| 摘要 |
<p>Magnetic stripe documents are identified and authenticated on the basis of repeatable magnetic characteristics of a stripe recorded with digital data. Stripes are sensed to provide an analog signal, only a portion of which is used, specifically, the portion storing leading zeros. Cyclically, the leading zeros are sampled and digitized as a target number of samples using a frequency locked loop. The target number of samples for each zero is then reduced by a selection process that attains a predetermined number of digital samples that represent a magnetized portion of a leading zero, specifically, a space between data transitions. Groups of selected predetermined number of digital samples are then combined to provide a card magnetic characteristic identifier. The harmonic content of the characteristic identifier is tested as a measure of the quality of the stripe sensing. A predetermined level of quality conditions verification. Documents are verified by correlating reference and recent characteristic identifiers. Specific forms of sensor structures are utilized for the applications involving multitudes of different documents and sensor structures.</p> |
