Radiolocation and Cave Communications

Page published 11-Apr-02. for a more recent list of references, please see the list given on the ppage that describes by book: Cave Radiolocation

bulletBooks by David Gibson: Sub-Surface Communications | Cave Radiolocation

Selected References on Paper

This list is designed to give you an introduction to the topics of Radiolocation and Cave Radio. These references can be read inconjunction with the Encyclopedia of Cave and Karst Science, due for publication in 2003, for which David Gibson wrote the radiolocation and communications in caves entries. David Gibson's articles from the lists below can be obtained from him - details of how to obtain them on-line will be given here as soon as possible (E-mail david(at)caves...etc. for further info).

Journals referenced below

References are made, in the lists below, to the following journals

List of References



Gibson, D. 2001a. Cave Surveying by Radio-Location - 1. Cave Radio & Electronics Group Journal, 43: 24-26.
France, S. 2001. Cave Surveying by Radio-Location - 2, Cave Radio & Electronics Group Journal, 44: 21-23.

The first two parts of a series on radiolocation that aims to bring together existing knowledge and to outline new techniques. Part 1 includes references to practical articles on beacon construction. Part 2 is a brief practical guide to radiolocation using a traditional France/Mackin beacon. Further parts in the series will appear in the CREG journal from time to time (and this web page will be updated accordingly).

Glover, R.R. 1976. Cave surveying by electromagnetic induction. In Surveying Caves, edited by B. Ellis, Bridgwater: British Cave Research Association.

A good introduction to radiolocation. Unfortunately, this book is out of print. The chapter is a little dated, and makes no reference to the use of spreadsheets as an aid to calculation, nor to errors caused by geophysical problems.

Further Reading

Gibson, D. 1996. How Accurate is Radio-location? Cave & Karst Science 23(2): 77-80.

A discussion of some of the geophysical causes of errors in radiolocation.

Gibson, D. 1998. Radiolocation Errors Arising from a Tilted Loop. Compass Points, 21: 18-20.

A discussion of the likely errors caused by not properly levelling a radio-location induction loop transmitter.

Gibson, D. 2000. A Channel Sounder for Sub-Surface Communications: Part 2 - Computer Simulation of a Small Buried Loop. Cave Radio & Electronics Group Journal, 41: 29-32.

Some theoretical background to recent work on radiolocation at extreme depth, using formulations given by Wait (1982).

Gibson, D. 2001b. Cave Radio Notebook. 46: The Role of Skin Depth in Cave Radio. Cave Radio & Electronics Group Journal, 45: 28.

A note explaining that for radiolocation, skin depth does not have the physical interpretation usually given.

Pease, B. 1997, Determining Depth by Radiolocation: An Extreme Case. Cave Radio & Electronics Group Journal, 27: 22-25.

This article is an important one, because it outlines the problem of radiolocating at a depth which is geophysically 'significant'. Further work by Pease and Gibson continues to follow from this article. It is, perhaps, worth reproducing the abstract (written by CREG Technical Editor David Gibson) in full here...
Abstract: Pease's 3496Hz narrow-bandwidth "DQ" radio-location beacon was used to determine the depth below the surface of the Dream Lake siphon in Culverson Creek Cave (Greenbriar County, West Virginia, USA), which conventional surveying had placed at around minus 670ft (-207m). The extreme depth (more than a skin depth), and the surface terrain (steep hillside) made radio-location difficult. Three methods were compared - the traditional field-angle determination, absolute signal strength and Gibson's ratiometric method. With a deduced "best-fit" conductivity, the experimental measurements all agreed with Shope's theoretical model but, when applied to a simple "free-space" model, resulted in very different estimates of the depth. Shope's model, encompassing all the experimental data, gave a depth estimate which was still too great by 137ft (42m). Furthermore, a conductivity measurement using a simple secondary field model did not agree with the "best-fit" required for Shope's model. These failures were attributed to inhomogenous rock; and it is surmised that a lower radio-location frequency would lead to a more accurate result.

Wait, J.R. 1982. Geo-Electromagnetism, New York: Academic Press

This is a highly mathematical book, but it describes in detail the behaviour of electromagnetic fields in a conducting medium and is the basis of current work in the field (e.g. see Gibson, 2000).

Lovett, B. 1999. Making an Entrance, Stage Left ... Descent. 147: 24

Referenced by the essay in the Encyclopedia of Cave and Karst Science, this article highlights how the use of radiolocation to help fix 'digging' points can be a threat to cave conservation.

Building Equipment

Bedford, M. 1993. Introduction to Radio Location, Cave Radio & Electronics Group Journal, 14: 16-18.
Bedford, M. 1995. Update - The France/Mackin Radio-location Beacon, Cave Radio & Electronics Group Journal, 20: 11.

An explanation of the basic technique, and the circuit diagram of the France/Mackin location beacon. The beacon is fairly straightforward to build, but the later Pease (1996) design may perform better.

Pease, B. 1996. 3496Hz Beacon Transmitter and Loop, Cave Radio & Electronics Group Journal, 23: 22-24.
Pease, B. 1996. The D-Q Beacon Receiver - Overview , Cave Radio & Electronics Group Journal, 24: 4-6.
Pease, B. 1997. Constructing the 3496Hz 'D-Q' Beacon Receiver, Cave Radio & Electronics Group Journal, 28: 3-7.

In these three articles, Brian Pease gives an overview of his radiolocation "double-quadrature" beacon design, followed by constructional details of the receiver and transmitter. This beacon is a more sophisticated device than the earlier France/Mackin design (Bedford, 1993), using a phase-locked loop to achieve low bandwidth and noise filtering. It also allows measurements to be taken, that facilitate the application of the Pease/Gibson depth-calculation algorithms. (Pease 1997, Gibson, 1996, 2000, 2001a).

Historical Further Reading

Brooks, N, & Ellis, B. 1956. An Independent Check on the Survey of Ogof Ffynnon Ddu. South Wales Caving Club Newsletter. 16: 1-2.

This is one of the earliest reports of cavers using radiolocation. No detail is given.

Glover, R.R. 1973. Cave Depth Measurement by Magnetic Induction, Lancaster University Speleological Society Journal, 1(3): 66-72

This paper is a precursor to (Glover 1976) and includes an appendix, contributed by one of the staff at Lancaster University [when I re-locate the journal I'll give his name] showing a mathematical derivation of the formula used in the 'depth by field angle' technique.

Mixon, W. & Blenz, R. 1964. Locating an underground transmitter by surface measurements. Speleo-Digest 1964. 3.1-3.13

Mixon, W. 1966, Locating an underground transmitter by surface measurements. National Speleological Society News. 24(4): 61,74-75.

These two articles cover the principles in a similar manner to Glover (1973, 1976).

Communications in Caves


Bedford, M. 1994. A Directory of Cave Radio Designs. Cave Radio and Electronics Group Journal. 18: 3-4.

A list of experimental cave radio designs, most of which were short-lived or only ever saw local usage. Some references. This article will be brought up to date with one scheduled for CREGJ 48, June 2002.

Bedford, M. 1999. Back to Basics with Cave Communications. Cave Radio and Electronics Group Journal. 37: 6-10.

A fairly comprehensive introduction to the various methods of cave communications; no circuit diagrams, but references to other sources of information.

Bedford, M. 2001. Introducing the HeyPhone, Caves & Caving. 91: 15-17

Article describing the "roll out" of the new HeyPhones (Hey, 2000) to the UK Cave Rescue Groups.

France, S. 1995. Induction Radio or Telephone? Cave Radio and Electronics Group Journal. 20: 7

A discussion of the pros and cons of single-wire telephones versus induction radios.

Gibson, D. 1997. Single Wire Telephones for Mines Rescue, Cave Radio and Electronics Group Journal. 27: 7-11.

A comprehensive review of commercial SWT equipment. This issue of the CREG journal was a "special feature" on SWT and guide-wire radio, (six articles).

Naylor, G. 1998. Introducing the Nicola System. Cave Radio and Electronics Group Journal. 34: 3-6.

Following an incident in the Gouffre Berger where flooding claimed two lives, an early-warning and rescue communication system was developed. This article gives the background and the results of initial tests.

Further Reading

Gibson, D. 1996. Radio Speleohistory. Cave Radio and Electronics Group Journal. 26: 3.

A short note, with early photographs depicting experiments in caves up to the 1920s.

Gibson, D. 1997. Ground Shorts with a Single-wire Telephone. Cave Radio and Electronics Group Journal. 28: 10-13.

This article dispels some of the myths surrounding SWT operation, explaining why cable short-circuits are not a problem, and why good earthing is not required.

Newman, G. 1993. The Caves of Thunder, Descent, 110: 26-27.
Newman, G. 1994. The Caves of Thunder Radios, Cave Radio and Electronics Group Journal. 16: 20-21.

This 1994 article explains how CB radios were adapted for cave communications in a large river cave, by Newman (1993)

Mackin, R.O. 1991. Communications. In Caving Practice & Equipment. Edited by D. Judson, Leicester: Cordee / British Cave Research Association.

An introduction to the various methods of cave communications; includes simple telephone circuits and a brief description of radiolocation.

Building Equipment

The following references will provide information for home constructors. The HeyPhone, Nicola System and Transverter systems are all are ongoing projects - upgrades, enhancements and further information have also been published.

Drummond, I. 1993. Converting CB Radios For Use As Low-Frequency Cave Radios. Speleonics. 19: 3-8.

The philosophy behind this design was that converting a CB radio to LF might prove to be simpler than building an LF radio from scratch.

Hamilton, P. 2000. Build a Single Wire Telephone with Alarm Call. Cave Radio and Electronics Group Journal. 40:7-9.

A design for a A single-wire telephone (SWT) with enhanced features - alarm, standby mode and a high-impedance input which reduces the requirement for earthing.

Hey, J. 2000. A New Rescue Radio - the Electronic Design. Cave Radio and Electronics Group Journal. 41: 4-10.

One of several articles describing the "Heyphone" and its development. This is an 87kHz SSB radio operating into earth electrodes or a tuned induction loop.

Lake, M. 1997. An Updated Michiephone. Cave Radio and Electronics Group Journal. 30: 15-17.

A single-wire telephone. An up-to-date version of Michie's 1974 design, which was originally used for cave rescues in New South Wales, Australia. This design is not as advanced as Hamilton (2000).

Naylor, G. 1999. The Nicola Mark II - a New Rescue Radio for France. Cave Radio and Electronics Group Journal. 38: 3-6.

Circuit diagram and component list for the Nicola radio. This is similar in concept to the Heyphone and R. Mackin's earlier Molefone, being a 87kHz SSB radio operating into earth electrodes or a tuned induction loop.

Historical Further Reading

Williams, B. 1995. Lamb Leer Cavern 1880-90: The Lake and the Talking Machine. Proceedings of the University of Bristol Speleological Society. 20(2): 135-151.

Possibly the first use of telephone communications in a cave.

Last updated 11th April 2002, David Gibson