ensors for detection and surveillance have, for many years, been an important part of the “armoury” of any modern defence force. Deployment of a wide variety of different sensing technologies greatly increases the chances of reliable detection, and often helps to limit the chances of being detected yourself. Common technologies include RADAR, SONAR, PIR, acoustic and vibration. Magnetic sensors, or “magnetometers”, manufactured by Bartington Instruments, are a versatile addition to this list, offering some unique advantages for air, land and sea operation.
Magnetometers monitor the magnetic field at the point where they are placed. Geomagnetism (the Earth's own magnetic field) ensures that an ambient field exists virtually everywhere. Typically in a military application, we are trying to detect or measure anomalies or distortions in this field, and to determine what caused this change and whether it is significant.
Magnetic sensing is relatively short range, compared to other technologies, with detection distance depending on the size and composition of the “target”. In spite of this, it offers several advantages over other techniques:
- Passive sensing – magnetometers that measure changes in the background field emit very little signal, hence making their presence difficult to detect.
- Magnetic shielding, to eliminate or mask a device's magnetic signature, is difficult to achieve.
- Magnetic sensors are relatively immune to environmental conditions, being unaffected by ambient light levels, and not requiring “line of sight” to the target to operate.
- Natural objects (animals, vegetation, etc...) are virtually steel-free, so are largely ignored by the sensors.
- Low power requirements make magnetometers ideal for portable and battery-powered systems
Bartington Instruments Ltd. (UK) is a world leader in the manufacture of high-precision and low power magnetic field sensors for use in defence applications. The range of sensors manufactured has been designed for deployment in most environments (air, land and sea).
LAND-BASED SURVEILLANCE
Surveillance and detection is an important aspect of perimeter security in both military and high value commercial establishments. Multi-sensor systems offer an excellent solution, combining several methods to detect a would-be intruder. Magnetic sensors can be used with PIR, acoustic and vibration sensors in such systems.
Bartington Instruments manufactures a range of miniature low power sensors, for surveillance applications. The Mag566 is used in systems for both vehicle and personnel covert surveillance. Combined with suitable data processing, it is possible to achieve vehicle type identification as well as detection. Our latest generation of very low power magnetometers offer low noise and very low power performance. They are designed for integration in multi-sensor systems and |
offer very high resolution measurements and ruggedness to meet military standards.
MAGNETIC SIGNATURE MEASUREMENT
An important aspect of avoiding detection is to reduce your magnetic signature, ideally to the extent that you cannot be detected by magnetic methods. Large objects, like ships and submarines, can have a significant signature, making them vulnerable to detection/attack by aircraft or mines. A magnetic measurement range consists of an array of magnetometers, and is used to measure an object's magnetic signature.
The Bartington Instruments Mag-03 and Mag-03RC range of magnetometers are widely used for both land and submersible applications. They offer low noise performance for high resolution measurements. The Mag-03RC offers submersible capability and operation over long cables. The recently introduced DAS1 Data Acquisition System provides data collection and processing, and can be linked to a large array of magnetometers and other sensors, to form the basis of a complete magnetic range system.
This same system can also be used as a marine and submarine detection system, being able to track and analyse the signature of incoming vessels. It creates the perfect basis for a harbour surveillance facility.
On a smaller scale, the Spectramag-6 offers a low cost solution where magnetic measurement of smaller items is required. Close proximity to magnetic mines, as experienced by navy divers, demands a high degree of “magnetic cleanliness”. On minesweepers, all objects taken on board must be carefully controlled to limit overall magnetic signature. Spectramag-6 can be combined with two Mag-03 magnetometers to form a magnetic hygiene facility, ideal for control of equipment, in these circumstances.
AIRBORNE MAGNETIC MEASUREMENTS
An alternative to land or marine surveillance systems is airborne magnetic measurement to detect possible threats. By measuring the magnetic anomalies of the Earth's magnetic field, airborne surveillance systems can locate submarines and other military vessels. Such a system comprises a total field magnetometer, a three axis magnetometer and a data acquisition system.
For this application Bartington Instruments has developed the Mag629, a three axis magnetometer that enables monitoring of the aircraft attitude in flight. This data is then used to correct the total magnetic field data for the aircraft interference. This magnetometer is designed to military standards and offers a wide operational temperature range and low noise.
Bartington Instruments Ltd. (UK) is a world leader in the manufacture of high-precision, low-noise fluxgate magnetometers, used in defence, geophysics and underwater applications. This includes single and three-axis fluxgate sensors, fluxgate gradiometers and magnetic susceptibility measuring equipment. Its products are used by armed forces throughout the world.
For further information on Bartington Instruments products and services please visit www.bartington.com |
