ADVANCING GPR FOR STANDOFF MINE DETECTION WITH CHELTON’S AMULET RANGE
By Daniel Goodliffe, Business Unit Manager and Neil Tisdale, Chief Engineer, Land Systems, Chelton Limited
INTRODUCTION
Chelton has leading edge expertise in developing advanced Explosive Ordnance Detection (EOD) systems using Ground Penetrating Radar (GPR) to support counter-IED and mine clearance operations. The high performing GPR sensors can detect objects that would typically evade metal detection such as those made from plastic or wood as well as improve clearance efficiency by reducing false alarms from metallic clutter.
Our GPR sensors can be found on Vallon detectors, one of the world’s leading manufacturers of Explosive Ordnance Detectors. Trusted by the US Marine Corps, The British Forces and The HALO Trust, well known for mine clearance, Chelton’s GPR sensors are proven in the battlefield to detect and clear mines from areas of conflict.
The nature of Improvised Explosive Devices (IEDs) is that their design is rapidly evolving with hostiles adapting quickly to new techniques to evade detection and be increasingly destructive. Often, they can include multiple trigger mechanisms which further increase the risk for search and removal operators. Instead, a new solution is needed to take the soldier out of the danger zone whilst still being able to identify and remove threats efficiently.
The following whitepaper demonstrates and concludes how Chelton has applied its extensive experience in GPR to the next-generation of stand-off detection systems removing search operators from the immediate danger they face in the field. Operating on the same low-burden principles offered by Chelton’s handheld EOD GPR technology, the philosophy that the capability is easy to train and operate remains unchanged.
THE EVOLUTION OF GPR
In 1944, Sappers (a.k.a Royal Engineers) in the British Army were pictured clearing the last mines from a Normandy beach. In these treacherous times, brave soldiers and humanitarians would clear roads of mines with slow and careful scanning using metal detectors.
To assist in identifying potential mines, Ground Penetrating Radar (GPR) was introduced; initially sold to the industry as a ‘magic, see everything radar’ for geological, civil engineering and historical uses, GPR was adapted for military purposes during the Falklands War by Chelton’s predecessor ERA Technology.
British Army ‘Sappers’ in 1944 excavating mines from Normandy Beach.
WHY LANDMINES ARE STILL A PROBLEM
We’re all familiar with the shots of Princess Diana walking through a minefield in Angola as part of a HALO managed mine clearance operation. Her determination for campaigning against landmines won many over with the signing of the Ottawa Mine Ban Treaty calling for all countries to unite and rid the world of landmines.
Over 60 countries across the world are still contaminated by landmines and thousands live with the continued dread of injuries to themselves or their families. Not only is the loss of life prevalent, but landmines deprive families and communities of land which could be better used for purposes such as agriculture. This deprivation impedes a country’s development for many years. The Landmine Monitor 2020 report stated that at least 156km2 of land was reported to have been cleared of landmines in 2019 and more than 123,000 mines were cleared and destroyed; an increase in the 98,000 landmines destroyed in 2018. Countries such as Afghanistan, Iraq and Yemen have all continued their commitment to landmine clearance despite ongoing conflict.
Though many nations are committed by international treaties not to use landmines, there are still a number of nations not bound by treaties and that continue to use mines. In addition, the international treaties have rightly focused on the use of anti-personnel mines due to the indiscriminate damage they can inflict on people especially civilians. However, anti-vehicle mines continue to present a danger to civilians, preventing safe travel and key post-conflict development activities such as farming.
IEDs, while no longer a new threat, continue to pose a danger to civilians particularly post-conflict. Abandoned Improvised Mines (AIM) is the new term for IEDs abandoned by those who buried them. Agencies who remove them, like The HALO Trust, could inadvertently make themselves a target by removing the AIM and consequently seeming to take sides in a conflict.
THE PRINCIPLES OF GROUND PENETRATING RADAR
GPR is a geophysical locating instrument which uses radio waves in the microwave band to capture images below the surface of the ground. Used in humanitarian missions for mine detection as well as by utility companies, it allows crews to pinpoint the exact location of items under the ground without disturbing it.
GPR operates by transmitting radio frequency (RF) signals into the ground. Objects buried within then reflect back a portion of the RF signal which the GPR detects and processes. Software within the GPR translates the signals received into a form that can easily be interpreted by the operator e.g. audio tones or visual images of the signal.
The HALO Trust using VMR3.
DATA WITHOUT THE DESTRUCTION
The possible applications of GPR are endless; from mine detection in the barren lands in Afghanistan to investigating the burial site of the world’s most famous playwright – all without breaking ground.
Not only can it provide invaluable information without disrupting the surface, GPR is extremely cost-effective, safe to use and can provide actionable data covering large areas made up of a variety of ground materials whilst penetrating at a range of depths through frequencymodulation.
Chelton has decades of experience in developing GPR solutions for humanitarian and military mine detection systems. With experience in research and development, product development, trials and evaluation, equipment delivery and in service support including training, documentation and logistics, Chelton has developed a range of single and dual sensor detection products including handheld detection systems, robot mounted remote detection systems and vehicle mounted detection systems.
Interactive Display on VMR3G.
The Explosive Ordnance Detection Systems (EODS) have key expertise in delivering complex detection equipment programmes and training solutions under short timescales into operational environments. The delivery team are supported by both an engineering department with key competencies in hardware, software, embedded systems and RF front-end architectures, as well as a manufacturing department highly skilled in volume production of niche, complex hardware capable of working reliably in the most demanding environments.
Chelton has leading-edge expertise in developing advanced EOD Systems using GPR to support Counter-IED and mine clearance operations. Our GPR technology is integrated to well-established Vallon detectors including the VMR3/G which utilises GPR to search for non-metallic components and VR1 Wirehound which can identify wires and cable components from 10cm in length. These high-performance systems are designed for the most demanding requirements and take GPR one step further with both handheld (dismounted), vehicle-based (mounted and stand-off) EODS GPR detection products, as well as innovative EODS virtual- reality (VR) training support systems. Our high-performance GPR detection systems are modular and scalable for simple integration onto a range of unmanned aircraft and ground vehicle systems (UAS and UGV) as well as more traditional platforms.
PERFECTING THE TECHNIQUE
The technique to effectively operate a handheld GPR system differs from that of a traditional metal detector. It is particularly important that the sensor head is swung in a low and controlled sweep pattern in order to accurately identify threats. As such, training is an important component for the effective use of GPR handheld systems.
This is where Chelton’s innovative training system comes in, available in both VR and non-VR, the system provides training for all our GPR products, providing data on the accuracy and control of the GPR search head, sweep angles and more. It also provides an environment where procedures can be practised, with the ability to place markers and choose from a variety of targets so that training can mirror the expected theatre of operation.
Chelton’s GPR Virtual Training System.
TURNING UP THE DIAL ON TRADITIONAL GPR
Chelton has applied its extensive GPR experience to the next-generation of stand-off detection systems, which takes the operator out of harm’s way by mounting GPR-based detection systems onto tactical vehicles and Unmanned Aircraft Systems (UAS).
Introducing Chelton’s newest offering – AMULET; a scalable, modular detection system capable of detecting buried IEDs, Anti-Vehicle Mines (AVM), and other Explosive Remnants of War (ERW) in a wide variety of soil conditions from a manned or unmanned platform. Designed meticulously to be low size, weight and power (SWaP), AMULET operates on the same low-burden principles instilled in our handheld Minehound EOD GPR technology maintaining the philosophy that the capability will remain easy to train and operate.
Vehicle Mounted EOD with AMULET Quadpack.
The sensor can be mission installed onto any tactical or robotic vehicle for fast deployment detecting metallic, minimum-metal and non-metallic threats including AVM mines as well as IEDs.
Chelton’s AMULET Quadpack.
THE UPRISING OF DRONES
The recent surge in professional grade Unmanned Aircraft Systems (UAS) has allowed larger and more complex payload applications to emerge. Combined with the intent to make IED and mines detection a standoff capability, a clear synergy exists between UAS and GPR.
UAS Mounted EOD with AMULET Quadpack.
A key desire remains to remove the human from the threat and danger of mine detection through the use of standoff detection methods. This would allow either a mounted or handheld system to remain at a safe distance whilst detecting the threat ahead of it. One approach is to use forward looking radar, however the difficulty with this approach is propagation into the ground. When a signal is fired at an oblique angle, it significantly lowers the strength of any returns reducing its ability to detect targets of interest. Through a surface, this angle, known as the ‘Brewster Angle’ exists, which prevents meaningful signal penetration into the ground. GPR works best looking directly downward and so the combination of a UAS that allows downward looking and standoff solves this capability gap.
UGV Mounted EOD with AMULET Quadpack.
With the recent improvements in endurance and payload capacity of commercial UAS systems combined with the reduction in size, weight and power of GPR systems the potential for UAS GPR mine detection has come of age. In addition to this, UAS systems can benefit from the advantage of scanning a large geographic area at high speed without sacrificing accuracy. The system is also able to map potential threats in real-time so that they can be actioned. Chelton is at the forefront of pioneering development of such systems, tailoring of the sensor system to the platform and requirement.
Chelton have demonstrated the capability of UAS mounted GPR using commercial off the shelf components by prototyping a TRL6 system and is currently looking to further enhance the capability. The AMULET GPR sensor is at TRL9 for operation as part of a modular system on vehicle applications. The sensor has been integrated to a commercial UAS system for development for field trials at TRL6.
AMULET UAS KEY COMPONENTS
The key components of a UAS GPR system are brought together to provide a demonstrator capability that will offer the potential for use in humanitarian and military scenarios. The UAS carries a payload comprising an AMULET QuadPack GPR system enabling the detection of landmines ensuring efficient data delivery to the operator. Table 1 describes key components for the successful integration of an AMULET UAS.
Table 1 – The AMULET Ingredients.
AMULET UAS QUADPACK
GPR data is acquired using the AMULET UAS QuadPack. The QuadPack antenna aperture on the underside of the enclosure must be kept approximately 15cm from the ground surface during steady flight with forward speed maintained at approximately 5kph. These bounds will allow for effective detection of buried threats such as Anti Vehicle Mines and large IED components. The AMULET UAS is not currently optimised for use against small threats; in this case, handheld search should be used.
INTELLIGENT DISPLAY
GPR data is displayed using the AMULET for Unmanned Systems Control and Display software which can be run on a ruggedized laptop, or an embedded computer with a separate display. The software provides a simple colour map, which shows detected mines or IEDs as a red anomaly against an otherwise black background. Signal strength builds from green through yellow to red allowing interpretation of the size and shape of the detected threat.
Proposed Approach
Chelton have previously conducted a test and evaluation work package that demonstrated the feasibility of mounting an AMULET Robot as shown on the images within this page.
The AMULET UAS QuadPack has so far been used in a demonstrator system and a detailed integration process would be required for any future trials.
UAS Mounted EOD with AMULET Quadpack.
Clearance Management Tool.
Concept of Use
AMULET UAS could be used for the search of suspect hazardous areas. The system would be particularly useful when the risk is too high for human operators, this could include river minefields, flooded minefields and immediately after conflict has ceased.
AMULET UAS intelligently calibrates itself using a first pass 1M altitude flight, where it gathers a free space reference signal to map out the terrain. AMULET UAS then begins its automated mine mapping process at 15cm, adjusting its course and altitude to match the previously mapped terrain contours keeping the GPR sensor at the optimum height for accurate identification of targets.
Integration with Clearance Management Tool
Chelton have developed a Minefield Clearance Management Tool (CMT) for use with all types of sensor systems that detect mines, IEDs and ERW. This CMT has been developed under the Mine and IED Detection Augmented by Satellite (MIDAS) project that also encompasses virtual training systems.
As an extension to the HMI for AMULET unmanned systems, Chelton would propose that the CMT, as shown, is used to allow threat recording and paperless reporting in an IMSMA compatible format.
The CMT runs on a laptop computer, or a tablet computer, and may be accessed remotely using a web- based interface. Individual detectors, be they handheld, vehicle or UAS mounted are equipped with Chelton supplied GNSS tracking systems capable of <5cm CEP precision. The track that each detector has followed, any associated detection data is then recorded electronically for reporting and assurance processes.
CONCLUSION
Landmines continue to pose a threat despite international efforts to ban their use. In addition, the rise in the use of IEDs and the recent Ukraine conflict have only further compounded the issue. While search operators from militaries and humanitarian organisations battle to remove threats from areas of conflict, they continuously put their safety at risk.
But there is a way to remove the threat to those who are there to help and that’s by utilising innovative search technologies with UAS and UGV systems which will protect the operator and take them out of the danger zone. This is where Chelton comes in.
With our extensive experience in GPR, we have developed innovative solutions for the next generation of stand-off detection systems. Not only will these systems allow more ground to be covered in less time and with more accuracy, it does so without the need for a search operator to be in the middle of an active minefield or battlefield.■
ABOUT THE AUTHORS
Daniel Goodliffe joined Chelton in 2005 following a graduate scheme and has progressed to undertake a wide range of roles across various parts of the business. Daniel has held roles in Project and Programme Management, Operations, Contracts & Commercial, Inside Sales and most recently as Business Unit Manager for our portfolio of Land product lines. Daniel has a Master’s Degree in Aerospace Engineering.
Email: daniel.goodliffe@chelton.com Tel.: +44 (0) 1628 472072
With a Masters and Doctorate, Neil Tisdale has been with Chelton for over 10 years working as an Engineer. After working in a variety of different engineering disciplines, Neil is now the Chief Engineer for Land Systems looking after our Explosive Ordnance Detection, Vehicle Intercom Systems and more.
Email: neil.tisdale@chelton.com Tel.: +44 (0) 1628 274930
Generic enquiries can be directed to info@chelton.com
ANNEX
SYSTEM OVERVIEW
Aim of the system: what can it detect/classify and under which conditions?
Chelton’s AMULET QuadPack for Unmanned Aerial Systems is suitable for the detection of metal, minimum-metal and metal free components thanks to its maximum sensitivity. The system is also ideal for searches at different depths and across a wide range of terrain.
CONOPS/CONUSE
The system uses Differential GPS (D-GPS) to provide high resolution positioning and height sensors to autonomously follow a mission profile. On-board processing provides assisted anomaly detection to output the size and position information of anomalies to a Clearance
What does the system look like?
CMT System Overview.
Management Tool (CMT) for real time tracking of anomalies during the mission.
Real time display of the GPR provides CScan and Bscan view of the data during the tuning procedure for the system. Data is logged onboard the UAS for detailed analysis of GPR data to allow post-processing.
Primary technology applied
The primary sensing technology used is GPR.
Conditions of use
Operational environmental conditions are limited by the commercial UAS system with wind speed limit (8m/s) and precipitation (not rain protected). Range of the remote control is specified as 2.1km, but regulation limits it to Visual-line-of-sight (VLOS) for trials.
Info on transmitted RF
- AMULET GPR – 300MHz – 3GHz, impulse transmission (330ps at 4MHz PRF)
- UAS Control frequency 2.4GHz – 2.483GHz, 16dBm EIRP
- GPS-RTK modem – UHF 403Mhz – 473MHz (12.5kHz band)
- Processor – WiFi 2.4GHz for real- time view of processed data
- CMT communications – Xbee WiFi 2.4GHz
Download PDF: Daniel Goodliffe and Neil Tisdale, Chelton – COUNTER-IED REPORT, Autumn 2022