Automatic gain control device, signal receiving apparatus, and signal receiving method

A signal receiving apparatus, comprising:

• an amplifier that controls a gain according to a gain control signal and amplifies a received signal to generate an amplified signal;
• an analog-to-digital (A/D) converter that converts the amplified signal into a digital signal;
• a Fourier transform unit that performs Fourier transform of the digital signal to a frequency domain signal to generate a Fourier transform signal;
• a demodulator that demodulates the Fourier transform signal to generate a demodulated signal;
• and
• an automatic gain control unit that divides the Fourier transform signal into a noise period and a symbol period, calculates the signal level of the noise period based on the signal level of the symbol period, and generates the gain control signal according to the signal levels of the symbol period and the noise period.

A signal receiving method, comprising:

• converting a received signal into a baseband received signal;
• amplifying the baseband received signal according to a gain to generate an amplified signal;
• performing Fourier transform on the amplified signal to generate a Fourier transform signal;
• dividing the Fourier transform signal into a noise period and a symbol period;
• calculating the signal level of the noise period based on the signal level of the symbol period and generating the gain control signal according to the signal levels of the symbol period and the noise period;
• and
• adjusting the gain according to the gain control signal.