专利名称：Television signal scrambling system发明人：Richard W. Citta,Dennis M. Mutzabaugh,Gary
J. Sgrignoli
申请号：US06/711947申请日：19850315公开号：US04706283A公开日：19871110
摘要：A television signal transmission system comprises a headend including a pair ofSAW filters having equal delays, one filter having amplitude and normalized phase versusfrequency response characteristics continuously varying between about -6 db and 180degrees at the picture carrier frequency and zero db and zero degrees at the soundcarrier frequency of the television signal, the second filter having substantially flatamplitude and normalized phase responses between the picture and sound carrierfrequencies. An RF video signal is applied to both filters, the output of the first filterbeing selected for transmission during at least a portion of the horizontal blankingintervals of the television signal with the output of the second filter otherwise beingselected for transmission. The transmitted signal is received by a decoder including a bi-phase stable phase modulation detector and third and fourth SAW filters havingresponse characteristics complementary to the headend filters. The received signal isapplied to both the third and fourth SAW filters whose outputs are selectively switchedto an output terminal in response to the phase modulation detector for restoring thereceived signal.
申请人：ZENITH ELECTRONICS CORPORATION
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