Monday, May 24, 2010

The US Navy’s Dual Band Radars

The US Navy’s newest light cruiser and aircraft carrier designs offer a wide array of new technologies. One is the Dual-Band Radar (DBR) system, which can be scaled up or down for installation in the new DDG-1000 Zumwalt Class “destroyers”, and the CVN-21 Gerald R. Ford Class aircraft carriers.

The DBR concept involves a significant change from current naval design approaches, and that change is not without risk. The USA’s GAO audit office has identified it as a significant risk to on-time fielding of the USS Zumwalt [DDG 1000], and any more development or testing snags could widen those impacts to include other ships. The radar is beginning to move from design to production, however, following a successful full-power “lightoff” of both DBR radars in an early April 2009 test.

DBR: Concept and Comparisons

CG-47 antennas
CG-47 antennas

At present, the radars used for scanning large areas and for focused targeting are completely separate pieces of equipment, that are only integrated by the ship’s combat system. The DBR will break from that approach by combining 2 different radar antennas, with the same back-end radar electronics and software driving both. The ship’s combat system will receive a single stream of data, and the radar itself will be able to mix and match its antennas as the situation requires. At the design tier, this approach allows fewer radar antennas, all flush-mounted with the superstructure for maximum stealth. At the tactical tier, integration at the radar level offers faster response time, faster adaptation to new situations, and better utilization of the ship’s power, electronics, and bandwidth. At the life-cycle maintenance tier, it allows one-step upgrades to the radar suite as a whole.

The tactical difference is easier to understand by comparing the present American state of the art with the DBR approach. The US Navy’s DDG-51 Arleigh Burke Class AEGIS destroyers and CG-47 Ticonderoga Class cruisers currently form the high end of its naval air defense capabilities. They use 2-4 different radars in their work, which are combined into a common picture by the ships’ AEGIS combat system.

The rotating AN/SPS-49 radar on the cruisers’ mast offers 2D (range and heading only) very long-range scans in the L-band. It serves as the primary air search radar aboard a wide array of ship types, from aircraft carriers to frigates, and is also used by CG-47 Ticonderoga Class cruisers.

SPY-1 variants
AEGIS operations

AEGIS ships have a more effective radar at their disposal, however: the AN/SPY-1B/D/E passive phased array S-band radar can be seen as the hexagonal plates mounted on the ship’s superstructure. SPY-1 has a slightly shorter horizon than the SPS-49, and can be susceptible to land and wave clutter, but is used to search and track over large areas. It can search for and track over 200 targets, providing mid-course guidance that can bring air defense missiles closer to their targets. Some versions can even provide ballistic missile defense tracking, after appropriate modifications to their back-end electronics and radar software.

The 3rd component is the AN/SPG-62 X-band radar “illuminators,” which designate targets for final intercept by air defense missiles; DDG-51 destroyers have 3, and CG-47 cruisers have 4. During saturation attacks, the AEGIS combat system must time-share the illuminators, engaging them only for final intercept and then switching to another target. 

In an era of supersonic anti-ship missiles that use final-stage maneuvering to confuse defenses, and can be programmed to arrive simultaneously, this approach is not ideal.

The US Navy’s Dual-Band Radar relies on products from 2 different manufacturers, but they’re integrated in a different way. They also use a different base technology. The use of active-array, digital beamforming radar technology will help DBR-equipped ships survive saturation attacks. Their most salient feature is the ability to allocate groups of emitters within their thousands of individual modules to perform specific tasks, in order to track and guide against tens of incoming missiles simultaneously. Active array radars also feature better reliability than mechanically-scanned radars, and recent experiments suggest that they could have uses as very high-power electronic jammers, and/or high-bandwidth secure communications relays.

Many modern European air defense ships, from the British Type 45 destroyers, to the Franco-Italian Horizon destroyers and FREMM frigates, to Dutch/German F124 frigates, use active array search and targeting radars.

SPY-3 operates
DBR operations

Raytheon’s X-band, active-array SPY-3 Multi-Function Radar (MFR) offers superior medium to high altitude performance over other radar bands, and its pencil beams give it an excellent ability to focus in on targets. 

SPY-3 will be the primary DBR radar used for missile engagements. Many anti-ballistic missile radars are X-band, and the SPY-3 could also be adapted for that role with the same kinds of software/hardware investments and upgrades that some of the fleet’s S-band, passive phased array SPY-1s have received.

On surface combatants, the AN/SPY-3 would also replace the X-band AN/SPQ-9 surface detection and tracking radar that is used to guide naval gunfire, and even track the periscopes of surfacing submarines. On carriers, it would take over functions formerly handled by AN/SPN-41 and AN/SPN-46 PALS air traffic radars, and would work in conjunction with the new GPS-derived Joint Precision Approach Landing System (JPALS).

Lockheed Martin’s SPY-4 Volume Search Radar (VSR) is an S-band active array antenna, rather than the SPY-1’s S-band passive phased array. The Navy was originally going to use the L-band/D-band for the DBR’s second radar, but Lockheed Martin had been doing research on an active array S-band Advanced Radar (SBAR) that could potentially replace SPY-1 radars on existing AEGIS ships. A demonstrator began operating in Moorestown, NJ in 2003. That same year, its performance convinced the Navy to switch to S-band, and to make Lockheed Martin the DBR subcontractor for the volume search radar (VSR) antenna. It also convinced Lockheed Martin to continue work on the project as a complete, integrated radar, now known as “S4R”.

S-band offers superior performance in high-moisture clutter conditions like rain or fog, and is excellent for scanning and tracking within a very large volume. While Lockheed Martin makes the VSR antenna, the dual-band approach means that Raytheon is responsible for the radars’ common back-end electronics and software.

The VSR/S4R’s nearest competitor would be Thales’ SMART-L, an active array L-band/D-band radar that equips a number of European air defense ships, and South Korea’s Dokdo Class LHDs. Unlike the DBR, however, the ships carrying it use the conventional approach of completely separate radar systems, integrated by the ship’s combat system.

Another American competitor may also be emerging, via the AMDR radar competition for future DDG-51 Flight III Arleigh Burke Class ships – and possibly for fleet refits, as well.

DBR: Contracts and Key Developments

DDG-1000 Features
DDG-1000: key features

May 3/10: Raytheon announces that the DBR’s smaller-scale Engineering Development Model has simultaneously tracked a target using both X- and S-band radars using a common radar suite controller. The test was performed aat the Navy’s Engineering Test Center in Wallops Island, VA.

March 31/10: Raytheon Integrated Defense Systems in Tewksbury, MA received a $9.8 million modification to previously awarded contract (N00024-05-C-5346) for CVN 78 dual-band radar common array power system and common array cooling system long-lead time materials and associated efforts. These materials, and associated engineering and management efforts, must be bought now, to ensure that critical production schedules are maintained for the CVN 78 program. 

Work will be performed in Andover, MA (87.8%); Sudbury, MA (10.4%); Tewksbury, MA (0.9%); and Portsmouth, RI (0.9%), and is expected to be complete by September 2010. The Naval Sea Systems Command in Washington, DC manages these contracts.

March 30/10: The US GAO audit office delivers its 8th annual “Defense Acquisitions: Assessments of Selected Weapon Programs report. With respect to DBR on the DDG-1000 and CVN-78 ship classes:

“The [DDG-1000’s AN/SPY-4] volume search radar has progressed in maturity and began testing with the multifunction radar in January 2009. However, program officials report that the tests were conducted without the volume search radar’s radome and at a lower voltage than required. The lead ship’s volume search radar will be installed in April 2013 – after the Navy has taken custody of the ship [DID: which means far less recourse from the prime contractor if things go wrong]. 

”....Testing of carrier specific dual band radar functionality [for CVN 78] is scheduled to conclude in fiscal year 2012. Dual band radar equipment will be delivered incrementally from fiscal years 2012 through 2014…. Given the recent decision to truncate the DDG 1000 program, CVN 21 program officials stated that the dual band radar production line may be idle for up to 4 years before production begins for CVN 79 [and so adding] costs associated with restarting the production line.”

Nov 16/09: Raytheon and the U.S. Navy recently completed a critical design review (CDR) for the Dual Band Radar, with respect to the USS Gerald R. Ford [CVN 78]. DBR is currently in production for the Zumwaltclass destroyers, and the CDR verified that it also meets the critical operational requirements of the Ford class aircraft carriers. 

Raytheon says that DBR’s modular, open architecture design meant that only minor modifications need to be made to accommodate specific differences between the 2 ship types, which makes a case for their ability to adapt the radar to a variety of naval surface combatants, if required. The firm is also competing in the USA’s AMDR program, where that kind of flexibility will be important. 

June 2009: Raytheon begins testing the first SPY-3 array at Andover, MA. 

April 23/09: Raytheon Integrated Defense Systems in Tewksbury, MA received a $217 million cost plus fixed fee modification to a previously awarded contract (N00024-05-C-5346) for 2 Volume Search Radars (VSR). Lockheed Martin makes the antennas for these radars, but Raytheon is the lead contractor, and also makes the radars’ common back-end electronics and software.

These S-band naval radars will be mounted on one of the new DDG-1000 Zumwalt Class destroyers, and on the inaugural CVN-21 carrier USS Gerald R. Ford [CVN 78]. Work will be performed in Moorestown, NJ (95%) and Sudbury, MA (5%), and is to be complete by March 2013. The Naval Sea Systems Command in Washington, D.C. manages this contract.

April 7/09: Raytheon announces a successful full-power “lightoff” of both DBR radars. Both radiated at high power during testing at the Navy’s Engineering Test Center in Wallops Island, VA. Following this successful lightoff test, the radar suite will begin an extended period of operational performance testing.

March 30/09: The US government’s GAO audit office issues GAO-09-326SP: “Defense Acquisitions: Assessments of Selected Weapon Programs.” Lockheed Martin’s S-band volume search radar, and the Total Ship Computing Environment, are rated as immature technologies. The report adds:

“Land-based tests of the volume search radar prototype originally planned for before ship construction will not be completed until June 2009 – over 2 years later than planned…. The Navy will not demonstrate a fully capable radar at its required power output until testing of the first production unit in 2011…. installation [of the volume search radar) will occur in April 2013 – after the Navy has taken custody of the ship.”

January 2009: The SPY-3 and SPY-4 radars are installed together since January at the Wallops Island Engineering Center, on the Virginia coast. The radars soon begin tracking aircraft targets of opportunity, and aircraft test runs begin in summer 2009 and will continue into the fall. 

DBR testbed
DBR testbed, Wallops

Dec 5/08: Raytheon Integrated Defense Systems in Tewksbury, MA received a $9 million modification to a previously awarded contract (N00024-05-C-5346) for one time engineering efforts. The purpose of this effort is to initiate the non-recurring engineering work required to make the selected Mission System Equipment (Dual Band Radar SPY-3 Array and REX; MK57 Vertical Launch System Electronics Module Controller Unit; Canister Electronic Units, and Total Ship Computing Environment) compatible with the Navy’s remote controlled Self Defense Test Ship (SDTS). The SDTS test will include the first missile firing with this advanced Mission System, against a difficult target set.

Raytheon will update selected Zumwalt Class Destroyer Mission Systems Equipment (MSE) for initial integration efforts at Wallops Island, VA, and follow-on installation on board the SDTS, in support of the Zumwalt TEMP (test and evaluation master plan). Work will be performed in Portsmouth RI (55%), Tewksbury, MA (25%), and Andover, MA (20%) and is expected to be complete by August 2009. All contract funds will expire at the end of the current fiscal year.

Dec 2/08: Raytheon announces a successful production readiness review of the mission systems equipment (MSE) for the DDG-1000 program. This comprehensive review was the culmination of more than 90 separate design and production reviews, and afterward the Zumwalt program completed a total ship system production readiness review – the final formal review before ship construction begins.

The Zumwalt Class MSE includes the following major subsystems: the Total Ship Computing Environment; Dual Band Radar; the external communications suite; MK 57 Vertical Launching System; AN/SQQ-90 Integrated Undersea Warfare Combat System; the Electro-Optical/Infrared suite; the Identification Friend or Foe integrated sensor suite; and the Zumwalt ship control hardware, including an integrated bridge, navigation, EO surveillance, and engineering control system components.

July 23/08: DDG-1000: Dead in the Water. Widespread reports indicate that the Navy is canceling the DDG-1000 program, capping construction at the 2 ships already ordered. A 3rd ship will eventually be ordered, but that ship is very likely to be the end of a program that once expected to field 32 ships.

Spring 2008: Raytheon’s SPY-3 X-Band completes at-sea testing off the California coast aboard the test ship Paul F. Foster, a former Spruance class destroyer. 

Oct 1/07: Raytheon announces a milestone in advancing the final development of the company’s Dual Band Radar (DBR) for the Zumwalt Class destroyers. Raytheon IDS led the government-industry team in the successful installation of the Lockheed Martin Volume Search Radar (VSR) array at the Surface Warfare Engineering Facility at the Naval Base Ventura County, Port Hueneme, CA. After extensive testing, Raytheon will now integrate the VSR with the SPY-3 X-band Multi-Function Radar to form the DBR. 

Another 5 months of extensive testing is set to begin, representing a critical step in testing the maturity of the technology prior to advancing to full system production. Raytheon’s X-band, SPY-3 has successfully completed extensive land- based and at-sea tests over the last 2 years. 

Sept 21/07: Raytheon Integrated Defense Systems in Tewksbury, Mass. received a $994.3 million cost-type modification to previously awarded contract (N00024-05-C-5346), covering key mission system equipment (MSE) production and engineering support services for the first 2 ships of class. The MSE includes the total ship computing environment infrastructure; acoustic sensor suite element – including the bow array sensor suite; dual band radar; electro-optic/infrared sensor; ship control system; identification of friend or foe; common array power and cooling systems; electronic module enclosures; and Mark 57 vertical launcher system. Raytheon is the mission systems integrator for the Zumwalt Class ships.

Work will be performed in Moorestown, N.J. (21%); Portsmouth, R.I. (20%); Andover, Mass. (18%); Tewksbury, Mass. (17%); Marlborough, Mass.; St. Petersburg, Fla.; Ft. Wayne, Ind. (17%); and Sudbury, Mass. (7%), and is expected to be complete by December 2012. The MSE is being procured for the program executive office for ships [PMS-500].

Feb 12/07: Raytheon Integrated Defense Systems in Tewksbury, MA received a not-to-exceed $305.7 million cost-type modification to previously awarded contract (N00024-05-C-5346) for DDG 1000 Mission System Equipment (MSE) and engineering support services. Work will be performed in Tewksbury, MA (47%); Portsmouth, RI (28%); and Moorestown, NJ (25%), and is expected to be complete by September 2007.

This is part of the DDG 1000 Ship Systems Detailed Design and Integration effort, and the hardware involved includes: Total Ship’s Computing Environment Infrastructure; Acoustic Sensor Suite Element – including the Bow Array Sensor Suite; Dual Band Radar; Electro-Optic/ Infrared Sensor; Ship Control System; Identification of Friend or Foe; Common Array Power and Cooling Systems; Electronic Module Enclosures; and the Mark 57 PVLS Vertical Launcher System.

Oct 24/06: Raytheon reports successful on-schedule integration of Lockheed Martin’s engineering development model S-Band array with receiver, exciter, and signal/data processing equipment for the Volume Search Radar (VSR) portion of the DDG-1000 destroyer’s Dual Band Radar (DBR). Raytheon had already developed and tested the X-band component of the DBR, known as the AN/SPY-3. Now the challenge is to integrate them together.

May 25/06: Raytheon announces that the U.S. Navy’s first shipboard active phased array multifunction radar, Raytheon’s AN/SPY-3, has successfully participated in a series of at-sea tests, including the first time the radar has acquired and tracked a live controlled aircraft while at sea. 

Sept 14/05: The DD (X) Program’s Flag-Level Critical Design Review (CDR) is completed for the overall system design, marking the end of Phase III and a process advertised as being “on schedule and within 1% of stated budget.” See the release for more details, which include important information about the program.
Note that this effort included an unusually thorough approach of CDRs for each of 10 Engineering Deveopment Models, representing a judgment that they have achieved enough have achieved both technical maturity and cost insight. The 10 EDMs were:
  • Wave-Piercing Tumblehome Hull
  • Infrared Mockups
  • Composite Deckhouse and Apertures
  • Dual Band Radar (DBR)
  • Integrated Power System
  • Total Ship Computing Environment (TSCE)
  • Integrated Undersea Warfare System (IUSW)
  • Peripheral Vertical Launching System (PVLS)
  • Advanced Gun System (AGS)
  • Autonomic Fire Suppression System (AFSS)
July 18/05: The National Team announces that they have successfully completed the Initial Critical Design Review for the DD (X) overall system design, allowing the program to pass on toward the Flag level review in September 2005 and enter detail design. 

This was a DD (X) Phase III program event that addressed the total system’s design maturity, and overall progress made to date on DD (X) engineering-development models of hardware and software components that have already been built, tested and reviewed by the National Team and the Navy. Examples include the integrated deckhouse and apertures, total ship computing environment, dual-band radar system, integrated under-sea warfare system, MK 57 advanced vertical launching system, automated gun system and wave-piercing tumblehome hull.

CVN-21 Drawings
CVN-21 Concept

Jan 14/05: DD (X) AN/SPY-3 Multi-Function Radar Passes Milestone B Criteria Tests. Raytheon anounces that the Engineering Development Model (EDM) for the AN/SPY-3 X-Band Multi Function Radar has successfully completed its Milestone B test event at the Navy’s Wallops Island, VA test range. The test served to assess the radar’s environmental, detection, and tracking performance.

2003: The US Navy changes the proposed VSR volume-search antenna from L-band to S-band, and makes Lockheed Martin the sub-contractor for the antenna.

2003: Lockheed Martin’s SBAR demonstrator begins operation in Moorestown, NJ.
2000: Lockheed Martin begin pursuing the S-Band Advanced Radar (SBAR project), as an internal development effort.

Nov 1/99: Microwave Journal reports that Raytheon has received a 5-year, $140 million, section 845, cost-plus-award-fee contract from the US Navy for engineering and manufacturing development of the next-generation Multifunction Radar (MFR), which will equip future aircraft carriers and destroyers.

This article can be found in its original format here.

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