无线电工程

以VHF系统接收机AGC电路为例介绍了传统自动增益控制电路工作原理,针对VHF系统接收出现杂音情况,阐明了传统AGC电路缺乏强干扰措施,影响VHF系统后续信号处理,造成通信中断。通过分析带内强干扰在传统AGC电路内的作用机制和无线电系统带内强干扰的AGC电压表现的规律,提出了在传统AGC电路上增加数字比较电路,自动识别带内强干扰,调整放大增益并在输出端进行放大限幅,进而消除带内强干扰。

The AGC circuitry of VHF system is taken as an example for introducing the working principle of foregoing Automatic Gain Control (AGC) circuitry.The foregoing AGC circuitry is short of discriminating ability against strong in-band jamming,therefore follow-up signal processing will be influenced,the correspondence will be broken off,and strong in-band jamming may occur in the downlink receiving.Through analyzing the function principle of bandwidth inside strong interference and the rule of AGC voltage under strong in-band jamming,an improved AGC circuitry is presented.In terms of adding a digital comparison circuit to the foregoing AGC circuitry,this device can identify strong in-band jamming automatically,adapt the gain amplifying and restrict the amplifying amplitude on the output to eliminate the strong in-band jamming.