探地雷達回波信號具有動態范圍大、頻帶寬等特點，如果不對回波信號進行處理直接進行A／D轉換，則會出現動態范圍不匹配的問題，嚴重影響雷達的探測深度和分辨率。為此，本文采用AD603設計了一時變增益放大器對回波信號進行處理，通過對不同時間的回波信號給以不同的增益來補償A／D轉換器的動態范圍的不足，達到與回波信號動態范圍相匹配的目的。本文給出了詳細的設計思想和原理電路圖，實測結果表明，文中所設計的時變增益放大器能滿足雷達系統的需求，具有很強的實用價值。
關鍵詞：探地雷達；時變增益；動態范圍
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