Abstract: A method for decoding information contained in a waveform having a series of peaks is disclosed which is particularly directed to a method for reading a magnetic stripe for example on a card that allows the information on the stripe to be read without the need for unidirectional, single stroke swiping motion of the stripe. Features are disclosed that permit the accurate decoding of magnetic stripe data to define the bi-phase coded bits in the presence of signal degradations caused specifically, but not exclusively, by variations in the read speed including stop events and reversals. The method uses sampling of the waveform at a variable rate based upon the area of the waveform. The samples are used to locate peaks in the waveform, the profiles of which are then compared using various criteria with trained model peaks to classify the peaks into different types based upon the intersection between the different bits allowed under the bi-phase coding rules.

Abstract: Displacement of an object from a sensor is detected using a fiber optic a discharge end of which is arranged adjacent to the space from the object. Light passing along the fiber optic is reflected at the discharge end and is also reflected by the object at a position spaced from the discharge end. These two reflected parts of the light interfere causing an interference pattern. The light path from the discharge end to the object is cyclically varied using a sinusoidal dither obtained either by physical movement or by electro-optical means. This allows the output from the photo diode detecting the return reflected light to be analyzed as an alternating signal varying over time rather than as a simple comparison of absolute values as is used in the conventional techniques.