Safety andsecurity system: a)fire detection and alarm. B)close circuit television. (A) safe and secured electical wiring is requring forfire alarm system. At the time of fire broke up in an building the fire alarm wiring and accessories must have the capacity to stand forcertain timeso that alarm etc. For fire alarm there are various system like manual automatic bellpaging telephone etc. In automatic alarm system sensorsare instaled in floor or a strategic locations . all control are being done in the centrally located control panel. (B.) close circuit television: most ofsecurity surveillance system coordinating latest inforation technology use cctv system normaly used in banks supormarketstop secured offces labaratoris industries and so on conventional cctv system use video cassetes for recording and playing images . with igh technology video recording can be stored into personal computer.captured videos will be digitally compresed and stored in to the hard diskof personal computer without the use of video cassette.type of switches: a single pole sinhle throw switch is two terminal elements. Its function is to connect the two terminals by shorting them or to disconnect the terminals by opening the path between them. We are familiar with use of such a switch in operating the electical appliances we use in our homes and offices. There are others switches with more terminals . however in every one of them terminals are either horted or openeed .these seitches have various uses. Block diagram of general communication system: information source. To transit information using electronice means there must be some system to convert them in a set os electrical signals . the examples can be cc camera used for converting optical visual message in to video signals. Transmitter. It manipulates the infomation from the message source and couples it into a transmission chanel in the form of a signal which matches the transfer properties of the channel. Channel. In communication theory and systems terminology the transmission medium where the signals are transmitted is called communcation channel. Receiver it extracts the weakened and distorted signal from the channel amplifies it and restores it to it original form and then pasces it in to the message destination.destination. recevied signal is converted to a message form mostly the original in put message category sent by the source to the user replica of the speakers voice in the telephone set of the user. Type of connectivity. Wired: wire communication means any aual transfer made in whole or in part through the use of facilities for the transmission of communication by the aid of wire cable or other like connection between the point of origin and th4 point of reception th eus e of such connection in a switching station furnished or operated by any person engaged in providing or operating such facilities for the transmission of interstate or foreign communications for communications affecting interstate or foreign commerce and such term includes any electronice storage of such communication. (2) wireless communication but the wireless communication that communication pattern made without wire . the wire is replaaced by transmission of electramagnetic waves through the air communication device cn thus exhibit one of the folowing characteristics.paging. a multistoried building or a big industry or a big complex require paging system for emergency paging to the in habitants . emergencyn paging means pasing information to th4 in habitants at any emergencey time like fire earth quack or any o fsuch type of emergency situatio to facilitate the in habitants take safe position or evacuate the complex. 1. Audio paging system: the audio paging system consist s of paging microphone ceiling wall speaker individual floor volume control main system console with playback unit batteries battery charger viltage stabilizer and so on 2. Radio paging system this is same as radio anouncement police army bdr use their own radio transmission system for transmission of information some private companies also use their own radio transmission system for their own business,3. Telephone paging system in a big building or complex telephone system can be used for passing announcement or nay n important information ot any body or to a group of people aat the remote end. The recipient of such announcement or information may have telephone set or pager normally pager unit have individual number like telephone number information to the pager unit can be passed through normal telephone .