Started before 3000 B.C . - Egyptians develop hieroglyphics .
1834 – Gauss & Weber build the electromagnetic telegraph.
1844 – S. F. B. Morse patent the telegraph.
1876 – A. G. Bell develops and patent telephone.
1895 – Marconi demonstrates wireless telegraphy .
1926 – Baird & Jenkins demonstrate the television .
1933 – E.H. Armstrong invents FM (Frequency Modulation).
1937 – A. Reeves conceives PCM(Pulse Code Modulation) .
1954 – Colour TV broadcasting begins.
1962 – First satellite communication.
1969 – Internet is invented.
1975s – PC(Personal Computer) come into use.
1981s – Modems become widespread.
1983 – First cellular telephone system become operational.
1989 – GPS is use for commercial and personal applications.
1989 – www is invented.
2000s – Era of digital signal processing.
History of communication:
Transmitter (Tx) Noise Receiver (Rx) Communications channel or medium Human message input (voice, code, pictures, data, etc.) Message for human application Information source Destination Communication System: Chapter 1: Introduction to Communication System Figure 1.1 : The basic elements of communication system.
Collection of electronic devices or circuits that convert the information into a signal that is more suitable for transmission over a given transmission medium . Eg. Microphone or microwave radio transmitter.
Transporting signal from the TX to the RX . Eg. Pair of wires that carry voice signal from a microphone to a headset.
Transmitter: Chapter 1: Introduction to Communication System Medium:
Chapter 1: Introduction to Communication System Collection of electronic devices or circuits that accepts the transmitted signal from the transmission medium and converts them back to their original form . Eg. Earphone or complex electronic receiver. Random, undesired electrical energy that enters the communication system via the communication media (i.e. inserted between TX and RX) and interferes with the transmitted message. Noise: Receiver:
Figure 1.2 : Basic transmitter block diagram. Signal source Base band converter Modulation and power amplification Transmission (Electromagnetic Field) Subsystem synchronization Transmitter: Chapter 1: Introduction to Communication System
Figure 1.3 : Basic receiver block diagram. Receiver: Chapter 1: Introduction to Communication System Amplification and demodulation Base band inverter Synchronization system Base band processing Electromagnetic field