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公开(公告)号:US4340305A
公开(公告)日:1982-07-20
申请号:US106842
申请日:1979-12-26
CPC分类号: G03F9/7049 , G11B15/602 , G11B17/34 , G11B21/10
摘要: First and second plates are formed with like periodic patterns. A laser beam illuminates the second plate through the alignment marks of the first plate to provide a pair of diffracted beams that are detected with alignment being indicated when the beams are of the same intensity.
摘要翻译: 第一和第二板形成有类似的周期性图案。 激光束通过第一板的对准标记照亮第二板,以提供当光束具有相同强度时指示的对准检测的一对衍射光束。
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公开(公告)号:US4507783A
公开(公告)日:1985-03-26
申请号:US470148
申请日:1983-02-28
CPC分类号: H04L1/0057 , H04L7/048
摘要: Circuitry for detecting errors in a digital bit stream comprising a succession of data blocks and wherein each data block incorporates a parity check. At an error monitoring location, a bistable device toggles in response to either a logical "1" or "0" in the bit stream. The output of the bistable device is sampled at a submultiple of the bit rate and compared with a predetermined criterion to detect bit errors.
摘要翻译: 用于检测包括一系列数据块的数字比特流中的错误的电路,并且其中每个数据块都包含奇偶校验。 在错误监视位置,双稳态器件响应于位流中的逻辑“1”或“0”来切换。 双稳态器件的输出以比特率的多项式进行采样,并与预定标准进行比较,以检测位错误。
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公开(公告)号:US4200395A
公开(公告)日:1980-04-29
申请号:US793259
申请日:1977-05-03
CPC分类号: G03F9/7049
摘要: First and second plates are formed with like periodic patterns. A laser beam illuminates the second plate through the alignment marks of the first plate to provide a pair of diffracted beams that are detected with alignment being indicated when the beams are of the same intensity.
摘要翻译: 第一和第二板形成有类似的周期性图案。 激光束通过第一板的对准标记照亮第二板,以提供当光束具有相同强度时指示的对准检测的一对衍射光束。
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