Walsh code
Encyclopedia : W : WA : WAL : Walsh code
The Walsh code is used to uniquely define individual communication channels. Walsh codes are “orthogonal” mathematical codes. As such, if two Walsh codes are correlated, the result is intelligible only if these two codes are the same. As a result, a Walsh-encoded signal appears as random noise to a PCS CDMA capable mobile terminal, unless that terminal uses the same code as the one used to encode the incoming signal.
Example
Denote W(k, n) as Walsh code k in n-length walsh matrix. It means the k-th row of H(m) Hadamard matrix, where n=2m. Here k could be 0,1,...,n-1W(0,1) = 1
W(0,2) = 1, 1
W(1,2) = 1,-1
W(0,4) = 1, 1, 1, 1
W(1,4) = 1,-1, 1,-1
W(2,4) = 1, 1,-1,-1
W(3,4) = 1,-1,-1, 1
W(0,8) = 1, 1, 1, 1, 1, 1, 1, 1
W(1,8) = 1,-1, 1,-1, 1,-1, 1,-1
W(2,8) = 1, 1,-1,-1, 1, 1,-1,-1
W(3,8) = 1,-1,-1, 1, 1,-1,-1, 1
W(4,8) = 1, 1, 1, 1,-1,-1,-1,-1
W(5,8) = 1,-1, 1,-1,-1, 1,-1, 1
W(6,8) = 1, 1,-1,-1,-1,-1, 1, 1
W(7,8) = 1,-1,-1, 1,-1, 1, 1,-1
Notice, it can also be constructed by walsh tree.
See also
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