Patent ID: 8094764

Claim:
A method of matching a time delay of a first received signal in a controlled propagation path to a second received signal over an uncontrolled propagation path, the method comprising: (a) sampling a first signal of a known source; (b) delaying the first sampled signal in a variable delay line under control of a delay control signal; (c) sampling the first signal after all delays over the controlled propagation path; (d) sampling the second signal received over the uncontrolled propagation path; (e) forming a delayed sample of the first received signal; (f) forming a delayed sample of the second received signal; (g) generating a first autocorrelation value from the sampled first signal and the delayed sample of the second received signal; (h) generating a second autocorrelation value from the delayed first signal and the delayed sample of the second received signal; (i) computing a difference value between the first autocorrelation value and the second autocorrelation value; (j) decreasing a delay control signal to more closely match the time delay between the first received signal and the second received signal in the case where the difference value is negative and its absolute value is greater than a predetermined threshold; (k) otherwise increasing the delay control signal to more closely match the time delay between the first received signal and the second received signal in the case where the difference value is positive and its absolute value is greater than the predetermined threshold; and (l) repeating steps (a)-(k).