Abstract:
A radar includes a transmitting antenna and receiving antenna formed by an array of radiant elements. Antenna beams are calculated in P directions by a BFC function. Detections of a target by secondary lobes of the beams are processed by an algorithm comparing levels received in a distance-speed resolution cell, a single detection at most not being possible for each distance-speed resolution cell. Processing means use the assumption that there may probably be more than one echo with a signal-to-noise ratio that is sufficient to be detectable, for a given resolution cell of the radar, either in speed mode or in distance mode, or, alternatively, a distance-speed depending on the processing implemented; and, if there is more than one echo detectable for each resolution cell out of the plurality of beams formed by BFC, only the echo and BFC that obtain maximum power or maximum signal-to-noise ratio are/is considered valid.
Abstract:
A radar includes a transmitting antenna and receiving antenna formed by an array of radiant elements. Antenna beams are calculated in P directions by a BFC function. Detections of a target by secondary lobes of the beams are processed by an algorithm comparing levels received in a distance-speed resolution cell, a single detection at most not being possible for each distance-speed resolution cell. Processing means use the assumption that there may probably be more than one echo with a signal-to-noise ratio that is sufficient to be detectable, for a given resolution cell of the radar, either in speed mode or in distance mode, or, alternatively, a distance-speed depending on the processing implemented; and, if there is more than one echo detectable for each resolution cell out of the plurality of beams formed by BFC, only the echo and BFC that obtain maximum power or maximum signal-to-noise ratio are/is considered valid.
Abstract:
The present invention relates to a method of eliminating ground echoes for a meteorological radar. The ground echoes being received from a predetermined area by a radar, the radar illuminating, for a predetermined number R of transmission recurrences, the area over a number P of distance cells, the method includes a step for calculating a spatial statistical parameter of the cluttered echoes received by the radar in response to the recurrences over an analysis path for distance cells, and a step to compare the spatial variation level of the spatial statistical parameter along the analysis path, the echoes being considered to be ground echoes when the level of said variation is greater than a predetermined threshold.
Abstract:
In a method and device for frequency-modulated continuous-wave radar detection with removal of ambiguity between the distance and the speed, the radar sends out at least alternately two parallel and discontinuous frequency modulation ramps that are slightly offset by a frequency variation (.DELTA.F), the frequency switching from one ramp to the other at the end of a given duration (Tf), the distance from a detected target being estimated as a function of the difference in phase (.DELTA..phi.) between a received signal (S.sub.1 (t)) corresponding to the first ramp and a received signal (S.sub.2 (t)) corresponding to the second ramp, the speed of the target being obtained from the estimated distance and the ambiguity straight line associated with the target. The disclosed method and device can be applied especially to radars for automobiles.
Abstract translation:在用于频率调制的连续波雷达检测的方法和装置中,消除距离和速度之间的模糊度,雷达至少交替地发送两个被频率变化稍微偏移的平行和不连续的频率调制斜坡(DELTA F ),在给定持续时间(Tf)结束时从一个斜坡到另一个斜坡的频率切换,从被检测的目标的距离被估计为接收信号(S1(t))之间的相位差(DELTA phi)的函数 ))和对应于第二斜坡的接收信号(S2(t)),从估计的距离获得目标的速度和与目标相关联的模糊直线。 所公开的方法和装置可以特别适用于汽车的雷达。
Abstract:
A method for detecting targets using a mobile radar having a rotary antenna, notably small targets buried in radar clutter, without increasing the number of false detections, includes determining pre-detections during N antenna revolutions, including determining pre-detections revolution by revolution, each pre-detection being stored in a grid of cells centered on the position that the radar occupied at the start of the current revolution, each grid cell corresponding to an azimuth range and a distance range. This step also includes, at the end of each revolution, a step of shifting all the pre-detections stored in the grid during the previous revolutions by the movement undergone by the radar during the last revolution. The method also includes determining detections, a target being detected from the moment that a set of pre-detections stored in the grid has its distances to the radar which constitute a linear progression during the N antenna revolutions.
Abstract:
The present invention relates to a method of eliminating ground echoes for a meteorological radar. The ground echoes being received from a predetermined area by a radar, the radar illuminating, for a predetermined number R of transmission recurrences, the area over a number P of distance cells, the method includes a step for calculating a spatial statistical parameter of the cluttered echoes received by the radar in response to the recurrences over an analysis path for distance cells, and a step to compare the spatial variation level of the spatial statistical parameter along the analysis path, the echoes being considered to be ground echoes when the level of said variation is greater than a predetermined threshold.
Abstract:
The present invention relates to a method for characterizing an atmospheric turbulence by representative parameters measured by a radar. The emission beam of the radar carried by an aircraft scanning the zone of the turbulence, a measured parameter being the total variance of the velocity of the turbulence σU, this total variance at a point x0 inside the turbulence is the sum of the spatial variance of the spectral moment of order 1 of the signals received by the radar Var[M1({right arrow over (x)})] and of the spatial mean of the spectral moment of order 2 of the signals received Mean[M2({right arrow over (x)})], the moments being distributed as a vector {right arrow over (x)} sweeping an atmospheric domain around the point x0. The invention applies notably in respect of meteorological radars fitted to aircraft such as airliners for example.
Abstract:
Detecting reflectors of an emitted electromagnetic pulse, using a received signal, by time-sampling the received signal and the emitted pulse at a same sampling frequency, each received sample corresponding to a return-trip distance for the emitted pulse between its transmitter and a possible reflector. The sampled received signal is divided by the emitted pulse sampled and temporally translated into an interval of duration equal to the emitted pulse divided into L samples, producing L results of the division. A weighted summing of the L results of the division is calculated, the sets of L weights each having a support on which the weights are not zero, every subinterval of length between L/n and L being the support for at least one set of weights and no support having a length of less than L/n, wherein the sums of the weights of a set all being equal, and n is a nonzero integer such that L/n is greater than or equal to 2. Finally, determining the minimum of the summations, wherein a nonzero minimum characterizes the amplitude of the pulse reflected by a reflector located at the distance corresponding to the start of a time interval being considered.
Abstract:
A method for detecting targets using a mobile radar having a rotary antenna, notably small targets buried in radar clutter, without increasing the number of false detections, includes determining pre-detections during N antenna revolutions, including determining pre-detections revolution by revolution, each pre-detection being stored in a grid of cells centered on the position that the radar occupied at the start of the current revolution, each grid cell corresponding to an azimuth range and a distance range. This step also includes, at the end of each revolution, a step of shifting all the pre-detections stored in the grid during the previous revolutions by the movement undergone by the radar during the last revolution. The method also includes determining detections, a target being detected from the moment that a set of pre-detections stored in the grid has its distances to the radar which constitute a linear progression during the N antenna revolutions.
Abstract:
Detecting reflectors of an emitted electromagnetic pulse, using a received signal, by time-sampling the received signal and the emitted pulse at a same sampling frequency, each received sample corresponding to a return-trip distance for the emitted pulse between its transmitter and a possible reflector. The sampled received signal is divided by the emitted pulse sampled and temporally translated into an interval of duration equal to the emitted pulse divided into L samples, producing L results of the division. A weighted summing of the L results of the division is calculated, the sets of L weights each having a support on which the weights are not zero, every subinterval of length between L/n and L being the support for at least one set of weights and no support having a length of less than L/n, wherein the sums of the weights of a set all being equal, and n is a nonzero integer such that L/n is greater than or equal to 2. Finally, determining the minimum of the summations, wherein a nonzero minimum characterizes the amplitude of the pulse reflected by a reflector located at the distance corresponding to the start of a time interval being considered.