lowest replaceable unit (LRU). The technical manual
lists the assemblies and components that can be replaced
during organizational level maintenance.
Electronics Technicians (NEC ET-1491 for FFG-7
Class ships or ET-1504 for all other ships) are
responsible for organizational level maintenance of the
AN/SPS-55. Preventive maintenance (PM) and
corrective maintenance (CM) include:
electrical and mechanical alignments;
adjustments, and calibration;
fault detection, isolation, and module or major
part repair/replacement; and
all correction and verification necessary to
restore the radar set to an operating condition.
Disposition and repair of failed components is
specified by the Source, Maintenance, and
Recoverability (SM&R) codes in the applicable
Allowance Parts List (APL). Send your repairable
modules to the Designated Overhaul Point (DOP) for
repair or condemnation.
AIR SEARCH (2D) RADARS
The two primary functions of air search radar are to
(1) detect aircraft targets at long ranges and (2)
determine their range and bearing. Some of the most
widely used two-dimensional (2D) air search radars in
the Navy are the AN/SPS-37A, AN/SPS-43,
AN/SPS-43A, AN/SPS-49(V), AN/SPS-40B/C/D/E,
and AN/SPS-65(V) aboard ships and the AN/GPN-27
(ASR) at shore installations.
We will not discuss the AN/SPS-29, AN/SPS-37,
and AN/SPS-43 radars, since the AN/SPS-49(V) radar
The AN/SPS-49(V) radar is the primary U.S. Navy
early warning air search 2D radar.
It is a
very-long-range radar, and provides long-range air
surveillance in severe clutter and jamming
environments. It primarily supports the anti air warfare
(AAW) mission on surface ships, but also provides
backup to the 3D weapon system radar. The
AN/SPS-49(V) radar is also used for air traffic control
(ATC), air intercept control (AIC), and antisubmarine
aircraft control (ASAC).
The AN/SPS-49(V) radar replaces the AN/SPS-29,
AN/SPS-37, AN/SPS-40, and AN/SPS-43 radars in
some ships, including the following ship types:
Current planning calls for installation of the
AN/SPS-49(V) radar in 160 U.S. Navy ships, plus
various shore installations.
General Theory of Operation
The AN/SPS-49(V) is a narrow-fan beam radar
developed from a Specific Operational Requirement. It
provides the capability to conduct air search operations
on a previously unused radar frequency. This minimizes
electronic interference between ships and increases the
difficulty for hostile electronic countermeasures
(ECM). The AN/SPS-49(V) provides good bearing
measurements to backup the 3D radar weapons system.
Its narrow beamwidth substantially improves resistance
The coherent side lobe canceler (CSLC) cancels
jamming and interference signals, providing the
AN/SPS-49(V) radar further resistance to jamming and
interference. The DMTI capability enhances detection
of low-flying, high-speed targets.
The AN/SPS-49(V)5 version, which has automatic
target detection (ATD) capability, has even more
sophisticated antijamming features. This version offers
improved clutter suppression and a digital interface to
the AN/SYS-2(V) IADT system. The AN/SPS-49(V)5,
does not cancel non-moving targets as with MTI,
instead it uses the newest development in doppler
processing, Finite Impulse Response (FIR) fibers.
These filters separate radar echo returns into fixed and
moving channels according to their doppler
characteristics. The moving channels contain moving
targets only. The fixed channels contain fixed clutter
and blind speed targets.
Rejection of non-moving
targets recurs at a later point in time in the clutter maps.
The AEGIS Tracker modification consists of a
PCB card set integrated into the signal data processor.
It adds an embedded tracker, with direct digital interface
with the AEGIS combat system, to the AN/SPS-49(V)7
radar (installed on AEGIS cruisers). With this
modification incorporated, the AN/SPS-49(V)7
nomenclature changes to AN/SPS-49(V)8.
The digital coherent side lobe canceler (DCSC) is
part of the Medium PRF Upgrade (MPU) modification.