A technique for decoding two frequency coherent phase recorded data using a digital decoder circuit

Two-frequency coherent phase (F2F) recording is a technique used for encoding data on magnetic stripe cards. In this method, a series of binary bits representing the data are encoded in terms of magnetised areas of different polarities along the tracks. The conventional method for decoding F2F is by using software. A purpose built digital decoder circuit can however greatly enhance the systems performance, such as speed. This paper describes a computerised security lock and access system using the digital decoder circuits to decode data retrieved from a hand held magnetic stripe card reader, and send it to the central computer via a parallel I/O converter.