时—频信号分析与雷达的多目标分辨

对于编队飞行的目标，由于它们之间的间距很小，常规雷达无法直接从距离和方位上区别目标。但利用目标回波多普勒频率的差别是有可能分辨目标的，这—般需要较长的相关处理时间。在这期间，目标本身的多普勒频率又是变化着的。本文分析了编队飞行目标多普勒频率的变化规律，指出多普勒回波信号的变化可以用线性调频（ＬＦＭ）信号模型来表示。本文提出了用时－频分析的方法来分辨编队目标，并用短时付氏变换（ＳＴＦＴ），Ｗｉｇｎｅｒ分布（ＷＤ）以及我们提出的自适应谱图（ＡＤＳＰ）方法对实测的雷达数据进行了分析。实验结果表明，自适应谱图具有与Ｗｉｇｎｅｒ分布相近的自分量信号分辨能力而没有其交叉项。它在噪声背景下的分辨性能大大优于Ｗｉｇｎｅｒ分布和短时付氏变换，因而是一种有效的多目标分辨方法。

Time-Frequency Signal Analysis and Resoluing Multiple Targets of Radar

Due to the short distance between planes which fly in a group,the ordinary radar can't distinguish them in both distance and azimuth. The difference among Doppler frequency of the targets may be used to separate them, but a long time of coherent processing is needed.The variation of Doppler frequency of the group flying targets is analyzed in this paper. It is found that they can be modeled as linear frequency modulated (LFM) signal. And the time-frequency analyzing methods are proposed to analyze the signal.The actual radar data is analyzed by short-time Fourier transform(STFT), Wigner distribution (WD) and adaptive spectrogram (ADSP) methods.It is shown by the experimental results that the ADSP has nearly the same resolution as the autoterms of WD and hasn't WD's crossterms. It is also shown that the ADSP is far suprior to both STFT and WD in the noise background.