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CREG Journal
Contents

Newssheet
CREG AGM Minutes, A New Editor for CREGJ, CREG Spring Field Meeting: Emphasis on Mining, Equipment Loan & PCBs, Diary Dates, International Speleo Congress, Post Vacant: CREG Chairman, The Future of BCRA's Special Interest Groups.

Virtually Prehistoric: Beneath the Surface at Grime's Graves Flint Mines, Norfolk
Grime's Graves is a network of underground shafts and galleries hewn from the chalk around 5,000 years ago. Catherine Tuck and Peter Topping describe how a three-dimensional laser scan of these workings has enabled archaeologists to explore the scale and complexity of the site.

An Introduction to High Frequency Radio in Tunnels
In recent CREG journals we have reported on experiments with HF, VHF and UHF radios in tunnels. The way these radio signals propagate is something of a mystery - does the tunnel act as a waveguide? If not, why not? In this article, David Gibson, Richard Rushton and John Rabson pool their thoughts. 1. How Propagation Varies with Frequency, 2. What is a Waveguide?, 3. A Bibliography of CREG information.

Comparative Propagation Tests Along a Railway Tunnel
Chris Trayner and John Rabson have conducted radio propagation tests from 28MHz to 433MHz in Boughton Brake railway tunnel. They here present the results, which show a fixed attenuation in dB/m for each frequency.

Web Watch
Peter Ludwig brings us another wide-ranging selection of Web sites. Online access to the sites mentioned is available from a page kindly provided by Martin Melzer.

CREG Award 2004 - the Man Behind the HeyPhone
John Hey was presented with the CREG Award for 2004. Here John & Rosy Rabson look at John's achievements.

Building and Setting up the HeyPhone
John Hey provides step-by-step instructions on how to build and align the HeyPhone. Electronic and mechanical aspects of the construction are described.

Reviewing our 16th Year: CREG in 2003 / 2004
CREG Secretary Mike Bedford provides an overview of activities over the last year and Treasurer Rob Gill presents his financial statement.

Assessing Single Wire Telephones: Field Meeting Report
Single wire telephones were the theme of CREG's most recent field meeting in the Yorkshire Dales. Mike Bedford reports on the weekend's activities with particular reference to what we learned about SWTs and what users want of new equipment.

Modifying the Firefly Slave Unit for Digital Cameras
John T. M. Lyles describes how he has modified the Firefly 2 flash slave unit to cope with the pre-flash emitted by some digital cameras. Information on how to fit the new parts into the Firefly case is provided.

Putting it on the Map: Using Excel as a Geographical Information System
With a bit of ingenuity Excel can be pressed into service as a simple GIS. Mike Bedford shows you how to plot geographical features on a base map.

Update: Digital Slave Unit
There are some points to note during the construction and use of David Gibson's new slave unit for digital cameras.

We Hear
A round-up of new from the world of cave-related radio and electronics edited by Mike Bedford... US Navy to Scrap ELF Transmissions, Raynet to the Rescue, Radio-location Book, Amateur Radio News (500kHz Allocation, another 100kHz at 7MHz).

Cave Communications for Young Cavers
Markus Boldt tells us about a special course at the international education camp for young cavers in the Swabian Alps.

Update:
HeyPhone in the Cuetzalan Tiger Rescue.

Letters to the Editor
Topics include Surface Station Underground, Bradway Railway Tunnel Tests, Underground Text Messaging, and LF Absorption.