Fast techniques for time delay estimation

Two multiplication-free correlators (the hybrid sign and polarity coincidence correlators) are analyzed as fast alternatives to the direct multiply-and-accumulate technique in time delay measurements. Their accuracy limits are given for general signal and noise spectra and their dependence on signal-to-noise ratio (SNR), observation interval, and signal bandwidth is analyzed for a reference case, PC (polarity coincidence) variance has been verified to decrease uniformly with increasing SNR while HS (hybrid sign) variance does not. PC is verified to be a powerful tool if a certain loss in accuracy can be tolerated or recovered by properly enlarging the observation interval.<
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