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A long-range locator is a class of fraudulent devices purported to be a type of metal detector, supposedly able to detect a variety of substances, including gold, drugs and explosives; most are said to operate on a principle of resonance with the material being detected.
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 rods or similarly useless devices. Virtually all such devices claim to operate on a resonant frequency 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; these are indistinguishable from dowsing rods.
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 calculators), 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 to function.
Author Tom Clancy came under fire for including the DKL Lifeguard, [1] a long-range locator purported to be useful for detecting people, in critical passages of his novel Rainbow Six . A study by Sandia National Laboratories proved the Lifeguard to be completely useless, [2] 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, the UK banned export of the GT 200, used by the government of Thailand, and the ADE 651, used by the government of Iraq, in January 2010.
An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal. It is a two-port electronic circuit that uses electric power from a power supply to increase the amplitude of a signal applied to its input terminals, producing a proportionally greater amplitude signal at its output. The amount of amplification provided by an amplifier is measured by its gain: the ratio of output voltage, current, or power to input. An amplifier is defined as a circuit that has a power gain greater than one.
Ultrasound is sound with frequencies greater than 20 kilohertz. This frequency is the approximate upper audible limit of human hearing in healthy young adults. The physical principles of acoustic waves apply to any frequency range, including ultrasound. Ultrasonic devices operate with frequencies from 20 kHz up to several gigahertz.
A PIN diode is a diode with a wide, undoped intrinsic semiconductor region between a p-type semiconductor and an n-type semiconductor region. The p-type and n-type regions are typically heavily doped because they are used for ohmic contacts.
A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, one that measures the direction of an ambient magnetic field, in this case, the Earth's magnetic field. Other magnetometers measure the magnetic dipole moment of a magnetic material such as a ferromagnet, for example by recording the effect of this magnetic dipole on the induced current in a coil.
A metal detector is an instrument that detects the nearby presence of metal. Metal detectors are useful for finding metal objects on the surface, underground, and under water. The unit itself consists of a control box, and an adjustable shaft, which holds a pickup coil, which can vary in shape and size. If the pickup coil comes near a piece of metal, the control box will register its presence by a changing tone, a flashing light, and or by a needle moving on an indicator. Usually the device gives some indication of distance; the closer the metal is, the higher the tone in the earphone or the higher the needle goes. Another common type are stationary "walk through" metal detectors used at access points in prisons, courthouses, airports and psychiatric hospitals to detect concealed metal weapons on a person's body.
A spectrum analyzer measures the magnitude of an input signal versus frequency within the full frequency range of the instrument. The primary use is to measure the power of the spectrum of known and unknown signals. The input signal that most common spectrum analyzers measure is electrical; however, spectral compositions of other signals, such as acoustic pressure waves and optical light waves, can be considered through the use of an appropriate transducer. Spectrum analyzers for other types of signals also exist, such as optical spectrum analyzers which use direct optical techniques such as a monochromator to make measurements.
A smoke detector is a device that senses smoke, typically as an indicator of fire. Smoke detectors are usually housed in plastic enclosures, typically shaped like a disk about 150 millimetres (6 in) in diameter and 25 millimetres (1 in) thick, but shape and size vary. Smoke can be detected either optically (photoelectric) or by physical process (ionization). Detectors may use one or both sensing methods. Sensitive alarms can be used to detect and deter smoking in banned areas. Smoke detectors in large commercial and industrial buildings are usually connected to a central fire alarm system.
In radio communications, a radio receiver, also known as a receiver, a wireless, or simply a radio, is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. The antenna intercepts radio waves and converts them to tiny alternating currents which are applied to the receiver, and the receiver extracts the desired information. The receiver uses electronic filters to separate the desired radio frequency signal from all the other signals picked up by the antenna, an electronic amplifier to increase the power of the signal for further processing, and finally recovers the desired information through demodulation.
In electronics, a limiter is a circuit that allows signals below a specified input power or level to pass unaffected while attenuating (lowering) the peaks of stronger signals that exceed this threshold. Limiting is a type of dynamic range compression. Clipping is an extreme version of limiting.
A pickup is a transducer that captures or senses mechanical vibrations produced by musical instruments, particularly stringed instruments such as the electric guitar, and converts these to an electrical signal that is amplified using an instrument amplifier to produce musical sounds through a loudspeaker in a speaker enclosure. The signal from a pickup can also be recorded directly.
A motion detector is an electrical device that utilizes a sensor to detect nearby motion. Such a device is often integrated as a component of a system that automatically performs a task or alerts a user of motion in an area. They form a vital component of security, automated lighting control, home control, energy efficiency, and other useful systems.
Explosive detection is a non-destructive inspection process to determine whether a container contains explosive material. Explosive detection is commonly used at airports, ports and for border control.
In electronics and signal processing, signal conditioning is the manipulation of an analog signal in such a way that it meets the requirements of the next stage for further processing.
A lightning detector is a device that detects lightning produced by thunderstorms. There are three primary types of detectors: ground-based systems using multiple antennas, mobile systems using a direction and a sense antenna in the same location, and space-based systems. The first such device was invented in 1894 by Alexander Stepanovich Popov. It was also the first radio receiver in the world.
An optical power meter (OPM) is a device used to measure the power in an optical signal. The term usually refers to a device for testing average power in fiber optic systems. Other general purpose light power measuring devices are usually called radiometers, photometers, laser power meters, light meters or lux meters.
The ADE 651 is a fake bomb detector produced by the British company Advanced Tactical Security & Communications Ltd (ATSC). Its manufacturer claimed it could detect bombs, guns, ammunition, and more from kilometers away. However, it was a scam, and the device was little more than a dowsing rod.
The GT200 is a fraudulent "remote substance detector" that was claimed by its manufacturer, UK-based Global Technical Ltd, to be able to detect, from a distance, various substances including explosives and drugs. The GT200 was sold to a number of countries for a cost of up to £22,000 per unit, but the device has been described as little more than "divining rods" which lack any scientific explanation for why they should work. After the similar ADE 651 was exposed as a fraud, the UK Government banned the export of such devices to Iraq and Afghanistan in January 2010 and warned foreign governments that the GT200 and ADE 651 are "wholly ineffective" at detecting bombs and explosives. The owner of Global Technical, Gary Bolton, was convicted on 26 July 2013 on two charges of fraud relating to the sale and manufacture of the GT200 and sentenced to seven years in prison.
The Alpha 6 is a fake "molecular detector" which, according to its manufacturer, can detect various substances from a distance, including explosives and drugs. The device has come under scrutiny following revelations about two similar devices, the ADE 651, which has become the focus of a fraud investigation in the United Kingdom, and the GT200, which tests have determined to perform no better than random chance.
The Quadro Tracker, also known as the Positive Molecular Locator, was a fake "detection device" sold by Quadro Corp. of Harleyville, South Carolina between 1993 and 1996. Around 1,000 were sold to police departments and school districts around the United States on the basis that it could detect hidden drugs, explosives, weapons and lost golf balls. In 1996, the FBI declared it to be a fake and obtained a permanent injunction barring the device from being manufactured or sold. Three principals of Quadro Corp. were charged with mail fraud and conspiracy to commit mail fraud, but were acquitted in a trial held in January 1997.
C-FAST was a device purported to be able to detect infection with the hepatitis C virus (HCV) from a distance, using electromagnetic radiation emanating from the virus' genome. At a press conference in February 2014, Egyptian generals presented the device as a result of decades-long secret military research.