Based on military seismic detection equipment, the SEISMIC SENTINEL, from inception, has been designed to be a cost effective alternative to its military cousins while maintaining equivalent functionality.
Soil, with varying degrees of efficiency, allows vibration disturbances from an impacting or movement generated source to be propagated. This transmission of vibrations through the ground is called seismic activity and can cover a wide dynamic range.
This seismic activity / vibration we are interested in for intrusion detection is very low in frequency and depending on distance from the sensor, low in amplitude / intensity.
The device that converts the soil transmitted vibrations into an electric signal is a geophone, usually just called the probe. It consists of a magnet suspended in the center of a copper wire coil and housed in a weather proof enclosure with a metal spike.
When seismic activity i.e. vibrations are transmitted via the metal spike to the magnet, very small electric currents are generated and transmitted by cable to the controller.
Sensing range for intrusion detection is dependent on one (1) main variable. Soil type. Loose, sandy soil is a poor transmitter of vibrations while packed soil is better. Mounting a probe in hard clay soil or into a road bed will increase sensing range.
Detection zone can be thought of sensing range as a circle with one (1) probe at the center. The diameter of this zone can range from approximately 50 feet for persons to more than 800 feet for sensing vehicle traffic depending on the soil and probe location. Probes can be paralleled to increase the detection zone.
The Controller is the heart of the Seismic Sentinel system and uses the latest in low noise and low power amplifier circuits. Not only does the electronics amplify and filter the signal it does so without amplifying the undesired electrical noise that is always present.
After conditioning and amplifying the signal is further refined via software before being displayed on the LED bar graph as relative amplitude. This added step of digital signal conditioning using a microprocessor is what makes the Seismic Sentinel so powerful.
Detecting people or vehicles (intruders) by underground vibrations they create when moving near a buried probe, is the ultimate in stealth surveillance.
Zone of detection:
A large diameter detecting area from the center location of a buried probe makes a very dynamic sensing system. When using seismic vibration monitoring the user only has to place a probe close to suspected intruder's path.
Portable or fixed location:
Rugged construction, battery or ac powered, makes the Seismic Sentinel suitable for any mission.Early warning for a camp site to monitoring a remote building for intruders.
Settable alert level:
A front selector switch allows setting the level of seismic activity at which to turn on the alert tone. This feature allows the user to ignore low level activity such as small animals but be alerted when the real threat is present.
10 position LED bar graph:
During normal operation the 9 LED positions indicate relative seismic activity strength.
The Seismic Sentinel designers used experience with the TRC-3 personnel detection system as a guide in creating a versatile and functional seismic detection system using current state of the art components. The Seismic Sentinel has taken a modern design approach for a low power, greater range, stealthy unit, and not use a radio link but instead a 2 wire connection from the probe. About any type of wire will work as the connection between the controller and the probe. We have units working at over 1/2 half a mile using surplus communication wire.