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U.S. Navy shipboard radars are used principally for surface and air search, height finding, weapons fire control, target illumination, and aircraft control. In a few cases two functions can overlap, with some advanced radars, such as the new SPY-1A provid- >ng multi-function capabilities in a single system.
In general, search radars use broad beams and sweep through 360° to indicate the presence of targets, but they cannot provide precise target location. The fire control radars use a narrow beam and dwell on a target to provide accurate information for deriving fire- control solutions for guns or missiles. Because antiaircraft missiles require target altitude information as well as bearing and distance, three-dimensional (3-D) search radars are usually necessary. Most U.S. naval 3-D search radars scan in frequency in the vertical plane and physically rotate in the horizontal plane. The earlier SPS-30 3-D radar scanned vertically by mechanical means with an “organ pipe” scanner continuously rotating to search in elevation.
The narrow-beam fire control radars are keyed to specific targets by ships’ search radars. In addition, most antiaircraft missiles require radar reflections from the target on which to home. These are generally provided by "searchlight” radars, so called because of their target illumination role and, to some extent, their resemblance to giant searchlights. Some older antiaircraft missiles also require a radar beam to follow or “ride” to the target aircraft. The only beam-riding missiles remaining in U.S. service are the Talos, now being phased out, and the Terrier BTN.
Aircraft control radars, which are unique to aviation ships (CV/CVN/ LHA/LPH), are used to guide aircraft into the proper approach pattern or glide path to the ship. These radars are designated in the SPN-series.
The most widely used radar in the
Navy is the SPS-10 surface search, found in most surface combatants, amphibious ships, and auxiliaries. Its 11-foot wide antenna has been a familiar sight on U.S. ships since its introduction in late 1953- It is generally considered a horizon-range radar, although significantly longer-range detections are made. Several hundred of the C-band SPS-lOs are in use. The newer X-band SPS-55, similar to the SPS-10 with higher resolution, is being fitted in new U.S. Navy ships, while the existing SPS-lOs are scheduled to be replaced by the solid-state SPS-67 using the same antenna.
The only other major surface search radars in U.S. service are X-band, BPS-series sets which are used in submarines for surface navigation. New SSNs and Trident SSBNs have the BPS-15 on retracting masts.
There are a number of 2-D air search radars in Navy use, and efforts are under way to reduce the inventory to a few, advanced sets. The oldest are the SPS-29, and the similar SPS-37, introduced in 1958 and I960 respectively. These P-band sets are found in the DDGs 31-33, DDGs 2-14, older missile cruisers, and some destroyers of the Forrest Sherman (DD-931) and Gearing PRAM classes.
There is also the old (1962) SPS-43A, which is found in most aircraft carriers and older missile cruisers. The SPS-29/
Explanation of Symbols____________ 37 use the same antenna, with the SPS-37A and SPS-43A having a larger antenna which provides longer detection ranges. For example, the SPS-37 A is reported to have an effective detection range of about 300 miles vice 230 for the SPS-37. The DDGs 2-14 will receive SPS-40C/D radars when they are modernized in the 1980s, while the cruisers of the Belknap (CG-26) and Leahy (CG-16) classes with the older radars will get the SPS-49. Ironically, the nuclear-propelled Bainhridge (CGN-25) emerged from her recent modernization with an SPS-37 still mounted aft (and an equally dated SPS-39 3-D radar forward).
The SPS-32 is a fixed-array 2-D radar, used with the SPS-33 “billboard” 3-D radar, in the nuclear-propelled cruiser Long Beach (CGN-9) and carrier Enterprise (CVN-65). These radars have not been completely successful, in part because of maintenance and reliability problems, and will be replaced in the Long Beach by the SPS-48 and SPS-49 during her forthcoming modernization. The SPS-49 will also replace the SPS-43A, a P-band radar.
Prefix—Joint service 1st symbol—Installation 2nd symbol—Type of 3rd symbol—Purpose 4th symbol—Series
B = underwater
equipment P = radar
G = fire control
N = Navigation
S = Surface ship
Q = multiple or
U = multi-platform
W = surface ship and
S = Search
W = Weapon control
Y = multi-function
NAVAL INSTITUTE PRESS (THE SHIPS AND AIRCRAFT OF THE U.S. FLEET)
Note: Major U.S. military electronic equipment is identified by the joint Army-Navy nomenclature system shown above. The prefix AN/is omitted from electronic equipment discussed in this feature.
The SPS-40 is a widely used UHF- band 2-D air search radar capable of very long-range detections. It is fitted in 125 cruisers, destroyers, frigates, amphibious ships, and some large auxiliaries. The SPS-40C/D will also be fitted in the DDGs 2-14. Existing sets
are being upgraded to the -40C/D configuration, which uses solid-state electronics to increase reliability from about 80 hours mean time between failure (MTBF) to some 200 hours.
The most effective rotating 2-D air- search radar in the U.S. Navy is the new SPS-49, a lower L-band radar. It was evaluated in 1965 on board the experimental destroyer Gyatt (DD-712), and an advanced version was evaluated in the cruiser Dale (CG-19) since 1975. This radar features high reliability, with MTBF said to exceed 300 hours. It is a very long-range radar and has a narrow beam, which helps to counter enemy jamming efforts.
The SPS-49 will replace SPS-37A/43A radars in cruisers and supplement the SPY-1 radars in Aegis ships. The new Oliver Hazard Perry (FFG-7)-class frigates also have the SPS-49, and several carriers will get it in the future.
Now being installed in carriers, missile destroyers, frigates, and helicopter carriers for air search are the SPS-58/65 radars. These L-band, pulse- doppler-like radars are used for both search and target acquisition for the Sea Sparrow point defense missile systems. The SPS-65 can “share” the
SPS-10 antenna while the SPS-58 has its own 16-foot antenna. These radars have no integral display, but use those of the ship’s naval tactical data system (NTDS).
Three-dimensional S-band search radars are necessary to provide accurate altitude information for surface-to-air missile systems and directing fighter aircraft. The older SPS-30 and SPS-39 radars, first deployed in the early 1960s, remain in service on board a few cruisers, carriers, and destroyers, with the SPS-39 in the Charles F. Adams (DDG-2)-class missile destroyers. The SPS-30 has been largely replaced by the SPS-48 and SPS-52.
The SPS-52 is an improved SPS-39. Since 1963, it has been installed in several carriers, missile cruisers, missile destroyers, the six Brooke (FFG-l)- class frigates, and the Tarawa (LHA- l)-class helicopter carriers. The flattops use the 3-D radar for aircraft control. This radar is credited with a range of 60 miles against small, high-speed targets, and out to much longer ranges against large, highflying aircraft. The sets in the older ships are being modified to improve reliability and performance.
The SPS-48, a radar first deployed in 1962, is found in carriers, missile cruisers, missile destroyers, and the two amphibious command ships of the Blue Ridge (LCC-19) class, in the last for aircraft control. The older SPS-48A sets are being updated with automatic detection and tracking (ADT) features and are redesignated SPS-48C. This radar is more capable than the SPS-52 and can support the Standard SM-2 long-range missile.
U.S. Navy narrow-beam fire control radars operate in the C- and X-bands. The oldest set in widespread use is the Mk-35 (predating the AN designations), which is mounted on the Mk-56 gunfire control system (GFCS) in several cruisers, destroyers, frigates, and LPD/LSD amphibious ships.
The SPG-49 is a Talos track/illu- minating radar, used in conjunction with the diminutive SPW-2 Talos guidance system. These are found only in four surviving Talos-armed ships (CG-5, CG-10, CG-11, and CGN-9).
The SPG-51 is a pulse-doppler tracking, illumination radar used with the Tartar/Standard-MR missile, and is found in cruisers, destroyers, and frigates armed with those missiles. In
SPS-10 above an SPS-40D
those ships armed with the larger, Terrier/Standard-ER missile, the SPG-55 illumination and guidance radar is provided. Most ships have two radar sets for each twin-armed launcher, and thus a “doube-end” missile cruiser with four SPG-55S could engage up to four air targets simultaneously.
Most of the Navy’s destroyers and frigates built since the mid-1950s have the Mk-68 GFCS with the SPG-53 radar for directing their 5-inch guns.
The newest radar of this type is the SPG-60, which both provides gun control data and permits Standard-MR missile tracking with the addition of an illuminator to the new Mk-86 GFCS. The SPG-60 is a monopulse radar, and is combined with the SPQ-9, a high-resolution, short-range, track-while-scan radar in the Mk-86. Thus, a single fire control system can serve several functions. The X-band SPG-60 is credited with a nominal range of some 50 miles. The separate target illumination radar (STIR) using the SPG-60 antenna mount is found in the FFG-7-class. The SPQ-9, working in the X-band frequencies, operates from a minimum of 150 yards out to 20 miles with the high scan rate of 60 revolutions per minute to detect and track incoming missiles as well as surface targets.
The SPG-60/SPQ-9 combination is found in the Mk-86 GFCS in new missile cruisers, Spruance (DD-963) class, and the Tarawa class, while the Aegis-armed DDG-47 class will have the SPQ-9 and a modified Mk-86 (Mod 9).
The Aegis missile ships will have four Mk-99 missile control directors which use the SPG-62 illumination channel radar to provide radar reflections for advanced Standard missiles.
The newer radars entering U.S. Navy service, and modifications to existing sets, permit improvements in logistics, training, maintenance, and effectiveness. The last is reflected in such features as automatic detection and tracking, increased ranges, more resistance to enemy countermeasures, and increased reliability. Thus, to some extent, the Navy’s radars are improving to help counter an increasing and changing threat from the Soviet Union and several Third World nations. At this time, only the still- to-be-deployed SPY-l of the Aegis system and its supporting systems will be capable of dealing with the ’’high threat” weapons that will exist in some foreign navies and air forces in the 1980s and 1990s. However, the SPS-48 and modifications to the SPS 48/49 should provide improved capabilities for area defense in non-Aegis ships, with the Navy shipboard surveillance radar systems (SSURADS) program seeking to provide increased capabilities. Also, the SYS-1 integrated automatic detection and tracking (IADT), now being planned for the DDG-2 class, improves target detection and shortens weapon reaction time by combining imputs from all radars into a single tactical picture, and improving track storage and updating.
The Aegis/SPY-1, to be described in the April issue of the Proceedings, is unquestionably the most capable shipboard radar in existence, and will, hopefully, be able to cope with such threats as the Soviet ‘‘Backfire’’ supersonic bomber carrying advanced AS-4 and AS-6 stand-off missiles in a heavy jamming environment. But the Aegis/sPY-i will not be operational in the U.S. Fleet until 1982, at the earliest, when the first ship of the DIXj-47 class is completed.