|
ELoran
Enhanced LORAN (commonly known as eLoran; also known as eLORAN, E-LORAN, or e-LORAN) is a long-range radio navigation system that uses terrestrial towers and the hyperbolic navigation technique. It is an advancement in receiver design and transmission characteristics which increase the accuracy and usefulness of traditional LORAN and LORAN-C. Interest has been renewed by the potential vulnerability of global navigation satellite systems, and their own propagation and reception limitations. With reported accuracy as good as ± 8 meters, the system becomes competitive with unenhanced GPS. eLoran also includes additional pulses which can transmit auxiliary data such as Differential GPS (DGPS) corrections, as well as ensure data integrity against spoofing. eLoran receivers use "all in view" reception, incorporating signals from all stations in range, not solely those from a single Group Repetition Interval (GRI), incorporating time signals and other data from up to forty statio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Navigation
Radio navigation or radionavigation is the application of radio waves to geolocalization, determine a position of an object on the Earth, either the vessel or an obstruction. Like radiolocation, it is a type of Radiodetermination-satellite service, radiodetermination. The basic principles are measurements from/to electric beacons, especially * Direction (geometry), Angular directions, e.g. by bearing, radio phases or interferometry, * Distance measuring equipment, Distances, e.g. ranging by measurement of time of flight between one transmitter and multiple receivers or vice versa, * Distance ''differences'' by measurement of multilateration, times of arrival of signals from one transmitter to multiple receivers or vice versa * Partly also velocity, e.g. by means of radio Doppler shift. Combinations of these measurement principles also are important—e.g., many radars measure range and azimuth of a target. Bearing-measurement systems These systems used some form of directional ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyperbolic Navigation
Hyperbolic navigation is a class of radio navigation systems in which a navigation receiver instrument is used to determine location based on the difference in timing of radio waves received from radio navigation beacon transmitters. Such systems rely on the ability of two widely separated stations to broadcast a signal that is highly correlated in time. Typical systems broadcast either short pulses at the same time, or continual signals that are identical in phase. A receiver located at the midpoint between the two stations will receive the signals at the same time or have identical phase, but at any other location the signal from the closer station will be received first or have a different phase. Determining the location of a receiver requires that the two synchronized stations be tuned in at the same time so the signals can be compared. This reveals a ''difference'' in time, corresponding to a relative distance closer to one station or the other. Plotting all the locations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LORAN
LORAN (Long Range Navigation) was a hyperbolic navigation, hyperbolic radio navigation system developed in the United States during World War II. It was similar to the UK's Gee (navigation), Gee system but operated at lower frequencies in order to provide an improved range up to with an accuracy of tens of miles. It was first used for ship convoys crossing the Atlantic Ocean, and then by long-range patrol aircraft, but found its main use on the ships and aircraft operating in the Pacific theater during World War II. LORAN, in its original form, was an expensive system to implement, requiring a cathode ray tube (CRT) display and a well trained operator. This limited use to the military and large commercial users. Automated receivers became available in the 1950s, but the same improved electronics also opened the possibility of new systems with higher accuracy. The U.S. Navy began development of Loran-B, which offered accuracy on the order of a few tens of feet, but ran into signi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Global Navigation Satellite System
A satellite navigation or satnav system is a system that uses satellites to provide autonomous geopositioning. A satellite navigation system with global coverage is termed global navigation satellite system (GNSS). , four global systems are operational: the United States's Global Positioning System (GPS), Russia's Global Navigation Satellite System (GLONASS), China's BeiDou Navigation Satellite System (BDS), and the European Union's Galileo. Two regional systems are operational: India's NavIC and Japan's QZSS. '' Satellite-based augmentation systems'' (SBAS), designed to enhance the accuracy of GNSS, include Japan's Quasi-Zenith Satellite System (QZSS), India's GAGAN and the European EGNOS, all of them based on GPS. Previous iterations of the BeiDou navigation system and the present Indian Regional Navigation Satellite System (IRNSS), operationally known as NavIC, are examples of stand-alone operating regional navigation satellite systems (RNSS). Satellite navigation de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Differential GPS
Differential Global Positioning Systems (DGPSs) supplement and enhance the positional data available from global navigation satellite systems (GNSSs). A DGPS can increase accuracy of positional data by about a thousandfold, from approximately to . DGPSs consist of networks of fixed position, ground-based reference stations. Each reference station calculates the difference between its highly accurate known position and its less accurate satellite-derived position. The stations broadcast this data locally—typically using ground-based transmitters of shorter range. Non-fixed (mobile) receivers use it to correct their position by the same amount, thereby improving their accuracy. The United States Coast Guard (USCG) previously ran DGPS in the United States on longwave radio frequencies between and near major waterways and harbors. It was discontinued in March 2022. The USCG's DGPS was known as NDGPS (Nationwide DGPS) and was jointly administered by the Coast Guard and the United ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Message Authentication Code
In cryptography, a message authentication code (MAC), sometimes known as an authentication tag, is a short piece of information used for authentication, authenticating and Data integrity, integrity-checking a message. In other words, it is used to confirm that the message came from the stated sender (its authenticity) and has not been changed (its integrity). The MAC value allows verifiers (who also possess a secret key) to detect any changes to the message content. Terminology The term message integrity code (MIC) is frequently substituted for the term ''MAC'', especially in communications to distinguish it from the use of the latter as ''media access control address'' (''MAC address''). However, some authors use MIC to refer to a message digest, which aims only to uniquely but opaquely identify a single message. RFC 4949 recommends avoiding the term ''message integrity code'' (MIC), and instead using ''checksum'', ''error detection code'', ''hash function, hash'', ''keyed hash'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Department Of Homeland Security
The United States Department of Homeland Security (DHS) is the U.S. United States federal executive departments, federal executive department responsible for public security, roughly comparable to the Interior minister, interior, Home Secretary, home, or Ministry of Public Security, public security ministries in other countries. Its missions involve anti-terrorism, border security, civil defense, Immigration to the United States, immigration and customs, border security, border control, cyber security, cybersecurity, Airport security, transportation security, Maritime security (USCG), maritime security and Air-sea rescue, sea rescue, and the mitigation of Weapon of mass destruction, weapons of mass destruction. It began operations on March 1, 2003, after being formed as a result of the Homeland Security Act of 2002, enacted in response to the September 11 attacks. With more than 240,000 employees, DHS is the third-largest Cabinet of the United States, Cabinet department, after t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Sea
The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia (country), Georgia, Romania, Russia, Turkey, and Ukraine. The Black Sea is Inflow (hydrology), supplied by major rivers, principally the Danube, Dnieper and Dniester. Consequently, while six countries have a coastline on the sea, its drainage basin includes parts of 24 countries in Europe. The Black Sea, not including the Sea of Azov, covers , has a maximum depth of , and a volume of . Most of its coasts ascend rapidly. These rises are the Pontic Mountains to the south, bar the southwest-facing peninsulas, the Caucasus Mountains to the east, and the Crimean Mountains to the mid-north. In the west, the coast is generally small floodplains below foothills such as the Strandzha; Cape Emine, a dwindling of the east end ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CHAYKA
Chaika or Chayka, the word for gull in several Slavic languages, may refer to: People * Chaika (surname), a Slavic surname (including a list of people with the name) * Chaika or Chayka, the call sign for astronaut Valentina Tereshkova Places * Kiev Chaika Airfield, an airfield in Ukraine * Chayka, Golden Sands, an area within the Golden Sands area, near the city of Varna, Bulgaria * Chayka, Varna, a neighborhood in the city of Varna * Chayka, Varna Province, a village in Provadiya Municipality, Varna Province, Bulgaria. * Chayka, Atyrau, a village in western Kazakhstan Technology * CHAYKA, a radio navigation system * Chaika (car), an automobile made in the former Soviet Union * Chaika (boat), a type of boat used by the Zaporozhian Cossacks * Chaika (camera), a 35 mm camera made in the former Soviet Union * Chaika watches, a women's brand of watch made in the former Soviet Union * Chaika L-4, a Russian amphibious aircraft * Polikarpov I-153 Chaika, a bipla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Navigational Aids
A navigational aid (NAVAID), also known as aid to navigation (ATON), is any sort of signal, markers or guidance equipment which aids the traveler in navigation, usually nautical or aviation travel. Common types of such aids include lighthouses, buoys, fog signals, and day beacons. Definition According to the glossary of terms in the United States Coast Guard Light list, an ''aid to navigation'' (ATON) is any device external to a vessel or aircraft specifically intended to assist navigators in determining their position or safe course, or to warn them of dangers or obstructions to navigation. Lateral marks Lateral marks indicate the edge of the channel. The standards are defined by the International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA). Approaching harbour port a vessel leaves port hand marks to port (left) and starboard hand marks to starboard (right). Port hand marks are cylindrical, starboard marks are conical. If the mark is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
