Many current satellites are programmed to be phased out by a new generation of extremely high- frequency  (ehf)  satellites.  The  military  strategic tactical  and  relay  (MILSTAR)  system  is  a  joint service program expected to be operational in the 1990s. VISUAL Visual means  for communications  are  the  preferred communicating  at  short  range  when weather   conditions   permit.   In   reliability   and convenience, visual communications often are the equal  of  radio  and  under  certain  circumstances are more secure than radio. For example, omni- directional  radio  transmissions  may  be  intercepted by  many  undesired  listeners,  whereas  unidirec- tional   visual   signals   are   limited   to   observers positioned  along  the  line  of  sight. Visual  signaling  systems  include  flaghoist, flashing  light,  and  semaphore. Flaghoist Flaghoist signaling can be a rapid and accurate communications  method  during  daylight  hours. International  alphabet  flags,  numbered  pennants, and special meaning flags can coordinate tactical maneuvers  and  ships’  movements  without  radio transmissions. All sailors are expected to recognize everyday flags. Sailors rely on the safety and informational messages relayed by these flags, such as “divers in  the  water”  or  “captain’s  on  board,”  to  help them  in  their  daily  routine. Flashing  Light Flashing light uses visible beams (or infrared light  during  tactical  nighttime  communications) to transmit Morse Code letters through an on/off method.  Directional  lights  are  pointed  so  that  only the addressee can read the message. Omnidirec- tional  lights  may  be  located  above  the  ship’s superstructure for all ships within range to copy the message. Semaphore Semaphore  is  a  communications  medium  by which  persons  signal  with  two  hand  flags,  moving their   arms   through   various   positions   to represent letters, numerals, and special signs. Semaphore  and  flashing  light  can  be  used interchangeably  for  many  purposes.  Semaphore is more rapid for short-distance transmission in clear daylight and may be used to send messages to  several  addresses  at  once  if  they  are  in suitable   positions. Because   of   its   speed, semaphore  is  better  adapted  to  the  sending  of long  messages  than  are  other  visual  methods. When  radio  silence  is  imposed,  semaphore  is the  best  substitute  for  handling  administrative traffic.  It  is  more  secure  than  a  light  or  radio because  it  provides  less  chance  for  interception by  unauthorized  persons. SOUND Sound   communications   systems   include whistles, siren, bells, and acoustics. Ships use the first  three  to  transmit  emergency  warning  signals (such as air-raid alerts) and navigational signals prescribed by the rules of the road. In wartime, ships  in  convoy  use  these  three  systems  to communicate  with  each  other. An underwater sonar system called Gertrude is  part  of  acoustic  submarine  communications. Used  primarily  for  hailing  NATO  ships,  it  may be used for radiotelephone or carrier-wave (c/w) transmission. PYROTECHNICS Pyrotechnics is the use of ammunition, flares, or fireworks to signal a message or to illuminate or mark targets. Most pyrotechnics for signaling are  of  the  “fireworks”  variety.  Common  sources are marine illumination cartridges, colored shell bursts  (parachute  flares),  aircraft  parachute flares,  reman  candles,  and  float-type  flares. The  meaning  of  a  pyrotechnic  signal  depends on  the  color  instead  of  the  type  of  pyrotechnic employed.  The  authorized  use  of  pyrotechnics for   communications   is,   in   general,   limited   to emergency signals. SUMMARY The  preceding  discussion  of  naval  warfare operations demonstrates that extensive planning is required if a mission is to be successful. When all of the warfare components function together, 12-20