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# format auto-updated on access: Wed 03-Apr-2024 16:35:02 +01:00

# sandbox: Journal 125 has gone to press and is due for publication in April 2024
CREG Journal 124 (0-20)
This issue has a cover date of March 2024 and was published on 3 April 2024.

Front Cover (1)
Cave diving instructor, Mauro Bordignon, inside Otoch-Ha in Mexico's Yucatán. Many lights making up over 60,000 lumens were staged to light up the area.Photo: Brandi Mueller.

Contents (2)
List of contents and masthead information.

News and Notes (2)
Editor, Delay - Rob Gill, Erratum: QDX-M - Ian Drummond, June Field Meeting - David Gibson

Starting out in Underwater Cave Photography (3-5)
Brandi Mueller describes her initial experiences in photography as a cave diver, and details the lessons learned. This offers valuable guidance to those who are new to this most demanding of photographic environments.

We Hear (6)
Roundup of news and events: Mike Bedford brings us the latest to impact the world of cave radio and electronics. Cave-Link Version 4, Discovery TX-500 Transceiver, Slimline Tough and Waterproof Laptop Cases.

Using Low-Cost Software to Obtain and Study Stalagmite Greyscale Data (7-10)
Where annual layers are found in stalagmites, these can be used to provide insights into palaeoclimate. Sebastian F.M. Breitenbach and Norbert Marwan present a low-cost and high-resolution method for acquisition and analysis of greyscale data from speleothems by means of the free open-source ImageJ software.

A Loop Antenna for the Micro HeyPhone (11-12)
The Micro HeyPhone is designed to use an earth electrode antenna. However, in some circumstances a loop antenna may be more practical. Chris Ross describes a 1 metre loop design for use on those occasions.

Cellular Networks for IoT (13-16)
Stuart France offers a candid review of cellular telecoms, viewed through the lens of caving projects, covering their evolution from the 1980s to the present. The capability of handheld mobile phones is quite different to the specialised modules which will transmit data from Internet-of-Things (IoT) caving projects to a webserver using public mobile phone networks.

Letters to the Editor (16)
Heyphone PCBs, Chris Ross.

Introducing the SWAR-2EX and SpellCom Wireless Rescue Communication Systems (17-20)
The SWAR-2EX wireless communication system provides communication during mine rescue operations. SpellCom provides similar functionality for use in caves and other underground spaces. Dawid Stachniak, of Sybet International, describes these systems.