voice frequency channel that has a range from
(4) Exchanges traffic between users whose equip
300-2800 Hertz (Hz) (2500 Hz bandwidth, (nominal 3
ment operates at different speeds and use different
kHz channel)) or 300-3400 Hz (3106 Hz bandwidth
codes and formats.
(nominal 4 kHz channel)). There are some instances,
c. The AUTODIN interface with a DCS Station is
such as with television or other wideband signals,
illustrated in figure 2-4. AUTODIN tributary stations
where the composite tones require a wider bandwidth.
are connected to the AUTODIN Switching Center
In these cases two or more adjacent channels are
(ASC) directly or via AUTODIN conditioned trunks of
specially prepared for transmission of the wideband
the Automatic Voice Network (AUTOVON). The ASC
is connected for transmission to another ASC via the
a. The voice frequency speech signals can originate
DCS Station which acts as the gateway to the DCS.
from 2-wire or 4-wire instruments with almost any
The traffic is cleared through the station and routed
type of signaling, The power for this circuit is gen-
out on predetermined and preconditioned circuits over
erated as the user speaks into the telephone and the
cable, radio, or satellite systems. These circuits can be
frequency complexity of the signal is that of ordinary
over Government owned facilities or over leased facil-
b. DC teletype signals originate at the teletype
d. The AUTODIN Switching Center can be con-
machine and consists of a series of coded pulses, (each
nected to another ASC over the AUTOVON as a
one unique to a keyboard character) where a direct cur-
primary route or, in the event of a failure of a primary
rent is either flowing or not flowing. The teletype
route, as a backup circuit through the establishment of
signal can be passed through the station as dc to
on-call patches. In addition, users of AUTODIN who
another teletypewriter, but most usually it is inputed
do not require full time access to the ASC can be con-
nected to the switching center over AUTOVON on a
to voice frequency carrier telegraph equipment where
the pulses generate tone signals for one channel of the
call-up basis. In cases where AUTODIN is routed over
VFCT composite output tone.
AUTOVON for restoral or for non-full period users of
the AUTODIN to gain access to the ASC, it is the
c. Voice frequency carrier telegraph systems accept
from 2 to 16 or more teletypewriter signals and multi-
responsibility of the technical controller at the ASC to
plexes the tones generated by each teletype signal into
establish the path. The controller dials up the distant
ASC or user, establishes voice contact, makes the re-
a composite "tone package". Each teletypewriter signal
occupies a different portion of the frequency spectrum
quired equipment connections to the circuit, and then
turns the circuit over for digital communications. Af-
of the tone package, which is then transmitted over a
ter restoral of normal routing or at the end of the user
single voice frequency channel.
real-time schedule, the originating technical controller
d. Data and facsimile terminal equipment functions
coordinates the release of the called-up circuit.
in the same manner as a VFCT terminal. In converts
the intelligence from mechanical linkage or light
2-14. Types of Signals
intensity into a unique data stream or series of tones
A technical controller can expect to find signals from
which can then be transmitted over a single voice fre-
any type of terminal equipment passing through the
quency channel. Data signals can originate at a single
TCF. The signals from these equipments include but
data terminal or from an AUTODIN Switching Center.
are not limited to dc teletype loops, speech, data,
e. At the Technical Control Facility the controller
facsimile and voice frequency carrier telegraph
monitors and tests these signals at the voice frequency
(VFCT). The signals may be broken down to a channel
level, except in those instances where a dc teletype
level or pass through the Technical Control Facility at
loop appears at a dc patch panel. Various types of test
the group or supergroup level. The terminal equip
equipment, which will be discussed later, are available
ment generating the data, facsimile and VFCT signals,
for the technical controller to check the quality and
produce a composite tone in the voice frequency range
level of the signals passing through the station.
and the tones are then normally transmitted over a
Section III. THE TECHNICAL CONTROL FACILITY
As noted in the previous section, the communications
a. The Technical Control Facility (fig. 2-5) is that
paths can be over any of the following transmission
element of a communications network that provides
media singly or in serial combinations:
the technical control, interfaces transmission elements
(1) Submarine cable.
of the DCS, and interfaces the user with the System.
(2) Land-line cable or wire circuits.
The management of the communications paths is done
(3) High frequency radio circuits.
at the TCF and subordinate Batch and Test Facilities.
(4) Tropospheric scatter radio circuits.