Patent ID: 6160443
Filing Date: 2000-12-12
Classification: H04L

Abstract:
A quadrature amplitude modulation (QAM) type demodulator comprising:a first automatic gain control (AGC) circuit outputting a first signal, the first signal being a function of a second signal from an analog-to-digital converter and being used to control an amount of gain of an amplifier, the amplifier being electrically coupled to and supplying an input signal to the analog-to-digital converter,a baseband conversion circuit electrically coupled to the analog-to-digital converter,a second automatic gain control (AGC) circuit including a digital multiplier, the second AGC circuit being electrically coupled to the baseband conversion circuit and outputting a third signal, the third signal being derived from a QAM signal after filtering and controlling an amount of gain of the digital multiplier,a receive filter electrically coupled to the digital multiplier,a carrier recovery circuit being electrically coupled to the receive filter and producing a fourth signal which is the QAM signal after filtering, the fourth signal being supplied to the second AGC circuit, anda symbol detection circuit being electrically coupled to the carrier recovery circuit and receiving the fourth signal,whereby a fifth signal on the output side of the symbol detection circuit is a demodulated data output signal.