The Seismic Sensor is developed for the purpose of perimeter security and/or protection of critical infrastructures. The main idea is to distinguish between human penetration/intruders, vehicles and/or occasional events in given territory.

• Sensitivity to human steps – up to 50 m (depending of the soil and terrain)
• Sensitivity to vehicle – up to 100 m (depending of the soil and terrain)
• Sensitivity to heavy track and chain machines – up to 300 m (depending of the soil and terrain)
• Determination of relative distance to the sensor (about 40% and 100%) from maximal detected distance.
• Probability of object classification – more than 70 %.

The design of the Seismic Sensor allows functioning as a single autonomous application or as an integrated part of multi-device surveillance system and can be successfully applied for different kind of terrains and soils. After the real-time signal analysis, the Seismic Sensor sends the code of the recognized object to the Control Centre. The ultra-low power consumption of the product offer very long operational life. The seismic sensor can be used as part of the larger sensory system or as a standalone devise.

SEISMIC SENSOR MAIN COMPONENTS

The Seismic Sensor comprises:

• Sensor unit –Metal head containing the probe/sensor and microcontroller with embedded algorithms. It generates information for the radio module. On the bottom of the head is bed for sharp skewer that helps grounding the sensor unit.
• Power unit – IP65 Metal box with battery power supply and radio transmitter/receiver. It transmits and retransmits digital information and provides necessary voltage for operation of seismic sensor.
• Sharp skewer – metal rod which is used to ground the sensor and for transfer the surface ground vibrations to the sensor unit.

SEISMIC SENSOR PRINCIPLE OF OPERATION

The sharp skewer should be screwed to the sensor unit. Thus, the sensor unit can be grounded. The digging of about 20 cm depth allows efficient operation of the sensor and protects against environmental influences (for example rain). The sensor unit should be connected to the power unit by cable. Because of the radio transmitting the power unit should be places on the ground level or mounted as higher as possible (the radio transmitting distance depends on the height of the antenna).

After setting up the seismic sensor, vibrations propagating along the surface of the ground are transmitted to weight through the skewer. The vibrations are transformed to voltage signal from differential sensor. The signal is amplified and processed in microcontroller with embedded algorithms for recognition.

Receiver-transmitter of the Seismic Sensor
The receiver-transmitter is designed to transmit and retransmit commands/digital information to the command post control. It is located in to the power unit. Radio module is a part of mesh network which is built from all radio modules located in different sensor devices. The mesh networking is set to transmit/retransmit signal in every 4 seconds. Most of the time radio modules are in “sleeping” mode in order to save battery power.

OPERATING INSTRUCTIONS FOR SEISMIC SENSOR

1. Screw the mounting spike to the seismic sensor base.
2. Spike the seismic sensor in the ground so that only the top lid stays over the ground. The sensor must be positioned vertically and densified with the ground to express better sensitivity. (It is possible also to bury the seismic sensor under the ground, so that the whole sensor can be hidden).
3. Connect the seismic sensor cable to the radio module. To reach reliable connectivity and sealing screw the metal nut to the radio module coupling and then press the cable plastic part toward the coupling. (The seismic sensor is powered up and starts to work immediately after the connection between sensor cable and the radio module.)
4. Place the radio module upright on the ground near to the seismic sensor.

To check the seismic sensor condition and/or connection go near or tap several times with the foot and wait for the arrival of alarm message to the command center or use the bidirectional communication potential.