21-09-2008, 11:14 AM
Definition
Landmines are affecting the lives and livelihood of millions of people around the world. The video impulse ground penetrating radar system for detection for small and shallow buried objects has been developed. The hardware combines commercially available components with components specially developed or modified for being used in the system. The GPR system has been desired to measure accurately electromagnetic field backscattered from subsurface targets in order to allow identification of detected targets through the solution of the inverse scattering problem. The GPR has been tested in different environmental conditions and has proved its ability to detect small and shallow buried targets.
Landmines and unexploded ordnance (UXO) are a legacy of war, insurrection, and guerilla activity. Landmines kill and maim approximately 26,000 people annually. In Cambodia, whole areas of arable land cannot be farmed due to the threat of landmines. United Nations relief operations are made more difficult and dangerous due to the mining of roads. Current demining techniques are heavily reliant on metal detectors and prodders.
Technologies are used for landmine detection are:
? Metal detectors--- capable of finding even low-metal content mines in mineralized soils.
? Nuclear magnetic resonance, fast neutron activation and thermal neutron activation.
? Thermal imaging and electro-optical sensors--- detect evidence of buried objects.
? Biological sensors such as dogs, pigs, bees and birds.
? Chemical sensors such as thermal fluorescence--- detect airborne and waterborne presence of explosive vapors.
In this seminars, we will concentrate on Ground Penetrating Radar (GPR). This ultra wide band radar provides centimeter resolution to locate even small targets. There are two distinct types of GPR, time-domain and frequency domain. Time domain or impulse GPR transmits discrete pulses of nanosecond duration and digitizes the returns at GHz sample rates. Frequency domain GPR systems transmit single frequencies either uniquely, as a series of frequency steps, or as a chirp. The amplitude and phase of the return signal is measured. The resulting data is converted to the time domain. GPR operates by detecting the dielectric contrasts in the soils, which allows it to locate even non-metallic mines.
In this discussion we deal with buried anti-tank (AT) and anti-personnel (AP) landmines, which require close approach or contact to activate. AT mines range from about 15 to 35 cm in size. They are typically buried up to 40cm deep, but they can also be deployed on the surface of a road to block a column of machinery. AP mines range from about 5 to 15cm in size. AT mines, which are designed to impede, the progress of destroy vehicles and AP mines which are designed to kill and maim people.
