Patent ID: 8405524

Claim:
A method for detecting the passage of vehicles, comprising the steps of: locating a geophone on the ground at a known location and, processing the signals from the geophone to derive a density statistic number corresponding to the number of regular non-intermittent peaks of the geophone signal above a threshold set above a measured background level, whereby the number of non-intermittent peaks above the threshold indicate the presence of a vehicle, the background level being set using a standard deviation technique as a background level surrogate, the background level being set without computing square roots, the background level being set using s_estimate = 2 * 1 512 ⁢ ∑ i = 1 512 ⁢  x i  , where x i is the sample of the geophone signal x at time i to estimate the standard deviation, and s_estimate is the estimate of the standard deviation.