Saluran transmisi

Sistem KomunikasiDasar-dasar komunikasiilustrasiIn a broad sense, the termcommunicationsrefers to the sending, receiving and processing of information by electronic means. Communications started with wire telegraphy in the eighteen forties, developing with telephony some decades later and radio at the beginning of this century.Radiocommunication, made possible by the invention of the triode tube, was greatly improved by the work done during World War II. It subsequently became even more widely used and refined through the invention and use of the transistor, integrated circuits and other semiconductor devices.informationThe communications system exists to convey a messageThis message comes from the information source in the sense of selecting one message from a group of messagesMessage = words, groups of words, code symbols or any other prearranged unitsThe meaning (or lack of meaning) of the information does not matter, from this P9int of view, only the quantity is importantInformation layout

transmittermessage arriving from the information source is electricaltransmitter is required to process, and possibly encode, the incoming information so as to make it suitable for transmissiona transmitter, the information modulates the carrierModulation may be amplitude modulation. frequency modulation. pulse modulationor any variation or combination of theseTypical radio transmitter

noisethe long distance signal will deteriorate during the process of transmission and reception as a result of some distortion in the systemNoise is unwanted energy, usually of random character. present in a transmission system. due to a variety of causesThe noise = greatest effect when the signal is weakestreceiverTransmitter receiverSimple Receivers simple crystal receiver, with headphones, to a far more complex radar receiver, with its involved antenna arrangements

diagram super heterodyne

modulationprocess of superimposing a low-frequency (long-wave) voice information component on a high-frequency (short-wave) carrier signalthe transmission of a continuous-wave (CW) signal

Signal sinus

Fourier series