Electronic Communication Technology Essay Example | Topics and Well Written Essays - 2500 words

Electronic Communication Technology - Essay Example However, because of the additional tubes it used, the receiver did not become common until the 1930’s when the levels of performance it provided became an essential requirement and the technology involved became cheaper too. The super-heterodyne receiver operates on the principle of heterodyning or frequency mixing in a non-linear fashion. Two different signals are mixed using an RF mixer, to produce an output that is the product of the instantaneous levels of the signals at both the inputs. The resulting output will contain signals at a frequency that is different from the two original signals. If f1 and f2 are the two original signals, the resulting new frequencies are expressed as the sum (f1 + f2) and difference (f1 – f2) of the two. If two signals, one at a frequency of 7.0 MHz and the other at a frequency of 8.0 MHz are heterodyned together, two new frequencies of 15 MHz and 1.0 MHz are produced. A suitable antenna is required to receive the radio signals, and they are often built into the receiver itself. The frequencies enter the circuitry from the antenna and then pass through the different stages of the receiver. The RF amplifier is the first stage of the super-het receiver, and it is used to amplify the signals prior to mixing. The level of amplification has to be carefully chosen. The amplifier must enable the signals to be sufficiently amplified with a good signal to noise ratio and must not overload the mixer. The amplified and tuned signals are then fed into a mixer circuit. A local oscillator is connected to the other port of the mixer. This local oscillator consists of a variable frequency oscillator that produces sine waves. The mixer combines the local oscillator signal with the original RF signal, and produces two new frequencies. The local oscillator may also be a frequency synthesiser. The mixer stage is used to enhance the received frequency to an intermediate stage. The signals leaving the mixer enter the IF stage.