In this paper, a fast digital AGC system is proposed based on Hilbert orthogonal detection which is used to de-tect the signal's amplitude information. However, the detection output creates fluctuations caused by the amplitude attenuation of Hilbert filter, which makes the signal output of the AGC system unsteady. By calculating the average value of the detector out-put, the detection output becomes steady. And in this paper, the ratio S between orthogonal detection output and input signal's amplitude is introduced to simply the theory analysis of the system. By simulating S, each parameter can be determined exactly for design and implementation of this system with FPGA. Combined with the theoretical method, the improved AGC system has the advantages of simple design, stability and better control.%提出一种快速数字AGC系统方案,系统中采用Hilbert(希尔伯特)正交检波方法,由于Hilbert滤波器的幅度衰减作用会导致检波输出产生波动,从而影响AGC系统输出信号的稳定性,通过在原检波输出端求平均值使检波输出稳定;同时引入正交检波输出与输入信号幅值的比值参数δ,简化系统的理论分析过程,在设计中通过仿真分析δ,能准确地确定系统的各参数值.基于以上改进的AGC系统结合文中的理论方法,使得该系统具有设计简单、工作稳定、易控制等优点.
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