CREG Journal (ISSN 1361-4800)

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Contents of journal 124
December 2023

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CREG Journal 124 (0-24) (PDF 3.7MB)        Individual articles may be available below

This issue has a cover date of December 2023 and was published on 5 December 2023.

 

Front Cover (1) (PDF 1.4MB)     

Ken Smith sending a text message in Rat's Nest Cave, Alberta, using a QDX-M radio on 137.5 kHz. The radio is the small box with red LED just above Ken's right hand. Photo: Gavin Elsley

 

Contents (2) (PDF 263KB)     

List of contents and masthead information.

 

News and Notes (2)  For download see previous item

Change, David Gibson.

 

Digital Cave Communications – Smaller, Lighter, Cheaper! (3-5) (PDF 739KB)     

Ian Drummond, VE6IXD, reports on the development and testing of a newly available low-cost digital transceiver, modified to operate on 137.5 kHz. Employing weak signal modes such as WSPR and FT8, ranges of up to 3 km have been achieved using small loop antennas.

 

ARCANA 2023 – Radiolocation Beacon and Receiver with Two-way Text Communication (6-8) (PDF 553KB)     

ARCANA 2023 breaks new ground in being designed for radiolocation, but providing communication from cave to surface and vice versa to assist in the efficient organisation of the location process. Jean-Louis Amiard provides an overview of the system.

 

A Semi-empirical Approach to Microwave Propagation Modelling in Caves (9-15) (PDF 696KB)     

Mike Bedford and Gareth Kennedy describe a semi-empirical approach for modelling microwave propagation in natural caves. The method provides significantly improved accuracy compared to modal analysis. In addition, it does not require access to a detailed lidar-derived 3D model and specialist software, as required for ray tracing, the other main method that has been applied to this type of environment.

 

We Hear (16) (PDF 287KB)     

Roundup of news and events: Mike Bedford brings us the latest to impact the world of cave radio and electronics. BHI Introduces ANC Headphones, Niobium to Improve Lithium-Ion Batteries, Inertial Navigation Device from Moasure.

 

Reciprocity and Radiation (17-20) (PDF 348KB)     

Reciprocity is a property of passive electrical networks and electromagnetic fields. In a previous article David Gibson showed that nonradiating cave radio antennas behave as passive networks and obey simple reciprocity laws. In this follow-up article he demonstrates the wellknown observation that radiating antennas also obey the reciprocity principle. This is a slightly more complex demonstration as it requires a discussion of radiation resistance, impedance matching and fundamental thermodynamics.

 

Building Blocks (21) (PDF 282KB)     

Suggestions to minimise the impact of corrosion on electronic devices for underground use, by Tony Haigh.

 

Earth Electrodes for Cave Radios – a Practical Guide for Deployment (22-23) (PDF 325KB)     

Pushing electrodes into the ground, as required for a cave radio antenna, might seem a trivial process but, as Mike Bedford explains, several aspects need to be considered in order to obtain the best performance. This article is #8 in our Fundamentals series.

 

Long-Range Cave Radio (24) (PDF 291KB)     

Ian Drummond, VE6IXD, and Ken Smith, VE6AGR, have achieved a range of several kilometres using sensitive receiving methods to receive the far magnetic field, as distinct from near-field components.