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CREG Journal 97 (0-24)
This issue has a cover date of March 2017 and was published on 1 March 2017.

Front Cover (1)
Mike Bedford preparing to lower the ZEB-REVO down Yordas Pot at the CREG Autumn 2016 Field Meeting. Photo: Chris Trayner

Contents (2)
List of contents and masthead information.

Cave Surveying with the GeoSLAM ZEB-REVO (3-5)
Stuart Cadge of GeoSLAM catalogues his experiences in using the company's ZEB-REVO handheld laser scanner in a couple of natural caves. Comparisons are drawn with the ZEB1 handheld scanner which had been used in the same caves a couple of years earlier.

Wet & Dry (6)
Ruggedisation, waterproofing & construction techniques – a roundup by Tony Haigh. Wireless through-the-case charging – is this the future?

Cave Radio and the Loran-C Spectrum (7-9)
Cave Radios operating at 87kHz are prone to interference from transmitters of the Loran-C navigation system. Robin Gape considers the Loran-C signal, the reasons for interference and suggests an approach to mitigate the problem.

Cave Radio and the Loran-C Spectrum [cregf:viewtopic.php?f=27&t=1402]
David Gibson takes issue with some of the points in Robin Gape's article, and gives some further information on the Loran-C spectrum, and how the interference might be countered. He also notes that the CREG search engine reveals a significant amount of prior discussion in the CREG journals. See the posting on the CREG forum, bcra.org.uk/cregf).

ZEB-CAM (9)
Stuart Cadge of GeoSLAM describes an add-on camera for the ZEB-REVO that provides images for feature recognition and context, synchronised with the point cloud data.

Letters and Notes (10)
Loop Orientation, Diary Dates.

Web Watch (10)
More gems from the Internet, unearthed by Peter Ludwig.

The Principle of Forward Error Correction (11-16)
The powerful techniques of forward error correction allow reliable communication even in poor conditions. Paul Nicholson describes the underlying principles and highlights the potential for text and data cave communications.

We Hear... (17)
News and events – Mike Bedford brings us the latest to impact the world of cave radio and electronics. Body Heat Harvester, DARPA AMEBA, Hyperspectral Imaging.

Developing a Static Rope Tester – Work in Progress (18)
As an extension to his ongoing work monitoring the behaviour of caving rope under dynamic load conditions using a specially-designed dynamic rope test rig, Bob Mehew has turned his attention to static loads. Here he describes his initial work with the newly-developed static rope test rig.

Introducing Data Modes for Cave Communications (19-21)
Data transmissions from caves have recently been received over a range of 360km using the WSPR system and signals have been received underground from much greater distances. Mike Bedford considers potential caving applications and reviews candidate coding schemes used by radio amateurs.

Underwater LiDAR – Bringing Laser Scanning to New Depths (22-24)
Mark Hardy of 3D at Depth, introduces the underwater laser scanner which, by its use of a green laser, is able to provide similar results to those which infrared laser scanners can achieve in air.

The Adventures of GREG (24)
Illustrations by Adrian Higgins with words by Mike Bedford.