Abstract: A system for verifying the authenticity of data contained in a magnetic medium using the remanent noise characteristics of the magnetic medium. In one embodiment, the invention includes a sensing unit configured to generate a signal indicative of the magnetic field of the magnetic medium, an analog-to-digital converter (ADC) in communication with the sensing unit and configured to digitize the analog signal, a filter in communication with the ADC configured to enhance the component of the signal associated with the remanent noise characteristic, a data extraction unit, in communication with the ADC and the filter configured to measure at least bit duration and peak location and an authentication extraction unit, in communication with the filter and the data extraction unit configured to extract a set of scaled samples from the output of the filter representative of the remanent noise characteristic.

Abstract: Apparatus and Methods for imaging magnetic fields and for using images of magnetic fields in the authentication of magnetic stripe cards or documents are disclosed. The systems described provide an increased tolerance for misalignments of magnetic reading heads. One preferred embodiment of the invention includes sensing circuitry for sensing an image of the magnetic field using an array of magnetic reading heads and sampling circuitry connected to the sensing circuitry.

Abstract: 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 a plurality of zeros. Cyclically, the 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 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.

Abstract: 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. 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.

Abstract: A data-bearing card is transported past a reading, writing or other communication head by at least one drive element connected to an electric motor through a preselected gear train. The mechanism moves the card at speeds corresponding to a preferred range of rates at which data borne by the card is intended to pass the communication head, and does so with a minimum of "jitter". In one particular embodiment, the gear train includes a worm screw driving a worm wheel for rotation with the drive element. In another embodiment, the electric motor is supported on a base oriented substantially parallel to the card being transported, and a shaft carrying the drive element and a first gear of the gear train is supported for rotation by at least one side plate detachably mounted to the base.

Abstract: A reduced-power dynamic magnetic transducer system includes a magnetoresistive read head, a low duty cycle pulse generator to supply power to the head, a signal processor, and a controller. As a data-bearing card is moved adjacent to the magnetoresistive read head, the pulse generator actuates the read head, thereby providing an intermittent signal representative of data recorded on the card. The intermittent signal is processed by the signal processor to reconstruct the original recorded data. The reconstructed data is utilized by the controller in conducting transactions with a user of the system.

Abstract: A device for degaussing magnetic transducers used with magnetic stripe cards includes a degaussing unit that drives a magnetic transducer with an electrical pulse, or a gradually increasing drive frequency, to eliminate the residual magnetism of the transducer. Logic circuitry controls the device to degauss with little or no additional equipment and avoids damage to the recordings, as on low-coercivity magnetic stripe cards.

Abstract: A digital system is disclosed for synchronizing data in a variable-rate pulse stream, as by the intervals of a magnetic recording medium. Functionally, an estimate is made of the size of a repeatedly recorded interval and the estimate is registered. In subsequent operation, the estimate is revised whenever it is found to differ from the recorded interval, based on an allowable tolerance. The revision is by a fixed percentage of the registered estimate. An oscillator drives a down counter which is variably pre-set in accordance with the prior timing history of the pulse stream (including a substantial number of pulses). Accordingly, each cycle of the down counter provides a variable sub-interval, a predetermined number of which are counted to provide each variable synchronizing interval. Comparisons of the synchronizing interval and the pulse stream serve to adjust pre-setting of the down counter to a current value.