Card magnetic strip reader system including a test system to check for correct identifying sequences (nulls) in addition to data stored on the strip by use of a frequency control loop

摘要

Identifying magnetic strip has digital data and repeating identifying data. A system is provided for reading magnetic strips on cards or documents which produces an analogue signal that is then digitized and can be stored in memory. Identification system for the magnetic strip has a detector for determination of the sampling interval in the analogue signal, a circuit for definition of a desired number of samples in the sample interval, a digitizer for sampling the signal according to the number of samples, a selection processor to select a predetermined number of digitized samples from the desired number of digitized samples and the repeating identifying data and a memory for storage of the digitized data samples for characterizing the document.