TM 55-1930-209-14&P-12
CHAPTER 2 RADIO COMMUNICATIONS SYSTEM
Section I. Description and data
2-1 Description. The radio communications system for Water Purification Barges includes a US Army tactical radio
ANNRC-46, two commercial marine radios, and three walkie-talkies. Each is designed to provide radio communications
with stations equipped with similar type radios operating on matching frequencies. This system, shown in Figure 2-1,
consists of the major components listed in Table 2-1. Individual radio equipment is shown In Figures 2-2 thru 2-4
Installation is shown on drawings listed in Appendix A. Additional information is contained in manufacturers' service
manuals/instructions listed in Section VI and US Army technical manuals listed in Appendix A
2-2 Capabilities
2-2.1 Army radio. The Army radio provides HF/FM communications with other military radio stations operating on
frequencies within the band assigned for military use. These may include other military ships such as Army or Navy
tugboats, military commanders and their headquarters and staffs, and military bases ashore. Transmission distance
normally Is 25 miles or less
2-2.2 Commercial marine radios. Commercial marine radios provide VHF/FM radio communications with commercial
(nonmilitary) radio stations equipped to operate In the FCC-assigned marine radio band (156 250 162 550 MHz). These
may include commercial tugboats, other commercial vessels, commercial shore stations allied with ships and seagoing
activities, and United States Coast Guard (USCG) ships and stations. Transmission distance is normally 25 miles or less
There are two marine radios, one In the barge dayroom and one In the workboat cabin. These are Identical pieces of
equipment, operate In the same manner, on the same channels/frequencies and are interchangeable. The barge-
mounted radio has a separate power supply to provide proper voltage for radio operation. The workboat-mounted radio
uses power from the workboat electrical system
2-2.3 Walkie-talkies. Three walkie-talkies provide short-distance communications (normally less than 5 miles) on three
preset frequencies In the FCC-assigned marine radio band They provide communications between crewmembers
carrying these transceivers, with the commercial marine sets In the barge dayroom and workboat cabin, and other radio
equipment operating on the same frequencies within the marine VHF/FM radio band Transmission distance is normally 5
miles or less
2-3 Special limitations. Operation of commercial marine radios must be in accordance with FCC regulations Operation
of Army radios must follow Army SSI/SOI. For specifics, refer to applicable service manual/instructions. According to
FCC regulations, marine radios are licensed primarily for safety of life and property. Therefore, distress and safety
communications have absolute priority. However, frequencies that are not reserved for these purposes may be used for
ship-to-ship and ship-to-shore official communications
2-1
