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Writing and Decoding Homologous Two Frequency Codes

IP.com Disclosure Number: IPCOM000082026D
Original Publication Date: 1974-Sep-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Vinal, AW: AUTHOR

Abstract

The well-known two-frequency code, or F2F code, as used in a variety of banking and credit card systems, is ordinarily written with separate stand-alone characters. A homologous code avoids the use of intercharacter gaps and stand-alone character properties. Coded messages written in homologous F2F code can be detected by the use of optical or magnetic scanners, which are hand held or stationary.

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Writing and Decoding Homologous Two Frequency Codes

The well-known two-frequency code, or F2F code, as used in a variety of banking and credit card systems, is ordinarily written with separate stand-alone characters. A homologous code avoids the use of intercharacter gaps and stand-alone character properties. Coded messages written in homologous F2F code can be detected by the use of optical or magnetic scanners, which are hand held or stationary.

A four-bit binary F2F homologous code example is shown in the figure. The ability to print the code in a homologous or unbroken line depends upon using a double representation for each coded F2F character. The first representation is arbitrarily defined as a lower case version of the character. The second version of the character is arbitrarily defined as the upper case. Both representations define the same character and the difference between character representations is the polarity of the signals or bars as represented in digital form.

In the figure, the lower case representation is the complement of the upper case representation for each character. All of the characters in both the upper and the lower case font have a command function associated with the transitional signal change at the end of the character designated as lower case (LC) and upper case (UC) labeled after the character. For example, if a character is written using the lower case representation and has as its ending transition an upper case command fu...