Radio History and Development - Essay Example

Radio History and Development Radio is the wireless transmission of signals by modulation of electromagnetic waves that have frequencies below those of light (Wikipedia). Radio waves are created whenever a charged object accelerates with a frequency that falls within the radio frequency. In radio this acceleration is caused by an alternating current in an antenna. This essay will highlight the radio history and its development. Radio technology was initially called ‘wireless technology’ which was further shortened to ‘wireless’ (White, 2003). This technology was applied where regular telephones lines were unreliable and impractical. The next stage was the development of the broadcasting of audio messages simultaneously to multiple locations initially using the dots-and-dashes of the telegraphic code and then the full audio. The discovery of radio waves or the electromagnetic waves have the capacity to transmit speech, pictures and other data invisibly through the air. Several claims have been made by different scientists for the development of radio. As early as 1860, James Clerk Maxwell predicted the existence of radio waves and in 1886 H D Hertz demonstrated the variations of electric current could be projected into space in the form of radio waves similar to those of light and heat (Bellis, 2006). Hertz demonstrated that the electromagnetic equations could be reformulated into a partial differential equation called the wave equation. He proved that radio radiation had all the properties of waves. No ground connection was used and his detector of radio waves can be considered to be a type of primitive radio transmitter and receiver sufficient for true space transmission, this was not sufficient for actual use as it had no grounding or earthing element. As the source of radio waves he used damped oscillating currents in a dipole antenna. This could be detected by another dipole antenna connected to a narrow spark gap. When cylindrical detectors were added to the dipole antenna, the radio waves could be detected about 20 meters from the transmitter. In 1872 Loomis, an American dentist utilized atmospheric electricity to eliminate the overhead wire used by the existing telegraph system. This did not contain any diagrams or specific methods (Wikipedia_radio). Marconi, an Italian proved the feasibility of radio communication. He initially used a transmitter to ring a bell in his attic laboratory and then experimented outdoors to communicate further (Wikipedia). He replaced the vertical dipoles used by Hertz with a vertical wire topped by a metal sheet with an opposing terminal connected to the ground. The Marconi conductor was a monopole conductor with no loading coil and the base was driven by a regular power supply. Marconi could transmit radio signals for about a mile by 1895. Marconi equipped the ships with life saving wireless communications, established the first transatlantic radio service and built the first stations for the British short wave service. Tesla was the first to apply the mechanism of electrical conduction to wireless practices. He demonstrated that intelligence could be transmitted without wires. He initially used the electromagnetic receivers (Wikipedia). Later the principle of sending signals through space to receivers was used. He produced surface waves by adding ground connection to the transmitter. By connecting one of the terminals to the earth and the other to an insulated body of a large surface, longer transmission range was achieved but this was still not public radio transmission as we know today. In 1894, J C Bose, an Indian physicist, demonstrated publicly the use of radio waves in India. He ignited gunpowder and rang a bell at a distance using electromagnetic waves demonstrating that communication signals can be sent without using wires. Bose was not interested in commercial application and hence did not file for any patent. In 1901 radiotelegraph service was started between five Hawaiian Islands. In 1903 an exchange of greetings was done through this service between President Theodore Roosevelt and King Edward VII (Bellis). In 1905 the Russo-Japanese war was reported through the wireless. In 1906 the US Weather Bureau tried notifying the weather conditions through this technology. In 1906 the first radio program broadcast was done by Fessenden in 1906 from Massachusetts (Wikipedia). The ships at sea heard a broadcast by Fessenden playing the violin and reading a passage from the Bible. The first radio news program was broadcast from Michigan in 1920. The first regular entertainment broadcasts started in 1922 from England. Aircrafts started using commercial AM radio stations for navigation in early twentieth century. In early 1930s amateur radio operators introduced the single sideband and frequency modulation. As early as 1920s radio was also used to transmit pictures visible as television. The first transistorized radio was introduced by Sony in 1960. It was small enough to be kept in the vest pocket and could be powered by a battery. It was found to be durable. The first radio communication satellite was launched in 1963. Gradually the long distance telephone network started to convert to a digital network by employing digital radios for many of its links. This occurred in late 1960s. Thereafter the US navy experimented with satellite navigation and in early 1990s personal computers were used with audio cards to process radio signals. Digital transmissions were applied to broadcasting in the late 1990s. Radio has been used for long time for sending messages through Morse code between ships and land. It has also been used to pass or orders between army and navy during WWI. Radio receivers were fully developed by 1920s and widespread broadcasting was possible including relay of radio programs. During the pre-war period radio was used to locate and detect the aircraft and ships with the help of radar. Amplitude Modulation or AM was used to send music and voice in the Medium Frequency radio spectrum. This was first used by Fessenden in 1906 but its extensive use came much later. The first licensed commercial radio services began in AM on in 1920s. AM radio is broadcast on several frequency bands – long wave, medium wave and short wave but AM radio has limitations (Wikipedia_broadcasting). AM radio is susceptible to atmospheric interference and lower fidelity sound and hence only talk radio and news programming can be broadcast on it. This is because most modern receivers do not pass the full spectrum of audio that AM radio can transmit. Music radio and public radio started being broadcast over FM broadcasting in the last 1960s. Frequency Modulation or FM minimizes static and interference from electrical equipment and the atmosphere. In FM louder sounds at the microphone cause the transmitter frequency to fluctuate farther. FM is transmitted in very high frequency (VHF) radio spectrum unlike AM. The VHF radio waves travel in straight lines and hence the reception range is limited to 50-100 miles. FM receivers are immune to lightning and spark interference. In 1937 the first experimental FM radio station was granted permit. In the 21st century, internet radio has been introduced which consists of sending radio-style audio programming over streaming over internet connections. No radio transmitters are involved at all in the process. Telex system used short wave radio by ending tones over single sideband (Wikipedia_radio). For many years, telex-on-radio was the only reliable way to reach the developing countries. Aircrafts use a 1200 Baud radioteletype service over VHF to send their ID, altitude and position, and receive connecting flight data. Microwaves use intensive radio waves to heat food. Radio waves are also used to transmit control data to a remote object. Cranes and locomotives use digital radio techniques to ensure safety and reliability. Thus, the radio and the radio waves have come a long way since its development and has a wide area of usage even today. References: Belis, M (2006), The Invention of Radio, 17 Oct 2006 White, T. H (2003), United States Early Radio History, 17 Oct 2006 Wikipedia_Radio, Radio, 17 Oct 2006 Wikipedia_broadcasting, AM Broadcasting, 17 Oct 2006 Wikipedia, History of radio, 17 Oct 2006 Wikipedia, Invention of Radio, 17 Oct 2006 Read More