Elements of a communication system
The above figure depicts the elements of a communication system. There are three essential parts of any communication system, the transmitter, transmission channel, and receiver. Each parts plays a particular role in signal transmission, as follows:
The transmitter processes the input signal to produce a suitable transmitted signal suited to the characteristics of the transmission channel.
Signal processing for transmissions almost always involves modulation and may also include coding.
The transmission channel is the electrical medium that bridges the distance from source to destination. It may be a pair of wires, a coaxial cable, or a radio wave or laser beam. Every channel introduces some amount of transmission loss or attenuation. So, the signal power progressively decreases with increasing distance.
The receiver operates on the output signal from the channel in preparation for delivery to the transducer at the destination. Receiver operations include amplification to compensate for transmission loss. These also include demodulation and decoding to reverse the signal procession performed at the transmitter. Filtering is another important function at the receiver.
The figure represents one-way or simplex (SX) transmission. Two way communication of course requires a transmitter and receiver at each end. A full-duplex (FDX) system has a channel that allows simultaneous transmission in both directions. A half-duplex (HDX) system allows transmission in either direction but not at the same time.
