SECURE  VOICE  SUBSYSTEM SSIXS  has  undergone  an  upgrade  (SSIXS  II)  that replaces   the   SSIXS   shore   equipment   with   new computer   equipment. Message Traffic Input At   the   broadcast   control   authority   (BCA),   the console   keyboard   operator,   high-speed   paper   tape reader,   or   Submarine   Message   Automated   Routing Terminal  (SMART)   enters   into   the   SSIXS   shore terminal  messages  addressed  to  submarines  that  have been  received  from  AUTODIN,  NAVCOMPARS,  or locally over the counter in the message center. Aboard the   submarine,   message   traffic   is   input   via   the teletypewriter   or   tape   reader   equipment.   SSN submarines  that  have  the  Data  Link  Control  System (DLCS)   installed   have   an   additional   input/output capability via the sensor interface unit (SIU) for over- the  horizon  targeting  (OTH-T  messages. Rf Transmission Link Control Ashore, the SSIXS subsystem shares access to the same  satellite  rf  terminal  equipment  as  the  other  uhf SATCOM   subsystems,   with   the   exception   of COMSUBGRU   SEVEN,   Yokosuka,   Japan,   which   is equipped  with  dedicated  AN/WSC-3  transceivers. Since  each  BCA  is  located  some  distance  away from   the   Naval   Computer   and   Telecommunications Area  Master  Station  (NCTAMS),   line   modems   and land  lines  are  required  for  interconnection.  The submarine  uhf  rf  terminal  is  the  single-channel,  half- duplex  AN/WSC-3.  SSIXS  transmissions  are  at  4800 bps. The capability to operate SSIXS in the DAMA net (see   the   section   on   DAMA)   has   been   successfully demonstrated   and   will   be   used   in   the   future.   Each subscriber  to  a  SSIXS  network  is  assigned  a  unique identification  number  that  is  used  in  all  transmissions to  or  from  the  subscriber.  The  identification  numbers are   stored   within   the   shore   station   and   subscriber processors and are used for the following purposes: At   the   shore   stations,   the   subscriber   iden- tification   number,   when   combined   with   broadcasts, determines   the   number   of   times   message   traffic   is transmitted to the subscriber. When a subscriber makes a transmission to the shore station, the identification number is included. The shore   station   will   not   acknowledge   a   transmission without receiving the identification number. The   subscriber   uses   the   number   to   screen incoming  message  traffic.  Any  data  that  is  not addressed to that particular subscriber is discarded. 3-10 The   Secure   Voice   subsystem   enables   the transmission of ship-to-ship, ship-to-shore, and shore- to-ship   voice   communications   via   satellite   relay. Figure   3-7   shows   a   Secure   Voice   subsystem. (AUTOSEVOCOM   has   been   replaced   by   radio wireline   interface   (RWI)   at   all   NCTAMS   shore activities.)  The  subsystem  transmits  and/or  receives secure voice communications via a half-duplex, push- to-talk  satellite  link.  Channels  on  each  of  the  four FLTSATCOM satellites have been allocated for use by the   Secure   Voice   subsystem.   Control   of   the   voice channels is maintained by the Secure Voice controller at  the  responsible  NCTAMS/  NCTS. The  subsystem  uses  digitized  voice  at  a  data  rate low   enough   to   be   compatible   with   a   3-kHz   voice channel  and  is  considered  narrowband.  The  sound  of Narrowband  Secure  Voice  is  very  distinctive.  Once you hear it, you won’t forget it. The system uses special analog-to-digital processing of the speech signal at the handset  terminal  and  the  rf  transmission  rate  is  2400 bps. The   Secure   Voice   subsystem   has   dedicated   rf channels  on  the  uhf  SATCOM  satellites  as  well  as dedicated  DAMA  time  slots  where  DAMA  nets  have been established. Voice  Transmission The  rf  terminal  installations  on  mobile  platforms determine   the   manner   in   which   a   Secure   Voice transmission is made. These mobile platforms maybe categorized into two types: The  small  ship/submarine  that  share  a  single- channel   AN/WSC-3(V)   uhf   transceiver   and cryptographic   equipment   between   NAVMACS   or SSIXS and a Secure Voice terminal. Larger ships that have two or more AN/ WSC- 3(V) uhf transceivers and cryptographic equipment are installed.  This  installation  normally  has  a  transceiver dedicated  to  Secure  Voice. Secure Voice use is accomplished by either of two methods.  In  the  first  method,  ships  access  a  Secure Voice  channel  if  the  channel  is  not  in  use.  The  ship contacts  another  ship  directly  by  using  the  available channel. When coordination of voice communications with shore commands is required, the ship contacts the voice controller who, in turn, tells the recipient(s) of an incoming voice transmission.