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公开(公告)号：US5121266A
公开(公告)日：1992-06-09
申请号：US354307
申请日：1989-05-19
CPC分类号： H04N9/7933 , H04N9/7921 , H04N9/83 , H04N9/832 , H04N9/833
摘要： A reproducing circuit for use in a magnetic recording and reproducing apparatus having a recording circuit operable to record a video luminance signal in either a conventional recording mode or in a High-Band mode has a first automatic gain control circuit for holding a level of a reproduced FM signal at an input thereof constant, a recording mode determination circuit having an input connected to the first automatic gain control circuit and responsive to an output of the first automatic gain control circuit for determining which the first or second recording mode is used to record the FM signal under reproduction, a first equalizer circuit for equalizing the reproduced FM signal suitably for the first recording mode, a second equalizer circuit for equalizing the reproduced FM signal suitably for the second recording mode, a switch circuit for selecting an output of either the first equalizer circuit or the second equalizer circuit according to an output of the recording mode determination circuit, a second automatic gain control circuit for holding an output level of the switch circuit, whereby the recording mode of the signal undergoing reproduction is automatically determined and the characteristics of the reproducing circuit is changed automatically suitably.
摘要翻译： 一种用于磁记录和再现装置的再现电路，具有可操作以记录常规记录模式或高频带模式中的视频亮度信号的记录电路，具有第一自动增益控制电路，用于保持所再现的电平 FM信号的输入恒定，记录模式确定电路具有连接到第一自动增益控制电路的输入，并且响应于第一自动增益控制电路的输出，用于确定使用第一或第二记录模式来记录 FM信号，用于对第一记录模式适当地均衡再现的FM信号的第一均衡器电路，用于适当地对于第二记录模式均衡再现的FM信号的第二均衡器电路，用于选择第一记录模式的输出的开关电路 均衡器电路或第二均衡器电路根据记录模式确定的输出 用于保持开关电路的输出电平的第二自动增益控制电路，由此自动确定进行再现的信号的记录模式，并且再现电路的特性自动适应地改变。
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公开(公告)号：US4786986A
公开(公告)日：1988-11-22
申请号：US113603
申请日：1987-10-28
摘要： A magnetic recording and reproducing apparatus of a cassette type has a first and a second recording mode converting a luminance signal of a video signal into an FM luminance signal having a first and a second carrier frequency and recording the FM luminance signal on a magnetic tape respectively. When the FM luminance signal is to be recorded according to the second recording mode, a magnetic tape having an excellent short wavelength recording characteristic is used for recording. A cassette containing this magnetic tape is provided with a configurational feature on its upper or lower half, and a detector for detecting this feature is disposed in the apparatus. When the detector detects that a magnetic tape is adapted for recording according to the first recording mode, the FM luminance signal is recorded according to the first recording mode, but when the detector detects that the magnetic tape is adapted for recording according to the second recording mode, the user can select either the first recording mode or the second recording mode as desired. A discriminating circuit is disposed in the reproducing system to discriminate as to whether the FM luminance signal was recorded according to the first recording mode or the second recording mode, and, on the basis of the result of discrimination by the discriminating circuit, the reproduced FM luminance signal is automatically processed in a processing circuit with a processing characteristic corresponding to the recording mode.
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