设(7,4)分组码中,用S1、S2、S3表示3个监督关系式中的校正子,规定S1、S2、S3的值与错码位置的对应关系如下表所列,则监督关系式S1、S2、S3应为( )。
A.
S 1 =a 6 ⊕ a 5 ⊕ a 4 ⊕ a 2 , S 2 =a 6 ⊕ a 5 ⊕ a 3 ⊕ a 1 , S 3 =a 6 ⊕ a 4 ⊕ a 3 ⊕ a 0
B.
S 1 =a 6 ⊕ a 5 ⊕ a 4 ⊕ a 3 , S 2 =a 6 ⊕ a 5 ⊕ a 2 ⊕ a 1 , S 3 =a 6 ⊕ a 4 ⊕ a 2 ⊕ a 0
C.
S 1 =a 5 ⊕ a 4 ⊕ a 3 ⊕ a 1 , S 2 =a 6 ⊕ a 4 ⊕ a 3 ⊕ a 2 , S 3 =a 6 ⊕ a 5 ⊕ a 4 ⊕ a 1
D.
S 1 =a 5 ⊕ a 4 ⊕ a 2 ⊕ a 0 , S 2 =a 6 ⊕ a 3 ⊕ a 2 ⊕ a 0 , S 3 =a 6 ⊕ a 4 ⊕ a 3 ⊕ a 0