AUTOMATIC GAIN CONTROL DEVICE OF ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING SIGNAL AND AUTOMATIC GAIN CONTROL METHOD USING THE SAME

摘要

PURPOSE: An AGC(Automatic Gain Control) device of an OFDM(Orthogonal Frequency Division Multiplexing) signal is provided to detect an OFDM signal by measuring power of a preamble signal, and to measure power of a signal received from the time when the signal is detected, in order to gain-control in the same method as a reference power, thereby minimizing a gain control time and obtaining stability. CONSTITUTION: A variable gain signal amplifier(31) amplifies a received OFDM signal. An A/D converter(32) converts an analog signal into a digital signal. A switching circuit(33) controls the digital signal to be inputted to a signal power measurer and signal controller(35) in detecting and controlling modes. The signal power measurer and signal controller(35) measures a signal power as moving a window every sample unit in a detecting mode, to transmit a signal to a signal power comparator(34), and measures an average signal power in a controlling mode to transmit a signal to a gain controller(36). The signal power comparator(34) compares the power of the measured signal with a critical value, to decide whether an available signal exists. The gain controller(36) generates a control signal for controlling the received signal at required level. A D/A converter(37) converts the control signal into an analog signal.