The International Morse Code and special signals are used for this means of communication. When transmitting by whistle, siren, fog horn, or other devices in which the length of sound can be controlled, you use a short blast to represent a dot and a long blast to represent a dash. When transmitting with a device that is struck to create sound, such as a bell, gong, or drum, use a single stroke to represent a dot and two rapid strokes to represent a dash. No heading or ending is used in sound signaling. The text is to be made twice, separated by a pause. LIMITATIONS The use of sound communication is normally limited to certain specified sound signals. The ones commonly used are those prescribed for vessels in the Rules of the Road. When sound signals are used in special circumstances, care must be exercised that they do not conflict with the more commonly used signals and thereby confuse ships and stations not familiar with the special signals. Sound signals other than those included in the Rules of the Road are not to be employed in pilotage waters and are only to be used in an emergency when short range radio is not available, or for sounding visual call signs on occasions when the OTC may wish to ascertain which ships are within hearing distance. Sound signals may only be used by the OTC or by an individual ship having vital information for the OTC. Signals made by any ship other than the OTC are to be followed by the call sign of that ship. RECEIPTING When The OTC signals by sound, one ship usually is directed to repeat back or receipt for the signal. When sound is used by an individual ship, the OTC is always to receipt for the signal with that ship's call sign followed by the prosign R. The OTC may direct another ship to receipt by making that ship's call sign followed by the prosign K. The designated station receipts by making the prosign DE followed by the prosign R. No ship is to relay a sound signal. EXECUTIVE METHOD The executive signal consists of a 5-second blast immediately following the repetition of the text. The execute to follow sign (IX) is not to be sent either in the text or preceding the 5-second blast. The signal is executed on termination of the 5-second blast. Ships are not to wait for any ship that may be ordered to repeat back or receipt. When ships are ordered to repeat back, they are to include the executive signal if one has been used. IDENTIFICATION OF SHIPS On occasion the OTC may wish to determine which ships are within hearing distance. This may be done by the OTC sounding the appropriate signal only once. On hearing this signal, ships are to reply by sounding their visual call signs once only as follows: 1. If addressed to one ship, immediately on hearing the signal. 2. If addressed to more than one ship, the ships will answer in alphabetical order of call signs. If no ship sounds within 30 seconds, the next ship in order is to sound. RADIOTELEPHONE LEARNING OBJECTIVES: Define radio- telephone (R/T). Describe the procedures for operating the radiotelephone and maintaining security; list precautions that should be observed when communicating by radiotelephone. Radiotelephone (R/T) is used for voice tactical and administrative communication by ships and aircraft. The time will come when, as a Signalman, you will need to use the R/T. Study this section to improve your ability to use voice communication procedures. There can be certain drawbacks to using the R/T. Poor voice communications (whether because of faulty equipment, adverse atmospheric conditions, or inept performance by an operator) can create confusion, reduce reliability and speed, and adversely affect operations. It is essential that all users observe established operating procedures. Basic guidance for voice radio communication is contained in Communications Instructions Radio- telephone Procedures, ACP 125. Various naval publications prescribe procedures for specific environments. 4-13