AN/SPS-49 Very Long-Range Air Surveillance Radar

The AN/SPS-49 Air Search Radar is a long-range, two-dimensional (range, bearing) air search radar whose primary function is to provide target position data to a ship command and control system. It provides for detection of targets as high as 100,000 feet and over a distance of 2 to 300 miles. The AN/SPS-49V, is installed in the following ship classes: CV/CVN, CG-47, FFG-7, LSD 41/49, and LHD.

The Radar Set AN/SPS-49 is an L-band, long-range, two-dimensional, air-search radar system that provides automatic detection and reporting of targets within its surveillance volume. The AN/SPS-49 performs accurate centroiding of target range, azimuth, amplitude, ECM level background, and radial velocity with an associated confidence factor to produce contact data for command and control systems. In addition, contact range and bearing information is provided for display on standard plan position indicator consoles.

The AN/SPS-49 uses a line-of-sight, horizon-stabilized antenna to provide acquisition of low-altitude targets in all sea states, and also utilizes an upspot feature to provide coverage for high diving threats in the high diver mode. External control of AN/SPS-49 modes and operation by the command and control system, and processing to identify and flag contacts as special alerts are provided for self-defense support.

The AN/SPS-49 has several operational features to allow optimum radar performance: an automatic target detection capability with pulse doppler processing and clutter maps, ensuring reliable detection in normal and severe types of clutter; an electronic counter-countermeasures capability for jamming environments; a moving target indicator capability to distinguish moving targets from stationary targets and to improve target detection during the presence of clutter and chaff; the Medium PRF Upgrade (MPU) to increase detection capabilities and reduce false contacts; and a Coherent Sidelobe Cancellation (CSLC) feature.

The AN/SPS-49 Medium Pulse Repetition Frequency Upgrade (MPU) incorporates key ship defense enhancements to the Navy's AN/SPS-49 air search radar. Specifically, it provides for increased detection of low-observable targets, reduces reaction time through internal firm track criteria changes, and enhances performance against electronic countermeasures and naturally occurring clutter. The AN/SPS-49 MPU is or is planned to be installed on the following ship classes: CV/CVN, FFG-7, LSD 41/49, and LHD.

The AN/SPS-49 long range 2-dimensional air surveillance radar used for early target detection. The long-range AN/SPS-49 radar operates in the presence of clutter, chaff, and electronic counter-measures to detect, identify, and control low-radar-cross-section threats traveling at supersonic speeds. AN/SPS-49 provides the front-end element for successful target identification, designation, and engagement with either long range (SM-1 or SM-2) missiles and/or short range local defense missiles. A key feature of the most recent version of the radar, the SPS-49A(V)1 is single-scan radial velocity estimation of all targets allowing faster promotion to firm track and improved maneuver detection. This is done using unique signal processing techniques originated and tested by the Radar Division of NRL using 6.1 and 6.2 Office of Naval Research (ONR) funds.

The AN/SPS-49(V) radar is a narrow beam, very long range, 2D air search radar that primarily supports the AAW mission in surface ships. The radar is used to provide long range air surveillance regardless of severe clutter and jamming environments. Collateral functions include air trafficcontrol, air intercept control, and antisubmarine aircraft control. It also provides a reliable backup to the three-dimensional (3D) weapon system designation radar.

Band L
Frequency Band:  
850 to 942 MHz three selectable 30MHz bands
48 discrete frequencies
Transmitting Power:360 kW peak
280 kW specified peak power
12-13 kW average power
Antenna Parameters:Parabolic Reflector stabilized for roll and pitch 7.3m/24 ft wide, 4.3m/14.2 ft high
Rotating Clearance Beamwidths: 8.7m/28.4 ft diameter 3.3-3.3 azimuth
Cosec2 11 elevation to 30, csc2 to 20 elev
Gain28.5 dB
Scan rate 6 or 12 rpm
Line-of-sight mechanical stabilization to 25 deg roll IFF antenna (AS-2188) mounted on boom
Range 250 nm
Minimum Range : 0.5 nmi
Frequency Selection: Fixed or frequency agile
Range Accuracy: 0.03 nmi
Azimuth Accuracy: 0.5 deg
PRF 280, 800, 1000 pps
Pulse width 125 microsecond

The AN/SPS-49(V) radar operates in the frequency range of 850 - 942 MHZ. In the long range mode, the AN/SPS-49 can detect small fighter aircraft at ranges in excess of 225 nautical miles. Its narrow beamwidth substantially improves resistance to jamming. The addition of coherent side lobe canceller (CSLC) capability in some AN/SPS-49(V) radars also provides additional resistance to jamming/interference by cancelling the jamming/interference signals. The moving target indicator (MTI) capability incorporated in the AN/SPS-49(V) radar enhances target detection of low-flying high speed targets through the cancellation of ground/sea return (clutter), weather and similar stationary targets. In 12 RPM mode operation, this radar is effective for the detection of hostile low flying and "pop-up" targets.

Features of this set include:

  • Solid state technology with modular construction used throughout the radar, with the exception of the klystron power amplifier and high power modulator tubes
  • Digital processing techniques used extensively in the automatic target detection modification
  • Performance monitors, automatic fault detectors, and built-in-test equipment, and automatic on line self test features

The AN/SPY-1 Aegis radar system is the most powerful of the CG-47 sensors. This system is the Nation's most advanced shipboard air search sensor providing location and targeting information to destroy airborne threats. However, the CG-47 had another air search radar system known as the SPS-49. The SPS-49 radar has some shortcomings and is not an adequate backup for the AEGIS SPY-l radar. Therefore, retaining the SPS-49 radar system seemed highly questionable to some. The Navy installed SPS-49 radar systems on the CG-47 class against the wishes of the House Appropriations Committee and contrary to a recommendation of the GAO. The CG-47' Project office officials and program sponsors disagreed, however, and contended that the SPS-49 provides a useful function and enhances operational flexibility. However, the long-range surveillance function can be performed by the Aegis radar system in a superior manner.

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