| 摘要 |
A method of reading on a record medium a two level code representing at least one character of a set of characters, each character having six consecutive transitional occurrences between the two levels of the code comprising: scanning the record medium to derive a time based electrical signal representative of said transitional occurrences; measuring four periods between alternate ones of said transitional occurrences; comparing each two overlapping periods to generate three ratios, each ratio representing not more than one of three possible values of nearly one, smaller than one and larger than one, and; decoding the values arrived at for said three ratios to define a character. The arrangement of the coded indicia on the record medium or the font of type for imprinting the same is such that, for each character, not more than two bits of the same level are arranged consecutively and two consecutive bits of a first level are not immediately followed by two consecutive bits of a second level.
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