A time-delay digital tanlock loop

We propose a nonuniform sampling digital tanlock loop (DTL) that utilizes a constant time-delay unit instead of the constant 90/spl deg/ phase shifter The new structure reduces the complexity of implementation and avoids many of the practical problems associated with the digital Hilbert transformer like the approximations and frequency limitations. The time-delay digital tanlock loop (TDTL) preserves the most important features of the conventional DTL (CDTL), such as reduced sensitivity to the variation of the signal power. It also introduces improvement over the first-order CDTL under suitable choice of the circuit parameters. The first- and second-order loops are analyzed for locking conditions and steady-state phase error.