Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1988-12-06
1990-07-17
Chin, Tommy P.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358148, 358158, H04N 504
Patent
active
049424726
ABSTRACT:
A detection circuit for a video tape recorder signal on the input of a TV set connected to a line synchronization separating circuit (11) in turn connected to a PLL (12) comprises a first phase comparator (15), the PLL (12) exhibiting a first time constant (I1, C1) corresponding to an operation on a normal TV signal. This circuit further comprises a switch (20) for switching the PLL on a second time constant (3I1, C1) shorter than the first one, a second phase comparator (22) for comparing the input and output phases of the first phase comparator, the second phase comparator being associated with a third time constant (I2, C2) shorter than the first and second ones, a threshold comparator (24) supplying to the switch (20) a control signal when the comparator output (22) is outside determined limits.
REFERENCES:
patent: 3715499 (1973-02-01), Steckler
patent: 3909735 (1975-09-01), Anderson et al.
patent: 4496978 (1985-01-01), Sakamoto
patent: 4536794 (1985-08-01), Fernsler
patent: 4636860 (1987-01-01), Duijkers
patent: 4660080 (1987-04-01), Dietz
patent: 4791488 (1988-12-01), Fukazawa
patent: 4809068 (1989-02-01), Nagai
patent: 4812907 (1989-03-01), Hathaway
Imbert Michel
Merval Jean-Marc
Chin Tommy P.
SGS-Thomson Microelectronics S.A.
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