Patent ID: 6847261
Filing Date: 2005-01-25
Classification: H03G

Abstract:
1. An automatic gain control method of achieving a constant output signal by controlling a gain variable amplifying means according to a control signal which is generated based on a level of an output signal which is derived by variably amplifying an input signal, the method comprising the steps of: a detecting step of detecting an amplified output signal; a control signal generating step of generating the control signal for the gain variable amplifying means based on a detected voltage signal obtained by detection; a detected voltage signal holding step of holding the detected voltage signal; a signal level detecting step of detecting a transmitting signal level from the input signal; a signal level holding step of holding the transmitting signal level; a comparing step of comparing the transmitting signal level held at present execution of the gain control with the transmitting signal level held at preceding execution of the gain control; and a control signal outputting step of outputting the control signal to the gain variable amplifying means based on the detected voltage signal held at preceding execution of the gain control when the present control signal for a gain variable amplifier is lower in level than the preceding control signal for the gain variable amplifier and the present transmitting signal level is reduced below the preceding transmitting signal level.