AN/TSC-124

The AN/TSC-124 was intended to be the Army's Milstar terminal. It was to be fielded in Army units in the early 1990s. It provided antijamming scintillation-protected, tri-service interoperable satellite communications to support critical C² communications. Exclusive of the SCS, the AN/TSC-124 was not intended to replace existing communications equipment on the battlefield; it augmented existing terrestrial C² nets when other communications means were degraded or destroyed. The traffic transmitted via the AN/TSC-124 terminals would normally be essential data communications. Voice communications, though possible, were not intended to be the primary method of communications through the Milstar-1 system. System efficiency decreases as voice traffic levels increase. Therefore, data traffic would have a higher priority for channel access throughout the system.

AN/TSC-124 terminals were intended to replace AN/MSC-64s, used within the Special Communications Service [SCS], to operate the Flaming Arrow Net in Europe and Korea.

At EAC in Europe and Korea, AN/TSC-124s would provide for connectivity between the theater main, theater alternate, theater Army main, theater Army alternate, the theater Army Milstar control center (TAMCC), and six discretionary headquarters such as major joint or allied unit headquarters, additional CINC support and the like. The theater TACSAT signal company would install, operate, and maintain the terminals.

The 235th Signal Detachment and 209th Signal Company were each to employ AN/TSC-124 terminals in support of Army and JCS operations worldwide to augment the theater assets if necessary.

The l12th Signal Battalion was to employ AN/TSC-124 terminals in support of Special Operations Command (SOCOM operations.

The AN/TSC-124 was designed as a commander's asset. Although regular and recurring association of terminals and headquarters would occur, the terminals could be employed at the commander's discretion. The commander could assign a priority of communications and fight the communications assets as a combat multiplier like any other weapons system.

The unique characteristics and capabilities of the terminals and associated satellite systems made structured nets unnecessary. Because the terminals operate with a DAMA technique, there was no requirement for dedicated channels. Because of the processing capabilities of the satellites and the ability to address discretely any terminal within the system, Milstar terminals can communicate with any other Milstar terminals, whether located within the same theater of operations or not. Different protocols, however, would be required for in-theater and out-of-theater communications. For network identification and TRANSEC key management, all AN/TSC-124 terminals operating within the Army spotbeam footprint on each satellite make up a network. Therefore, separate nets are unnecessary. However, partitions may be formed by selecting and distributing different COMSEC keys and addresses to the users; for example, distributing like keys to those users who want to operate together to the exclusion of others. The discrete addresses would then be furnished in a format similar to the telephone books now employed. Terminal-to-terminal connectivity would remain possible, with end-to-end communications being possible only if like COMSEC keys are employed at each I/0 device.

The AN/TSC-124 consisted of the terminal, prime mover, antenna, and trailer-mounted power generator. The AN/TSC-124 would be installed in one S-250 or equivalent shelter, and transported under tactical conditions by a standard 1 l/4-ton truck. A 3 kilowatt generator would be mounted on a standard 3/4-ton trailer that will be towed by the prime mover. Backup power was provided by an under-hood power plant installed on the vehicle.

The terminal could communicate at the halt; communicating while moving was a planned improvement that will come with future technology. Terminal setup and teardown times were not to exceed 30 minutes by a team of three MOS 31C soldiers.

Critical, operator-replaceable spares were to be carried to enhance system survivability and ensure rapid repair and return to service. Additionally, crew, crew weapons, personal bags and equipment, camouflage netting, tents, and the like would be carried on the vehicle or in the terminal. C130/C141/STOL aircraft roll-on/roll-off with no preparation is possible.

The terminal was to be able to accept up to four individual user inputs of data or voice at rates of 75 bps to 2.4 kbps by using user-controlled interface devices (UCIDs). The devices could be remoted 2,500 feet (758 meters) from the terminal using conventional field wire. Four DR-8s, modified to accept and dispense WF-16 field wire, were provided with the terminal. The DR-8s will provide a minimum remoting capability independent of customer field wire resources.

Compatibility with the Milstar standard I/O and COMSEC devices (for data, the AN/UGC-74 and KG-84; for voice, the ANDVT) as well as the single subscriber terminal (SST), lightweight digital facsimile, and the Army Command and Control System (ACCS) hardware was provided. Each terminal would be furnished with one AN/UGC-74 and one ANDVT for operator use.

It was hardened to the effects of electromagnetic pulse (EMP)/high altitude EMP (HEMP) and will operate in EW/NBC environments.

The system would adapt to changes in the jamming environment and changes in traffic demands regardless of environment. The terminal used spread spectrum, burst, FH, and other techniques to reduce the vulnerability to RDF, interception, exploitation, and jamming. The AN/TSC-124 will be interoperable with all other Milstar terminals.

Sources and Resources

• FM 24-11 TACTICAL SATELLITE COMMUNICATIONS, 20 September 1990