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Airband
Airband or aircraft band is the name for a group of frequencies in the VHF radio spectrum allocated to radio communication in civil aviation, sometimes also referred to as ''VHF'', or phonetically as ''"Victor"''. Different sections of the band are used for radionavigational aids and air traffic control. In most countries a license to operate airband equipment is required and the operator is tested on competency in procedures, language and the use of the phonetic alphabet. Spectrum usage The VHF airband uses the frequencies between 108 and 137 MHz. The lowest 10 MHz of the band, from 108 to 117.95 MHz, is split into 200 narrow-band channels of 50 kHz. These are reserved for navigational aids such as VOR beacons, and precision approach systems such as ILS localizers. , most countries divide the upper 19 MHz into 760 channels for amplitude modulation voice transmissions, on frequencies from 118 to 136.975 MHz, in steps of 25 kHz. In Europ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Very High Frequency
Very high frequency (VHF) is the ITU designation for the range of radio frequency electromagnetic waves ( radio waves) from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high frequency (UHF). VHF radio waves propagate mainly by line-of-sight, so they are blocked by hills and mountains, although due to refraction they can travel somewhat beyond the visual horizon out to about 160 km (100 miles). Common uses for radio waves in the VHF band are Digital Audio Broadcasting (DAB) and FM radio broadcasting, television broadcasting, two-way land mobile radio systems (emergency, business, private use and military), long range data communication up to several tens of kilometers with radio modems, amateur radio, and marine communications. Air traffic control communications and air navigation systems (e.g. VOR and ILS) wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Spectrum
The radio spectrum is the part of the electromagnetic spectrum with frequencies from 0 Hz to 3,000 GHz (3 THz). Electromagnetic waves in this frequency range, called radio waves, are widely used in modern technology, particularly in telecommunication. To prevent interference between different users, the generation and transmission of radio waves is strictly regulated by national laws, coordinated by an international body, the International Telecommunication Union (ITU). Different parts of the radio spectrum are allocated by the ITU for different radio transmission technologies and applications; some 40 radiocommunication services are defined in the ITU's Radio Regulations (RR). In some cases, parts of the radio spectrum are sold or licensed to operators of private radio transmission services (for example, cellular telephone operators or broadcast television stations). Ranges of allocated frequencies are often referred to by their provisioned use (for example, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iridium Communications
Iridium Communications Inc. (formerly Iridium Satellite LLC) is a publicly traded American company headquartered in McLean, Virginia. Iridium operates the Iridium satellite constellation, a system of 66 active satellites and 9 in-orbit spares used for worldwide voice and data communication from hand-held satellite phones and other transceiver units. The nearly polar orbit and communication between satellites via inter-satellite links provide global service availability. History The Iridium communications service was launched on November 1, 1998, formerly known as Iridium SSC. The first Iridium call was made by Vice President of the United States Al Gore to Gilbert Grosvenor, the great-grandson of Alexander Graham Bell and chairman of the National Geographic Society. Motorola provided the technology and major financial backing. The logo of the company represents the Big Dipper. The company derives its name from the chemical element iridium, which has an atomic number of 77, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capture Effect
In a radio receiver, the capture effect, or FM capture effect, is a phenomenon associated with FM reception in which only the stronger of two signals at, or near, the same frequency or channel will be demodulated. FM phenomenon The capture effect is defined as the complete suppression of the weaker signal at the receiver's limiter (if present) where the weaker signal is not amplified, but attenuated. When both signals are nearly equal in strength or are fading independently, the receiver may rapidly switch from one to another and exhibit flutter. The capture effect can occur at the signal limiter, or in the demodulation stage for circuits that do not require a signal limiter. Some types of radio receiver circuits have a stronger capture effect than others. The measurement of how well a receiver rejects a second signal on the same frequency is called its capture ratio. It is measured as the lowest ratio of the power of two signals that will result in the suppression of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aircraft Emergency Frequency
The aircraft emergency frequency (also known as GUARD) is a frequency used on the aircraft band reserved for emergency communications for aircraft in distress. The frequencies are 121.5 MHz for civilian, also known as International Air Distress (IAD) or VHF Guard, and 243.0 MHz—the second harmonic of VHF guard—for military use, also known as Military Air Distress (MAD) or UHF Guard. Earlier emergency locator transmitters (ELTs) used the guard frequencies to transmit, but an additional frequency of 406 MHz is used by a more modern emergency locator transmitter. History The choice of 121.5 MHz was made by ICAO in conjunction with ARINC and the ITU. Monitoring In the United States, the emergency frequency is monitored by most air traffic control towers, FSS services, national air traffic control centers, military air defense and other flight and emergency services, as well as by many commercial aircraft. The notice to airmen FDC 4/4386 requires "…all aircr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Organisation For The Safety Of Air Navigation
The European Organisation for the Safety of Air Navigation, commonly known as Eurocontrol (stylised ''EUROCONTROL''), is an international organisation working to achieve safe and seamless air traffic management across Europe. Founded in 1960, Eurocontrol currently has 41 member states and is headquartered in Brussels, Belgium. It has several local sites as well, including an Innovation Hub in Brétigny-sur-Orge, France, the Aviation Learning Centre (ALC) in Luxembourg, and the Maastricht Upper Area Control Centre (MUAC) in Maastricht, the Netherlands. The organisation employs approximately two thousand people, and operates with an annual budget in excess of half a billion Euro. Although Eurocontrol is not an agency of the European Union, the EU has delegated parts of its Single European Sky regulations to Eurocontrol, making it the central organisation for coordination and planning of air traffic control for all of Europe. The EU itself is a signatory of Eurocontrol and all EU me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ICAO
The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international air transport to ensure safe and orderly growth. ICAO headquarters are located in the '' Quartier International'' of Montreal, Quebec, Canada. The ICAO Council adopts standards and recommended practices concerning air navigation, its infrastructure, flight inspection, prevention of unlawful interference, and facilitation of border-crossing procedures for international civil aviation. ICAO defines the protocols for air accident investigation that are followed by transport safety authorities in countries signatory to the Chicago Convention on International Civil Aviation. The Air Navigation Commission (ANC) is the technical body within ICAO. The commission is composed of 19 commissioners, nominated by the ICAO's contracting states and appo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distance Measuring Equipment
In aviation, distance measuring equipment (DME) is a radio navigation technology that measures the slant range (distance) between an aircraft and a ground station by timing the propagation delay of radio signals in the frequency band between 960 and 1215 megahertz (MHz). Line-of-visibility between the aircraft and ground station is required. An interrogator (airborne) initiates an exchange by transmitting a pulse pair, on an assigned 'channel', to the transponder ground station. The channel assignment specifies the carrier frequency and the spacing between the pulses. After a known delay, the transponder replies by transmitting a pulse pair on a frequency that is offset from the interrogation frequency by 63 MHz and having specified separation.''Annex 10 to the Convention on International Civil Aviation, Volume I – Radio Navigation Aids''; International Civil Aviation Organization; International Standards and Recommended Practices. DME systems are used worldwide, usi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marker Beacon
A marker beacon is a particular type of VHF radio beacon used in aviation, usually in conjunction with an instrument landing system (ILS), to give pilots a means to determine position along an established route to a destination such as a runway. According to ''Article 1.107'' of the International Telecommunication Union's (ITU) ITU Radio Regulations (RR) a marker beacon is defined as "a transmitter in the aeronautical radionavigation service which radiates vertically a distinctive pattern for providing position information to aircraft". History From the 1930s until the 1950s, markers were used extensively along airways to provide an indication of an aircraft's specific position along the route, but from the 1960s they have become increasingly limited to ILS approach installations. They are now very gradually being phased out of service, especially in more developed parts of the world, as GPS and other technologies have made marker beacons increasingly redundant. Types There ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultra High Frequency
Ultra high frequency (UHF) is the ITU designation for radio frequency, radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter (one decimeter). Radio waves with frequencies above the UHF band fall into the super-high frequency (SHF) or microwave frequency range. Lower frequency signals fall into the VHF (very high frequency) or lower bands. UHF radio waves propagate mainly by Line-of-sight propagation, line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. They are used for UHF television broadcasting, television broadcasting, cell phones, satellite communication including GPS, personal radio services including Wi-Fi and Bluetooth, walkie-talkies, cordless phones, satellite phones, and numerous other applications. The Institute of Electrical and Electronics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instrument Landing System
In aviation, the instrument landing system (ILS) is a precision radio navigation system that provides short-range guidance to aircraft to allow them to approach a runway at night or in bad weather. In its original form, it allows an aircraft to approach until it is over the ground, within a of the runway. At that point the runway should be visible to the pilot; if it is not, they perform a missed approach. Bringing the aircraft this close to the runway dramatically increases the range of weather conditions in which a safe landing can be made. Other versions of the system, or "categories", have further reduced the minimum altitudes, runway visual ranges (RVRs), and transmitter and monitoring configurations designed depending on the normal expected weather patterns and airport safety requirements. ILS uses two directional radio signals, the ''localizer'' (108 to 112 MHz frequency), which provides horizontal guidance, and the ''glideslope'' (329.15 to 335 MHz frequency ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medium Frequency
Medium frequency (MF) is the ITU designation for radio frequencies (RF) in the range of 300 kilohertz (kHz) to 3 megahertz (MHz). Part of this band is the medium wave (MW) AM broadcast band. The MF band is also known as the hectometer band as the wavelengths range from ten to one hectometer (1000 to 100 m). Frequencies immediately below MF are denoted low frequency (LF), while the first band of higher frequencies is known as high frequency (HF). MF is mostly used for AM radio broadcasting, navigational radio beacons, maritime ship-to-shore communication, and transoceanic air traffic control. Propagation Radio waves at MF wavelengths propagate via ground waves and reflection from the ionosphere (called skywaves). Ground waves follow the curvature of Earth. At these wavelengths they can bend (diffract) over hills, and travel beyond the visual horizon, although they may be blocked by mountain ranges. Typical MF radio stations can cover a radius of several hun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
