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Airplane Scatter
Airplane scattering (or most often reflection) refers to the reflection of a radio signal by the metal structure of a passing aircraft. It is observed on radio waves from high frequency to VHF through to microwaves and, besides back-scattering, yields momentary propagation up to even in mountainous terrain. The most common back-scatter applications are air-traffic radar, bistatic forward-scatter guided-missile and airplane-detecting trip-wire radar, and the US space radar. It is also a less common propagation mode used by radio amateurs. History Airplane scatter itself had been discovered in 1930, but radio amateur usage lagged until the late 80s. The advent of inexpensive SDR based and distributed real time flight tracking enabled precise scheduling, increasing feasibility. Radio amateur usage Compared to a single trail of meteor scatter, the time of opening caused by a single airplane is longer it can be from 30 seconds up to a few minutes. Slight asymmetry can some ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Frequency
High frequency (HF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters (ten to one hundred meters). Frequencies immediately below HF are denoted medium frequency (MF), while the next band of higher frequencies is known as the very high frequency (VHF) band. The HF band is a major part of the shortwave band of frequencies, so communication at these frequencies is often called shortwave radio. Because radio waves in this band can be reflected back to Earth by the ionosphere layer in the atmosphere – a method known as "skip" or " skywave" propagation – these frequencies are suitable for long-distance communication across intercontinental distances and for mountainous terrains which prevent line-of-sight communications. The band is used by international shortwave broadcasting stations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airport Surveillance Radar
An airport surveillance radar (ASR) is a radar system used at airports to detect and display the presence and position of aircraft in the ''terminal area'', the airspace around airports. It is the main air traffic control system for the airspace around airports. At large airports it typically controls traffic within a radius of 60 miles (96 km) of the airport below an elevation of 25,000 feet. The sophisticated systems at large airports consist of two different radar systems, the ''primary'' and ''secondary'' surveillance radar. The primary radar typically consists of a large rotating parabolic antenna dish that sweeps a vertical fan-shaped beam of microwaves around the airspace surrounding the airport. It detects the position and range of aircraft by microwaves reflected back to the antenna from the aircraft's surface. The secondary surveillance radar consists of a second rotating antenna, often mounted on the primary antenna, which interrogates the transponders of airc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bistatic Radar
Bistatic radar is a radar system comprising a transmitter and receiver that are separated by a distance comparable to the expected target distance. Conversely, a conventional radar in which the transmitter and receiver are co-located is called a monostatic radar. A system containing multiple spatially diverse monostatic or bistatic radar components with a shared area of coverage is called ''multistatic radar''. Many long-range air-to-air and surface-to-air missile systems use semi-active radar homing, which is a form of bistatic radar. Types Pseudo-monostatic radars Some radar systems may have separate transmit and receive antennas, but if the angle subtended between transmitter, target and receiver (the bistatic angle) is close to zero, then they would still be regarded as monostatic or pseudo-monostatic. For example, some very long range HF radar systems may have a transmitter and receiver which are separated by a few tens of kilometres for electrical isolation, but as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bistatic Radar
Bistatic radar is a radar system comprising a transmitter and receiver that are separated by a distance comparable to the expected target distance. Conversely, a conventional radar in which the transmitter and receiver are co-located is called a monostatic radar. A system containing multiple spatially diverse monostatic or bistatic radar components with a shared area of coverage is called ''multistatic radar''. Many long-range air-to-air and surface-to-air missile systems use semi-active radar homing, which is a form of bistatic radar. Types Pseudo-monostatic radars Some radar systems may have separate transmit and receive antennas, but if the angle subtended between transmitter, target and receiver (the bistatic angle) is close to zero, then they would still be regarded as monostatic or pseudo-monostatic. For example, some very long range HF radar systems may have a transmitter and receiver which are separated by a few tens of kilometres for electrical isolation, but as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amateur Radio Operator
An amateur radio operator is someone who uses equipment at an amateur radio station to engage in two-way personal communications with other amateur operators on radio frequencies assigned to the amateur radio service. Amateur radio operators have been granted an amateur radio license by a governmental regulatory authority after passing an examination on applicable regulations, electronics, radio theory, and radio operation. As a component of their license, amateur radio operators are assigned a call sign that they use to identify themselves during communication. About three million amateur radio operators are currently active worldwide. Amateur radio operators are also known as radio amateurs or hams. The term "ham" as a nickname for amateur radio operators originated in a pejorative usage (like "ham actor") by operators in commercial and professional radio communities, and dates to wired telegraphy. The word was subsequently adopted by amateur radio operators. Demographics {, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software-defined Radio
Software-defined radio (SDR) is a radio communication system where components that have been traditionally implemented in analog hardware (e.g. mixers, filters, amplifiers, modulators/demodulators, detectors, etc.) are instead implemented by means of software on a personal computer or embedded system. While the concept of SDR is not new, the rapidly evolving capabilities of digital electronics render practical many processes which were once only theoretically possible. A basic SDR system may consist of a personal computer equipped with a sound card, or other analog-to-digital converter, preceded by some form of RF front end. Significant amounts of signal processing are handed over to the general-purpose processor, rather than being done in special-purpose hardware (electronic circuits). Such a design produces a radio which can receive and transmit widely different radio protocols (sometimes referred to as waveforms) based solely on the software used. Software radios have signif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tracking (commercial Airline Flight)
Flight tracking is a service that involves the tracking of flights, aircraft and airport activity, often using software. Overview Flight tracking enables travellers as well as those picking up travellers after a flight to know whether a flight has landed or is on schedule, for example to determine whether it is time to go to the airport. Aircraft carry ADS-B transponders, which transmit information such as the aircraft ID, GPS position, and altitude as radio signals. These radio transmission are collected by civilian ADS-B receivers located in the vicinity of the aircraft. These ADS-B receivers are only able to collect information on flights within radio-range of their position, so the data they collect is usually sent to a central server which aggregates feeds from numerous individual receivers throughout the world. Flight tracking can be integrated with travel management and travel tracking services, allowing increased automation of travel software. This application of fligh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteor Burst Communications
Meteor burst communications (MBC), also referred to as meteor scatter communications, is a radio propagation mode that exploits the ionized trails of meteors during atmospheric entry to establish brief communications paths between radio stations up to apart. There can be forward-scatter or back-scatter of the radio waves. How it works As the Earth moves along its orbital path, millions of particles known as meteoroids enter the Earth's atmosphere every day, a small fraction of which have properties useful for point-to-point communication. When these meteoroids begin to burn up, they create a glowing trail of ionized particles (called a meteor) in the E layer of the atmosphere that can persist for up to several seconds. The ionization trails can be very dense and thus used to reflect radio waves. The frequencies that can be reflected by any particular ion trail are determined by the intensity of the ionization created by the meteor, often a function of the initial size of the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aviation Transponder Interrogation Modes
The aviation transponder interrogation modes are the standard formats of pulsed sequences from an interrogating Secondary Surveillance Radar (SSR) or similar Automatic Dependent Surveillance-Broadcast (ADS-B) system. The reply format is usually referred to as a "code" from a transponder, which is used to determine detailed information from a suitably equipped aircraft. In its simplest form, a "Mode" or interrogation type is generally determined by pulse spacing between two or more interrogation pulses. Various modes exist from Mode 1 to 5 for military use, to Mode A, B, C and D, and Mode S for civilian use. Interrogation modes Several different RF communication protocols have been standardized for aviation transponders: Mode A and Mode C are implemented using air traffic control radar beacon system as the physical layer, whereas Mode S is implemented as a standalone backwards-compatible protocol. ADS-B can operate using Mode S-ES or Universal Access Transceiver as its transpor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Automatic Dependent Surveillance – Broadcast
Automatic may refer to: Music Bands * Automatic (band), Australian rock band * Automatic (American band), American rock band * The Automatic, a Welsh alternative rock band Albums * ''Automatic'' (Jack Bruce album), a 1983 electronic rock album * ''Automatic'' (Sharpe & Numan album), a 1989 synthpop album * ''Automatic'' (The Jesus and Mary Chain album), a 1989 alternative rock album * ''Automatic'', a 1997 electronic album by Le Car * ''Automatic'' (Dweezil Zappa album), a 2000 hard rock album, or the title song * ''Automatic'', a 2003 punk rock album by The Turbo A.C.'s * ''Automatic'' (Stitches album), a 2006 punk rock album, or the title song * ''Automatic'' (VNV Nation album), a 2011 futurepop album * ''Automatic'', a 2013 reggae-rock album by Iration * ''Automatic'' (Don Broco album), a 2015 rock album * ''Automatic'' (Kaskade album), 2015 album by Kaskade * ''Automatic'' (Mildlife album), 2020 album by Mildlife Songs * "Automatic" (Danny Fernandes song), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Gain Antenna
A directional antenna or beam antenna is an antenna which radiates or receives greater power in specific directions allowing increased performance and reduced interference from unwanted sources. Directional antennas provide increased performance over dipole antennas—or omnidirectional antennas in general—when greater concentration of radiation in a certain direction is desired. A high-gain antenna (HGA) is a directional antenna with a focused, narrow radiowave beam width, permitting more precise targeting of the radio signals. Most commonly referred to during space missions, these antennas are also in use all over Earth, most successfully in flat, open areas where there are no mountains to disrupt radiowaves. By contrast, a low-gain antenna (LGA) is an omnidirectional antenna with a broad radiowave beam width, that allows the signal to propagate reasonably well even in mountainous regions and is thus more reliable regardless of terrain. Low-gain antennas are often used in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tropospheric Scatter
Tropospheric scatter, also known as troposcatter, is a method of communicating with microwave radio signals over considerable distances – often up to and further depending on frequency of operation, equipment type, terrain, and climate factors. This method of propagation uses the tropospheric scatter phenomenon, where radio waves at Ultra high frequency, UHF and Super high frequency, SHF Frequency, frequencies are randomly scattered as they pass through the upper layers of the troposphere. Radio signals are transmitted in a narrow beam aimed just above the horizon in the direction of the receiver station. As the signals pass through the troposphere, some of the energy is scattered back toward the Earth, allowing the receiver station to pick up the signal. Normally, signals in the microwave frequency range travel in straight lines, and so are limited to ''Line-of-sight propagation, line-of-sight'' applications, in which the receiver can be 'seen' by the transmitter. Communicat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
