Administrative Circuits

OPERATIONAL OR TACTICAL CIRCUITS Most voice circuits used at sea are operational or tactical nets; some circuits, however, are often used to pass administrative traffic. These circuits are subcategorized into two distinct types: short and long range. Short-range operational communications normally use the UHF frequency spectrum (225 to 400 MHz) and low-power, line-of-sight equipment. Because of these frequency and equipment characteristics, the maximum effective range is usually 20 to 25 miles. This limited UHF range offers no security, and transmissions are always subject to enemy interception. However, since these transmissions are limited somewhat to the local geographic area, interception by an enemy would be difficult. On the other hand, the range of UHF communications may be extended through the proper use of relay procedures. More and more, our modern and high-speed ships must report to OTCs from longer distances than the older ships they replaced. Long-range frequencies in the medium- and high-frequency spectrum (2 to 32 MHz) are, therefore, used. From your study of module 4, you will remember that the propagation characteristics of these frequencies make them desirable for long-range communications. To further increase the range capabilities of long-range communications, we use single-sideband (SSB) methods. ADMINISTRATIVE CIRCUITS Administrative circuits are normally used only in port and may include both short- and long-range communications. Voice circuits that are neither operational nor tactical are included in the administrative category. Seldom is there such a circuit in at-sea communication plans. Harbor common circuits and tug control nets are two examples of administrative nets. Naturally, these nets assume an operational function during situations requiring emergency procedures, such as natural disasters and civil uprisings. Circuit requirements vary from port to port, as established by the senior officer present afloat (SOPA). Both the UHF and MF/HF circuits may be used for administrative nets. TYPES OF NETS There are two types of R/T nets: directed and free. The type of net to be used is determined by the operational situation. Regardless of the type of net used, a Net Control Station (NECOS) is assigned to monitor the circuit or circuits and enforce circuit discipline. NECOS is the senior net member or designated authority. The NECOS is responsible for implementing operational procedures and enforcing discipline and security on the net. Enforcement of circuit discipline, however, is not the only reason for having a NECOS. Sometimes there are so many stations sharing a common circuit that a NECOS is necessary to facilitate the handling and passing of R/T traffic. Directed Net On a directed net, stations must obtain permission from the NECOS before communicating with other stations on the net. The exception to this rule is when a station has FLASH traffic to send. Also, transmissions on the directed net may be accomplished with a predetermined schedule. Free Net On the free net, member stations don’t need NECOS permission to transmit. Net members must ensure that the net is not in use before initiating a call-up. A free net, however, does not relieve the NECOS of the responsibility for enforcing operational procedures and maintaining proper circuit discipline. Both free and directed nets normally use collective call signs. Figure 2-1 diagrams an R/T net that consists of the following stations: USS Key, USS Mariano G. Vallejo, USS James K. Polk, USS Kamehameha, and USS Tecumseh. In this example, we will assume that the NECOS is Key. Notice that the collective call sign for the entire net is Poseidon. Figure 2-1.—Radiotelephone net. 2-15