A  navy  that  operates  on  a  worldwide  scale requires the services of a global communications network. Commanders must be able to pass the word—to  communicate—whenever  necessary  in any  mode.  They  must  be  able  to  communicate between  and  among  ships  separated  by  varying distances and from and to ships, shore stations, and  aircraft.  The  ability  to  communicate  makes possible effective command and control. That, in turn, ensures the responsiveness of every mobile nerve   center   in   the   fleet   to   the   tactical   and strategic   needs   and   services   of   every   other element.  A  global  organization  of  communica- tions  stations  with  hundreds  of  radio  and landline  circuits  supports  each  force  of  ships. This  support  means  a  force  of  ships  is  never out   of   touch   with   its   base   of   operations. Orders  and  information  affecting  the  successful outcome  of  the  force’s  mission  are  exchanged swiftly   and   accurately   throughout   every   level of   command.   The   direct   result   of   reliable communications   is   a   tightly   directed   fighting unit. Naval  messages  are  sent  and  received  in  a variety of ways. The primary method is through the  use  of  electrically  transmitted  communica- tions;   other   types   include   visual,   sound,   and pyrotechnic    communications. ELECTRICAL Electrical  communications  are  sent  by  wave propagation  through  the  atmosphere  or  by electrical   conductors   (wires)   that   connect   the sending  and  receiving  equipment.  Atmospheric propagation  is  potentially  the  least  secure  method since  anyone  with  a  receiver  can  intercept  the transmission.   However,   most   communications circuits  use  cryptographic  devices  to  distort transmissions. Speed  of  delivery  is  one  reason  radio  is  the Navy’s most important means of communication. However,  it  is  also  the  only  effective  means  by which the activities of widespread naval forces can be   continuously   coordinated. Radiotelephone  (R/T) Radiotelephone  (R/T)  microphones  are installed in strategic places on ships, such as the combat information center (CIC) and the bridge. The  communications  spaces  provide  transmitter and  receiver  service  to  these  remote  operating positions. Crew members communicate by speak- ing into a transmitting microphone connected to an  assigned  frequency. Although  R/T  is  the  least  secure  form  of  all radio  communications,  some  systems  may  now employ  cryptographic  devices. Teletype The mental and manual actions performed by an  operator  in  converting  letters  to  Morse  code (and  vice  versa)  are  replaced  in  teletype  by electrical  and  mechanical  actions.  To  transmit a  message,  the  operator  types  on  a  keyboard similar  to  that  on  a  typewriter.  Each  key  that is  pressed  feeds  a  sequence  of  signals  into receiving   machines   causing   them   to   type   the message  automatically. Teletype signals may be sent by landline (wire), radio, or satellite communications systems. Both the military services and commercial communica- tions  companies  such  as  Western  Union  use teletype   communications. The  primary  shipboard  use  of  radio  teletype (RATT) is for task-group and ship-to-shore com- munications.  Fleet  broadcasts,  which  formerly used   high-frequency   (hf)   radio   transmissions exclusively, are now making use of satellite com- munications.  Automated  information  exchange systems also use satellites, with attendant high data rates. Facsimile Recent  technological  improvements  have  made commercial facsimile (FAX) machines a common and  relatively  inexpensive  piece  of  office  equip- ment.  Many  commands  use  these  to  transmit urgent  correspondence  over  standard  or  secure telephone  lines.  The  “fuzzy”  message  trans- mission  quality  is  exchanged  for  almost  instan- taneous printed copies of graphic or typewritten documents. Military FAX machines are used to transmit photographs,   charts,   and   graphic   or   pictorial intelligence   information   electronically.   Signals are  transmitted  either  by  landline  or  by  radio. 12-18