signal or the polarized state of the radar signal and without adopting a plurality of jammers to run at the same time, and cross-polarization jamming can be generated adaptively, so that a stable and effective jamming effect can be achieved, the angle measurement accuracy of a monopulse radar can be greatly reduced, and the cost for development and maintenance can be greatly reduced.

An improved system is provided for aiming a shotgun-based or other countermeasure system so as to be able to countermeasure incoming rockets or projectiles. In one embodiment a shotgun aimed and controlled by the subject system projects a pattern of pellets to intercept a rocket-propelled grenade or incoming projectile. The fire control system uses a CW two-tone monopulse radar to derive range and angle of arrival within 150 milliseconds, with range and angle of arrival measurements having approximately twice the accuracy of prior CW two-tone monopulse radars. The improvement derives from using all of the information in the returned radar beams and is the result of the recognition that one can use the Sum and Difference signals to assemble a two-by-two Rank One matrix that permits using singular value decomposition techniques to generate range and angle of arrival matrices in which all available information is used and in which noise is eliminated.

Embodiments of the invention are concerned with improvements to Doppler radar systems, and are suitable for use with frequency scanning radar systems.

In one arrangement the improvements are embodied in a frequency scanning radar controller for use in controlling a frequency generator; the frequency generator is arranged to generate a plurality of sets of signals, each set of signals having a different characteristic frequency and comprising a plurality of signals transmitted at a selected rate, and the radar controller is arranged to select the rate in dependence on the characteristic frequency.

The invention can be embodied in a pulsed radar, for which each set of signals comprises a set of pulsed signals and each pulsed signal is repeated at a selected repetition rate. The radar controller is then arranged to modify the repetition rate in dependence on the characteristic frequency of the pulsed signal. The invention can alternatively be embodied in a frequency modulated radar system, for which each set of signals comprises a sequence of modulation patterns. The radar controller is then arranged to modify a given modulation pattern in dependence on the characteristic frequency of the signal being modulated.

The invention discloses a velocity ambiguity resolving method based on a coherent frequency agile radar. Through the method, the problem that target detection is not accurate due to distance-velocityambiguity in pulse radar system signal processing is solved. According to the implementation method, a radar pulse echo signal is received; a baseband pulse echo signal sampling matrix is obtained; pulse compression is performed; a radar Doppler vector group is constructed; Doppler offset frequency is determined, and the velocity of a motion target is calculated; velocity ambiguity resolving is performed on the radar pulse echo signal; and target detection is performed through sparse recovery. According to the method, the accurate velocity of the motion target is calculated through the Dopplervector group, velocity phase compensation is performed on the radar pulse echo signal to realize velocity ambiguity resolving, and the target is detected through sparse recovery. The method is low ininterception and resistant to interference, the velocity of the motion target can be accurately calculated, complexity is low, and the problem of distance-velocity ambiguity in pulse radar system signal processing can be solved. The method is applied to the field of radar target detection.