Channel Characterisation and System Design for Sub-Surface Communications

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Channel Characterisation and System Design for Sub-Surface Communications by David Gibson

ISBN 978-1-4457-6953-0. Softbound, 298pp, A4.

Published by the author via Lulu Enterprises, Inc. See lulu.com/content/5870557

Corrigenda: If you have a copy of the unpublished edition (V1.1; 2004) you may wish to download this corrigenda.

Description: Based on the author's PhD thesis, this book is a theoretical study of subterranean radio communication, with the focus being on methods that depend primarily on the penetration of electromagnetic fields through the ground. Through-the-earth communication using e-m fields - specifically magnetic induction - plays a role in search and rescue systems used in the mining industry. It is also used for borehole telemetry, pipeline location and by cavers and pot-holers. Chapters describe propagation, antennas, and the design of transmitters and receivers. A figure of merit - the specific aperture - is introduced as an aid to antenna design. A crucial aspect of all systems is the signal to noise ratio, for which the strategy of noise-matching is introduced. The design of a wide-band low-frequency sounder is described, for channel evaluation using a non-ideal binary sequence. A method of calculating the inverse of a generalised sequence is described, for which cross-correlation results in a system identification signal.

Keywords: atmospheric noise, cave radio, channel sounding, electromagnetic theory, inverse sequence, mine rescue, noise-matching, noise temperature, propagation, radiolocation, sequence design, specific aperture, sub-surface communication.

About the author: David Gibson studied maths and engineering at Cambridge University and was president of the university's caving club in 1979-80. By profession an electronic design engineer, he has also been the technical editor of the journal of the British Cave Research Association's Cave Radio and Electronics Group for many years. His many articles on cave radio and related cave-electronics topics have provided a firm and unique basis for further studies in this area. This book is essentially his PhD thesis from the University of Leeds, which was completed in 2003, whilst he was self-employed as a free-lance design engineer. David Gibson now works for the UK's Mines Rescue Service in its research and consultancy division.

Chapter Summaries

1 SUB-SURFACE COMMUNICATIONS
Mine Applications / Cave and Geophysical Applications / Sub-Surface Penetration of Electromagnetic Fields / Bibliography
2 PROPAGATION
Electric v. Magnetic Fields / A Simple Model of a Loop Antenna / Electrical and Magnetic Properties of the Ground / Derivation of an Optimum Frequency / A Model for a Uniform Half-Plane / Orientation of Transmitter and Receiver / Computer Simulation of a Buried VMD / Radiolocation at Skin-depth Distances
3 SPECIFIC APERTURE: A FIGURE OF MERIT FOR INDUCTION LOOP ANTENNAS
Deriving a 'Figure of Merit' / Observations using 'Specific Aperture' / Using 'Specific Aperture' with a Receiving Antenna / Using 'Specific Aperture' with a Radiating Antenna / Buried Transmitter Loops
4 ANTENNA DESIGN
H-field Antennas / E-field Antennas / J-field Antennas / Cable-based Communications / Designing Induction Loops using Specific Aperture / Application to Ferrite-cored Antennas / Air-core v. Magnetic-cored Antennas / Proximity and Skin Effects / Exotic Antennas
5 TRANSMITTER DESIGN
Tuned v. Untuned Antennas / Air-core v. Ferrite-core Antennas / Comparison by Power Dissipation / Driving a Tuned Antenna / Matching the Antenna to the Amplifier / Driving an Untuned Antenna / Damped Antennas / Modulation Methods
6 NOISE AND RECEIVER DESIGN
Tuned v. Untuned Antennas / Air-core v. Ferrite-core Antennas / Signal to Noise Ratio / Atmospheric Noise Temperature Ratio / Up-link v. Down-link Operation / Optimum Frequency in the Presence of Noise / Noise Factor of a Receiver Antenna / Untuned Antennas / Amplifier Noise / Interference
7 CHANNEL SOUNDING
Outline of Proposed Method / Design Calculations / Integrating Sounding Into a System
8 SEQUENCE DESIGN FOR SYSTEM IDENTIFICATION
Derivation of an Inverse Sequence / Noise Factor / System Synchronisation / Noise factor of a code-locked loop
9 CHANNEL SOUNDER: DESIGN & RESULTS
Design Evolution / Evaluation of Prototype / Analysis of Results
10 CONCLUDING REMARKS & RECOMMENDATIONS FOR FURTHER WORK
APPENDICES
Propagation / Driving an Inductive Load / Receiver Noise-Matching / Sequence Design / Cave Locations for Trials / Channel Sounder Design / Data Processing