Underground Pressure Sensor measures the mechanical impulses induced by pedestrian intruder or vehicle passing over two buried tubes and gives information for the object type and movement direction. The tubes can be buried parallel to the protected area border or crosswise to the road at 10-15 cm deep and at 1.5 m to each other. At the end of each tube the pressure sensor converts the pressure change to electric signal which is then analyzed by microprocessor with DSP capabilities. The sensor automatically detects and classifies targets, determines the direction of passing, with accuracy of 5 m. The sensor is static and sends information for the recognized object to the Command Post Control Computer and/or to the Portable Command Post and can be used as part of larger sensory system. The sensor is designed to transmit data through cable (RS-485) and optional via radio module.

Markets
The Underground Pressure Sensor is used for detecting any intruders nearby any infrastructure and can distinguish between human steps, vehicles, heavy tracks and chain machines.
It is typically used to protect critical infrastructures, security installations, any government facilities, military camps, state borders.

Detection Method – How it works?
Underground Pressure Sensor Scheme

Underground Pressure Sensor measures the mechanical impulses induced by pedestrian intruder or vehicle passing over two buried tubes. The mechanical impulse created in one place of the tube propagates in both directions along the tube, reaches the both ends of the tube where it is cached with two properly tuned microphones. The two impulses time delay and amplitude difference allows calculating the exact place of passing.

System Advantages

  • High selectivity to ambient seismic noise;
  • Determine the direction and exact location of crossing the perimeter;
  • Low false alarms rate;
  • Practically invisible;
  • Low cost per secured linear meter;

System Layout
According to the customer requirements the system is designed in two different layouts:

Communication transmission through wire:
Communication transmission through wire

In this layout the sensor consist of sensory body composed of microcontroller and four microphones, two tubes buried underground at 10-15 cm deep, RS-485 data interface module and cable integrating data transfer capabilities and power supply. The data can be transmitted at distance up to 1200 m without repeater module. This system layout is recommended for usual stationary sensor system build around some buildings and/or facilities.

Communication through radio:
Communication through radio

In this layout the sensor consist of sensory body composed of microcontroller and four microphones, two tubes buried underground at 10-15 cm deep, 868 Mhz radio module, accumulator battery for autonomous power supply. The radio module can transmit data at 600 m in rough terrain and at 2000 m by direct site of view. The further data transition is accomplished with radio translator modules. This system layout is suitable for remote and difficult to access places without possibility for permanent power supply.

System Features

  • Distinguish between: human steps, vehicle and noise;
  • Gives the direction of movement – inside or outside the perimeter;
  • Gives the place of passage – accuracy of 5 m.;
  • Very low infrastructural expenses;

Specifications

Enclosure
IP67
Operating temperature
-35° C to +70° C
Relative humidity
100%
Operating voltage
5 V DC.
Cable power supply
12/24 V DC.
Power consumption
17mA at 12 V DC.
Passing object minimal weight
45 [kg]
Frequency range
low pass 150 [Hz]
Tube length
up to 150 [m]
Working temperature
-35° C ÷ +70° C
Sensor body
1.6 [kg]
Tube Diameter
18 [mm]
Underground Pressure Sensor measures the mechanical impulses induced by pedestrian intruder or vehicle passing over two buried tubes and gives information for the object type and movement direction.