The basic elements that form a communication system are :
-The transmitter : which processes the input signal to produce a transmitted signal suited to the characteristics of the transmission channel. Signal processing for transmission almost always includes modulation and may include coding.
-The transmission channel : which is the electrical medium that bridges the distance from source to destination.It may be a pair of wires, coaxial cable, or a radio wave or laser beam.Every channel experiences 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, and demodulation and decoding to reverse the signal-processing performed at the transmitter. Filter is another important function of the receiver.