Patent ID: 6621332
Filing Date: 2003-09-16
Classification: H04L

Abstract:
A demodulator comprising:a first calculation unit separating an analogue waveform into a frequency component to calculate xy coordinate values, on an xy plane, of the frequency component; a first angular difference detector detecting an angular variation value according to respective signs of current xy coordinate values supplied from said first calculation unit and respective signs of preceding xy coordinate values; a second calculation unit calculating an angle value of said frequency component according to respective absolute values of xy coordinate values supplied from said first calculation unit; a subtractor subtracting a preceding angle value from a current angle value supplied from said second calculation unit; a second angular difference detector classifying a subtraction result supplied from said subtractor as one of a plurality of angle regions to detect an angular difference value; and a demapper performing demapping according to a sum of the angular variation value supplied from said first angular difference detector and the angular difference value supplied from said second angular difference detector.