CREG Journal (ISSN 1361-4800)

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Contents of journal 51
March 2003

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CREG Journal (PDF 2.1MB)        Individual articles may be available below

Contents

 

Newssheet

Cave Radio Test Sites; CREG Award; HeyPhone PCBs.

 

A Resistance Meter for Earth-Current Systems

Measurement of the loop resistance of an earth-current system with a d.c.-based meter is not practicable because of the presence of d.c. potentials. John Hey describes an a.c. meter that gets round this problem.

 

Radio Tests in Essex Road Railway Tunnel

CREG was recently approached by Railtrack (now Network Rail) and asked to advise on management and safety communications for a casualty evacuation exercise in a railway tunnel. John Rabson reports.

 

LF Propagation on Simulated Railway Tracks

Propagation tests in tunnels have indicated that the tracks themselves may guide low frequency radio waves. As it is not always easy to get access to a railway line, some experiments have been performed above ground. John Rabson reports.

 

Vision in Low-Lighting Conditions

Previous definitions of scotopic or dark-adapted vision, used in the CREG journal, may have been wrong. David Gibson reports.

 

Amateur Radio Licensing - an Update

Over the past year more than 6000 of the new amateur radio Foundation licences have been issued. John Rabson, G3PAI, explains the new arrangements and why this development is significant for cave radio.

 

Practical Battery Management

How should batteries used for essential rescue equipment be stored? Mike Bedford gives some advice on battery management in response to queries from the cave rescue community.

 

Portable Fuel Cells to Replace NiMH and Li-ion Cells?

Stephen Voller, of Voller Energy, became frustrated with the short life of the batteries in his mobile phone and laptop computer, so he set up a company to develop miniature fuel cells to replace them.

 

Web Watch

Another list of sites from Peter Ludwig.

 

Check Your Resistors

A cautionary tale by John Rabson.

 

Wet & Dry

Mike Bedford reviews some more items of rugged equipment - a laptop, a walkie-talkie and a camera.

 

Matching & Output Impedance: A Common Fallacy? (16-17) (PDF 247KB)     

We often hear about 'output impedance' and 'matching' but David Gibson suggests that the terms are misunderstood by many designers, and he makes proposals for specifying low-frequency power amplifiers.

 

Cave Rescue Wish List

Jopo asked the BCRC committee what new items of cave electronic equipment would be helpful to them.

 

HeyPhone Testing in the Lamprechtsofen

Fay Hartley of Four Iron Caving Club took two HeyPhones on a trip to Austria and shows that performing the actual testing can be less than half the battle.

 

CREG's Equipment Initiative

Mike Bedford describes how CREG is now starting to serve the wider caving community by loaning equipment and by providing PCBs for projects at cost.

 

HeyPhone Documentation: More Updates

Mike Bedford outlines new and updated documentation, which is available on the HeyPhone Website.

 

Speleonics

Lumileds Lighting, Flashgun Slave Unit and more. Contributions summarised by John Rabson.

 

Piecewise Modelling of Antennas

The NEC series of programs is used for calculating the behaviour of antennas. Brian Pease discusses his experiences with the latest version.

 

Cave Radio Notebook

54: Noise Shielding, 55: Measurement of V & I at LF. 56: Specific Aperture. Column edited by David Gibson.

 

Making Sense of Atmospheric Noise Temperature Ratio

The often-quoted CCIR noise data is probably irrelevant for predicting the performance of equipment with magnetic loop antennas. David Gibson explains why.

 

Letters to the Editor

Letters.