Circuit Restoral/Coordination

stream. DAMA was designed to interface the Navy UHF SATCOM baseband subsystem and the AN/WSC- 5 and AN/WSC-3 transceivers. The TD-1271/U Multiplexer includes a modem integral to the transceiver. The baseband equipment input or output data rate with DAMA equipment can be 75, 300, 600, 1,200, 2,400, 4,800, or 16,000 bits per second (bps). The DAMA transmission rate on the satellite link (referred to as “burst rate”) can be 2,400, 9,600, 19,200, or 32,000 symbols per second. Circuit Restoral/Coordination When a termination is lost in either or both directions, communications personnel must observe special guidelines. During marginal or poor periods of communications, the supervisors should assign a dedicated operator to the circuit if possible. When normal circuit restoration procedures are unsuccessful and/or a complete loss of communications exists, an IMMEDIATE precedence COMMSPOT message should be transmitted (discussed earlier). Every means available must be used to re-establish the circuit, including messages, support from other ships or NAVCOMTELSTAs, or coordination via DAMA if available. The guidelines established in NTP 4, CIBs, and local SOPs are not intended to suppress individual initiative in re-establishing lost communications. Circuit restoral is dependent upon timely action, quick decisions, and the ability of personnel to use any means available to restore communications in the shortest possible time. SPECIAL CIRCUITS During certain communications operations, you may be required to activate and operate special circuits. Some of the most common special circuits are discussed next. UHF AUTOCAT/SATCAT/MIDDLEMAN RELAY CIRCUITS Shipboard HERO conditions and emission control (EMCON) restrictions often prohibit transmission of RF below 30 MHz. To provide an uninterrupted flow of essential communications without violating HERO and EMCON restrictions, AUTOCAT, SATCAT, and MIDDLEMAN were developed. With these techniques, the range of tactical UHF circuits (voice or teleprinter) can be extended by relay of AM UHF transmissions via HF or satellite. AUTOCAT accomplishes this using a ship; whereas SATCAT uses an airborne platform for automatically relaying UHF transmissions. MIDDLEMAN requires an operator to copy the messages with subsequent manual retransmission. The three techniques just discussed use three different types of circuit for reception and relay of UHF transmissions. These circuits are as follows: A voice circuit where some units send and receive on one frequency, and other units send and receive on any other frequency; A voice circuit where all units transmit on one frequency and receive on another frequency; and A RATT circuit where all units transmit on one frequency and receive on another frequency. FLEET FLASH NET The Fleet Flash Net (FFN) is composed of senior operational staffs and other designated subscribers. The purpose of the FFN is to distribute high-precedence or highly sensitive traffic among subscribers. A receipt on the net constitutes firm delivery, and the message need not be retransmitted over other circuits to receipting stations. The FFN is explained in more detail in Mission Communications, NTP 11. ANTENNA SYSTEMS Operation of communication equipment over the entire range of the RF spectrum requires many types of atennnas. You will need to know the basic type of antennas available to you operationally, their characteristics, and their uses, Very often, you, the operator, can mean the difference between efficient and inefficient communications. You will have a choice of many antennas and must select the one most suitable for the task at hand. Your operational training will acquaint you with the knowledge necessary to properly use the antennas at your disposal, However, your operational training WILL NOT acquaint you with the WHY of antennas, in other words, basic antenna theory. The following topics are intended to familiarize you with basic antenna terminology, definitions, and characteristics. 2-14