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Graphics Interchange Format  |  1997-01-13  |  95KB  |  499x663  |  4-bit (16 colors)

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OCR: Suppose: (15,5) - binary BCH code with g( D) = D" + D8 + D3 + D+ + Dª + D+1 x(D) =0 -> all - zeros code word transmitted 3 errors occur at positions 2,5, 14 -> y(D) = D14 + D5 + D2 Then syndromes: Si= y(x) = 07 S2 = y(a2) = a14 S3 = x SA = 013 Ss = Q10 Algorithm at work: o(D) Output Sequence Comment 0(D) =1 0 Cannot produce S, 0x2 = a =S Cannot produce Ss S.S ., a =S. a= s ., 0=Ss Cannot produce Ss S1, S2 .S. , SA a"=S ,, a =S. Okay, so: error locators o(D)=1+0 D+a'D2 +a D' =(1+a D)(1+a D)(1+a"D) Table 4: Massey-Berlekamp algorithm in progress.

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