发明名称 |
A SYNCHRONOUS VIDEO DETECTOR CIRCUIT USING PHASE-LOCKED LOOP |
摘要 |
In a synchronous video detector circuit using a phase-locked loop, the synchronous detection of a video IF signal is effected with a synchronous carrier signal reproduced by the PLL including a voltage-controlled oscillator. Each of a phase comparator of the PLL and a synchronous video detector has its input terminal connected to an output terminal of a video IF amplifier by untuned coupling, and arranged on the output side of the synchronous video detector is a phase-locked mode detector for detecting that the PLL is in its phase-locked mode. The phase-locked mode detector is adapted to control the band width of a low-pass filter of the PLL in either a narrow band mode or a wide band mode and the low-pass filter is controlled to operate in the narrow band mode only when the PLL is in the phase-locked mode of operation. The black and white noise included in the output signal of the synchronous video detector are both cancelled by a noise cancellation circuit including a black noise detector for pulse noise cancellation purposes. |
申请公布号 |
EP0080280(B1) |
申请公布日期 |
1986.08.20 |
申请号 |
EP19820305831 |
申请日期 |
1982.11.02 |
申请人 |
MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD. |
发明人 |
ISOBE, MITSUO;KUTSUKI, TETSUO;YAMAGUCHI, NAMIO;TANAKA, TOSHIHIDE |
分类号 |
H03B5/12;H04N5/21;H04N5/455;(IPC1-7):H04N5/44 |
主分类号 |
H03B5/12 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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