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Chapter 5

Communications

PRINCIPLES AND DEVELOPMENTS IN COMMUNICATIONS SYSTEMS

MOBILE SUBSCRIBER EQUIPMENT AREA COMMUNICATIONS SYSTEM

COMBAT NET RADIO SYSTEM

DISCOM RADIO NETS

SIGNAL SECURITY

COURIERS

PRINCIPLES AND DEVELOPMENTS IN COMMUNICATIONS SYSTEMS

Communications systems are essential for gathering and disseminating data. Personnel need them to plan and execute operations. Commanders use them to perform C2 functions and to supervise performance. Effective management of DISCOM functions depends on adequate communications to keep abreast of changing situations and requirements.

The DISCOM relies on both its organic communications assets and the support of the division signal battalion. Communications equipment and systems in the division and corps are changing. The MSE system replaces the area communications system (Figure 5-1) described below. SINCGARS and IHFR replace the FM-VHF (AN/VRC-12) series radios and AM-SSB (AN/GRC-106) radios.

These changes affect how the DISCOM units connect to the area system. Under the old area system, the DISCOM extension platoon in the area signal company provides signal facilities to the DISCOM. Services include --

• Automatic telephone central office and switching facilities for trunk and local telephone circuits. The area telephone system is common user. It is automatically switched and designed as transparent to the users. Dial-up services include not only voice service but also data transfer, facsimile, and other forms of electronically formatted information. Cable/wire installation teams install the internal cables and local telephone circuits. They lay cable/wire to tagged junction boxes. Subscribers install local telephone circuits to the junction boxes. If time permits, the cable/wire teams help install wire in the DISCOM CP.
• Secure multichannel LOS communications terminals for access to the automatic switched network. The LOS multichannel is the most common and most frequently used system in the division. The BSA and the DSA are normally in the division multichannel system in the initial deployment of the multichannel system. However, this depends on the timing of the DSA or BSA moves through the operational area and their locations relative to the threat force.
• Net-radio interface facility for secure single-channel FM radio access into the division automatic switched network. The basic single-channel radio net which passes personnel and supply information is the administrative and logistics net.
• Secure single-channel HF RATT terminals for entry into the GP RATT net. The GP RATT net provides hard-copy communications traffic between the DSA and the BSAs and extended distance communications.
• Secure multichannel TACSAT terminal at the DISCOM for access to the automatic switched network over extended distances. TACSAT assets supplement existing LOS multichannel systems. When tactical situations disperse the division beyond any service by LOS, the TACSAT communications network is essential. It maybe the primary means of connection between the forward elements of the division and the various support bases.

DISCOM units' switchboards tie into the area system based on their location in the division. With the MSE area system, personnel are not able to enter the 4-wire digital system using the organic 2-wire switchboards and telephones. The DISCOM retains its organic 2-wire switchboards for local security purposes and internal operations.

MOBILE SUBSCRIBER EQUIPMENT AREA COMMUNICATIONS SYSTEM

MSE is the area common user voice communications system within the corps. It is the backbone of the corps system and deploys from the corps rear boundary forward to the maneuver battalion main CP. The MSE system is comprised of four functional areas:

• Area coverage.
• Wire subscriber access.
• Subscriber terminals.
• Mobile subscriber access.

AREA COVERAGE

Area coverage means MSE provides common user support to a geographic area, as opposed to dedicated support to a specific unit or customer. These nodes are called node centers. They are under the control of the corps signal officer.

At division level, the signal battalion operates four of these nodes. Connected to these nodes, via LOS radios, are small extension node switchboards and large extension node switchboards. The following switchboards are organic to the division signal battalion:

• 16 SEN switchboards, 12 of which are capable of supporting 26 subscribers each and 4 of which are capable of supporting 41 subscribers each.
• 1 LEN switchboard capable of supporting 176 customers.

The G3 determines the location of switchboards based on the recommendations of the division C-E officer. The C-E officer considers the commander's intent, customer requirements, and other factors of not consistently METT-T. Switchboard locations are assigned to specific units.

WIRE SUBSCRIBER ACCESS

Wire subscriber access points provide the entry point (interface) between fixed subscriber terminal equipment owned and operated by users and the MSE area system operated by signal units. DISCOM users tie into the area system through a configuration of MSE switchboards. The interface points are --

• The signal distribution panel (junction box) J1077. Each panel can provide up to 13 subscriber access points.
• The remote multiplexer combiners which provide up to eight subscriber access points.

Beyond these two interface points the using units are responsible for the installation and operation of fixed subscriber terminal instruments as well as the installation and maintenance of the WF 16 field wire from the instruments to the interface points into the area system.

FIXED SUBSCRIBER TERMINALS

Subscriber terminals used by the DISCOM units are digital nonsecure voice telephones. These provide full duplex digital, 4-wire voice as well as a data port for interfacing the AN/UXC-7 facsimile for informal record traffic, the TACCS computers for CSS STAMISs, the AN/UGC-144 (the single subscriber terminal) for formal record traffic, the unit-level computers for the unit-level logistics STAMIS, and ATCCS for the CSSCS. Tables 5-1 through 5-4 portray the assignment of this equipment for DISCOM units.

COMBAT NET RADIO SYSTEM

The combat net radio structure is designed around three separate radio systems; each has different capabilities and transmission characteristics. The three systems are --

• Single-channel objective tactical terminal.
• Improved high frequency radio.
• Single-channel ground and airborne radio.

SCOTT is a stand-alone transportable tactical satellite communications terminal which is transparent to the DISCOM. The other two systems, IHFR and SINCGARS, provide the primary means of voice transmission of C2 information and the secondary means for data transmission, which is required if data transfer requirements are not met by the MSE system.

Current CNR equipment in the DISCOM consists of the AN/GRC-106 and the AN/VRC-l2 series radios. The IHFR and SINCGARS series respectively replace these radios. For a description of the new radios, refer to FM 24-24. SINCGARS is a new family of VHF-FM radios. These radios are designed for simple, quick operation using a 16-element keypad for push-button tuning. They are capable of short-range or long-range operation for voice or digital data communications. The planning range is 8 to 35 kilometers. They also operate in a jam-resistant, frequency-hopping mode which can be changed as needed. IHFR is a family of high frequency radios consisting of the AN/PRC-104 man-pack radio and the AN/GRC-193 vehicular radio.

DISCOM RADIO NETS

DISCOM COMMAND/OPERATIONS NET (FM)

The principal radio net operated by the DISCOM headquarters is the DISCOM command/operations net (Table 5-5). This net is used to command and control elements of the DISCOM in performance of its CSS mission and its internal functions as a major subordinate command of the division. The NCS is the S2/S3 section. Stations in this net monitor the division command/operations net and the division intelligence net. This net is also used for rear operations as required.

The MSB command/operations net is used to command and control the elements of the MSB both from a tactical and a CSS mission perspective. Net control is maintained by the S2/S3 section. The S2/S3 section and support operations section collocate and use a combination of remotes and installed radios to operate in the DISCOM command/operations net and the DISCOM logistics operations net. The company command nets provide C2 for the companies of the MSB. Table 5-6 depicts the nets for the MSB.

The AMCO commander uses the AMCO to command and control elements of his company. Table 5-7 shows the stations in this net.

Table 5-8 depicts the nets for the FSB.

SIGNAL SECURITY

As part of the overall operations security program, DISCOM elements consistently practice signal security. Guidelines include --

• Remoting antennas away from CP by at least 1 kilometer.
• Constructing and using directional antennas.
• Using terrain features, such as hills, vegetation, and buildings, to mask transmissions.
• Dispersing transmitters.
• Maintaining radio or radio listening silence; using radio only when absolutely necessary.
• Distributing codes on a need-to-know basis.
• Using only authorized call signs and brevity codes.
• Using wire and messengers whenever possible.
• Using available secure voice/RATT devices.
• Maintaining net discipline and control.
• Using authentication and encryption codes specified in the current SOI.

• Keeping transmission short (less than 20 seconds).
• Reporting all COMSEC discrepancies to the NCS.
• Using lowest transmitter power output consistent with good communications.
• Avoiding significant surges in traffic on single-channel radio nets.

COURIERS

Courier service, although slow, is a reliable means of exchanging information. In the LID, courier service is the norm rather than a backup means. A DISCOM element performs this service for the DISCOM, not a signal unit. With the high density of elements in the DSA and BSA, use of couriers and wire lessens the risk of substantial radio use.