104 results about "Pulse-Doppler radar" patented technology

A system and method for implementing a maximum likelihood estimator for making a joint estimation of range, range rate, and acceleration of a target utilizing a pulse doppler radar. The MLE of target motion parameters are determined by keystone processing a baseband signal, and generating a first estimate of the motion parameters based on the processed signal. The first estimate is utilized to set up sampling intervals for the performance of a coarse search. Then a fine search is performed using Newton's method to determine the MLE.

A radar processing system is disclosed with an improved cluster target resolution capability. The invention provides a system and method for processing radar returns and generating first and second contiguous range/doppler cells. Within the cells, first and second dichotomous angle measurements corresponding to radar returns in the first and second contiguous range/doppler cells are derived. An adaptive threshold is then applied to the angle measurements to determine whether the first and second measurements correspond to first and second targets in the first and second range/doppler cells respectively.

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

The invention discloses a distance-speed synchronous pull-off deception jamming recognition algorithm based on gradient projection, and belongs to the field of radar anti-jamming. According to a PD radar, the radar is generally jammed through distance-speed synchronous pull-off jamming, the deception jamming can conduct pull-off jamming on distance information and speed information at the same time, and thus the difficulty for accurately choosing and tracking a target of the PD radar is increased. The method comprises the following steps that (1) signals received by the radar are sampled, and a complete atom library is established according to the time-variant characteristic of a distance-speed synchronous jamming echo; (2) when the AGC voltages and the target number of a receiver are suddenly changed, it is judged that the target is jammed; (3) the Doppler frequency of the target is obtained through a gradient projection method, then the target speed is figured out, and accordingly anti-jamming is performed according to the target speed. The distance-speed synchronous pull-off deception jamming recognition algorithm based on gradient projection is high in jamming recognition capability, easy in engineering realization, high in engineering application value and large in popularization prospect.

A method of removing returns from rain in Doppler radar systems (and corresponding apparatus and computer software) comprising receiving a Doppler radar return signal, transforming the signal into a range versus frequency map, for a plurality of range cells, performing a fit over frequency, for the plurality of range cells, calculating a total energy, for the plurality of range cells, comparing the calculated total energy to a threshold value, and replacing the return signal for a range cell with another signal if for the plurality of range cells the comparing step is positive.

The invention discloses an HT-STC-TBD (Hough Transform and Successive Target Cancellation Based Track-Before-Detect) detection method for multiple weak targets under a radar-ranging fuzzy condition and belongs to the field of radar data processing. The HT-STC-TBD detection method comprises the following steps: (1) sending a measured target value which is detected by a high/middle pulse repetitionfrequency radar (such as an airborne pulse Doppler radar) into a data processing computer and then acquiring all the possible states of a target in the data processing computer; (2) performing Hough transformation on the possible states, thereby acquiring an energy accumulation column diagram; (3) searching for a peak value of the energy accumulation column diagram and performing Hough inverse transformation according to a peak value coordinate so as to confirm a valid detecting data point; (4) eliminating a false track, modifying a state of the target and realizing once target tracking; (5) eliminating the influence of the last detection and secondarily detecting the target; and (6) repeating the steps (3)-(5) till all the targets are detected, thereby realizing the tracking and detection of multiple weak targets.

The invention belongs to the technical field of target detecting in radar signal processing and relates to weak target detecting of an impulse Doppler radar under strong clutters. The weak target detecting of the impulse Doppler radar under the strong clutters is characterized in that a clutter image of a full-distance Doppler unit is set up, a constant false alarm threshold is formed by utilizing the distance unit constant false alarm algorithm, clutter strength classes are divided based on strength of echo waves around a to-be-detected unit and strength of noise at the base of the radar, detection threshold coefficients are automatically amended based on clutter classes. A zone where the clutters are stronger has a larger detection threshold coefficient. The weak target detecting of an impulse Doppler radar under strong clutters solves the problem that under strong clutters, false alarm of the radar is enhanced so that time is severely wasted and performances are reduced of a radar system and can be applied to the field of military and civil Doppler radars which perform weak target detecting under strong clutters.

The present invention provides a pulse Doppler radar polarization anti-jamming method under a complicated interference environment. By utilizing the method of the present invention, the inhibition capability aiming at various interference, such as chaffs, active suppression, cheat, etc., can be improved substantially, and the targets can be detected effectively. The method is realized by the following technical scheme of inputting a radar dual polarization echo signal, determining whether the active suppression-type interference exists, when the suppression-type interference exists, carrying out the polarization cancellation; then calculating the target signal walking time between the front and back pulses, and carrying out the range walking correction on a pulse sequence; and then carrying out the phase-coherent accumulation on a dual polarization channel, shifting the zero to a frequency spectrum center in a frequency shift manner, identifying the channel number of a target in a Doppler-range two-dimensional matrix, setting a two dimensional tracking gate of the target, and carrying out the two dimensional constant false alarm detection in the tracking gate; finally, carrying out the target polarization ratio detection determination, and outputting a signal passing the detection determination as a target signal after the interference inhibition, thereby improving the correct detection probability of the target.

Radar systems use time delay measurements between a transmitted signal and its echo to calculate range to a target. Ranges that change with time cause a Doppler offset in phase and frequency of the echo. Consequently, the closing velocity between target and radar can be measured by measuring the Doppler offset of the echo. The closing velocity is also known as radial velocity, or line-of-sight velocity. Doppler frequency is measured in a pulse-Doppler radar as a linear phase shift over a set of radar pulses during some Coherent Processing Interval (CPI). An Interferometric Moving Target Indicator (MTI) radar can be used to measure the tangential velocity component of a moving target. Multiple baselines, along with the conventional radial velocity measurement, allow estimating the true 3-D velocity of a target.

The invention discloses a signal processor of a laser Doppler radar based on an FPGA (field programmable gate array), and relates to the field of radar signal processing. The signal processor comprises an ADC (analog to digital converter) sampling unit, a storage unit and an FPGA processing unit, wherein the FPGA processing unit comprises an ADC configuration module, a storage interface module, a sampled data receiving module, a data input module, an intermediate frequency wave trap module, a diploid down sampling module, an FFT (fast Fourier transform) module, a pulse accumulating module, a peak extracting and Doppler frequency output module and a control module. After electrification, the FPGA configures an ADC and waits an external trigger signal; after the signal is effective, the FPGA begins receiving data sampled by the ADC; and the sampled data are all stored in the storage unit for caching through the FPGA, and then are read in the FPGA from the storage unit to be subjected to processing. By using the signal processor, the characteristics of the FPGA are adequately utilized; the processing speed is quick; the structure is simple; the problems of intermediate frequency interference, large data size and the like when the laser Doppler radar is used for speed measurement are solved; and the cost and the complexity of the laser Doppler radar are controlled beneficially.

This invention is related to an automated traffic surveillance system to monitor traffic comprising of a plural number of Doppler radars, circuitry for processing radar signals, and data recording and displaying devices. Although the system is mainly designed for roadside traffic surveillance, it can be used in different applications, such as mounted on a host vehicle. The system will provide continuous surveillance of all incoming and leaving traffic.

The invention discloses an optimization method for detecting weak and small sea surface targets by combining multi-frame echoes and phase-coherent accumulation. The optimization method comprises the steps that a pulse Doppler radar is utilized to mechanically scan movable sea surface targets within a detection range so as to obtain the echoes of the pulse Doppler radar, pulse compression processing is conducted on the echoes of the pulse Doppler radar to obtain Doppler radar echo data undergoing pulse compression processing, it is determined that the starting pulse of Kth window sliding is the Kth pulse, and Tth-frame pulse compressed echo data undergoing Kth window sliding interception is obtained, further pulse compressed echo data undergoing Kth window sliding interception after movable target detection processing and the Hth column of elements are sequentially calculated, further a complete N * (N''-L + 1) dimensional data matrix is obtained, two-dimensional constant false alarm detection is conducted on the complete N * (N''-L + 1) dimensional data matrix to obtain the N * (N''-L + 1) dimensional data matrix undergoing the two-dimensional constant false alarm detection, and if the element values contained by the N * (N''-L + 1) dimensional data matrix undergoing the two-dimensional constant false alarm detection are greater than 0, the echoes of the pulse Doppler radar contain weak and small moving sea surface targets.

The invention discloses a small celestial body soft landing autonomous navigation method based on optical and Doppler radars, and belongs to the field of deep space detection. The method comprises the following steps: building a dynamic model for a small celestial body soft landing detector, building a standard gravitational field model for a small celestial body, and carrying out the linearization of the dynamic model; building an autonomous navigation measurement model, introducing Doppler radar range finding and speed measurement information on the basis of an autonomous optical navigation method, transmitting a radar wave beam through a Doppler radar, measuring the relative distance between the radar wave beam and the surface of the small celestial body and the relative speed information, and obtaining the real-time position and speed information of the detector; and solving the real-time navigation state information based on a nonlinear system filtering algorithm according to the landing dynamic model of the small celestial body and the measurement model. The method can improve the estimation precision and filtering convergence speed, achieves the quick precise estimation of the state of the detector, and provides support for the precise soft landing task navigation of the small celestial body.

The invention provides a micro moving false target generation method aiming at a pulse Doppler radar. The technical scheme comprises two steps of the first step, according to a scattering center model of a false target and a micro moving mode, calculating a false target modulation parameter in a DSP; and the second step, using the modulation parameter to carry out in-pulse modulation on an enemy PD radar signal intercepted by a jammer so as to generate a false target echo signal in FPGA. In an existing method, a micro moving characteristic is not considered during false target generation so that identification is easy. By using the method in the invention, the above problem is effectively solved.

The invention provides a polarization anti-jamming method for a pulse Doppler radar, in order to suppress the oppressive towed jamming. Signals are simultaneously received by setting primary and secondary antennas whose polarization modes are orthogonal to each other, polarization cancellation weight coefficients of the three channel signals of the sum, azimuth difference and pitch difference of the primary antenna are determined by using the polarization characteristic differences of both, when the jamming energy is strong, the polarization cancellation weight coefficients can be adaptively estimated without knowing a jamming polarization vector and actual receiving gains of the primary antenna, then the pulse Doppler radar can obtain non-jamming signals after the polarization cancellation, and the continuous angle tracking of a real target is realized. The method of the invention is applied to the pulse Doppler radar, can effectively suppress the oppressive towed jamming, and enhancethe detection and tracking performance of the radar.

The invention relates to clutter intensity divided self-adaptive dynamic target detection. An M times echo data of pulse Doppler radar in a coherent processing interval is rearranged, the arranged data is divided into primary and secondary channels, wherein the auxiliary channel adopts an FFT (Fast Fourier Transform Algorithm) to process, and an auxiliary channel clutter map is established as the basis of the selection of the primary channel fir filter bank weight coefficient; the primary channel is realized by adopting the fir filter bank; and the number of the weight coefficients of each filter is 4 which respectively correspond to different ground clutter and weather clutter situations, and one of the four weight coefficients is selected as the fir filter weight coefficient of the primary channel according to the auxiliary channel clutter map. The self-adaptive dynamic target detection provided by the invention has the advantages that the primary and secondary channels are adopted to process, the auxiliary channel is processed by adopting FFT, and the primary channel is realized by adopting the fir filter bank; and the auxiliary channel clutter map is established to indicate the current clutter background of the radar, and the weight coefficient of the primary channel fir filter is selected according to the clutter intensity.

The invention relates to a zero distance calibration system and method for pulse Doppler radar. The calibration system comprises a circulator, a limiter, a low noise amplifier, isolators, a mixer, a delay line, an up-converter, a first amplifier, a second amplifier, a power divider and an antenna, wherein the circulator, the limiter, the first isolator, the low noise amplifier, the second isolator and the mixer which are sequentially connected in series constitute a reception channel; the delay line and impedance matching networks in front of and behind the delay line constitute a delay channel; the up-converter, the third isolator, the first amplifier, the fourth isolator, the second amplifier, the circulator and the antenna which are sequentially connected constitute a transmission channel; the delay channel is connected between the transmission channel and the reception channel, and electrical signals are converted into sound signals to be subjected to time delay propagation in sound transmission media.

The invention discloses a method used for fast detecting and pulse Doppler radar pulse jitter estimating. The method comprises the steps that echo signal data of a stationary object or processed echo signal data are collected; windowing and Fourier transform in direction are carried out on the data to acquire a frequency-domain data matrix; Doppler filtering is carried out on the frequency-domain matrix data, and modular operation is carried out, so as to acquire a Doppler spectrum; the ratio of the zero-Doppler frequency amplitude of the acquired Doppler spectrum to the maximum non-zero Doppler frequency amplitude is acquired; and jitter amplitude is evaluated according to the ratio. According to the invention, the residual clutter intensity of a strong stationary target signal during Doppler processing can be evaluated, and the ability of jiggle target detection of a radar system is evaluated.

The invention discloses a method for detecting a rapid artillery type dim target. A radar signal processing system applies the improved dynamic programming detection algorithm to echo waves in all directions in a parallel mode; data in the slow time-distance domain in each direction are converted to a Doppler-distance domain at first; then, a first threshold pre-judging is carried out on the converted Doppler-distance domain data; continuous K-frame Doppler-distance data obtained after being preprocessed are copied according to the speed fuzzy number range, and Doppler dimension coordinate values of the copied data are adjusted; then the dynamic programming algorithm is applied to each fuzzy number datum, and a corresponding value function accumulation value and a target motion state matrix are obtained; a radar detection result is displayed by combining the value function accumulation values of all the fuzzy numbers. By means of the characteristic of the rapid artillery type dim target, the improved dynamic programming algorithm is applied to pulse Doppler radar signal processing, and the radar detection probability is effectively improved.

Method for generating a model of the effect of phase noise during use of a Doppler radar system including calculating, using a processor, an initial signal-to-clutter ratio (SCR) representing a ratio of power received from echoes from a target by the radar system to power resulting from clutter reflection received by the radar system. The initially calculated SCR is modified as a function of a range ambiguity and range resolution. A Doppler frequency of interest is calculated based on velocity of a target, target heading and radar frequency, along with a Doppler filter bandwidth, frequency components and a measure of clutter signal passing through the Doppler filter of interest by summing products of the phase noise for each frequency by the Doppler filter bandwidth. This measure indicates effectiveness of target detection by the Doppler radar system as a function of distance.

The invention provides a maneuvering target multi-frame track-before-detect method applied to a pulse-Doppler radar, which can carry out real-time estimation on the target radial acceleration and the current acceleration mean value by using Doppler information of a state in an accumulating path during a dynamic planning value function accumulation process. Thus, the adaptability of the dynamic planning track-before-detect method to the maneuvering target can be effectively improved. In addition, estimation on the target radial acceleration and the current acceleration mean value is guided by measurement and can be adaptively completed, and specific target prior information is not needed.

The invention discloses a random pulse Doppler radar angle-Doppler imaging method based on compressed sensing. The method comprises the following steps of 1, obtaining space-time compressed sampling data on the basis of a radar system; 2, performing spatial discretization treatment on Doppler frequency space and spatial frequency in the space-time compressed sampling data, and obtaining a space-time oriented dictionary; 3, on the basis of the space-time oriented dictionary, estimating a space-time power spectrum, and obtaining an angle-Doppler image containing clutter and targets. The method effectively solves the problem of target and clutter Doppler ambiguity, improves the clutter suppression and target detection performance, lowers the number of pulses transmitted by a radar system, and can transmit other radar waveforms or observe multiple angles at the same time at identical pulse coherent processing intervals, thereby effectively improving the radar time dimension complexing ability; on the condition of the identical pulse number, the Doppler resolution capability can be effectively improved; the radar waveform low intercept and capture capacity and the anti-jamming capability are stronger.