CREG Journal (ISSN 1361-4800)

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Contents of journal 57
September 2004

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CREG Journal (PDF 2.7MB)        Individual articles may be available below

Contents

 

Newssheet

Is this the Penultimate CREGJ?, CREG AGM, CREG Autumn Field Meeting, Equipment Loan and PCBs, Diary Dates, Post Vacant: Chairman.

 

Underground Text Messaging

This cave radio transmits text and features a keypad and display not unlike a mobile phone. Data packets feature several levels of coding for error detection and correction, and are transmitted at 55 bit/s D-BPSK on a 42.6kHz carrier. Designer Beat Heeb has achieved cave communications at up to 1000m for 5W power.

 

Design Guidelines for General-purpose Caving Equipment

Mike Bedford suggests that we need to pay closer attention when designing or building equipment for use by ordinary cavers. The requirements are very different from those which apply to experimental equipment used by electronics enthusiasts.

 

Measuring the Concentration of Radon Underground

Electronic measurement of radon in caves is not a simple matter. John Rabson reviews the current methods - direct measurement, filter paper and track etching.

 

Cuetzalan Tiger: The HeyPhone's Moment of Fame

The Cuetzalan Tiger Expedition hit the world's headlines as six cavers were trapped for eight days by rising water. Here Kev Welch and Michelle Gigg describe how the Combined Services Caving Association built a pair of HeyPhones and the important role they played in this ill-fated expedition.

 

Meanwhile, Back at the Ranch ...

While members of the Combined Services Caving Association were trapped underground in Mexico, media interest turned to the HeyPhone which expedition members were using to maintain contact with the outside world. Here John Hey describes his 'one moment of fame'.

 

Slave Unit for Digital Cameras

The built-in flashguns in digital cameras often emit a double pulse, which causes a problem when they are used with conventional slave units. David Gibson describes an upgrade to his slave unit that aims to solve this problem.

 

Communication in Slate and Gypsum: two new Geologies Investigated

The HeyPhone is tested in a couple of Welsh slate mines and a Gypsum mine. Useable communication was achieved in both as John Rabson and Mike Bedford report. A brief summary of work to date in rock other than limestone is also given.

 

Web Watch

Compiled by Peter Ludwig. Online access to the sites mentioned is available from a page kindly provided by Martin Melzer.

 

An Electronic Compass and Clinometer Using Optical Sensor

David Gibson proposes another method of using an optical sensor to read the position of a compass or clinometer disc. Correction: The final column in Table 2 (p23) should read (top to bottom), 0-1-1-0 and not 0-0-1-1

 

An Electronic Compass and Clinometer: Review.

John Rabson summarises a recent article from Compass Points describing an ECC designed by Dave Edwards & members of SWCC.

 

We Hear

A round-up of news from the world of cave-related radio and electronics. Subjects include 2.4GHz wireless networks, persona; gas monitors. Cross-well electromagnetic imaging, and Extreme Archaeology. Column edited by Mike Bedford.

 

Improved Communications in the Standedge Tunnels

Recent investigations having shown that UHF performed better than VHF in this environment, further tests were carried out at a wavelength of 23cm (1.3GHz). End-to-end communications were achieved with a mean RF power of 1W. John Rabson describes.some successful experiments.

 

Speleonics

Three topics for the price of one this time: data loggers, Fireflies and humidity, and fabrication of mechanical parts and PCBs. Summary by John Rabson.

 

Single-Wire Telephones: Q&A

For cave communications the emphasis is often on radio. But in many cases Single Wire Telephones should be considered as an alternative. David Gibson answers a few questions and summarises the state of the art.

 

Update: Detecting CO2

David Gibson invites comment on an electrochemical detector and Neville Michie describes the methods he has used.

 

Update: D-Q Beacon & Rx

Use in 50Hz mains areas and underwater by Brian Pease.

 

Letters to the Editor

Topics include moving coil meters, UV light sources, and scanning receivers.