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bar codes (Hamming code (Parity bits are located at powers of 2, Parity…
bar codes
Hamming code
Parity bits are located at powers of 2
Parity check starts from current parity bit Pn
check n bits skip n bits
If there is one error, it is the sum of number of error bit
Can’t correct 2 bit error but can detect it
UPC
101+number system+ODD+01010+EVEN+modulo check+101
(n,k)
modulo check
right to left
next highest multiple of 10 - 3*odd+even
EAN-13
country code+prefix and item number+check digit
difference
ink spreading
1(start)-0(end) or 0(start)-1(end)
except for T4
2D barcode
Ordered grid of light and dark spots with a finder parrern
Require 2d scanner typically camera or imaging technology