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Bar codes: The little symbol that could Nikki Candelore Discrete Math: Summer ’08 Professor Langston
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What is a bar code?
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What we take for granted Store’s Centralized Computer Electronic Cash Register and Scanner Manufacturer Centralized Computer EID
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U.P.C: Younger than you’d think 1930s – Harvard punch cards 1950s – Drexel blanks and bars 1970s catalysts 1974, Wrigley’s gum in Troy Ohio Rising inflation and impact of labor grocery profitability Deux ex machina – 1973 FDA regulation change on labeling provides real impetus for change Consumer outrage at prices being removed 1990s – take off
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Source: (Brown 4) U.P.C: Younger than you’d think
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Universal Product Code: Main Features Source: (http://www.barcodeart.com/science/science.html)http://www.barcodeart.com/science/science.html
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Universal Product Code: Main Features Source: (Brown 282, 287) and (http://electronics.howstuffworks.com/upc1.htm) Module InterpretationNumber Systems Chars U.P.C. Digits
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Universal Product Code: Built in Checks Inverted bars after middle guard bar Splotches Check Digit Calculation Sum odd digits (1, 3, 5..) Multiply this by 3 Sum even digits (2, 4, 6..) Add this to value in Step 2 Determine then number that added to the above value would generate a multiple of 10
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Universal Product Code: Built in Checks Check Digit Calculation: Example Sum odd digits (1, 3, 5..) 6+9+8+0+0+9 = 32 Multiply this by 3 32*3 = 96 Sum even digits (2, 4, 6..) 3+3+2+0+3 = 11 Add this to value in Step 2 96+11 = 107 Determine then number that added to the above value would generate a multiple of 10 107 + 3 = 110 Therefore 3 is our Check Digit
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Other types of Bar Codes U.P.C. symbol Code 39 Interleaved Two of Five Source: (Gieco 30)
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Code 2 of 5 and Interleaved 2 of 5 Source: (Baker 21)
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Code 39 Source: (Baker 21)
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The Future: 2D bar codes 2D bar codes build on existing technology Stacks Matrices Check words Fun applications p8t.ch website – 2D patches that when scanned links to URL p8t.ch Source: (http://www.barcodeman.com/faq/2d.php)http://www.barcodeman.com/faq/2d.php PDF417 Stacked Matrix
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The Future: Radio Frequency Identification Electronic device uses radio frequencies to communicate No need for line of sight Holds more information than a bar code Can be read from or written to Security issues remain a concern, particularly for consumers Source: (http://www.howstuffworks.com/rfid.htm)
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The Future?
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