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by David Gibson, MA PhD MIEE
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.
Volume 1 of the draft edition (softbound, 300pp, A4) is now available from stock - see below.
Books by David Gibson: Sub-Surface Communications |
Cave Radiolocation
Sub-surface or through-the-earth communication using electromagnetic fields - and specifically magnetic induction equipment - plays a key role in search and rescue systems used in the mining industry and, increasingly, by cavers and pot-holers. Similar equipment is used for radio-location, sub-surface surveying and geophysical measurements.
I have been studying the techniques for many years now, and have written numerous papers and articles on the subject, many of them for the British Cave Research Association's (BCRA)'s Cave Radio & Electronics Group. My PhD thesis also covered this topic, with its emphasis on Channel Characterisation and System Design for Sub-surface Communications.
I am acknowledged as one of a small number of experts on sub-surface communications. I currently work as a research project manager in the UK's Mines Rescue Service Ltd, where I am one of a team of scientists and engineers undertaking research work on behalf of the mining industry, with funding from the European Commission, UK Government, HSE and industry.
Sub-surface radio communication is not new, but information on such systems is hard to come by. I am intending to publish a book based on my PhD thesis, which brings together my many articles and papers. As far as I know, this will be the only work that will provide this information - under one cover - for investigators and designers. Unfortunately, this project has been delayed due to pressure of work but, because of the amount of interest, I have issued a draft edition. The final published version of the book is not now expected before mid 2006. Contact david(at)caves...etc. for further information.
The draft edition will be issued in three volumes, as they become available.
The 'published' edition of the book will incorporate volume 1 and volume 3 of the draft text, with volume 2 issued as a separate work.
Volume 1 of the draft edition is now available from stock, with immediate delivery. The prices are in the table below. Volumes 2 & 3 are not now expected before mid 2006 (but see Book: Cave Radiolocation for a shorter version of Volume 2, now available). Volumes 2 and 3 will be offered free of charge to purchasers of volume 1. Please note that this draft edition is an unpublished work. It will not be issued to the general public - essentially, you are purchasing it as part of a consultancy package from me (and the cost is less than a day's consultancy at my standard rate! - see my CV). If you are a cave radio experimenter with a proven history (i.e. you are a member of your national caving organisation and perhaps also a contributor to a cave radio publication) then I will consider giving you a discount. Likewise, if you are a full-time research student please ask your supervisor to contact me.
The edition described above is soft-bound. I can supply a hard binder for an additional £16. This is a good-quality 'spring-back' binder into which you can insert the soft-bound volume. Im selling this at 'cost price' (including postage) but it is, unfortunately, rather expensive.
Click on one of the price links to visit my Payments Page with the information pre-filled in on the form. Various payment methods are possible, but the simplest, for orders from outside the UK, is for you to pay by credit card via Paypal.
| Item | Full Price Version | Discount Rate for Cave Radio Experimenters |
| Sub-Surface Communications, Volume 1, (softbound, 298pp, A4) | £195, which includes airmail postage and insurance worldwide; plus free copy of Cave Radiolocation, and free copy of Volume 2 and Volume 3 if I ever get around to producing them. | £22 non-profit "reserve price", which covers only the printing and UK postage. (Printing and binding is expensive!) Make me an offer for a figure above this, based on your ability to pay, and the worth you put on the contents. I suggest something around £35. This price does not include any further updates. Please add £5 for overseas postage by airmail. |
| Spring-back binder | £16 | £16 |
| Cave Radiolocation (softbound, 70pp, A4) | £45, which includes airmail postage and insurance worldwide. | £10 non-profit "reserve price", which covers only the printing and UK postage. (Printing and binding is expensive!) Make me an offer for a figure above this, based on your ability to pay, and the worth you put on the contents. I suggest something around £15. |
Page last updated 30th August 2005, David Gibson
A book by Dr David Gibson MA PhD MIEE bringing together his many articles and papers on sub-surface communications systems. (370pp, A5 soft-bound, 85 figures, 33 tables, with index and CD-ROM containing program listings). Originally expected to be available from June 2003, its now not expected till mid-2004, although a draft edition is available from 10th Jan 2004 - see above. Contact david(at)caves...etc. for further information.
(This information is available as a formatted flyer in PDF format. Download 126K ).
Sub-surface or through-the-earth communication using electromagnetic fields - and specifically magnetic induction equipment - plays a key role in search and rescue systems used in the mining industry and, increasingly, by cavers and pot-holers. Similar equipment is used for radio-location, sub-surface surveying and geophysical measurements.
The use of fast desktop computers allows a mathematical model of the propagation to be investigated in detail, demonstrating the preferred orientation of the antennas and the existence of an optimum frequency that is dependent on depth and other parameters. Computer simulations demonstrate a reduction in accuracy of radiolocation at skin depth distances, and methods of correcting this inaccuracy are introduced.
The transmitter and receiver antennas for portable induction loop systems are usually air-cored loops or magnetic-cored solenoids, tuned to resonance. However, the preferred antenna often depends on the intended use of the communication system, with untuned antennas having an advantage in some situations. The use of toroid (anapole) structures and rotating magnets as transmitters is discussed briefly. A figure of merit - the specific aperture - is introduced as an aid to antenna design.
Internal (amplifier) noise can be reduced by noise-matching, although special account has to be taken of the inductive antenna. Internal noise is often swamped by external (atmospheric) noise, for which several mitigation strategies are discussed. Differing up-link and down-link noise performance may dictate different antennas. External noise is frequently characterised by the atmospheric noise temperature ratio, but data derived using the standard electric field antenna cannot be applied to a study of magnetic noise.
The design of a wide-band low-frequency channel sounder is described, with which it is intended to perform a detailed channel evaluation using a binary sounding sequence. A simple method of calculating the inverse of such a sequence is introduced, for which cross-correlation with the inverse sequence at the receiver results in a system identification signal that is used to maintain synchronism with the transmitter. The extreme wideband nature of the system results in a low efficiency, which is countered by using signal-averaging techniques at the receiver. Preliminary results are reported, in which the sounder was used to capture background noise.
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.
Last updated 12th October 2004, David Gibson