CREG Journal (ISSN 1361-4800)

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Contents of journal 39
March 2000

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CREG Journal (PDF 9.6MB)        Individual articles may be available below

Contents

 

Flood Pulse Measurement: Preliminary Results from DYO

A low-cost prototype flood-pulse logger, designed by Stuart France using PIC microcontrollers, has produced promising results in Dan-yr-Ogof.

 

Computer Simulation of a Small Buried Loop

Evaluating the magnetic fields from a buried loop antenna requires a large amount of computing power. Reno Lippold explains his implementation of Wait's equations in the MathCad package, and compares the results with Shope's earlier simulation.

 

Pulse discharge circuits for Flashguns

Electronic flashgun design is aided by knowledge of the characteristic of the energy discharge circuit. In these notes David Gibson gives a brief introduction to the modelling of the capacitor and inductor circuits.

 

Simple Caver Counter offers Improved Performance

Ian Drummond uses a low-cost, off-the-shelf data logger to implement a caver counter. Successful operation over a period of a year is reported.

 

LORAN - Know your Enemy

LORAN is a major source of interference to cave radios operating in the vicinity of 100kHz. John Hey provides some background information.

 

Digital Wall Mapping at Wakulla Springs, Florida

A surveying and inertial navigation tool for cave diving has been developed by Brian Pease. Here he describes its first trials to John and Rosy Rabson.

 

Foot-candles

Our occasional notes on photometry, optics and opto-electronics. David Gibson discusses pulsed light sources.

 

Photography News

David Gibson reports on the forth-coming field meeting, and on plans for a BCRA photography group.

 

Web Watch

Sites of interest to cave-electronics enthusiasts, listed by Peter Ludwig.

 

Selected Further Reading

If a topic in this issue interests you, this 'further reading' list from CREG journals, compiled by David Gibson, may be of use.

 

Flood Pulse Logger uses Low Cost Data Logger

Julian Coward describes a simple water level logger, using a commercially available HOBO logger and Motorola pressure sensor.

 

Wet & Dry

Cave radio in rugged plastic Pelican cases.

 

An On-line CREG Journal Digest

David Gibson describes his on-line database which includes a search-engine written in JavaScript. With the output in HTML and the data source in plain ASCII, this results in some cross-platform portability. The principles could be applied to the National Cave Registry database.

 

A Pre-Selector for a Cave Radio Receiver

The performance of a receiver can be much improved by careful control of signal levels and bandpass filtering applied before the mixer stage. Jean-Jacques Fauchez describes an add-on filter for his Cournouze receiver.

 

An Introduction to PSK31

PSK31 is a new digital coding scheme developed by radio amateurs for use on the shortwave band. Some cave radio experimenters have suggested that it might prove useful at LF. Mike Bedford provides the basic facts.

 

Speleonics

The prominent topic recently has been infrared films. Jeremy Davis reviews the past three months of postings.

 

Letters to the Editor

So where now?, Electronic publishing, SNAP beacon.