| 摘要 |
An apparatus for detecting a cavity comprising a signal receiver, a signal analyzer and a threshold excedent determination processor. The signal receiver receives a reflected signal resulting from an interaction of multi-frequency irradiating signal(s) with at least one cavity. The irradiating signal may include an electromagnetic or acoustic signal above a cavity dependent cutoff frequency with a randomized spectral component. The signal analyzer computes cavity detecting statistic(s) of the reflected signal. The cavity detecting statistic(s) may include an autocorrelation function. The autocorrelation function may be a Fourier transform of the power spectral density of the reflected signal. The threshold excedent determination processor generates a notification when cavity detecting statistic(s) exceed a threshold. The threshold may include a multi-variable function. The cavity may be the bore of a weapon. The apparatus may be configured to determine the bearing from the cavity to the apparatus. |
