stabilizing   gyros   used   in   today’s   ships. The maintenance   and   operation   of   these   gyros   is   the responsibility   of   the   Interior   Communications   (IC) technicians.   Figure 1-13 shows a phantom view of a gyro you might see on your ship. The primary purpose of the stable element for fire control   equipment   is   to   measure   accurately   any deviation of the reference element (antenna, director, launcher,  etc.)  from  the  horizontal  plane.    Deviation measurements are sent to the fire control computer to create a stationary foundation from which to solve the fire  control  problem.     They  are  also  sent  to  the  gun director,   radar   antenna,   or   optical   equipment, depending  upon  the  fire  control  system,  to  stabilize these units of the fire control system. Q5.    What is the switching time of a duplexer called? Q6.    What are the two types of lens antennas? Q7.    What determines the position of a phased array antenna beam? Q8.    What part of a radar system provides computer control for an equipment group? Q9.    What   is   the   primary   purpose   of   the   stable element for fire control equipment? TYPES OF RADAR SYSTEMS Because of different design parameters, no single radar  set  can  perform  all  the  many  radar  functions required for military use.    The large number of radar systems   used   by   the   military   has   forced   the development of a joint-services classification system for accurate identification of radars. Radar systems are usually classified according to their specific function a n d    i n s t a l l a t i o n    v e h i c l e . T h e    j o i n t - s e r v i c e standardized classification system divides these broad categories for more precise identification. Since  no  single  radar  system  can  fulfill  all  the requirements   of   modern   warfare,   most   modern warships, aircraft, and shore installations have several radar  sets,  each  performing  a  specific  function. A s h i p b o a r d r a d a r i n s t a l l a t i o n m a y i n c l u d e surface-search  and  navigation  radars,  a  3D  radar,  an air-search radar, and various fire-control radars. Figure 1-14 is a listing of equipment identification indicators. You   can   use   this   table   and   the   radar nomenclature to identify the parameters of a particular radar set.   The example given explains the equipment indicators for the AN/SPY-1A radar system. The  letters  AN  were  originally  adopted  by  the Joint Army-Navy Nomenclature System, also known as   the   AN   system,   to   easily   classify   all   military electronic   equipment. In   1985,   Military   Standard MIL-STD-196D   changed   the   name   of   the   Joint Army-Navy   Nomenclature   System   to   the   “Joint Electronics  Type  Designation  System  (JETDS)”,  but the  letters  AN  are  still  used  in  identifying  military electronics equipment. AIR-SEARCH RADAR The primary function of an air-search radar is to maintain a 360-degree surveillance from the surface to high altitudes and to detect and determine ranges and bearings of aircraft targets over relatively large areas. The following are some uses of an air-search radar:    Give   early   warning   of   approaching   enemy aircraft and missiles, by providing the direction from which an attack could come.   This allows time to bring antiaircraft defenses to the proper degree of readiness and to launch fighters if an air attack is imminent.    Observe   constantly   the   movement   of   enemy aircraft. When   it   detects   an   enemy   aircraft, guide   combat   air   patrol   (CAP)   aircraft   to   a position suitable for an intercept.    Provide   security   against   attacks   at   night   and during times of poor visibility.    Provide  information  for  aircraft  control  during operations   that   require   a   specific   geographic 1-12 Figure 1-13.—Phantom view of a gyro.