Abstract: An intrusion warning system for protecting a partition, for example, a wall, ceiling, window, fenced cage, against intrusion by cutting through and/or climbing over. A vibration detector is mounted on the partition and the partition vibration detected by sensing the electric signal generated by the detector. The sensed electric signal is filtered, AM detected, shaped and processed to determine if an intrusion type event has occurred. Since research has determined that the materials composing a partition cause the vibration frequency induced into the detector to vary considerably, the system has a plurality of band filters to allow selection of the band to best monitor the partition for a given application. The system supports this selection with a built in display for the input level through an input amplifier and filters for the frequency band selected. A given stimulus to the detector thus can be analyzed for each band and the band providing the highest output selected.