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Information about Radiolocation

Radiolocation is the process of finding the location of something through the use of radio waves. It generally refers to passive uses, particularly radar — as well as detecting buried cables, water mains, and other public utilities. It is similar to radionavigation, but radiolocation usually refers to passively finding a distant object rather than actively one's own position. Both are types of radiodetermination.

The angle at which a signal returns, as well as the time is takes to return can (or must) both determine where an object is. In Doppler radar, the Doppler shift is also taken into account, determining velocity rather than location (though it helps determine future location).

A stud finder can also be an example of radiolocation, if it uses radio waves rather than ultrasound.

Mobile phones

Radiolocation is also used in cellular telephony via base stations. Most often, this is done through trilateration between radio towers. The location of the Caller or handset can be determined several ways:
  • angle of arrival (AOA) requires at least two towers, locating the caller at the point where the lines along the angles from each tower intersect
  • time difference of arrival (TDOA) works using multilateration, except that it is the networks that determine the time difference and therefore distance from each tower (as with seismometers)
  • location signature uses "fingerprinting" to store and recall patterns (such as multipath) which mobile phone signals are known to exhibit at different locations in each cell
The first two depend on a line of sight, which can be difficult or impossible in mountainous terrain or around skyscrapers. Location signatures actually work better in these conditions however. TDMA and GSM networks such as Cingular and T-Mobile use TDOA.

CDMA networks such as Verizon Wireless and Sprint PCS tend to use handset-based radiolocation technologies, which are technically more similar to radionavigation. GPS is one of those technologies.

Hybrid solutions, needing both the handset and the network include:
  • assisted GPS (wireless or TV) allows use of GPS even indoors
  • Advanced Forward Link Trilateration (A-FLT)
  • Timing Advance/Network Measurement Report (TA/NMR)
  • Enhanced Observed Time Difference (E-OTD)
Initially, the purpose of any of these in mobile phones is so that the public safety answering point (PSAP) which answers calls to an emergency telephone number can know where the caller is and exactly where to send emergency services. This ability is known within the NANP (North America) as wireless enhanced 911. Mobile phone users have a selection to also permit the location information gathered to be sent to other phone numbers or data networks, so that it can help people who are simply lost or want other location-based services. By default, this selection is usually turned off, to protect privacy.

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In geography, location is a position or point in physical space that something occupies on Earths' surface. A real location can often be designated using a specific pairing of latitude and longitude, a Cartesian coordinate grid (e.g.
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Radio Wave may mean:
  • Radio frequency
  • Radio Wave 96.5, a radio station in Blackpool, UK

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Radar is a system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain.
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cable is one or more wires or optical fibers bound together, typically in a common protective jacket or sheath. The individual wires or fibers inside the jacket may be covered or insulated. Combination cables may contain both electrical wires and optical fibers.
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Water is a common chemical substance that is essential to all known forms of life.[1] In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor.
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Mains may mean or refer to, or be a subject of:
  • Mains electricity ("line power" in the United States)
  • Electricity transmission
  • Public utility, about "mains services", including electricity, natural gas, water, and sewage disposal

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A public utility (usually just utility in British English) is a company that maintains the infrastructure for a public service (often also providing a service using that infrastructure).
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Radio navigation or radionavigation is the application of radio frequencies to determining a position on the Earth. Like radiolocation, it is a type of radiodetermination.

RDF / ADF / NDB

The first system of radio navigation was the Radio Direction Finder, or RDF.
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As defined by FS-1037C, radiodetermination is the determination of the position, velocity and/or other characteristics of an object, or the obtaining of information relating to these parameters, by means of the propagation properties of radio waves.
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angle (in full, plane angle) is the figure formed by two rays sharing a common endpoint, called the vertex of the angle. The magnitude of the angle is the "amount of rotation" that separates the two rays, and can be measured by considering the length of circular arc swept
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In telecommunication, signalling (UK spelling) or signaling (US spelling) has the following meanings:
  • The use of signals for controlling communications.

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time.

One view is that time is part of the fundamental structure of the universe, a dimension in which events occur in sequence, and time itself is something that can be measured.
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Doppler radar uses the Doppler effect to measure the radial velocity of targets in the antenna's directional beam. The Doppler effect shifts the received frequency up or down based on the radial velocity of target (closing or opening) in the beam, allowing for the direct
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Doppler effect, named after Christian Doppler, is the change in frequency and wavelength of a wave as perceived by an observer moving relative to the source of the waves. For waves that propagate in a wave medium, such as sound waves, the velocity of the observer and of the source
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velocity is defined as the rate of change of position. It is a vector physical quantity, both speed and direction are required to define it. In the SI (metric) system, it is measured in meters per second (m/s). The scalar absolute value (magnitude) of velocity is speed.
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A stud finder (also stud detector or stud sensor) is a handheld device used to determine the location of framing studs used in light-frame construction after the walling surface has been installed.
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Ultrasound is a cyclic sound pressure with a frequency greater than the upper limit of human hearing, this limit being approximately 20 kilohertz (20,000 hertz).

Ability to hear ultrasound


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mobile phone or cell phone is a long-range, portable electronic device used for mobile communication. In addition to the standard voice function of a telephone, current mobile phones can support many additional services such as SMS for text messaging, email, packet switching
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The term base station can be used in the context of land surveying, wireless computer networking, and wireless communications.

Land surveying

In the context of external land surveying, a base station is a GPS receiver at an accurately-known fixed location which is used to
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Trilateration is a method of determining the relative positions of objects using the geometry of triangles in a similar fashion as triangulation. Unlike triangulation, which uses angle measurements (together with at least one known distance) to calculate the subject's location,
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Radio masts and towers are, typically, tall structures designed to support antennas (also known as aerials in the UK) for telecommunications and broadcasting, including television. They are among the tallest man-made structures.
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The calling party (also called caller, call originator or A-party) is a person who (or device that) initiates a telephone call over the public switched telephone network, usually by dialing a telephone number.
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A transceiver is a device that has both a transmitter and a receiver which are combined and share common circuitry or a single housing. If no circuitry is common between transmit and receive functions, the device is a transmitter-receiver. The term originated in the early 1920s.
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Intersection has various meanings in different contexts:
  • In mathematics and geometry
  • Intersection (set theory), the set of elements common to some collection of sets.

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Multilateration, also known as hyperbolic positioning, is the process of locating an object by accurately computing the time difference of arrival (TDOA) of a signal emitted from the object to three or more receivers.
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Seismometers (in Greek seismos = earthquake and metero = measure) are used by seismologists to measure and record the size and force of seismic waves. By studying seismic waves, geologists can map the interior of the Earth, and measure and locate earthquakes and
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The pattern is a form, template, or model (or, more abstractly, a set of ) which can be used to make or to generate things or parts of a thing, especially if the things that are created have enough in common for the underlying pattern to be inferred, in which case the things are
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multipath is the propagation phenomenon that results in radio signals' reaching the receiving antenna by two or more paths. Causes of multipath include atmospheric ducting, ionospheric reflection and refraction, and reflection from terrestrial objects, such as mountains and
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Line-of-sight propagation refers to electro-magnetic radiation travelling in a straight line. The rays are therefore deviated or reflected by obstructions and cannot travel over the horizon. Beyond that, material disperses the rays.
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mountain is a landform that extends above the surrounding terrain in a limited area. A mountain is generally steeper than a hill, but there is no universally accepted standard definition for the height of a mountain or a hill although a mountain usually has an identifiable
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