As we mentioned earlier, the fleet broadcast is the primary means for delivering messages to afloat commands. This section discusses a few of the other types of circuits by which a ship can transmit its message traffic ashore or to other ships for delivery or relay.
There are three methods of operating communications circuits: duplex, simplex,
The mode of operation at any given time depends upon equipment and frequency availability.
Duplex describes a communications circuit designed to transmit and receive simultaneously. In such operations, each station transmits on a different frequency and both stations transmit concurrently. Both stations are required to keep transmitters on the air at all times and to send a phasing signal at the request of the distant end.
Figure 1-11 shows a diagram of a UHF/HF full-duplex FSK (frequency-shift keying) single-channel teleprinter relay circuit. There are two types of duplex operation: full duplex and half duplex. Full duplex (FDX) refers to a communications system or equipment capable of transmitting simultaneously in two directions. Half duplex (HDX) pertains to a transmission over a circuit capable of transmitting in either direction, but only one direction at a time. Small ships traveling in company normally use duplex in a task group common net in which they terminate with a larger ship that is serving as net control. The net control ship provides the ship-shore relay services. Ships traveling independently can use this system for anon-call ship-shore termination to transmit their outgoing messages.
Figure 1-11.-UHF/HF full-duplex FSK single-channel teleprinter relay circuit.
Simplex is a method of operation that provides a single channel or frequency on which information can be exchanged (figure 1-12). Simplex communications operation is normally reserved for UHF and those ships that do not have sufficient equipment for duplex operation. In some cases, a simplex circuit can be established when equipment casualties occur. Where no HF simplex frequency is indicated or guarded, ships requiring a simplex ship-shore circuit must call on a duplex ship send frequency. The ship must state "SIMPLEX" in the call-up, indicating that the ship cannot transmit and receive simultaneously When a ship requests simplex operation on duplex circuits, the shore station may be required to shift transmitters prior to acknowledging call-up. If no reply is received within 45 seconds, the ship should repeat the call-up procedures. If a third attempt is required, the ship should check equipment to ensure proper operation.
Figure 1-12.-UHF/HF netted simplex FSK teleprinter relay circuit
Note - "Other Statistics" should be "Other Stations"
Semi-duplex communications circuits, used primarily on task force/task group/ORESTES, are a combination of the simplex and duplex modes. All stations except the net control station (NECOS) transmit and receive on the same frequency. The NECOS transmits and is received on a second frequency. The NECOS may transmit continuously, whereas all other stations must transmit in accordance with simplex procedures.
The UHF/HF relay method permits long-range, uninterrupted communications during periods of hazardous electromagnetic radiation (HERO). Figure 1-13 shows a block diagram of a UHF/HF voice relay circuit. Modern radio and radar transmitting equipments produce high-intensity RF fields. It is possible for RF energy to enter an ordnance item through a hole or crack in its skin or to be conducted into it by firing leads, wires, and the like. Here is an example of HERO. An aircraft carrier is arming aircraft on board. During arming operations, all HF transmitters must be secured to prevent possible detonation of the ordnance. To maintain its ship-shore communications, the carrier transmits to a relay ship via a UHF circuit. The relaying ship then retransmits the signal on a HF circuit to a terminated NAVCOMTELSTA. On-line radioteleprinters can be relayed, as well as voice, using this circuit.
Figure 1-13.-UHF/HF voice relay circuit.
SECURE VOICE WORLDWIDE VOICE NETWORK
The secure voice network is designed to provide real-time voice communications between forces afloat and operational commanders ashore, using either HF or satellite connectivity. This system is commonly referred to as GPS Worldwide HICOMM.
This system consists of three separate networks. Each network has an area control station controlled by a FLTCINC; either CINCLANTFLT, CINCPACFLT, or CINCUSNAVEUR. Each area has subarea control stations determined by each FLTCINC to ensure worldwide coverage.
Satellite System Control
The secure voice system, using satellite transmissions, has limited shore access points at the four COMMAREA master stations and NAVCOMTELSTA Stockton, California. These sites serve as the interface channel to both the wideband and narrowband voice systems in order to extend calls to operational commanders ashore.
If a ship, aircraft, or shore station needs to enter the secure voice network, it must be prepared to do so with minimum time delay.
Units desiring to enter the net on a temporary basis must specify the length of time and purpose for entering the net. They must also obtain permission from the appropriate control station. The area net control station (NECOS) is responsible for completing all calls originating from senior commands to all commands, ships, or aircraft within the specific FLTCINC's net. Certain rules must be observed when on the secure voice net, as follows: HF transmitter tuning is prohibited on secure voice.
Transmitters must be calibrated and pretuned on a dummy load. Final tuning may be accomplished during live transmissions. All stations must maintain a continuous log on secure voice. The actual time of significant transmissions must be entered into the log. When available, recording devices must be used in lieu of a paper log. The net operates as a free net unless otherwise directed by the area FLTCINC. NECOS retains the prerogative of exercising control over all transmissions to ensure proper circuit discipline.
Full-period terminations are dedicated circuits that provide communications between shore stations and afloat commands. These terminations require allocation of limited NCTAMS/NCTS assets. Therefore, the criteria for requesting, approving, and establishing such circuits is necessarily strict.
Afloat commands and individual units can request full-period termination during special operations, deployments, intensive training periods, or exercises when primary ship-shore circuits will not suffice. Commands should request full-period terminations only when traffic volume exceeds speed and capability of ship-shore circuits and when operational sensitivity requires circuit discreetness or effective command and control necessitates dedicated circuits. The heavy demands placed upon NCTAMS/NCTSs for full-period terminations require maximum cooperation between shore stations and afloat commanders prior to and during an operation. Ships having a need for a full-period termination, either for training or operational requirements, must submit a termination request to the COMMAREA master station at least 48 hours prior to activation time. Emergency commitments or a command directive may necessitate a lead time of less than 48 hours. Whenever possible, however, the 2-day limit must be honored to achieve maximum preparation and coordination. NTP 4 gives details of required information that must be included in a termination request message. The COMMAREA master station will assign a shore station for a ship's termination circuit. Once the shore station has been assigned, both the ship and the station may begin coordination to identify specific equipment keylists and frequencies needed to effect termination. The shore station will also act as NECOS. Two hours prior to the scheduled termination, the shore station can coordinate with the ship by telephone, local circuitry, or by primary ship-shore. When the ship shifts terminations, the securing of the current termination and the establishment of a new termination should coincide with a broadcast shift whenever possible. The ship must submit a COMMSHIFT message.
There are six types of full-period terminations, as follows:
Single-channel radioteleprinter using either radio path or landline transmission media;
Single-channel low-data-rate satellite access using satellite transmission media;
CUDIXS special satellite access for NAVMACS-equipped ships using satellite transmission media;
Multichannel radioteleprinter using either radio path or landline transmission media;
Multichannel radioteleprinter using SHF satellite transmission media;
and Tactical intelligence (TACINTEL) access for TACINTEL-equipped ships using satellite transmission media.
To ensure that circuit equipment is in peak operational condition, complete system back-to-back off-the-air tests must be completed 24 hours prior to termination activations. Check cryptoequipment back- to-back after daily crypto changes and prior to putting circuits into service. An aggressive PMS and quality monitoring program is essential. When checking equipment, look for power levels, scorch or burn marks, proper operation of interlocks, and cleanliness. When cleaning and inspecting antennas, look for cracks, chips, or blistering of insulators. Also check for deterioration, loose connectors, and correct insulator resistance.
COMMSPOT reports will be submitted by all ships, including nonterminated units, any time unusual communication difficulties are encountered. Ships will submit the COMMSPOT to the terminating communications station. Timely submission of COMMSPOT reports is necessary to minimize further deterioration of the situation. Rules and general instructions for preparing JINTACCS formatted COMMSPOT reports are found in the Joint Reporting System (General Purpose Reports), NWP 1-03, Supp-1 (formerly NWP 10-1-13).
PRIMARY SHIP-SHORE CIRCUITS
Primary ship-shore (PRI S/S) circuits are encrypted FSK/PSK teleprinter nets that permit ships to transmit messages for delivery ashore. This service is available to units that do not maintain a full-period ship-shore termination. Navy tactical UHF satellites or the HF/UHF spectrum may be used to conduct ship-shore circuit operations. Ships may use this circuit for coordinating and establishing a full-period termination with the shore station. The frequencies for NCTAMS and NAVCOMTELSTAS that guard primary fleet ship- shore circuits are listed in applicable CIBs distributed by the COMMAREA master stations. These frequencies are subject to change by the cognizant FLTCINC or by the NCTAMS.
OVER-THE-AIR TRANSFER (OTAT) AND OVER-THE-AIR REKEY (OTAR)
There are significant vulnerabilities associated with the handling of paper cryptographic material. Sound application of over-the-air transfer/rekey (OTAT/OTAR) procedures and techniques can reduce the amount of paper keying material required and reduce the potential for compromise. These procedures and techniques are contained in the NAG-16B Procedures Manual for Over-the-Air Transfer (OTAT) and Over-the-Air Rekey (OTAR). OTAT/OTAR also makes the transfer of keying material more responsive to rapidly changing operational requirements. The use of NAG-16B was developed and verified by extensive use during operation Desert Shield/Storm. The specified procedures served as an effective vehicle for transferring keying to satisfy rapidly changing joint and Navy requirements. Expanded definitions, general procedures, and equipments are found in NAG-16B.