See figure 2-10 for a list of weapon systems and
their sensors related to the Mk 86 GFCS on a
SPRUANCE class destroyer.
AN/SPQ-9 Radar
The AN/SPQ-9 Surface Surveillance and Tracking
Radar, developed by Northrop Grumman Norden
Systems, Melville, NY, is a track-while-scan radar
used with the Mk-86 Gunfire Control system on
surface combatants. Since it is a typical fire control
radar, we will discussed it in more detail to help you
understand the basic function of fire control radar.
The AN/SPQ-9B detects sea-skimming missiles at
t h e h o r i z o n , ev e n i n h e a v y c l u t t e r, w h i l e
simultaneously providing detection and tracking of
s u r f a c e t a r g e t s a n d b e a c o n r e s p o n s e s . T h e
AN/SPQ-9B is available as a stand-alone radar or as a
replacement for the AN/SPQ-9 in the Mk 86 Gun Fire
Control System, which will be integrated into the Mk 1
Ship Self Defense System (SSDS).
The Radar Set AN/SPQ-9B is a high resolution,
X-band narrow beam radar that provides both air and
surface tracking information to standard plan position
indicator (PPI) consoles. The AN/SPQ-9B scans the
air and surface space near the horizon over 360 degrees
in azimuth at 30 revolutions per minute (RPM).
Real-time signal and data processing permit detection,
acquisition, and simultaneous tracking of multiple
targets. The AN/SPQ-9B provides raw and clear plot
(processed) surface video, processed radar air
synthetic video, gate video, beacon video synchro
signals indicating antenna relative azimuth, Azimuth
Reference Pulses (ARP), and Azimuth Change Pulse
(ACP). The radar will maintain its capabilities in the
presence of clutter from the sea, rain, land, discrete
objects, birds, chaff, and jamming.
The AN/SPQ-9B has three modes of operation: air,
surface, and beacon. The air and surface modes have a
s u b m o d e f o r C o m b a t S y s t e m s t r a i n i n g . T h e
AN/SPQ-9B complements high-altitude surveillance
radar in detecting missiles approaching just above the
sea surface. The system emits a one-degree beam that,
at a range of approximately 10 nautical miles, can
detect missiles at altitudes up to 500 feet. Since the
beamwidth expands over distance, the maximum
altitude will increase at greater ranges.
The air mode uses the Pulse-Doppler radar for
detecting air targets. When the AN/SPQ-9B radar
detects an air target and initiates a track, it will
determine the target’s position, speed, and heading.
The air mode has a sector function called the Anti-Ship
Missile Defense (ASMD). When the radar is radiating,
the air mode is enabled continuously.
The surface mode generates a separate surface
frequency and an independent pulse with a pulse
repetition interval (PRI) associated with a range of
40,000 yds. In the surface mode, the AN/SPQ-9B radar
has 360-degree scan coverage for surface targets. The
radar displays raw and clear plot video, has a submode
called Surface-Moving Target Indicator (MTI), and
operates concurrently with the air mode. While the
radar is in the radiate state, the surface mode is enabled
continuously.
2-7
Figure 2-8.—A 5”/54 Mk 45 gun mount.
