surface targets and low-flying aircraft and (2) determine their  range  and  bearing.  Some  of  the  more  commonly used surface search and navigation radars in the Navy are  the  AN/SPS-10,  AN/SPS-67(V),  AN/SPS-64(V)9, and  AN/SPS-55.  Since  the  AN/SPS-10  will  soon  be replaced  by  the  similar  AN/SPS-67(V),  we  will  not discuss  the  AN/SPS-10  in  this  chapter. AN/SPS-67 The  AN/SPS-67(V)  radar  is  a  two-dimensional (azimuth and range) pulsed radar set primarily designed for   surface   operations.   It   can   also   detect antiship-missiles (ASM) and low-flying aircraft. The AN/SPS-67(V)1  is  the  primary  surface  search  and navigation radar, with limited air search capability, for the  following  types  of  ships: AO CG DDG LHD AOE CGN FF LPH AOR CV LCC LSD BB CVN LHA TAH On DDG51 class ships, the AN/SPS-67(V)3 radar performs  navigation,  station  keeping  and  general surface   search   duties. Additionally,    the AN/SPS-67(V)3 supports the combat systems as shown below:   Primary combat mission (ASUW)—provides a quick  reaction,  automated  target  detection  and track  capability    Secondary combat mission (AAW)—detects low elevation  (conventional)  threats. General  Theory  of  Operation The AN/SPS-67(V) radar set operates in the 5450- to  5825-MHz  frequency  range,  using  a  coaxial magnetron as the transmitter output tube. To enhance radar performance for specific operational or tactical situations, the receiver-transmitter can operate in a long (1.0 %sec), medium (0.25 %sec), or short (0.10 %sec) pulse   mode.   The   corresponding   pulse   repetition frequencies (prf) are 750, 1200, and 2400. The  AN/SPS-67(V)3  version  has  a  new,  high  data rate,  nuclear  survivable,  low-profile  antenna  and pedestal assembly that replaces the AN/SPS-10 antenna and pedestal assembly. In addition, the synchro signal amplifier function is integrated into the radar. Some special operating features included in the AN/SPS-67(V) radars areas follows: Automatic  Frequency  Control  (AFC) Automatic  tuning Fast  Time  Constant  (FTC) Interference  Suppression  (IS) Anti-log circuit (Target Enhance) Sensitivity Time Control (STC) Video  Clutter  Suppression  (VCS) Built-In-Test  (BIT)  Equipment Sector Radiate (SR) Ships Heading Marker (SHM) Jitter mode Stagger  mode The   following   additional   special   operating functions are included in the AN/SPS-67(V)3 model: Synthesized Channel Frequency Selection RF Sensitivity Time Control (RFSTC) Antenna  bearing  squint  correction Digital  relative  to  true  bearing  conversion Full-time  relative  and  true  bearing  synchro output at the ante ma controller Relative   or   true   bearing   synchro   output selectable at the Radar Set Control (RSC) for the video processor unit Digital Moving Target Indicator (DMTI) Selectable  environmental  sector Constant False Alarm Rate (CFAR) threshold gating  by  external  control Centroid   function Track function Coherent  EMI  suppression  in  the  DMTI  channel Jam  strobe  detection Wraparound test by external control Target selectable threshold gating by external or internal control 2-2