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CREG Journal 77 (0-20)
This issue has a cover date of March 2012, but was actually published on 3 May 2012.

Newssheet (3)
Page Count, Back Issues, 2012 Cave Technology Symposium, Field Meetings, Diary Dates.

We Hear (4)
News and events - Mike Bedford brings us the latest to impact the world of cave radio and electronics. 3D Laser Scanning for Crash Scene Investigation, Metal Cored PCBs, New eLORAN Module, Underwater Surveying.

Journey to the Centre of the Planet - My Small Part (5-7)
The BBC recently produced a two-part TV series with Richard Hammond that included a segment about the Floridan Aquifer. Brian Pease was recruited to surface track a through-dive at a cave spring and provide voice communications. He reviews the programme segment and reveals some of the pressures and the huge organisational and technical complexities behind the scenes.

Web Watch (7)
Peter Ludwig presents a short selection of links of interest.

Methods of Measuring Ground Resistivity (8-9)
It is sometimes necessary to measure the resistivity of the ground. The Wenner array of four equally spaced earth electrodes is commonly used, but this is not always the most appropriate. John Rabson describes some alternatives.

XKCD Circuit Diagram (9)
Randall Munroe presents his take on a circuit diagram.

Loop Antennas v. Ferrite Rods: A Case Study (10-14)
An induction radio's transmitting antenna may be an air-cored loop or a ferrite-cored solenoid. Because there are so many variables involved it is difficult, in the general case, to compare the two types of antenna and it is not possible to state, unequivocally, which type of antenna will perform better. However, in specific practical situations, a comparison is possible. In this article David Gibson describes one such case.

Wet & Dry (15)
Ruggedisation, waterproofing & constructional techniques. Column edited by Mike Bedford.

Cave Detection by Earth Resistivity Surveying (16-20)
Mike Bedford describes how surface-based electrical resistivity measurements can be used to build up a three-dimensional resistivity map of the sub-surface and, potentially, identify unknown caves.

The Adventures of GREG (20)
Illustrations by Adrian Higgins with words by Mike Bedford.