3.
EAC/Corps Systems/Networks Interface.
a. Overview. Interface between the EAC and MSE networks takes place at several
locations called entry points or gateways. The TCS(A) area network connects with at least two
nodes of each corps area system. It is at these nodes that the two systems are interconnected. In
addition, the command links supplied by the TCS(A) provide direct links between the two
systems connecting the theater Army HQ to each of its corps HQ (Figure 3-2, page 3-4).
Termination of the systems takes place at the AN/TTC-39 circuit switch in the EAC network,
and at the node switch (AN/TTC-47) for the MSE network. The networks can be linked together
by line-of-sight (LOS) radio systems (AN/TRC-173/174), by troposcatter (AN/TRC-170), or by
satellite (AN/TRC-85/93).
b. Planning considerations. For the two systems to properly operate, the following items
must be coordinated between the two networks:
(1) Group data rate. The AN/TTC-39, the transmission media, and the node switch
must be on the same group rate. The recommended data rate for planning purposes is 512
kilobits (32 channels at 16 kilobits per channel), except when operating over satellite, in which
case a group data rate of 576 kilobits should be used.
(2) Timing source. For the switches to operate together, they must be synchronized.
The node switch should always be set at master for timing purposes. The AN/TTC-39 switches
setting will depend on the transmission media being used (Tables 3-1 through 3-3, pages 3-13
through 3-15).
(3) Cable modulation. The cable between the switches and transmission media
should be set for diphase modulation.
(4) Cable length. This is set, based on the number of cable reels used by the node
switch and AN/TTC-39 with the transmission media (1, 2, 3, or 4).
(5) Cable transmit/cable receive. This is set, based on the number of cable reels used
to ensure adequate power is supplied to the cable to transmit and receive signals.
(6) Signaling channel (CCS). This is set at channel 1 for both the node switch and
AN/TTC-39.
(7) Traffic channel. This is the number of operating channels passing traffic (must be
the same number for both switches).
(8) Control node. This is the node having technical control between the two
switches. Normally, the switch at the higher HQ (EAC) is the controlling node.
SS0121
3-12
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