1.School of Physics and Electronic Information，Yantai University，Yantai 264005，China； 2.Naval Air University，Yantai 264005，China
Abstract： In the process of radar to sea detection, the near-range sea clutter echo power is high, which seriously affects the radar receiver work and subsequent signal processing. In order to balance the gain and sensitivity of radar receiver, a reasonable design of sensitivity time control (STC) curve is needed. This paper introduces four STC design curve methods using GARCH model, polynomial function, radar distance equation and exponential function, and compares and analyzes the near-range sea clutter suppression performance of the four STC curves by using the measured data under high and low sea conditions. The experimental results show that the STC curves in the form of radar distance equation have significant performance in suppressing sea clutter in both high and low sea states; the STC curves modeled by GARCH model are suitable for low sea states; the STC curves in the form of polynomial and exponential are close to each other in different sea states.
Key words : radar；sea clutter；sensitivity time control
0 引言
對(duì)海雷達(dá)探測(cè)海上艦船、浮冰、航道浮標(biāo)、漁船等目標(biāo)時(shí)，容易受到海雜波的干擾。雷達(dá)探測(cè)目標(biāo)接收信號(hào)過程中，近距離區(qū)域，海雜波干擾很強(qiáng)，需要對(duì)雜波信號(hào)進(jìn)行抑制衰弱，否則將無法區(qū)分雜波信號(hào)和目標(biāo)信號(hào)，在高海況背景下檢測(cè)小目標(biāo)尤為困難。為確保雷達(dá)接收機(jī)能在高、低海況下正常工作，準(zhǔn)確顯示出檢測(cè)目標(biāo)，需要使用靈敏度時(shí)間控制(Sensitivity Time Control，STC)進(jìn)一步擴(kuò)展動(dòng)態(tài)范圍，抑制近距離海雜波的強(qiáng)度，增強(qiáng)遠(yuǎn)距離目標(biāo)的信號(hào)強(qiáng)度，保證接收機(jī)的靈敏度，提高接收機(jī)的性能[1-6]。文獻(xiàn)[7]論述了一種根據(jù)目標(biāo)的回波電壓隨距離二次方變化的特性，設(shè)置數(shù)字信號(hào)實(shí)時(shí)控制大動(dòng)態(tài)中頻放大器的方法，用來解決目標(biāo)信號(hào)強(qiáng)度隨距離降低的問題。文獻(xiàn)[8]提出一種自適應(yīng)增益靈敏度控制的方法，通過統(tǒng)計(jì)距離維信息，對(duì)海雜波包絡(luò)進(jìn)行擬合，形成接收端的反饋來控制系統(tǒng)的靈敏度和視頻畫面質(zhì)量。文獻(xiàn)[9]中提出一種雷達(dá)接收機(jī)靈敏度時(shí)間控制方法，根據(jù)雷達(dá)距離方程中雷達(dá)回波功率與雷達(dá)距離四次方成反比的規(guī)律，對(duì)STC控制深度和控制距離分別分擋控制。許多文獻(xiàn)對(duì)STC曲線的設(shè)計(jì)方法都有所提出或論述，但是，STC常規(guī)曲線和其他方式設(shè)計(jì)STC曲線的性能對(duì)比的相關(guān)研究較少，本文采用高、低兩種海況的實(shí)測(cè)數(shù)據(jù)對(duì)四種STC設(shè)計(jì)曲線方式性能進(jìn)行對(duì)比，希望能得到對(duì)高、低海況不同海雜波背景下有實(shí)用性的STC曲線，確保雷達(dá)接收機(jī)在不同海況下正常工作。
