针对传统自动增益控制(AGC)系统稳定时间和控制精度相互关联又彼此矛盾的问题,基于反馈式对数AGC环路,提出一种输出精度可控、稳定时间可调的数字AGC系统。通过对环路增益因子的巧妙拆分,实现了稳定时间和控制精度的独立可控。推导了AGC环路方程,求解了时间常数和控制精度的解析表达式,分析了低信噪比条件下功率估计方法的性能。采用平方和功率估计法对AGC系统进行了计算机仿真。仿真结果表明,该系统环路稳定时间不随输入信号幅度的改变而改变,可根据实际工程需求,对稳定时间和控制精度进行调节,在低信噪比下也具有优良的性能。

A new digital AGC system with independent adjustable control accuracy and settling time is proposed based on feedback logarithmic AGC loop for the conflicting issues between control accuracy and settling time in traditional AGC system. By smartly splitting the single loop gain factor to two independent loop gain factor, one is used to control steady-state accuracy, the other is used to control settling time, the independent adjustment of settling time and control accuracy is achieved. AGC loop equation is derived. Analytical expression of time constant and control accuracy is solved. Performance of the power estimation methods between sum of squares and maximal values of slip windows are analyzed in low SNR, which indicates that sum of squares power estimation method has better performance in low SNR. The computer simulations of the AGC system are given using sum of squares power estimation method. The results indicate that the settling time of the system don't change with the input signal amplitude, the settling time and control accuracy can be adjusted according to the actual engineering requirements, the system has excellent performance even in low SNR.