| 摘要 |
<p>An information system comprising: a medium having an information pattern encoded as changes in two values of a medium characteristic, including start and end key patterns which have characteristic value changes spaced a fixed distance apart, and including intermediate characteristic value changes, which, with the key patterns, encode information; two sensors spaced from each other the fixed distance for sensing the medium characteristic value changes as the medium and the sensors are moved relatively to each other, and for producing signals representative thereof; and circuitry for processing the signals from the sensors to produce an information signal. <IMAGE></p> |
