摘要
高速运动目标脉间存在越距离单元走动,且多普勒频谱混叠,脉间相参积累困难.利用长时间的信号积累,来提高微弱高速运动目标在低信噪比下的检测性能理论上是一种有效方法,但积累时间长,使得目标回波越距离单元走动,相参积累更加困难.进行速度提前预估计的方法,能很好提高检测性能,但增加了技术难度,并且需要长的检测时间.本文研究一种改进的Keystone变换方法,该方法是通过计算不同模糊系数时的所有回波脉冲峰值位置的方差,记录下方差最小时的模糊系数,利用该模糊系数,结合运用SINC函数插值实现的变换方法.该变换方法不受目标回波积累时间的限制,无需预先估计目标速度,可同时实现解多普勒模糊和补偿距离走动.仿真结果表明,与进行匹配滤波后相参积累的方法相比,结合最小方差法和Keystone变换的方法,能有效补偿距离走动,去除多普勒模糊,有效提高了高速运动目标回波脉冲积累的信噪比,改善了雷达的检测性能.
The target echo migration usually exceeds a range resolution cell,when the target is moving with a high ve-locity.This causes Doppler frequency spectrum aliasing,and makes it troublesome to accumulate the pulses. Theorily,when the high-velocity target’s signal is at low signal to noise ratio（SNR）,accumulating for longer time could develop the detection ability.However,during longer term accumulation,the waves of pulses may exceed several range resolution cells.This makes it much more difficult to pulses accumulation.Estimating speed before detection could develop detection ability in theory.But in fact,it’s very difficult to measure the speed.Even realized,it needs much longer time to archive.This is very difficult to come true in practice.In this paper,theoretical derivation will be carried on particularly.It tells why there would be range migration and Doppler ambiguity,and how to compensate them.Based on the theoretical derivation,a modified method which is based on Keystone transform is put forward.The method is to calculate the differences of all the points of pulses’peaks,which is gotten at different ambiguity factor,and to note the Doppler ambiguity factor when the difference is minimum.This Doppler ambiguity factor can be used to compensate Doppler ambiguity as is shown below.Keystone transform can be realized by the method of SINC interpolation and the method of calculating Doppler ambiguity factor.This method is not restricted＆amp;nbsp;by the accumulation time,and doesn’t need to estimate the speed before detection.What’s more,this method could compensate the range migration and Doppler ambiguity without acknowledging the target’s speed.The result shows that,compared with other methods,this method could compensate the range migration and Doppler ambiguity without acknowledging the targets’speeds.It is not restricted by the detection time.It also develops the SNR of the pulses of high-velocity targets,and Radars’detection ability in wideband radar.This method is of great value in practice,especially in millimeter wave radar.
出处
《南京大学学报（自然科学版）》
CAS
CSCD
北大核心
2014年第1期30-34,共5页
Journal of Nanjing University（Natural Science）
基金
江苏省产学研联合创新资金--前瞻性联合研究项目(BY2012187)
关键词
越距离单元走动
KEYSTONE变换
多普勒模糊
相参积累
range resolution cell
keystone transform
doppler ambiguity
pulses accumulate
range resolution cell
keystone transform
doppler ambiguity
pulses accumulate
