Long range locator
Encyclopedia
A long range locator is a device purported to be a type of metal detector
Metal detector
A metal detector is a device which responds to metal that may not be readily apparent.The simplest form of a metal detector consists of an oscillator producing an alternating current that passes through a coil producing an alternating magnetic field...

 used to detect deposits of gold or similar precious materials; most are said to operate on a principle of resonance with the material being detected.

Theory of operation

Many treasure hunters swear by the devices; however, skeptics have examined the internals of many such devices and found those that have been examined to be incapable of operating as advertised, and have dismissed them as overpriced dowsing
Dowsing
Dowsing is a type of divination employed in attempts to locate ground water, buried metals or ores, gemstones, oil, gravesites, and many other objects and materials, as well as so-called currents of earth radiation , without the use of scientific apparatus...

 rods or similarly useless. Virtually all such devices claim to operate on a resonant frequency
Resonance
In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...

 principle where the device is said to emit an electromagnetic signal, either through an antenna or a probe, that will respond to a specific substance such as gold, silver, or sometimes even paper money, and that the device will indicate the presence of such material by indicating a change in direction relative to the operator.

This theory of operation is not supported by scientific theory; the devices have not been shown to work in blind testing, and the resonance principle invoked has not been shown to work in laboratories (and is not consistently employed by LRL manufacturers). In addition, the Inverse-Square Law limits the effective possible signal strength of any putative LRL; moreover, not only does this attenuation apply to the supposed emissions from the LRL devices, but the return signals from the sought-after targets are further attenuated by the same constraints. Since most of these LRL devices are powered by low voltage, low current AA, AAA or 9v cells, the resultant power available for emissions is quite minuscule at best, and the return signal would suffer even greater attenuation. Examples exist of LRL devices having no internal power source at all, and these are advertised as being self-powered or powered by ambient static electricity
Static electricity
Static electricity refers to the build-up of electric charge on the surface of objects. The static charges remain on an object until they either bleed off to ground or are quickly neutralized by a discharge. Static electricity can be contrasted with current electricity, which can be delivered...

; these are indistinguishable from dowsing rods.

Scientific evaluation

Many such devices contain non-functional circuitry or naively constructed approximations of radio transmitters. A few do have functional circuitry, putting out a weak signal with a function generator or a simple timer circuit, but are still largely useless in comparison with a coil-based metal detector; others have been found to contain intentionally obfuscated or completely superfluous components (from individual components such as inductors or ribbon cables up to, in some cases, pocket calculator
Calculator
An electronic calculator is a small, portable, usually inexpensive electronic device used to perform the basic operations of arithmetic. Modern calculators are more portable than most computers, though most PDAs are comparable in size to handheld calculators.The first solid-state electronic...

s), often indicative of intentional fraud, incompetence, or both, by the designer. Such functioning circuitry as exists in such devices usually has no obvious way (motor, solenoid, etc) to connect to any rotating joint in the device either, meaning the devices are often entirely dependent on the ideomotor effect
Ideomotor effect
The ideomotor effect is a psychological phenomenon wherein a subject makes motions unconsciously. As in reflexive responses to pain, the body sometimes reacts reflexively to ideas alone without the person consciously deciding to take action. For instance, tears are produced by the body...

 to function.

Media exposure and controversy

Author Tom Clancy
Tom Clancy
Thomas Leo "Tom" Clancy, Jr. is an American author, best known for his technically detailed espionage, military science, and techno thriller storylines set during and in the aftermath of the Cold War, along with video games on which he did not work, but which bear his name for licensing and...

 came under fire for including the DKL Lifeguard, a long range locator purported to be useful for detecting people, in critical passages of his novel Rainbow Six
Rainbow Six
Tom Clancy's Rainbow Six is a media franchise created by American author Tom Clancy about a fictional international counter-terrorist unit called "Rainbow." The franchise began with Clancy's novel Rainbow Six, which was adapted into a successful series of tactical first-person shooter video games.-...

. A study by Sandia National Laboratories
Sandia National Laboratories
The Sandia National Laboratories, managed and operated by the Sandia Corporation , are two major United States Department of Energy research and development national laboratories....

 proved the Lifeguard to be completely useless, and other designs by the Lifeguard's creator Thomas Afilani have been shown to contain numerous dummy components with no clear function.

Accusing the manufacturers of fraud, Great Britain banned export of the GT 200 (used by the government of Thailand) and also the ADE 651 (used by the government of Iraq) in January 2010.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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