CHAPTER 2 FACILITY ClRCUlT DESCRIPTION

TM11-5895-932-14&

CHAPTER 2

FACILITY

ClRCUlT

DESCRIPTION

2-1. General

minals. As with the ASCs, AMME also performs

other functions in connection with the transmission

This chapter provides an introduction to the

of the data and message traffic. The AMME

circuits and signals that are handled by the PTF.

contains equipment to record all traffic; send

The introduction is made on a block diagram and

traffic to the proper remote terminal (if addressed

simplified circuit diagram level. Complete circuit

properly), provide AUTODIN routing symbols on

details including pin numbers, and cable routing is

outgoing messages; and other message handling

available in the plant-in-place records (para 3-3)

functions. The AMME equipment is leased and

which are available at every telecommunication

maintained by a private contractor.

station. Detailed functioning of the individual

(3) Remote terminals. There are several

items of equipment represented by the blocks in

different equipment configurations used at the

the block diagram is covered in separate manuals

remote terminals. The equipments required depends

(app A).

on the traffic intended to the remote terminal

2-2. Station Description

(narrative teletype or fast speed data). A remote

a. The PTF described in this manual is part of

terminal may have any combination of a card

the Automated Telecommunications Station at

reader, a card punch, a line printer, and a visual

Letterkenny Army Depot, Chambersburg, Pen-

display unit (VDU); fast data systems have

nsylvania. The station itself is a Defense Com-

equipments unique to their needs.

munication System (DCS) Automatic Digital

2-3. Facility Signal Block Diagram

Network (AUTODIN) tributary station, part of a

a. Station Signal Routing (fig. 2-1). The signal

worldwide system of tributaries interconnected

flow for received and transmitted traffic to the

through 19 Automatic Switching Centers (ASC),

telecommunications station passes through the

which function to route messages and data traffic

PTF. The received signal flow from the ASC enters

between tributaries. Each ASC essentially func-

the station through signal line filters to the PTF,

tions to receive, store, and forward messages

is processed and fed to AMME, where the heading

between tributaries and ASCs but also performs

is read, and fed back through the PTF to the

other functions in connection with the traffic it

intended remote terminal. A transmitted signal

handles, such as error indication, proper delivery

from a remote terminal follows the reverse of a

address, timely delivery (automatic time mark),

received signal, from the remote terminal to the

and message security. The ASC also contains

PTF, to AMME, back to PTF, and then to the

equipment which is used to interface with different

ASC.

types of equipment contained at the tributary

b. ASC Signal. The signal received from, and

stations and to transmit and receive the digital

also transmitted to the ASC, is a data message

messages on the voice frequency communications

which has been incrypted for message security and

channels used between stations.

changed to an analog signal for transmittal on the

b. For the purpose of this discussion the Let-

voice frequency lines between stations. On the

terkenny Automated Telecommunications Station

block diagram (fig. 2-1) the ASC signal is shown

can be separated into three functional sections: the

entering the PTF at the signal line filter panel

Patch and Test Facility (PTF), the Automated

(SLF).

Multimedia Exchange (AMME);

and a system of

(1) The ASC signal proceeds through the PTF

remote terminals.

to and from the AMME through several significant

(1) PTF. The patch and test portion of the

blocks. The blocks represent equipment which

station is used to terminate all communication

lines for the station. It contains equipment for

either modifies the signal, such as the modem or

cryptobay, or provides access to the signal for

testing, such as the patch panel blocks. The

signal line filter panel, which contains a separate,

shielded, low pass filter for every signal line that

enters the PTF, prevents the signal lines from

radiating unwanted and possibly security com-

promising signals.

2-1