CREG Journal (ISSN 1361-4800)

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Contents of journal 110
June 2020

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CREG Journal 110 (0-24) (PDF 5.0MB)        Individual articles may be available below

This issue has a cover date of June 2020 and was published on 1 June 2020.

 

Front Cover (1) (PDF 1.4MB)     

Mike Bedford, in an archaeological lime kiln, conducting preliminary tests on the use of ordinary coaxial cable as a low-cost leaky feeder for communication along cave passages. Photo: Mike Bedford

 

Contents (2) (PDF 366KB)     

List of contents and masthead information.

 

Evaluating Coaxial Cables for use as Leaky Feeders (3-5) (PDF 698KB)     

Ordinary low-cost coaxial cable can be used as a leaky feeder for communication along cave passages. Mike Bedford reports on tests to compare the performance of two main types of cable, and to determine the optimal operating frequency.

 

Underwater Robot for Minimally-invasive Cave Research (6-8) (PDF 554KB)     

Michael Ross reports on his use of the commercial Navatics Mito underwater robot for exploring flooded caves.

 

Letters to the Editor (9) (PDF 287KB)     

PIC Microcontrollers Mike Bedford, Flashgun Slaves David Gibson.

 

The Adventures of GREG (9)  For download see previous item

Illustration by Adrian Higgins, and words by Mike Bedford.

 

Battery Connectors for Caving (10-11) (PDF 710KB)     

The underground environment places substantial demands on connectors. Joe Duxbury compares a number of connectors that can be used to interconnect battery packs to cap-lamps and be useful in other underground applications.

 

Web Watch (11) (PDF 389KB)     

A solitary link this time, from Peter Ludwig.

 

Building Blocks (12) (PDF 323KB)     

Considerations when adding ‘processing power’ to a project. By Tony Haigh.

 

Regenerative Brake Charges Your Caving Lamp Whilst You Abseil (13-16) (PDF 337KB)     

A caver abseiling down a pitch will lose potential energy, which is converted into heat in his abseiling device; but what if it were converted into useable energy instead? David Gibson explains the principles behind regenerative braking and how you might use the braking energy to charge a battery. However, this is for theoretical interest only, and definitely not something to try out in practice!

 

A Store-and-Forward Repeater for use with PMR Radios (17) (PDF 292KB)     

Low-cost store-and-forward units allow a PMR radio to be used as a single-frequency simplex repeater unit as Fred Rattray reports.

 

Early Radio Broadcasts from Caves (18-19) (PDF 547KB)     

John Rabson delves into several high-profile radio broadcasts from caves dating back to the 1930s.

 

Overview of Radio Repeater Types (20) (PDF 438KB)     

Mike Bedford presents the main types of radio repeater, and explains the key differences between them. This article is #4 in our Fundamentals series.

 

Flashgun Slave Redesign Notes (21) (PDF 239KB)     

David Gibson’s design for a flashgun slave unit first appeared in the CREG journal almost 30 years ago. It had a number of unique features that meant it was ideal for cave photography. Nowadays, cheap wireless slave units are readily available and there is probably no need for a home-built optical design. But, were a ‘retro’ optical device ever to be needed, David Gibson explains how he would modify his earlier design.

 

We Hear (22) (PDF 324KB)     

Roundup of news and events: Mike Bedford brings us the latest to impact the world of cave radio and electronics. The Search for Life in Martian Caves, Introducing the Cave Rover Project, Lidar: From Cars to Caves.

 

goTenna – Mesh Networking for Off-grid Communications (23-24) (PDF 404KB)     

Mike Robinson, Product Manager at goTenna, introduces this technology, outlining how it could find applications above ground during expeditions or for rescue, and describing how it has also been employed underground.