CREG Journal (ISSN 1361-4800)

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Contents of journal 72
September 2009

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CREG Journal 72 (0-24) (PDF 5.5MB)        Individual articles may be available below

This issue has a cover date of August 2009, but was actually published on 17 September 2009.

 

Newssheet (3)

2010 Cave Technology Symposium, Cover Dates, CREG Prize 2009, Cover Picture, Diary Dates.

 

A Prototype Cave Radio to Avoid Loran Interference (4-6)

John Hey describes a prototype radio, based on his original HeyPhone design that operates at a lower frequency to avoid interference from Loran. This prototype includes new phasing circuits and some simplifications to the HeyPhone design which accommodates the obsolescence of some components.

 

Unexpected Propagation in Falkenstein Cave, Germany (7)

Cave radio tests in south-west Germany revealed unusual propagation with reception on the surface being possible only within a 100mm × 100mm area. Chris Ross speculates that local geology, and in particular iron-bearing rock in volcanic vents, was responsible for the routing of the LF signal.

 

An All-In-One Electronic Cave Surveying Device (8-10)

This device consists of a Laser Disto equipped with an add-on board carrying a 3-axis electronic compass/clinometer and a wireless Bluetooth connection. The board is powered by the Disto and fits entirely inside the original case. It allows measurement of distance, azimuth, and inclination with a single button press. Beat Heeb describes the resulting compact, robust and easy-to-use surveying device.

 

Letters to the Editor (11)

Future Directions, Measuring the Quality of a Caving Light, Cave Intrusion Alarm

 

Assessing Speech Intelligibility over a Communication Channel (12-15)

Mike Bedford summarises various methods for calculating or measuring the speech intelligibility of a communication channel and concludes that subjective intelligibility testing is a good candidate for assessing potential improvements to cave communication devices. The Modified Rhyme Test (MRT) is described in some detail and practical guidance is given on utilising it.

 

Web Watch (15)

Peter Ludwig offers yet more links to intriguing items on the Internet. Batteries, LEDs and even helicopters!

 

Use of Audio DSP Noise Filters to Reduce the Effect of Loran Interference (16-18)

Rob Gill describes a trial of three audio digital signal processing devices to measure their effectiveness in reducing Loran interference on a HeyPhone cave radio link. The trial employed the ANSI Modified Rhyme Test to measure the impact these devices had on speech intelligibility.

 

We Hear (19-20)

News and events. Mike Bedford brings us the latest to impact the world of cave radio and electronics.

 

Introducing the Equivital Physiological Monitor (21-23)

Hidalgo's Ekta Sood describes the company's Equivital physiological monitor. The Equivital System, which provides indications - either locally or remotely - of the wearer's vital signs and welfare status, has been trialled for use by emergency services world-wide.

 

Recording Fluorescence with a Digital Camera (23-24)

Mike Bedford reports on successful tests of photographing fluorescent minerals using a digital camera.

 

The Adventures of GREG (24)

Illustrations by Adrian Higgins with words by Mike Bedford.