Aviation Electronics Technician 1 - Historic Naval Ships Association

Figure 5-21.-TDS Interface block diagram.Transmitting devices include coaxial lines, low- orhigh-power transmitters, or microwave relay links.The reproducing device is a television receiver, atelevision monitor, or some form of electro-opticalprojection system.This chapter will discuss the camera tubes(pickup devices) and picture tubes (reproducingdevices). For most uses in aircraft, coaxial cablesprovide the means for transmitting the video signalsfrom the pickup to reproducing devices.TELEVISION FUNDAMENTALSTelevision transmission of a picture from onepoint to another involves a process in which light,reflected from an object or scene, is converted intoelectrical impulses of varying magnitude. Thisprocess is accomplished by means of synchronizedscanning. In synchronized scanning, the picture isexamined by the camera and reproduced by theviewing monitor. This is done point-to-point and in aregular pattern. The process is carried out so rapidlythat the entire picture is scanned many times eachsecond, and the eye sees it as a single complete image.The basic television system is shown infigure 5-22. Notice that it consists of a transmitterand a monitor. An image of the scene is focused onthe camera pickup device. An electron beam in thedevice scans the optical image and produces anFigure 5-22.-Basic television system.5-17