SUBMARINE SATELLITE INFORMATION EXCHANGE SUBSYSTEM (NON-DAMA)

communications. These improvements help increase message traffic through-put rates and traffic volume, and improve link reliability. Figure 3-5 shows both sides of the CUDIXS/NAVMACS subsystem. Message Traffic Input At shore facilities, the primary collection point for message traffic to be transmitted or received on the CUDIXS/NAVMACS rf link is NAV- SUBMARINE SATELLITE INFORMATION EXCHANGE SUBSYSTEM (NON-DAMA) SSIXS was designed to compliment vlf and mf/hf communication links between shorebased submarine broadcast control authorities (BCAs) and submarines. Figure 3-6 shows a SSIXS subsystem. This subsystem provides the submarine commander the ability to receive messages transmitted via satellite at scheduled intervals ( “ G r o up Broadcasts”). Between Group Broadcasts, submarines may transmit messages to the BCA, including a request for messages held in queue. The shore terminal responds with acknowledgements for the received messages and transmits all messages addressed to that particular submarine. Two modes, Group Broadcast and Query/Response, permit the submarine to be active or passive, depending on what the submarine commander wants. One 25-kHz wideband channel on each of the four FLTSATCOM satellites has been allotted to SSIXS. A single SSIXS network may have up to 120 submarine subscribers. COMPARS. Rf transmission Link Control (Non-DAMA) The CUDIXS baseband equipment shares a common rf terminal with other subsystems. At the shore facilities this terminal is a uhf transceiver, AN/WSC-5(V). Aboard ship, NAVMACS uses a uhf transceiver, AN/WSC-3(V). All uhf satellites have 25- kHz-wide channels allocated for CUDIXS/ NAVMACS transmissions. Each channel is operated as a half-duplex uhf link, with a data transmission rate of 2400 bps. The rf modulation is differential encoded phase-shift keying (DPSK). Figure 3-6.—SSIXS subsystem. 3-9