Ground penetrating radar (GPR) is being developed to detect landmines using impulse GPR. The system works by transmitting nanosecond pulses from an antenna and analyzing the return signals, which show differences when a landmine is present. It uses hardware including an impulse generator, antenna system, pulse extender, A/D converter, processor and visual display. The processor filters signals to identify signals indicating a landmine. While GPR can accurately detect mines with centimeter resolution even without metals, challenges include false alarms from background signals and the need for more advanced arrays to increase scan speeds.
3. Introduction
> Around every 22 minutes one person some where in the world is killed or injured
by a land mine.
> Nearly 50 million unexploded land mines in 60 countries around the world.
> Large portions of land go unused due to fear of mines.
> Modern mines can be constructed with plastics and composites.
6. Technology used to Detect the land mines:
> Metal detectors
> Nuclear magnetic resonance
> Thermal imaging and electro optical sensors
> Biological sensors
> Chemical sensors
10. Ground Penetrating Radar:
> The impulse GPR system has been developed in the International Research
Centre for Telecommunications Transmission and Radar(IRCTR).
> This ultra wide band radar provide centimetere resolution to locate even small
targets.
> Two distinct types of GPR Time domain , Frequency domain.
> Time domain or Impulse GPR transmits discrete pulses of nano sec duration and
digitize the return at GHZ sample rate.
> Frequency domain GPR system transmit single frequency & amplitude &phase of
the return signal is measured.
11. Antenna System:
> The GPR system performance strongly depends on the antenna system.
> The antenna system consist of transmitter and receiver
> The transmit antenna should :
> Radiate Ultra-Wideband
> Radiate Electro-magnetic energy
12. Pulse extender:
> It will amplify the ground reflection signal upto the maximum level acquired A/D
converter.
> It amplify the samples of digital signals which are converted from analog signal.
13. A/D Converter:
> The transmitter sends out a series of EM pulses then listens with the receiver
connected to high speed samples which in-turn feeds to A/D converter.
> This information is converted from nano sec to milli sec.
> It provides 12 bit accuracy and 66dB linear dynamic range.
14. Processor:
> The processor filters the signals
> This signals shows presence or absence of surrogate mine in the soil.
> Processor selects the mine detecting signal and passes to the visual display.
15. Visual display:
> It helps to see the range of targets.
> It displays the position of land mine.
16. Implementation:
> The impulse generator produces 0.8ns monocycle pulse.
> The generator spectrum covers a wide frequency band from 500MHZ on
3dB level.
> After striking the mine, pulses return and are received by the receiver
antenna.
[Cont..]
17. Applications
GPR has many applications in number of fields:
> In case of Earth science it is used to study bedrocks ,soils , ground water and ice.
> Engineering applications include non-destructive testing of structures and
pavements, locating buried structures and studying of soils.
> GPR is used to define landfills contaminant plums and other remediation sites.
> Military uses include detection of mines ,unexploded ordnance and tunnels.
18. Advantages:
> GPR has accurate measurements.
> GPR locates even a small targets.
> It has been well founded by the defense.
> GPR operates by detecting the dielectric soils when allows it to locate even no
metallic mines.
> GPR has been tested in different environmental conditions.
19. Limitations:
> GPR is more power hungry
> Thus false alarms are easily generated from the background itself.
> The sensors such as GPR are larger and heavier.
20. Future scope:
> Army mine fields is to measure detection probabilities under realistic conditions.
> Plans to speed up the scan rate with advanced arrays are under the way.
22. Conclusion
Impulse GPR system is used for detecting anti-tank and antipersonnel mines.
Through iterative design, build test cycles, and scored testing at Army mine lanes,
steady progress is being made.