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Hand Held Mine Detector

As the above given illustration suggests, the mine detector to be developed consists of a detection element having both high frequency (microwave band) and low frequency (induction) channels. Both channels are employed simultaneously. The operation results of the induction channel are displayed on the monitor as an image as well. The detection element is placed inside the square frame of the two-dimensional scanner covered with the dielectric casing. Images received from both detection channels are processed in a real-time mode and displayed on the LCD monitor which is mounted on a handle in front of the operator. The mine detector handle has a counterweight block accommodating both interface and computer units, as well as a power source.

MiRascan ground-probing holographic radar that makes it possible to detect and identify slightly deepened (up to 20 cm) objects by their shape has been developed in the Remote Sensing Laboratory. The principle of the multifrequency sounding of the condensed media (construction structures, soils, etc.) was assumed as a basis of the radar design.

In the initial segment of this work, the mock-up of a wide-span mine detector MiRascan, which included, in the capacity of a detecting element, a five frequencies ground penetrating radar receiving signals in two crossed polarities. The detector's sensor was installed on the cart, which was set in motion by an operator manually.

In the course of further research, the mock-up of the mine detector MiRascan underwent modernization. Basic features of it were as follows:

1. On the lower flange of the GPR cylindrical antenna, the head of the metal detector was installed;
2. On the upper flange of the radar antenna, a generator metal detector block was installed;
3. On the axes of chassis front wheels of the mine detector the electrical motors working in the impulse mode were installed;
4. Remote control system of the mine detector movement was assembled. The operator via the remote control box, connected to the cart by the cable of 15 m length, exercises control over the movement of the mine detector.

The scanning in the lateral direction is carried out at the expense of electromechanical movement of the SHF device of the radar, and in the longitudinal direction due to the movement of the entire radar. The scanning results are displayed in the form of gray scale images on the monitor screen. Since it is difficult for an operator to perform a simultaneous analysis of all images on different frequencies, one animated image is formed in which sequential frames correspond to different frequencies.

The mock-up of the mine detector makes it feasible to survey the lane of movement 112 cm wide and to display the scanning results on the screen of a personal portable computer in real time.

The experiments to detect and identify mock-ups of the plastic-cased anti-personnel and antitank mines were conducted under the full-scale conditions. The experiments were performed on the special proving ground. The proving ground had sites with the key types of soils: sand, chernozem, loamy soil, etc., which ensures wide variation in their dielectric properties.

The mock-ups of the antitank plastic-cased mines of the types of TM-62P3 (manufactured in Russia), TC/6 and TC/2.5 (manufactured in Italy), of the anti-personnel plastic-cased mines of the types PMN-2 and MS-3 (manufactured in Russia), as well as of the metallic antitank mines of the types of TM-62M and PTM-3 (manufactured in Russia) were used in the capacity of the tested objects. All the mines except the PTM-3 mine had a round cross-section view, and the PTM-3 mine had a rectangular cross-section.

Wide-span System for Humanitarian Demining Operations

Introduction. Our team had taken an initiative in the development of MiRascan subsurface sounding radar to enable the operator to detect and identify objects buried under the ground at low depth (up to 20.0 cm) basing on their shape analysis. The operating principle of the radar design is based on the method of multi-frequency sounding of a condensed media (like building structures, grounds, etc.). The method offered has no counterpart in the world practice so far. (Russians Launch Anti-Bugging Radar. Microwave Journal, February 1998, Vol. 41, No. 2, pp. 47, 48). The creators of MiRascan radar are Russian Federation Government prize-winners in the field of science and technology for 1999.

One of the main problems while liquidating the aftereffects of local conflicts is mine clearance of the territories that were mined as a result of combat operations. The special difficulty in the process of humanitarian mine clearance is presented by the fact that minefields were laid as a rule chaotically, without compiling proper mine-field records (charts), as well as the fact that mines with antidisturbance fuses were also installed.

As a rule, the minefields are combined, which means that they include both antitank and anti-personnel mines. The major part of the mines has round cross-section view. The antitank mines have diameter of about 300 mm, and the average diameter of the anti-personnel mine amounts to 75 mm. Some types of the mines contain practically no metal, which substantially impedes their detection. In this case the key give-away factor lies in the blasting charges of the mines, the dielectric properties of which differ from analogous characteristics of the ground that covers them. Thus, relative permittivity e_r for the typical explosives is between 3.5 and 4.0. At the same time dielectric properties of the ground in the considered frequency range vary within a wide range from 2.6 to 25.0, depending on the composition and moisture content of the ground. The lowest value of the range is related to absolutely dry sand, which is found in the desert. In the overwhelming majority of cases er for the ground exceeds the analogous value for the blasting charge.

The heterogeneities of the surface, as well as a great number of foreign objects in the ground, especially in the urbanized localities create substantial difficulties in the mine detection operations. The dielectric contrast of these heterogeneities with reference to the ground frequently exceeds the contrast of the plastic-cased mines, which results in an inadmissible level of false alarms. At the same time, in accordance with the requirements of the UN, the probability of mine detection should amount to 99.6% at the low level of false alarms. But these requirements are not met by the existing technical means. Very often the mine-probing rod and snuffer dogs are the only aids of the sapper.

Description. The development of the wide span gears making the most of the spatial filtering to reduce the level of false alarms is one of the approaches to achieve the set aim. The mock-up of such mine detector using Russian-made mine detectors of the MMP type in the capacity of the search elements was designed in late 1980s.

The new design considers possibilities for the enhancement of efficiency of mine detection operations that thanks to usage of multifrequency SHF transducers coupled with metal detector and to generation of the radio images of the terrain in the lane of movement of a mine detector. An experimental mock-up with the transducer providing for scanning in two dimensions has been developed, and algorithms for the representation of information on the display screen in the form of animated images have been put forward. Proposed methods may find their use during peacekeeping and humanitarian operations. Fig. 1 presents the block diagram of the radar MiRascan.

The scanning in the lateral direction is carried out at the expense of electromechanical movement of the radar, and in the longitudinal direction due to the movement of the cart. The scanning results are displayed in the form of gray scale images on the monitor screen. Since it is difficult for an operator to perform a simultaneous analysis of all images on different frequencies, one animated image is formed in which sequential frames correspond to different frequencies.

The mines were deepened in the ground to the depth of 1 cm for the anti-personnel mines and to 5-8 cm for the antitank mines. The experiments were conducted on the two types of soils: heavily moistened sand and heavily moistened chernozem with turf cover. The soils had the natural moisture content close to the saturation as the experiments were carried out a day after the long heavy showers.

 

Diagram of mines arrangement in the proving ground	Microwave images of mine mock-ups in the examined lane with sandy soil