Patent ID: 7487411

Claim:
A method of detecting the current bit in a symmetrical differential phase shift keying modulated signal, comprising the steps of: calculating said current bit symbol S n using the recursive expression S n =S n−r *e (j*Π*bn/2) *e ((j*Π*bn−1)/2) . . . e (j*Π*bn−(r−1)/2) e (j*Π*bn/2) =S n *conj( S n−r )*e (j*Π*bn−1/2) *e (j*Π*bn−2/2) * . . . *e (j*Π*bn−(r−1)/2) wherein r is the number of past bits used for the detection of the current bit, S n−r is the r th past symbol, b n is the current bit and S n is the current symbol and n is the sequence index, j is the square root of −1; calculating the summation of all the r estimated bits using the equation b n — estimated =[S n *conj( S n−1 )+ S n *conj( S n−2) *e (j*Π*bn−1/2) +S n *conj( S n−3 )*e (j*Π*bn−1/2) *e (j*Π*bn−2/2) + . . . +S n *conj( S n−r )*e (j*Π*bn−1/2) *e (j*Π*bn−2/2) * . . . *e (j*Π*bn−3/2) ] wherein b n — estimated is the current estimated bit; and determining said current bit using the formula bit=sign(imag( b n — estimated)).