CREG Journal (ISSN 1361-4800)

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Contents of journal 116
December 2021

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CREG Journal 116 (0-24) (PDF 4.8MB)        Individual articles may be available below

This issue has a cover date of December 2021 and was published on 6 December 2021.

 

Front Cover (1) (PDF 2.0MB)     

Measuring the efficiency and colour rendering index of power LEDs. Photo: Knut Brenndörfer

 

Contents (2) (PDF 270KB)     

List of contents and masthead information.

 

News and Notes (2)  For download see previous item

Spring 2022 Field Meeting, Web Watch. Rob Gill.

 

Stereo Photography from the Basics to the Experimental (3-6) (PDF 668KB)     

3D cave photography can produce some impressive results but isn't without its challenges. Mike Bedford summarises the classic methods of capturing stereo pairs before investigating some more experimental techniques.

 

LEDs for Lighting and Photography: Efficiency and Colour (7-10) (PDF 667KB)     

Knut Brenndörfer focuses on the efficiency and colour rendering index of power LEDs and their influence on common applications as cave lights and for taking photos in caves.

 

We Hear (11) (PDF 469KB)     

Roundup of news and events: Mike Bedford brings us the latest to impact the world of cave radio and electronics. Customisable Project Boxes, Cave-proof Phones, Drones to the Rescue.

 

Letters to the Editor (12) (PDF 279KB)     

SSB Generation, Ian Drummond; Router Problems at the British Cave Science Centre, David Gibson.

 

Web Watch (12)  For download see previous item

Peter Ludwig looks at ultra-fast charging batteries, developments which may help us keep disease-free on future expeditions and a very long snorkel.

 

Applications of Cave Communications – an Overview (13-14) (PDF 322KB)     

To set the scene for those new to cave technology, Mike Bedford investigates why and how communication facilities are used in caves and speculates on possible future applications. This article is #6 in our Fundamentals series.

 

Building Blocks (15) (PDF 731KB)     

'Push-to-Talk over Cellular' (PoC): How and why you might use it, by Tony Haigh.

 

A Base Station for the Lovell Earth Return Telephone (17) (PDF 378KB)     

Chris Ross describes a development of the Lovell single-wire telephone, adding a call button and loudspeaker to form a base station.

 

Underground Communication - The Early Days (18) (PDF 349KB)     

Extensive research into methods of subsurface communication dates back almost one hundred years. Mike Bedford reviews some pioneering work, which drew some very different conclusions from those that now apply to cave communications.

 

Class-D SSB Modulator - Demonstrator Code Listing (20-21) (PDF 275KB)     

As an appendix to his article in CREG Journal 115 that described a class-D SSB modulator, David Gibson gives a brief introduction to MATLAB and its free alternative GNU Octave, and then lists the code that produced the plotted graphs featured in the article.

 

Position Encoder Uses Single-Track Gray Code: Part 1 (22-24) (PDF 371KB)     

There are many examples, in electronic equipment design, where it is necessary to measure linear or rotary position, which is often achieved using an optical or magnetic encoder. Simple encoders detect only changes in relative position; multi-track encoders can measure absolute position but, as David Gibson explains, a single-track encoder can, under the right conditions, also encode absolute position.