APPARATUS FOR AUTOMATIC GAIN CONTROL IN CABLE MODEM, AND LOCK-TIME DERIVATION METHOD OF USING IT

摘要

An automatic gain control apparatus in a cable modem, and a method for deriving a lock-time using the same are provided to perform automatic gain control in connection with a received signal level by enabling the received signal to converge into an error range rapidly when an amplitude of the received signal is deviated from the error range. An automatic gain control apparatus in a cable modem includes a gain control unit(24), an amplitude control unit(23), a low pass filtering unit(22), and a signal amplitude control unit(21). The gain control unit(24) measures power of a digital input signal transferred from the outside. The gain control unit(24) calculates an amplitude of an average signal by accumulating the measured power for a predetermined section to calculate an error value with an amplitude of a preset signal. The amplitude control unit(23) receives the error value adjusted by the gain control unit(24) and controls an amplitude of the signal. The low pass filtering unit(22) receives the signal output through the amplitude control unit(23) and performs low pass filtering for the received signal. The signal amplitude control unit(21) receives the filtered signal through the low pass filtering unit(22) and controls the amplitude of the signal.