A Unified Approach to Closed-Loop Time Delay Estimation Systems

Hagit Messer

Research output: Contribution to journalArticlepeer-review


Recently, closed-loop delay estimation systems (CLDES) have gained considerable interest. In this paper, two generalized configurations for a closed-loop delay estimation system are discussed. The indirect correlation (IC) configuration is compared to the conventional CLDES–the direct correlation (DC) configuration. It is shown that the baseband equivalents of the two configurations differ only by the input noise. However, the noise power in the IC configuration is far less than that of the DC configuration. Using the known procedure for calculation of the variance of the time delay estimator, we show that the two configurations result in the same variance. However, this procedure is known to be incorrect since, for the direct correlation configuration (which is known to have an intrinsic noise that persists even when the input signals are ideal), the variance is nonzero for zero input SNR. Thus, we suggest another procedure for variance calculation that overcomes this problem, and it is shown, using our expression, that the variance of the time delay estimator is smaller for the IC configuration, provided the input SNR is not less that 0 dB.

Original languageEnglish
Pages (from-to)854-861
Number of pages8
JournalIEEE Transactions on Acoustics, Speech, and Signal Processing
Issue number6
StatePublished - Jun 1988
Externally publishedYes


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