SYSTEM INTRODUCTION

1-4 Facsimile transmission is not intended to be a replacement for teletypewriter and other general methods of transmission. It is an important communications supplement and provides a means of handling certain types of graphic and pictorial intelligence by swift communications methods. It is widely used by the Navy weather information services and ship and station weather centers to obtain the latest weather maps. Chances are the photo you saw in the newspaper was transmitted by facsimile. Q5. What is the main use of a radio teletypewriter? Q6. What is facsimile? SYSTEM INTRODUCTION Until recently, RADIO COMMUNICATIONS brought to mind either telegraphy (cw), voice (AM), or possibly radio teletypewriter (rtty) communications. Today, radio communications has become a highly sophisticated field of electronics. Even small Navy ships have the capability to "come up" on the commonly used ship-to-ship, ship-to-air, and ship-to-shore communications circuits. These circuit operations are accomplished through the use of compatible and flexible communications systems. A communications system (as you will see later in this chapter) consists of two or more equipment sets (sets will be explained a little later). Communications systems follow the system subdivision shown in figure 1-1. Systems are arranged and interconnected to perform a circuit operation that cannot be performed by any single piece of equipment. Navy communications systems vary from the simple to the very complex, depending upon the circuit operations involved. Because a Navy ship must use every inch of available space, the communications equipment may be spread over several portions of the ship, for instance, receivers in one location, transmitters in another, and terminal equipment in another. The equipment must be installed in such a manner that it is flexible and can be used interchangeably with other installed communications equipment. Consequently, large numbers of sets which make up the shipboard communications system are installed and are capable of operating separately and simultaneously. Flexibility is provided through a complex arrangement of interconnections. These allow the physically separated equipment to be selectively switched (patched) by you into different circuit configurations.