LEASAT Telemetry Tracking and Command Susbystem

The secure voice subsystem is a narrowband UHF link that enables secure voice communications between ships. It also allows, connection with wide-area voice networks ashore. Tactical Intelligence (TACINTEL) Subsystem TACINTEL is specifically designed for special intelligence communications. Control Subsystem The Control subsystem is a communications network that facilitates status reporting and management of FLTSATCOM system assets. Officer in Tactical Command Information Exchange Subsystem (OTCIXS) OTCIXS is designed as a communications link for battle group tactical operations. Teleprinter Subsystem (ORESTES) ORESTES is an expansion of the existing teleprinter transmission network. LEASAT TELEMETRY TRACKING AND COMMAND SUBSYSTEM The LEASAT Telemetry Tracking and Command subsystem is a joint operation between the U.S. Navy and contractors for controlling LEASATS. The installation of subsystem baseband equipment and RF terminals aboard ships and aircraft is determined by communications traffic levels, types of communications, and operational missions. Since Fleet Satellite Broadcast message traffic is a common denominator for naval communications, it is received by numerous types of ships. In some installations, such as large ships, the fleet broadcast receiver represents one part of the FLTSATCOM equipment suite. A typical configuration on a large ship would include fleet broadcast, CUDIXS/NAVMACS, secure voice, OTCIXS, TADIXS, teleprinter, and TACINTEL equipment. The FLTSATCOM subsystems apply some form of automated control to the communications being transmitted with the exception of the secure voice and control subsystems. This includes message or data link processing before and after transmittal and control of the RF network (link control) in which the messages are being transmitted. The automation of these functions is handled by a processor. Much of the message processing before transmission and after receipt is fully automatic and does not require operator intervention. The actual message or data link transmission is fully automated and under the control of a processor. Within the limitations of equipment capability, each subsystem addresses the unique requirements of the user and the environment in which the user operates. DEMAND ASSIGNED MULTIPLE ACCESS (DAMA) DAMA was developed to multiplex several subsystems or users on one satellite channel. This arrangement allows more satellite circuits to use each UHF satellite channel. Multiplexing The number of communications networks being used is constantly increasing. As a result, all areas of the RF spectrum have become congested. Multiplexing is a method of increasing the number of transmissions taking place in the radio spectrum per unit of time. Multiplexing involves the simultaneous transmission of a number of intelligible signals using only a single transmitting path. As we mentioned earlier, the Navy uses two multiplexing methods: time- division multiplexing (TDM) and frequency-division multiplexing (FDM). We have already discussed FDM with the AN/UCC-1. Additional information concerning both methods can be found in Radio- Frequency Communication Principles, NEETS, Module 17. A UHF DAMA subsystem, the TD-1271/U Multiplexer, was developed to provide adequate capacity for the Navy and other DOD users. This subsystem was developed to multiplex (increase) the number of subsystems, or users, on 1 25-kHz satellite channel by a factor of 4. This factor can be further increased by multiples of 4 by patching 2 or more TD-1271s together. This method increases the number of satellite circuits per channel on the UHF satellite communications system. Without this system, each satellite communications subsystem would require a separate satellite channel. Transmission Rates The DAMA equipment accepts encrypted data streams from independent baseband sources and combines them into one continuous serial output data 2-13