探地雷達(dá)回波信號具有動(dòng)態(tài)范圍大、頻帶寬等特點(diǎn)，如果不對回波信號進(jìn)行處理直接進(jìn)行A／D轉(zhuǎn)換，則會(huì)出現(xiàn)動(dòng)態(tài)范圍不匹配的問題，嚴(yán)重影響雷達(dá)的探測深度和分辨率。為此，本文采用AD603設(shè)計(jì)了一時(shí)變增益放大器對回波信號進(jìn)行處理，通過對不同時(shí)間的回波信號給以不同的增益來補(bǔ)償A／D轉(zhuǎn)換器的動(dòng)態(tài)范圍的不足，達(dá)到與回波信號動(dòng)態(tài)范圍相匹配的目的。本文給出了詳細(xì)的設(shè)計(jì)思想和原理電路圖，實(shí)測結(jié)果表明，文中所設(shè)計(jì)的時(shí)變增益放大器能滿足雷達(dá)系統(tǒng)的需求，具有很強(qiáng)的實(shí)用價(jià)值。
關(guān)鍵詞：探地雷達(dá)；時(shí)變增益；動(dòng)態(tài)范圍
Abstract：The echo of ground penetrating radar(GPR)has a characteristic of large dynamic rang~ If the echo of GPR
doesn’t be processed and direct is adopted analog-to-convert，the dyn amic range of analog-to-digital converter(ADC)in data acquisition circuit can’t match the need of GPR system and the problem will affect the exploration depth and resolution of GPR．In order tO solve the problem，a time varying gain(TVG)method which attenuates the strong signal reflected from shallow layer while am plifies the weak signal reflected from deep layer is presented in the paper．A novel voltage-controlled amplifier(VCA) 03 is used in the design of VGA．The scheme of design is given in the paper．The experiment measure result testifies that the circuit can satisfy the need of GPR and iS valid．
Keywords：GPR；time varying gain；dyn amic range