Super Heterodyne Receiver - Essay Example

All modern television and radio receivers virtually use the principle of super heterodyne. The super heterodyne receiver reduces to the same intermediate frequency value. In order to accomplish this, it requires that the super heterodyne receiver be able to vary incessantly the frequency that is being mixed into the signal in order to keep the same difference (Jerry 1172). This paper will discuss Super Heterodyne Receiver and its various aspects. History The history of Super Heterodyne Receiver can be traced back to 1905 when Reginald Fessenden, a Canadian inventor, described proposed method to produce an audible signal from an Alexanderson transmitter.

However, Edwin Armstrong, a United States Major, devised the principle of super heterodyne receiver in 1918 during the First World War in France. Armstrong invented this device as a way to overcome the deficiencies of early vacuum tube triodes that were being used as high-frequency amplifiers particularly in radio (Drentea 38). These amplifiers were used in equipment for radio direction finding and Armstrong realized that if these receivers could be operated at a much higher frequency, they would be better and more effective.

At that time, however, there were no practical short wave amplifiers because of the existing limitations of triodes. Before Armstrong’s invention, it had been noticed that if regenerative receivers were allowed to move into oscillation, it would be possible for other nearby receivers to start picking up stations on frequencies that were different from those that were actually being transmitted on by stations. Several years later, Armstrong deduced that this was as a result of a supersonic heterodyne that was between oscillator frequency and the carrier frequency of the station (Jerry 1173).

Therefore, Armstrong realized that that super heterodyne was a potential solution to the amplification problem of short wave. For example, he realized that to monitor 1500 kHz frequency could require setting up an oscillator at 1560 kHz, therefore producing a heterodyne difference of 60 kHz; such a frequency could then be amplified more conveniently by the day’s triodes (Tsui 79). Eventually, Armstrong sold his patent for super heterodyne to Westinghouse, who in turn sold to RCA. RCA later monopolized the super heterodyne receivers market until 1930.

Super heterodyne receivers gained more prominence in the 1930s with vacuum tube technology improvements. This situation could also be attributed to the rapid increase in the number of broadcasting stations that created demand for higher-performance and cheaper receivers. Introduction of tubes particularly designed for operation of super heterodyne receivers, notably the pentagrid converter, significantly reduced the advantage that preceding receiver designs had. Commercial production of super heterodyne receivers by the mid-1930s largely replaced the production and use of preceding receivers designs specifically tuned radio frequency receivers.

Eventually, the principle of super heterodyne was virtually taken up for all commercial TV and radio designs (Drentea 102). Design and Operation Principle of Super Heterodyne Receiver The operation principle of super heterodyne receiver mainly relies on the use of frequency mixing or heterodyning. The signal from an antenna is adequately filtered to reject the image frequency (Tsui 90).