Cryptography – Key management – Having particular key generator
Patent
1985-03-15
1987-11-10
Buczinski, Stephen C.
Cryptography
Key management
Having particular key generator
380 15, H04N 7167
Patent
active
047062835
ABSTRACT:
A television signal transmission system comprises a headend including a pair of SAW filters having equal delays, one filter having amplitude and normalized phase versus frequency response characteristics continuously varying between about -6 db and 180 degrees at the picture carrier frequency and zero db and zero degrees at the sound carrier frequency of the television signal, the second filter having substantially flat amplitude and normalized phase responses between the picture and sound carrier frequencies. An RF video signal is applied to both filters, the output of the first filter being selected for transmission during at least a portion of the horizontal blanking intervals of the television signal with the output of the second filter otherwise being selected for transmission. The transmitted signal is received by a decoder including a bi-phase stable phase modulation detector and third and fourth SAW filters having response characteristics complementary to the headend filters. The received signal is applied to both the third and fourth SAW filters whose outputs are selectively switched to an output terminal in response to the phase modulation detector for restoring the received signal.
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Citta Richard W.
Mutzabaugh Dennis M.
Sgrignoli Gary J.
Buczinski Stephen C.
Koltak Melissa L.
Zenith Electronics Corporation
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