Digital Gradiometric Magnetometer

• This novel magnetometer shows mass and location of ferrous objects in real time, displayed in a simple graphic interface to the user.
• Unlike other magnetometers, the DGM doesn’t need calibration, and is immune to all types of electromagnetic, or other, interference.
• DGM can be deployed by someone on foot, on vehicles, from the air, and buried or suspended, to find objects in place, or to monitor check points.

Background
Innovation
Benefits
Project Development
In Summary

Background
The earth generates its own magnetic field. This field is present over the entire surface of the globe at varying magnitudes and directions depending upon geographic location. This magnetic field also permeates the entire earth from core to crust including all oceans, and extends into space where it is called the magnetosphere. When a ferrous metal object is exposed to the earth’s magnetic field, a secondary field is induced through and around that object. This induced secondary field is less intense than the earth field, but if the object has sufficient mass and the magnetometer has adequate resolution, the object can be detected and certain properties of the object itself can be measured, such as size and location. Traditional magnetometry is used in archeology to find shipwrecks, subterranean foundations, fire pits, and other ancient artifacts. It is also used extensively in geophysics for oil and mineral exploration. Any object or geologic formation that interacts with the earth’s magnetic field has the potential of being detected with a magnetometer. Of particular interest to MRT are objects such as Improvised Explosive Devices (IED), Explosively Formed Projectiles (EFP), Land Mines, Small Arms such as hand guns and grenades, Suicide Bomb Vests, Unexploded Ordnance (UXO), and Large Weapons Caches, many of which can be detected by means of magnetometry.

Innovation
Although traditional magnetometers currently on the market can detect, locate, and map many types of these ordnance, they are not widely used for this purpose due to high cost, high energy consumption (making them less portable), and complex computer software programs that require highly trained operators. By contrast, the DGM technology is low cost, low energy consumptive (allowing long term portable operation), and simple to operate without the need for any computer data manipulation. In addition, traditional magnetometers, regardless of type, collect magnetic field information in the time domain, that is, data points are recorded one after the other in serial fashion. After a survey or interrogation is complete, these data must then be manipulated by complex computer software as a means to convert them to a meaningful map or grid location in the spatial domain. This is akin to looking through a soda straw to find a nickel lying in the desert; such a task is arduous, time consuming, and fraught with oversight errors. Our DGM technology is unique and revolutionary in this regard because it has the capacity to collect magnetic information directly in the spatial domain, in real time. Collecting information in the spatial domain – in real time – means that the operator can detect, locate, and map target objects as a survey or interrogation is conducted, not at some later date or time. This design architecture represents a fundamentally unique paradigm in the field of magnetometry.

Traditional currently available magnetometers are highly susceptible to electromagnetic interference from both natural and manmade sources. This is particularly problematic in battlefield environments that often have dense military and civilian radio frequency traffic. Because the DGM technology employs a unique differential sensing methodology, it is intrinsically immune to electromagnetic interference of any type whether manmade or naturally occurring. In addition, standard magnetometer systems require complicated calibration that must be frequently repeated, even over short periods of operation (such as hours). By contrast, the DGM system never requires calibration. In fact, after fabrication, the instrument does not require factory calibration before shipping it to the end user. In terms of ease of use, stability, and reliability, this feature of DGM technology is unmatched.

Benefits
The DGM instrument will find utility in the following applications:

• Real time three dimensional detection, location, and mapping of IED/EFP threat ordnance for military patrols in any battlefield environment. This utility would be particularly useful for saving lives and reducing injuries in any modern wartime conflict. For example, a daily aerial survey of a patrol or supply roadway may be accomplished as a means to detect any newly placed threat ordnance, whether buried or roadside emplaced. The DGM technology has the capacity to detect such ordnance through asphalt or concrete pavements below which large anti-vehicle IEDs are often placed.

• Real time detection and location of small arms, grenades, and suicide bomb vests donned or carried by pedestrian traffic walking towards or through a check point. Because the DGM technology collects magnetic field information in the spatial domain, it can be buried beneath a path leading through a chokepoint and continuously monitor the entire width of the path. If a pedestrian carrying a weapon or donning a bomb vest walks over the DGM system, the object will be detected and displayed to an operator in real time. This person may then be engaged at a distance, before approaching the checkpoint kiosk.

• Since there is no practical limit to the length of the sensing array employed by the DGM, it can be configured to continuously monitor vehicle traffic over the entire width of a roadway whether it is dirt, gravel, or paved. The DGM sensing array may be buried beneath or suspended above the roadway. Configured in this manner, traffic may be monitored as to activity, count, or vehicle size restrictions. For example, if only small cars are allow through a particular roadway chokepoint, or into a garage or other area, the DGM will alarm when a large vehicle or truck is detected; this is accomplished by means of measuring the mass of the detected object.

• In the case of roadway chokepoint monitoring, the physical length and mass of the passing vehicle can also be determined by the DGM. This allows the system to detect a large mass of ferrous metal concealed within the trunk of a passenger vehicle, or within the body of a small truck. Alerted in this manner, the vehicle can be tracked, stopped, or inspected for evidence of a bomb. This would be very useful for entrances to embassies, consulates, targeted hotels, power plants, barracks, etc.

• Mounted on an unmanned aerial vehicle (UAV), very large areas could be surveyed by the DGM system for weapons stockpiles or large weapons caches. For example, a single UAV helicopter traveling at just 50 km/hr could survey the complete land area of Iraq for stockpiles of weapons, located on the surface or buried, in just 73 days. Conventional methods would take years. Ten such vehicles each equipped with DGM systems could complete this survey in just over 7 days (searching 12 hours/day). In this case, a detailed map of the entire countryside of Iraq could be produced showing anomalistic concentrations of buried ferrous metal. These sites could then be targeted for close inspection by bomb disposal teams.

• Although the DGM instrument is not suited for detection of many anti-personnel land mines (because some are made of plastic and nonferrous metals), it can detect many types of anti-vehicle land mines and UXO that plague many areas and roadways in a number of countries. Notwithstanding this limitation, DGM technology may be useful as a follow up survey in areas cleared by conventional land mine detection equipment, principally inductive type metal detectors and dogs. Both dogs and conventional metal detectors are limited to just centimeters with regard to maximum detection depth. In contrast, the DGM can detect objects to a depth of 6 meters or more depending upon the mass of the ordnance. Once a field or area is cleared of shallow land mines, the DGM may be employed to detect large ordnance that often threatens operators of farm equipment, well drillers, or subsurface construction like building foundations and irrigation trenches.

Notwithstanding the DGM’s limited utility for land mine detection, the same mathematical algorithms developed for the DGM can be applied to a different sensing technology more suited for anti-personnel mine detection, location, and mapping. These may include IR, UV, acoustic energy, magneto-induction, and others; multi-sensor platforms are possible.

Project Development
MRT has completed the sensory architecture, array geometry, differential and gradiometric signal processing algorithms, and preliminary mathematical modeling required for the electronic system design. We are now prepared to design and construct a demonstration model for testing and evaluation. Since this is largely an engineering effort, that is, no further research or science is required, we expect that when properly funded, this phase of development could be completed in less than two years.

Provisional patent disclosures have been filed and accepted by the US and PCT patent authorities.

In Summary
The United Nations Mine Action Service estimates some 110 million anti-tank and anti-personnel land mines in place globally. World wide, approximately 800 deaths and 1,200 terrible injuries are caused by abandoned landmines, many are female children. These numbers are a sad commentary on our so called civil society. MRT is strongly motivated to do something positive to remediate or otherwise preempt these insidious threats from harming military and civilian populations. If our DGM technology is fully realized and implemented, we believe it has the potential for saving many lives and limbs throughout the world.