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38-401: A three-dimensional radar is mounted on a base that allows for 360 degrees of rotation. The target can be located at a given azimuth . The range of the target is also identified due to the time it takes the beam to go out and back to the receiver. What makes this radar system different is its ability to detect the height of the target above the surface of the water. With these three pieces of data

76-407: A 360 degree circle, east has azimuth 90°, south 180°, and west 270°. There are exceptions: some navigation systems use south as the reference vector. Any direction can be the reference vector, as long as it is clearly defined. Quite commonly, azimuths or compass bearings are stated in a system in which either north or south can be the zero, and the angle may be measured clockwise or anticlockwise from

114-497: A central point are preserved. Some navigation systems use south as the reference plane. However, any direction can serve as the plane of reference, as long as it is clearly defined for everyone using that system. If, instead of measuring from and along the horizon, the angles are measured from and along the celestial equator , the angles are called right ascension if referenced to the Vernal Equinox, or hour angle if referenced to

152-419: A horizontal angle measured clockwise from a north base line or meridian . Azimuth has also been more generally defined as a horizontal angle measured clockwise from any fixed reference plane or easily established base direction line. Today, the reference plane for an azimuth is typically true north , measured as a 0° azimuth, though other angular units ( grad , mil ) can be used. Moving clockwise on

190-462: A range exceeding 200 nmi (370 km) and can track targets up to 69 degrees in elevation. The AN/SPS-48E is capable of providing target range, bearing and altitude information using a frequency-scanning antenna using a range of different frequencies in E band and F band with three power modes: high, medium and low. SPS-48 radars stack multiple beams in a train of pulses at different frequencies. The beams scan different elevation areas, allowing

228-462: A rotating joint that spins the radar in azimuth. The AN/SPS-48 is carried by US Navy ships such as Nimitz -class aircraft carriers , Wasp -class amphibious assault ships , Tarawa -class amphibious assault ships and San Antonio -class amphibious transport docks . Azimuth An azimuth ( / ˈ æ z ə m ə θ / ; from Arabic : اَلسُّمُوت , romanized :  as-sumūt , lit.   'the directions')

266-529: A separate Mk 112 ASROC launcher. These were unofficially spoken of as Ter/AS (tear-ass) launchers. The class was also equipped with two twin 3"/50 caliber guns for defence against sub-sonic aircraft. In the early 1980s, the Terrier missiles were replaced with RIM-67 Standard missiles ; and during the NTU program in the late 1980s and early 1990s the class had its Standard SM-1 system upgraded to utilize SM-2ER Block II ,

304-638: A single cabinet. The number of Lowest Replaceable Units is reduced by 87%, and mean time between critical failure is improved over the AN/SPS-48E(V) by 104%. The new commercial off-the-shelf (COTS) radar processor's computing capabilities will be sustained through a planned tech-refresh program. More intuitive and interactive built-in-test and embedded maintenance and operator training makes available all radar technical, engineering, and logistics data and allows remote monitoring and distance support, while ensuring accurate and timely configuration management. With

342-399: Is called the azimuth. When used as a celestial coordinate , the azimuth is the horizontal direction of a star or other astronomical object in the sky . The star is the point of interest, the reference plane is the local area (e.g. a circular area with a 5 km radius at sea level ) around an observer on Earth's surface , and the reference vector points to true north . The azimuth

380-408: Is east or west. The directions are chosen so that the angle, stated between them, is positive, between zero and 90 degrees. If the bearing happens to be exactly in the direction of one of the cardinal points , a different notation, e.g. "due east", is used instead. We are standing at latitude φ 1 {\displaystyle \varphi _{1}} , longitude zero; we want to find

418-413: Is the horizontal angle from a cardinal direction , most commonly north , in a local or observer-centric spherical coordinate system . Mathematically, the relative position vector from an observer ( origin ) to a point of interest is projected perpendicularly onto a reference plane (the horizontal plane ); the angle between the projected vector and a reference vector on the reference plane

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456-618: Is the angle between the north vector and the star's vector on the horizontal plane . Azimuth is usually measured in degrees (°), in the positive range 0° to 360° or in the signed range -180° to +180°. The concept is used in navigation , astronomy , engineering , mapping , mining , and ballistics . The word azimuth is used in all European languages today. It originates from medieval Arabic السموت ( al-sumūt , pronounced as-sumūt ), meaning "the directions" (plural of Arabic السمت al-samt = "the direction"). The Arabic word entered late medieval Latin in an astronomy context and in particular in

494-468: Is the angle measured at our viewpoint by a theodolite whose axis is perpendicular to the surface of the spheroid; geodetic azimuth (or geodesic azimuth ) is the angle between north and the ellipsoidal geodesic (the shortest path on the surface of the spheroid from our viewpoint to Point 2). The difference is usually negligible: less than 0.03 arc second for distances less than 100 km. Normal-section azimuth can be calculated as follows: where f

532-445: Is the flattening and e the eccentricity for the chosen spheroid (e.g., 1 ⁄ 298.257 223 563 for WGS84 ). If φ 1 = 0 then To calculate the azimuth of the Sun or a star given its declination and hour angle at a specific location, modify the formula for a spherical Earth. Replace φ 2 with declination and longitude difference with hour angle, and change the sign (since

570-420: Is the reason why the X and Y axis in the above formula are swapped. If the azimuth becomes negative, one can always add 360°. The formula in radians would be slightly easier: Note the swapped ( x , y ) {\displaystyle (x,y)} in contrast to the normal ( y , x ) {\displaystyle (y,x)} atan2 input order. The opposite problem occurs when

608-513: The Belknap -class cruisers by 1975. The AN/SPS-48E was first introduced 1987. The component count was reduced compared to the -48C (126,000 versus 280,000) and Built-In Test (BIT) capabilities were added, reducing the MTBF and manpower requirements. Performance improvements included improved resistance to jamming and ECM, better detection of smaller targets and targets on the horizon, high-angle tracking, and

646-609: The Kidd -class destroyer, though it is unclear if it received the SPS-48B variant in practice. The AN/SPS-48C added Automatic Detection and Tracking to the AN/SPS-48 system. The first prototype with ADT capability was manufactured by Gilfillan for evaluation at Mare Island mid-1964. It contained a special-purpose "pipeline processor" that had large amounts of memory for scan-to-scan comparisons and to identify and save blips that seemed to persist near

684-526: The celestial meridian . In mathematics, the azimuth angle of a point in cylindrical coordinates or spherical coordinates is the anticlockwise angle between the positive x -axis and the projection of the vector onto the xy - plane . A special case of an azimuth angle is the angle in polar coordinates of the component of the vector in the xy -plane, although this angle is normally measured in radians rather than degrees and denoted by θ rather than φ . For magnetic tape drives , azimuth refers to

722-411: The horizontal coordinate system , used in celestial navigation , azimuth is one of the two coordinates . The other is altitude , sometimes called elevation above the horizon. It is also used for satellite dish installation (see also: sat finder ). In modern astronomy azimuth is nearly always measured from the north. In land navigation, azimuth is usually denoted alpha , α , and defined as

760-485: The 3-inch guns were replaced with two 4 cell Harpoon Surface-to-surface missile launchers, and two Phalanx CIWS systems were installed. The derivative USS Truxtun shared the weapons systems outfit of the Belknap class, but was nuclear-powered , larger and substantially unrelated in design (for example, many weapons systems in different locations, such as the aft-facing GMLS). Most information related to nuclear cruisers

798-655: The Chief of Naval Operations on 21 February 1966. The AN/SPS-48 replaced AN/SPS-39 on the Belknap , Coontz and Leahy classes between 1967 and 1975 under the Guided Missile Frigate Anti-Air Warfare Modernization Program. Moving Target Indicator (MTI) capability, needed to see targets in clutter and weather, was added to the SPS-48 radar system with the upgrade to the SPS-48A. This upgrade

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836-528: The ability to accept and execute commands from external air defense or shipboard combat systems. It was included as part of the New Threat Upgrade . The AN/SPS-48G program addresses problems of long-term obsolescence through a system redesign that improves the radar's reliability, maintainability, and supportability through technology improvements, open architecture (OA) design, and improved logistics processes while reducing lifecycle cost. It only affects

874-544: The air targets exact 3D location it is available for interception/removal via either the ship's weapon system or through linked weapons platforms located elsewhere. It is the predecessor of the AEGIS system currently in use on Arleigh Burke -class destroyers and Ticonderoga -class cruisers . The AEGIS AN/SPY-1 B/D radars are electronically scanned phased arrays, while the SPS-48E is frequency scanned in elevation, and mounted on

912-423: The angle between the tape head(s) and tape. In sound localization experiments and literature, the azimuth refers to the angle the sound source makes compared to the imaginary straight line that is drawn from within the head through the area between the eyes. An azimuth thruster in shipbuilding is a propeller that can be rotated horizontally. Belknap-class cruiser The Belknap -class cruiser

950-515: The azimuth from our viewpoint to Point 2 at latitude φ 2 {\displaystyle \varphi _{2}} , longitude L (positive eastward). We can get a fair approximation by assuming the Earth is a sphere, in which case the azimuth α is given by A better approximation assumes the Earth is a slightly-squashed sphere (an oblate spheroid ); azimuth then has at least two very slightly different meanings. Normal-section azimuth

988-408: The coordinates ( X 1 , Y 1 ) of one point, the distance D , and the azimuth α to another point ( X 2 , Y 2 ) are known, one can calculate its coordinates: This is typically used in triangulation and azimuth identification (AzID), especially in radar applications. There is a wide variety of azimuthal map projections . They all have the property that directions (the azimuths) from

1026-414: The hour angle is positive westward instead of east). The cartographical azimuth or grid azimuth (in decimal degrees) can be calculated when the coordinates of 2 points are known in a flat plane ( cartographical coordinates ): Remark that the reference axes are swapped relative to the (counterclockwise) mathematical polar coordinate system and that the azimuth is clockwise relative to the north. This

1064-527: The layout of the below-deck units. The plan is to back-fit the existing AN/SPS-48E population from 2011 through 2020, with the SPS-48G units. They will support fleet 3D air search requirements through 2050 and beyond for the ship classes that have SPS-48G. The earlier 1st and 2nd stage RF amplifiers are replaced with a solid state transmitter and the receiver, processor, and Auxiliary Detection Processor, formerly housed in individual equipment cabinets, are combined into

1102-409: The radar's central processor has the ability to place the target in an X,Y,Z, 3 dimensional space. For the SPS-48 in particular, the antenna is mechanically rotated to scan azimuth, while beams are electronically steered to cover elevation by varying the transmitter frequency. The 4,500 lb (2,000 kg) antenna is capable of rotating at 7.5 or 15 rpm. According to ITT Exelis, the system has

1140-423: The sailing frigates of old), but in the 1975 fleet realignment , they were reclassified as guided missile cruisers (CG). When commissioned, the main armament of the Belknap class was a 5-inch/54-caliber Mk. 42 gun on the quarterdeck and a twin-rail RIM-2 Terrier Mk 10 Missile Launcher on the foredeck. The Mk 10 Mod 7 launchers in this class were also capable of launching RUR-5 ASROC to eliminate need for

1178-475: The same location. This processor also built clutter maps on each 360-degree scan and looked for changes in the map, which it saved as possible targets. These blips and clutter changes that may be possible targets were sent to the NTDS, which did further comparisons to determine which ones had motions characteristic of a ship or airplane. This system would go to sea for operational evaluation in 1967 and be incorporated into

AN/SPS-48 - Misplaced Pages Continue

1216-411: The stack to cover up to 69 degrees of elevation. The NTDS Technical and Operational Requirements, written in 1956, called for two radar systems: a three-dimensional search radar with a range of more than 200 miles that can turn over targets to missile and gun radars, and a two-dimensional long-range search radar able to detect relatively small targets at ranges over 250 miles, which can hand targets to

1254-645: The three-dimensional radar once they enter its range. The former eventually became the AN/SPS-48; the latter became the AN/SPS-49 . Development of the SPS-48 in particular started in 1960 in response to shortcomings of the AN/SPS-39. A development contract for two service models (XN-1 and XN-2) was awarded in June 1960. XN-1 completed system testing in April 1962 and was operated until December 1962 to collect reliability data ashore. XN-2

1292-712: The use of the Arabic version of the astrolabe astronomy instrument. Its first recorded use in English is in the 1390s in Geoffrey Chaucer 's Treatise on the Astrolabe . The first known record in any Western language is in Spanish in the 1270s in an astronomy book that was largely derived from Arabic sources, the Libros del saber de astronomía commissioned by King Alfonso X of Castile. In

1330-402: The zero. For example, a bearing might be described as "(from) south, (turn) thirty degrees (toward the) east" (the words in brackets are usually omitted), abbreviated "S30°E", which is the bearing 30 degrees in the eastward direction from south, i.e. the bearing 150 degrees clockwise from north. The reference direction, stated first, is always north or south, and the turning direction, stated last,

1368-512: Was a class of single-ended guided-missile cruisers (their missile armament was installed only forward, unlike "double-ended" missile cruisers with missile armament installed both forward and aft) built for the United States Navy during the 1960s. They were originally designated as DLG frigates ( destroyer leaders ; the USN use of the term frigate from 1950 to 1975 was intended to evoke the power of

1406-473: Was delivered July 1962 and installed aboard USS  Preble  (DLG-15) for shipboard evaluation. A production contract of 13 radars was awarded in June 1963. Unit #6 was installed on USS  Worden  (DLG-18) between March and June 1965 for reliability testing by the Operational Test and Evaluation Force. Testing results were positive, and the AN/SPS-48 was formally approved for service use by

1444-715: Was first evaluated with the USS ; Biddle  (DLG-34) in 1968. The AN/SPS-48B is noted as being installed on the Nimitz class aircraft carriers prior to the USS  Abraham Lincoln  (CVN-72) . The Spruance -class destroyer, known in development as the DX, was designed with accommodations for replacing the AN/SPS-40 B radar with the AN/SPS-48B for the DXG variant. This variant eventually became

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