Method and apparatus for automatic gain control

The invention relates to used for transmitting signals into the digital signal in the system is of a method and a device for automatic gain control. The device using predetermined size gain control step number of the analogue form realizing adjustable signal device for automatic gain control (208), and realizing digital signal device of backward gain control through a particular mould (446 and 448), so on digital regulation, front signal power and an adjusting, same. Filled with gain control for; the device further - comprising a predetermined measurement circulation by maximum power signal and preset threshold value of the signal maximum energy's device (410, 412, 214 and 420), a determine (430 and 432) comparison device (426 and 428), and an, and obtaining value is greater than the threshold value; and realizes the automatic gain control of used signal, the compensation module signal in aggregate of the gain control device (436).