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Electromagnetics and Communication

An Electromagnetic Geophysical Instrument for Groundwater Exploration

  • September 2020

Clean drinking water is one of the primary human needs and a basic requirement for economic development. A lack of water to meet daily needs is a reality for 1 in 9 people around the world. Not only is this currently a significant problem, but also globally it is getting worse as cities and populations grow, leading to an ever-increasing demand for fresh water. The safest kind of water supply is the use of groundwater. Since groundwater has a natural protection against pollution by the covering layers, it requires only minor water treatment.

  • The initial state of project was configuration of components with the Raspberry Pi 3B.
  • The GPS has been configured with the Raspberry Pi 3B and the data from the GPS about the Latitude and Longitude have been logged into an excel file which can be used to track it on a Map at later stage.
  • The ADC has also been configured which will convert the data received and convert it into digital format that can be stored and used for a later analysis part.
  • For ease of understanding the data, the ADC output and the co-ordinates received by the GPS will all be stored in an excel file column wise. For this different program codes had to be merged and that has been successfully done.
  • For starting and stopping the survey directly through power supply, the Raspberry Pi have been successfully programed. Now physical switches can be used which would act as START and STOP Survey switches.
  • The Low Noise Amplifier (LNA) circuit has been designed using SMD components and TI IC2048, and the PCB for it is also ready.
  • 5 coils with different number of windings have been made which can be used as the Transmitter Coil. After testing, the coil which produces best output will be chosen as final.

There are several geophysical methods of exploration in the search for hydro geological data. A great advantage of such methods is that it can cover a large survey area in a short period of time. Commercially available EM and AEM systems are time consuming, bulky and expensive. With existing AEM systems there is also the need of a pilot and an aircraft, which will increase the operation costs significantly. A conventional EM instrument that is inexpensive, portable and airborne is not available on the market. In this project, the focus will be on the controlled source electromagnetic method to obtain information about the soil.

Electromagnetic (EM) exploration is a commonly used survey method to obtain information about the subsurface, specifically electrical ground conductivity. The magnetic and gravitational fields emanating from the Earth's interior hold essential information concerning seismic activities and the internal structure. Geophysical survey methods that utilize the electromagnetic principles will be used for determining the presence of Groundwater. EM exploration involves the propagation of continuous-wave electromagnetic fields in the earth. In most cases, inductive coupling between the soil and the exploration system is used to obtain information about the subsurface.

The basic principle behind controlled source EM exploration is a current-source driving a transmitter coil. If the primary magnetic field propagates through the soil, it will induce small circular currents inside the soil known as Eddy current in the subsurface. The current-voltage relationship will provide information about the electrical conductivity of the subsurface. The Eddy currents in turn generate a weak secondary magnetic field that has the same frequency, but a lower amplitude and is shifted in phase. The transmitted and received EM-signals from the coils need to be amplified and filtered to be digitally processed. Data acquisition is done by integrating latitude and longitude values acquired with the help of the GPS sensor and the store the measured signals on a SD-card.

The project work is not fully completed and we are yet to test the set up and if needed modify the design for better accuracy.

  • The future scope of the project includes the mounting of the instrument onto the Unmanned Aerial Vehicle (UAE) and necessary modifications to be done in the instrument.
  • Miniaturization and weight reduction of the instrument so as to mount on UAE.
  • Students can be offered internships related to this work.

Principal Investigator

Co-Investigators

  • Yash Mistry

    Final year EXTC student

  • Sunny Ganger

    Final year EXTC student

  • Nitin Panchal

    Final year EXTC student

  • Romil Shah

    Final year EXTC student

Sponsored by

Funding Received

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