SECURE VOICE SUBSYSTEM
SSIXS has undergone an upgrade (SSIXS II) that
replaces the SSIXS shore equipment with new
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.
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(AUTOSEVOCOM has been replaced by radio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 wont 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
The Secure Voice subsystem has dedicated rf
channels on the uhf SATCOM satellites as well as
dedicated DAMA time slots where DAMA nets have
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.