Facility Signal Block Diagram-CONT.

TM11-5895-932-14&P

monitoring signals at different points in the signal

(a) The signal on the ASC side of the WU

modem is a carrier or tone at 1800 Hz. The carrier

routing chain.

c. Remote Terminal Signal (fig. 2-2). The in-

is frequency modulated (fm) at the digital rate

(2400 bits /second) with the data (message) in-

formation and data flow between the AMME and

the remote terminals are voice frequency (vf) signals

formation. The purpose of the WU modem is to

(analog) compared to the digital data between the

convert the signal received from the ASC to

AMME and ASC. The remote terminal lines are

digital, direct current signal, for use by the

shown entering the PTF.

AMME and convert the digital signal originating

in the AMME to the fm signal transmitted to the

(1) Following the circuits through from the

ASC. The baud rates to the ASC are 1200 and

AMME through the PTF, several significant

blocks are encountered. The most significant block

4800.

is the modem (modulator/demodulator) which

(b) On the AMME side of the WU modem,

transposes the dc digital signal (used in the

data, control and clock signals are exchanged with

AMME) into the analog frequency signal which is

the AMME. The data contains the message in-

used on the voice frequency transmission lines to

formation received from or to be transmitted to the

ASC. The control signals are dc levels which are

the individual remote terminals. The second most

exchanged between the AMME and the modem

significant black is the red/black isolator which

functions to electrically separate the red signal

which allows the AMME to control the modem.

from the black signal wiring. Other blocks

The clock signals am used in controlling the

remaining are the patch panel blocks and the

transfer of the individual data bits between the

signal line filter panel. The patch panels and the

AMME and the modem.

(3) The Communication Security (COMSEC)

signal line filter panel function in the same manner

as in the AUTODIN signal line described

equipment provides for security of the data

(message) transmitted by encrypting them

previously.

automatically. Received data, which has been

(2) The teletype dc circuit channels pass

encrypted at the ASC, is decrypted automatically

through the PTF low and high level dc black patch

in the crypto equipment. The COMSEC equipment

panels. They can be wired through the red-black

provides a dividing point between red and black

isolators, red dc patch panel, digital line interface

signal lines.

unit low-high dc interface, and signal line filter

(4) As the communication lines move between

panel. The remote terminals for these lines are

the AMME and the signal line filter panel they

teletypewriters and require high level dc voltages

encounter three patch panels: the vf, the red dc,

to operate. The function of a digital line interface

and the black dc. The lines normally pass through

unit (DLIU) is to transpose the low level digital

the patch panels but can be interrupted or

signals used in the AMME to high level signals

monitored by use of patch cords or plugs. The

used to transmit the message. Other blocks in the

patch panels are used for testing, rerouting and

PTF signal flow function as previously explained.

2-4