The function of the Cave Radio & Electronics Group is to provide a forum where electronics enthusiasts and cavers can meet to discuss their ideas, through CREG publications and meetings. You will reach a wide and varied audience throughout the world. We would also like to encourage cavers to provide feedback. You do not have to be an electronics expert to subscribe to our journal - yes, it contains much specialist information, but we hope that it can also be used as a forum for feedback from cavers who will be using electronic equipment.

• Communications (Low Frequency Inductive Radio, Conventional Radio, UHF radio in tunnels, Guide-wire Radio, Single-wire Telephones, and Earth Current Signalling)
• Radio-location
• Lighting & Battery Chargers
• Electronic Photographic Equipment
• Cave Detection
• Waterproof Electronics
• Caving on the Internet
• History of cave communications
• Underground video techniques
• Data loggers (used by hydrologists and other cave scientists)
• Electric drills underground (for fixing SRT/ladder anchor points)
• Caver counters (for cave conservation purposes)

Right: A television image transmitted from a cave in March 1997. [Mike Bedford].

The Journal caters for most tastes by providing constructional projects, reports of practical experiments, general-interest features and original theoretical papers. Constructional projects have included David Gibson's highly-popular flashgun slave unit, now used by most cave photographers in the UK; Brian Pease's sophisticated radio-location beacon using a narrow-band phase-locked loop and, of course, John Hey's induction radio which has performed very well in trials in the UK and France.

Experimental write-ups have included earth-current techniques as away of improving the range of cave radios, capacitive and inductive couplers for single-wire telephones, radio spectrum surveys, speech processing, and experiments with a variety of VHF and UHF radios in tunnels.

General-interest features have looked at video techniques underground, electronic bat detection, the use of telephones for cave exploration in the 19th century. We have had several "special features" on lighting, photography and computing. For the theoretician we have discussed - amongst many topics - losses in tuning capacitors, receiver front-end design, bandwidth v. performance issues, earth current principles, myths surrounding impedance-matching of amplifiers, use of solar panels, and so on.

Letters to the Editor: We welcome letters to publish in the Journal. Whatever your interest, you might find others who are willing to share information. So whether your interest is magnetic field surveys for archaeology, VLF behaviour during earthquakes, metal detectors, video techniques, medical devices (e.g. TENS pain relief equipment, pulse oximeters), diving equipment, sensors for earth science research, earthquake monitoring, or some other "fringe" activity; we would like to hear from you.

Our Bibliography of Underground Communications is now out of print. Production of a new edition will depend of a volunteer stepping forward to do this. Our CREG Journal Digest, a list of all CREG articles, is also out of print, although there arte plans to bring out a new edition late in 2006. In the meantime, you can view a list of CREG journal articles, indexed by journal issue, and you can search a database of CREG articles as part of BCRA's Science Index.

Two weekends a year are designated as field meetings. These normally take place in the Spring and the Autumn, and visit the various caving area of the UK. The field meetings allow people to demonstrate equipment and techniques, carry out experiments, and share ideas. The exact programmes differ, depending on the interests of those attending, but typically include practical work during the days, and a few short talks or slide shows on the Saturday evening. Usually, there is also plenty of time to discuss issues informally over a pint in a local pub. Many people have had their introduction to cave radio through our field meetings, and we have welcomed visitors from France, Belgium, Canada and the USA.

The following activities have featured at field meetings over the last few years...

• Training in radio-location techniques
• Demonstrations of new cave radios
• Talks on GPS, licensing, speech compression
• Discussion on electronic aids for cave photographers
• Experiments with capacitively-coupled single wire telephones
• Demonstration of cave detection by earth resistance measurement
• Field tests of new commercial induction radios and carrier-based single-wire telephones
• Experiments with an earth-current/induction radio hybrid system
• Underground operation on the 73kHz amateur radio band
• Demonstration of equipment for scanning the LF band
• Tests with emergency lighting based on high brightness LEDs