TM 1-1510-225-10 3C-49 Selection   of   the   map   function   causes   system parameters to be optimized on the three lowest ranges to improve resolution and identification of small forgets at   short   ranges.      The   reflected   signal   from   various ground  surfaces  is  displayed  as  magenta,  yellow,  or cyan (most to least reflective). The    radar    system    consists    of    three    units: indicator,    receiver/transmitter,    and    antenna.        The indicator is mounted in the cockpit and contains all the controls used to operate the radar. The receiver/transmitter is located on the radio  rack.  The antenna,  which  is  fully  stabilized  for  aircraft  pitch  and roll,  is  in  the  avionics  compartment  in  the  nose  of  the aircraft. b.    Controls, Indicators, and Functions.   Refer to Figure 3C-22. (1)   INT  /  OFF.    Rotary  control  used  to  turn system on and off, and to adjust (intensity) of display.   STARTUP, STBY, and 100 will be displayed. (2)   Display Area.    Displays  visual  indication, in   color,   of   rainfall   intensity   with   range   marks   and identifying numerics. (a)  Mode    Field.        Selected    function    is displayed  as  STBY,  WX,  CYC, MAP, or TEST.  WAIT is  displayed  until  the  initial  RT  warm-up  period  has expired and the Indicator and Antenna are synchronized. (b)  Auxiliary    Field.        Color    bar    relates displayed colors to signal reflectivity levels 1, 2, and 3 displayed beneath color bar. 1    For WX, CYC, and TEST, color bar is green, yellow, and red.  For MAP, color bar is cyan, yellow, and magenta. 2    VAR  replaces  1,  2,  3  in  WX  and MAP  when  GAIN  control  is  not  in  detented   PRESET  position. 3    FRZ is displayed as a blinking word when freeze function is selected. (c)  Target   Field.      Blank   unless   target alert is enabled causing letter T in red rectangle to be displayed.      Flashing   alert   symbol   TGT      in   a   red rectangle     is     displayed     when     red-level     target     is detected within the target alert sector. (d)  Range  Mark  Numerics.  Five labeled range  marks  are  displayed  on  each  range.    The  fifth range   mark   label   is   larger   serving   to   identify   the selected   range.      Range   and   azimuth   marks   and numerics   are   displayed   in   cyan   for   WX,   CYC,   and TEST; in green for MAP. (3)   10 / 25 / 50 / 100 / 200 / 300.  Momentary push  buttons  used  to  select  one  of  six  ranges.    For each  selected  range,  five  range  marks  are  displayed.   At   system   startup,   100-mile   range   is   automatically selected.    Internal  memory  for  range  push  buttons  is always active. (4)   TILT.    Rotary  control  used  to  select  tilt angle   of   antenna   beam   with   relation   to   earth   (with stabilization   on)   or   with   relation   to   airframe   (with stabilization off). Clockwise rotation tilts beam upward 0 to 10; counterclockwise rotation tilts beam downward 0 to 10. (5)   AZ  MK.         Slide  control  used  to  either display or not display azimuth markers at 30 intervals. (6)   STAB.  Slide control used to turn antenna stabilization on or off. (7)   TGT  ALRT.    Slide  control  used  to  turn target  alert  function  on  or  off.    When  enabled, letter T in red rectangle is displayed to identify that target alert function  is  active.    Target  alert  is  active  only  when radar gain is calibrated; i.e., in WX with GAIN PRESET and  in  CYC  or  TEST.    The  symbol  TGT     in  a  red rectangle  is  displayed  and flashes once each second whenever   a   red-level   target   is   detected   within   the target   alert   section   (range   from   60   to   160 nm  and within      7.5   of   aircraft   heading).      Target   alert   is deactivated   automatically   if   MAP   is   selected   or   if variable GAIN is used, but is reactivated automatically when   operating   controls   are   restored   to   valid   alert settings.