Patent ID: 6310924
Filing Date: 2001-10-30
Classification: H04L

Abstract:
A digital demodulator wherein an IF signal is based on a signal received through an antenna, and including a carrier wave demodulator which demodulates a carrier wave with respect to an output signal from an IF output unit, and the IF output unit performs a segment/field synchronization, timing recovery, channel equalization, etc. with respect to the output signal from the carrier wave demodulator, the carrier wave demodulator additionally comprising:a mixer for multiplying an IF signal from the IF output unit and a local oscillating signal from a local oscillator;a low pass filter for eliminating an image frequency component generated during an operation of the mixer;an AID converter for converting an output signal from the low pass filter into a digital signal;a multiplier for multiplying an output data from the A/D converter and cos.omega.t and sin.omega.t which are combined signal values and converting into a base band width signal frequency;a demultiplexer for separating a base band width digital data into an I-signal component and a Q-signal component;a frequency/phase difference detector for performing a signal processing and compensating for a detected frequency and phase difference;an analog low band width pass filter for filtering an output signal from the frequency/phase difference detector;a local oscillator for compensating for the frequency/phase difference filtered by the analog low pass filter and providing an oscillating frequency which is synchronized with the IF signal inputted from the IF output unit to the mixer; andwherein the digital combined signal value of the multiplier is multiplied as ordered by the values of +1, +1, -1, -1 as sample values outputted sequentially from the A/D converter.