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Swerling Target Models

The example illustrates the use of Swerling target models to describe the fluctuations in radar cross-section. The scenario consists of a rotating monostatic radar and a target having a radar cross-section described by a Swerling 2 model. In this example, the radar and target are stationary.

旋转1与2型型号

在旋转1和2个目标模型中,总RCS来自许多大约相等的单个RC的独立小散射器。扫描中的每一个脉冲可能会变化(旋转2),或者在由多个脉冲组成的完整扫描中可能是恒定的(旋转1)。无论哪种情况,统计数据都具有两个自由度的卡方概率密度函数。

Dwell Time and Radar Scan

为简单起见,从旋转雷达开始,旋转时间为5秒,对应于旋转或扫描速率为72度/秒。

Trot = 5.0; scanrate = 360/Trot;

雷达的主要半动力梁宽度(HPBW)为3.0度。在目标被主梁照亮的过程中,雷达脉冲撞击目标并反射回到雷达。点亮目标的时间段称为“停留时间”。这次也称为扫描。雷达将处理目标的3扫描。

HPBW = 3.0;tdwell = hpbw/scanrate;nscan = 3;

The number of pulses that arrive on target during the dwell time depends upon the pulse repetition frequency (PRF). PRF is the inverse of the pulse repetition interval (PRI). Assume 5000 pulses are transmitted per second.

prf = 5000.0;pri = 1/prf;

一个停留时间的脉冲数为

np =地板(tdwell*prf);

放up a Swerling 2 model

您可以通过适当地使用方法的方法RadarTargetSystem object™. To effect a Swerling 2 model, set theModelproperty of the分阶段系统对象™'swerling1'or'Swerling2'。Both are equivalent. Then, at the every call to themethod, set theUpdatercsargument totrue。这意味着每个脉冲都会更新雷达横截面。

放the target model to'swerling1'

tgtmodel ='Swerling2';

放up radar model System object™ components

设置辐射天线。假设天线的工作频率为1GHz。

FC = 1E9;天线=分阶段。异位剂(异位剂)('BackBaffled',真的);散热器=分阶段。放射线('OperatingFrequency',,,,fc,'传感器',天线);

Specify the location of the stationary antenna.

radarplatform = phase.platform('初始位置',[0; 0; 0]);

指定固定目标的位置。

targetplatform = phased.Platform('初始位置',,,,[2000; 0; 0]);

The transmitted signal is a linear FM waveform. Transmit one pulse per call to themethod.

waveform = phase.linearfmwaveform(“脉冲宽”,,,,50e-6,...'输出格式',,,,“脉冲”,,,,'NumPulses',,,,1);

放up the transmitting amplifier.

发射机= phased.Transmitter('峰值功率',,,,1000.0,'获得',40);

设置传播环境是自由空间。

频道= phased.freespace('OperatingFrequency',,,,fc,...'TwoWayPropagation',真的);

Specify the radar target to have a mean RCS of 1 m2 and be of the Swerling model type 1 or 2. You can use Swerling 1 or 2 interchangeably.

target = phase.radartarget(“平均值”,1,'OperatingFrequency',,,,fc,...'Model',tgtmodel);

放up the radar collector.

collector = phasted.collector('OperatingFrequency',1E9,...'传感器',天线);

定义匹配的过滤器以处理传入信号。

wav = waveform();filter =分阶段。...“系数”,getMatchedFilter(波形));

处理循环进行3次扫描2个目标的扫描

  1. Generate waveform with unit amplitude

  2. 放大发射波形

  3. 沿所需方向辐射波形到目标

  4. 传播波形到雷达目标和从雷达目标传播

  5. Reflect waveform from radar target.

  6. 收集辐射以创建接收信号

  7. 匹配过滤器收到的信号

提供雷达回报振幅的记忆

Z =零(NSCAN,NP);tp =零(nscan,np);

输入循环。放Updatercstrueonly for the first pulse of the scan.

为了M = 1:NSCAN T0 =(M-1)*TROT;t = t0;updatercs = true;为了k = 1:np
t = t + pri;txwav = transmitter(wav);

发现雷达和目标位置

[Xradar,vradar] = radarplatform(t);[XTGT,VTGT] = targetPlatform(t);

辐射波形到靶标

[〜,ang] = rangeangle(XTGT,Xradar);radwav =散热器(txwav,ang);

Propagate waveform to and from the target

propwav =通道(radwav,radarplatform.initialposition,...targetPlatform.InitialPosition,[0; 0; 0],[0; 0; 0]);

Reflect waveform from target. Set theUpdatercsflag.

reflwav = target(propwav,updatercs);

收集接收的波形

collwav = collector(reflwav,ang);

将匹配的过滤器应用于传入信号

y =过滤器(collwav);z(m,k)= max(abs(y));tp(m,k)= t;
结尾结尾

绘制脉冲振幅

Plot the amplitudes of the pulses for the scan as a function of time.

情节(tp(:),z(:),,,,'。')xlabel('Time (sec)')ylabel('Pulse Amplitude'

请注意,脉冲振幅在扫描中有所不同。

Histogram the received pulse amplitudes

数字;历史(z(:),25)Xlabel('Pulse Amplitude')ylabel('数数'