wireless communication devices

One desirable feature of radio transmission is that it should be carried without wires (i.e.,) radiated into space. At audio frequencies, radiation is not practicable because the efficiency of radiation is poor. However, efficient radiation of electrical energy is possible at high frequencies (>..

Basic Principles of Wireless Radio Communication - Let us now discuss the basic principles of wireless radio communications. We shall mainly concentrate on the principle of amplitude modulation and demodulation. The simplest scheme of wireless ..

It is mainly done through geostationary satellites. These satellites are fitted with special devices. These devices can receive signals from an Earth station and transmit them again in different directions. These special devices are called transponder..

Communication Satellites - Communication satellites are normally geostationary satellites. They have devices called transponder which receive signals from an earth station and transmit them in different directions. The signals in the form of electromagnetic radiation a..

Satellite Communication - It is mainly done through geostationary satellites. These satellites are fitted with special devices. These devices can receive signals from an Earth station and transmit them again in different directions. These special devices are ..

It is present in abundance They have no moving parts and hence require little maintenance and work quite satisfactorily without any focusing device It does not cause any environmental pollution like the fossil fuels and nuclear power Solar cells last a longer time and have low running cos..

Amplitude Modulation - When the amplitude of high frequency carrier wave is changed in accordance with the intensity of the signal, it is called amplitude modulation. In amplitude modulation, only the amplitude of the carrier wave is changed in accordance with the intensity of the signal. However, ..

The transmission lines used in telephony are of two kinds: open- wire and cable. The open-wire lines are gradually being superseded by cable construction, either overhead or underground, for two principal reasons. In the first place, many more circuits can be accommodated-there is a standard cable ..

Do we use dry cells for operating electrical appliance? It is not impossible to tap continuous supply of energy from electrochemical cells. Electrical circuits in homes, factories and offices receive such energy form local power companies. In most countries the energy is supplied via oscillating e...