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# format auto-updated on access: Fri 01-Dec-2017 18:13:32 +01:00

# sandbox: Journal 100 has gone to press and is due for publication in December 2017
CREG Journal 100 (0-32)
This issue has a cover date of December 2017 and was published on 1 December 2017.

Front Cover (1)
The Micro HeyPhone, a modernised analogue SSB cave radio. The design is based on the original HeyPhone, which is shown in the background. Photo: Ian Cooper.

Contents (2)
List of contents and masthead information.

The Electronics of Dreams (3-4)
As the CREG Journal reaches issue 100, Chris Howes, editor of Descent, reflects on the evolution of the Group and its Journal against the backdrop of developments in underground technology – and looks to the future...

The Micro HeyPhone Project: a Conventional Cave Radio for a New Generation (5-10)
Ian Cooper introduces a project to produce a conventional but modernised analogue SSB cave radio that is suitable for home construction. The design is based on the SSB modulation and demodulation circuitry of the HeyPhone but with the RF I/Q signal generation and all the control functionality implemented in a micro-controller. The radio is considerably smaller than the original HeyPhone and is housed in an off-the-shelf case to obviate the need for mechanical engineering.

DMT PILOT 3D – a New Approach to 3D Documentation of Subterranean Cavities (11-14)
In recent years, the surveying of cave chambers has been revolutionised by laser scanning and handheld devices such as the GeoSlam ZEB1 and ZEB-REVO have extended this to cave passages. Now, Daniel Schröder and Gero Steffens introduce a multi-sensor handheld device that employs the optical technique of structure from motion instead of LiDAR.

Notes and Announcements (14)
CREG Spring Field Meeting, CREG Prize, Journal Content.

We Hear... (15)
News and events – Mike Bedford brings us the latest to impact the world of cave radio and electronics. Research Project Targets Sub-surface Communication, Ubiquitous Internet Moves Closer to Reality, Paper-thin Lensless Cameras to Offer Several Benefits.

100 and Beyond: Readers Recall (16-17)
What are the most memorable moments over the last 100 issues of CREGJ? We asked subscribers for their highlights. Contributions from: Stuart France, Rosy Rabson, Rob Gill, Mike Bedford, John T. M. Lyles, John Rabson, Ian Drummond, Brian Pease & David Gibson.

A Digital Future for the Wemyss Caves, Scotland (18-22)
Joanna Hambly, Mike Arrowsmith and Marcus Abbott describe how an archaeologically important cave site has been recorded using a variety of surveying methods including laser scanning, photogrammetry, structured light scanning and reflectance transformation imaging.

The CREG Journal Search Engine (23-24)
Click on the search icon at bcra.org.uk/cregj and you will be taken to the CREG Journal Search Engine. This is still under development but is already a useful tool for searching through the 100 issues of the CREG Journal, which contain some 1500 articles. As well as plain-text and wildcard searches, the engine offers powerful 'regular expression' searches. It scans the article titles and abstracts and allows the user to display the results in different ways. Popup boxes provide help at a number of places. In this article David Gibson provides some technical background information to his coding but, as he says - this is not a User Manual because it doesn't need one.

Letters to the Editor (25)
Loop Orientation (Ian Drummond), Scurion Batteries (Bob South).

Yorkshire Dales Field Meeting: Autumn 2017 (26)
Micro HeyPhone, HF cave radio, audio propagation along tunnels, 3D surveying: Robin Gape reports on CREG's most recent get together, aimed at promoting experimental work and discussion.

Wet & Dry (28)
Ruggedisation, waterproofing & construction techniques – a roundup by Tony Haigh. Revisiting the Loop Antenna.

A 7MHz Beacon Transmitter for HF Cave Radio Experimentation (29-30)
HF cave radio trials often involved taking delicate and expensive amateur radio equipment underground. Fred Rattray, G4SPR, has based a beacon design on the 'Pixie', a small, popular and extremely low-cost transceiver design.

Web Watch (30)
Peter Ludwig unearths more fascinating links for us to explore.

Using an Audio DSP Filter with a Cave Radio (31-32)
The use of Digital Signal Processing (DSP) to reduce noise and improve intelligibility is now commonplace. An audio DSP filter can be incorporated into the receiver or provided as a separate standalone device. Rob Gill reviews a DSP filter module from bhi Ltd, presents an assessment of intelligibility improvement using a Modified Rhyme Test (MRT) and considers fully-automating the test procedure.