Patent ID: 6021168
Filing Date: 2000-02-01
Classification: H04N

Abstract:
A clock recovery circuit for an MPEG-2 system decoder, comprising:a digital signal processor including:program clock reference (PCR)/system clock reference (SCR) detection means for receiving a transport or program stream and detecting a PCR or SCR from the received transport or program stream;addition/subtraction means for, if the PCR or SCR detected by said PCR/SCR detection means is an initial value, subtracting a clock value of a desired number of bits from the detected PCR or SCR starting from the least significant bit to generate a first value and, if the detected PCR or SCR is not the initial value, subtracting lower-order bit values of said first value corresponding to said desired number from lower-order bit values of the detected PCR or SCR corresponding to said desired number, subtracting said clock value from the subtracted result to generate a second value and adding said clock value to said first value starting from the least significant bit to generate a system time clock;storage means for storing said first value from said addition/subtraction means therein; andcontrol means for checking whether the PCR or SCR detected by said PCR/SCR detection means is the initial value and controlling operations of said means in accordance with the checked result;digital/analog conversion means for converting said second value from said addition/subtraction means into an analog value;filtering means for filtering an output value from said digital/analog conversion means;a voltage controlled oscillator for generating a system clock which is varied in frequency according to an output value from said filtering means; andcounting means for generating said clock value of said desired number of bits in response to said system clock from said voltage controlled oscillator in such a manner that it generates lower-order 9 bits of said clock value by repeatedly counting a desired range and the remaining higher-order bits of said clock value by counting by one whenever counting said desired range.