Abstract: A container monitoring system can generally comprise a first door controller, a second door controller, and a controller module. The first door controller module can be disposed in communication with a controller module. The first door controller module can be configured to receive a first random generated code from the controller module and further configured to store the first random generated code. The second door controller module can be disposed in communication with the controller module. The second door controller module can be configured to receive a second random generated code from the controller module and further configured to store the second random generated code. The controller module can be configured to separately interrogate the first door controller and the second door controller and configured to establish an alarm condition based on one or more signals received from the first door controller and the second door controller.

Abstract: A container monitoring system can generally comprise a first door controller, a second door controller, and a controller module. The first door controller module can be disposed in communication with a controller module. The first door controller module can be configured to receive a first random generated code from the controller module and further configured to store the first random generated code. The second door controller module can be disposed in communication with the controller module. The second door controller module can be configured to receive a second random generated code from the controller module and further configured to store the second random generated code. The controller module can be configured to separately interrogate the first door controller and the second door controller and configured to establish an alarm condition based on one or more signals received from the first door controller and the second door controller.

Abstract: A structure intrusion may be determined. For example, a signal may be received corresponding to a wave propagating in the structure. Next, the received signal may be analyzed. Based on the analysis in a “passive mode”, a breach may be determined to have occurred in the structure when the received signal indicates that at least one aspect of the received signal crosses a predetermined threshold. Furthermore, based on the analysis in an “active mode”, a breach may be determined to have occurred in the structure when comparing the received signal to a baseline waveform indicates that at least one aspect of the received signal varies from the baseline waveform by a predetermined amount. The wave propagating in the structure may comprise an elastic wave and may be in an acoustic frequency range or in an ultrasonic frequency range.

Abstract: A structure intrusion may be determined. For example, a signal may be received corresponding to a wave propagating in the structure. Next, the received signal may be analyzed. Based on the analysis in a “passive mode”, a breach may be determined to have occurred in the structure when the received signal indicates that at least one aspect of the received signal crosses a predetermined threshold. Furthermore, based on the analysis in an “active mode”, a breach may be determined to have occurred in the structure when comparing the received signal to a baseline waveform indicates that at least one aspect of the received signal varies from the baseline waveform by a predetermined amount. The wave propagating in the structure may comprise an elastic wave and may be in an acoustic frequency range or in an ultrasonic frequency range.