| 摘要 |
A RECEIVER FOR PROCESSING A VSB MODULATED SIGNAL CONTAINING TERRESTRIAL BROADCAST HIGH DEFINITION TELEVISION INFORMATION AND A PILOT COMPONENT INCLUDES AN INPUT ANALOG-TO-DIGITAL CONVERTER (19) FOR PRODUCING A DATASTREAM WHICH IS OVERSAMPLED AT TWICE THE RECEIVED SYMBOL RATE, AND A DIGITAL DEMODULATOR (22; 3) WITH A DATA REDUCTION NETWORK (330, 332)IN A PHASE CONTROL LOOP. A SEGMENT SYNC DETECTOR (24; FIGS. 4, 5) USES AN ABBREVIATED CORRELATION REFERENCE PATTERN TO RECOVER A TWICE SYMBOL RATE SAMPLING CLOCK FOR THE DIGITAL CONVERTER (19). A DC OFFSET ASSOCIATED WITH THE PILOT COMPONENT IS REMOVED (26; 6) FROM THE DEMODULATED SIGNAL BEFORE IT IS APPLIED TO AN NTSC INTERFERENCE DETECTION NETWORK(30; 7). THE INTERFERENCE DETECTION NETWORK INCLUDES A COMB FILTER NETWORK (710, 718) RESPONSIVE TO A TWICE SYMBOL RATE SAMPLED DATA DATASTREAM, AND EXHIBITS A SAMPLE DELAY DIMENSIONED TO AVOID ALIASING IN THE COMBED FREQUENCY SPECTRUM (FIG. 8), THEREBY .INCREASING THE EFFECTIVENESS OFNTSC CO-CHANNEL INTERFERENCE DETECTION.FIGURE 4
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