Advantages Of Frequency Modulation

Experiment # 01

Introduction to Amplitude Modulation (AM) And Frequency Modulation (FM).

1.1 Introduction:

The central model of communication is depicted in Fig. 1.1 (Fundamental model of communication). In this key model, every message-bearing sign, exemplified by s (t), is simple and is a capacity of time. A framework works on zero, one, or a few signs to deliver more flags or to just retain them)). In electrical building, we speak to a framework as a create, getting info signals (generally originating from the left) and delivering from them new yield signals. This graphical representation is known as a square outline. We signify information signals by lines having bolts indicating into the container, yield signals by bolts indicating endlessly.

The use of non-linear amplifiers, e.g. class C, etc. means that transmitter efficiency levels will be higher - linear amplifiers are naturally feeble.

1.3.3 Dis-Advantages of Frequency Modulation: One of the small dis-advantages of frequency modulation is that the demodulator is a little more fancy, and hence lightly more expensive than the very simple diode detectors used for AM. Also requiring a tuned circuit adds cost. However this is only an issue for the very low cost broadcast receiver market. Some phase modulation and quadrature amplitude modulation formats have a higher spectral efficiency for data transmission that frequency shift keying, a form of frequency modulation. As a result, most data transmission system use PSK and QAM. The sidebands for an FM transmission theoretically extend out to infinity. To limit the bandwidth of the transmission, filters are used, and these introduce some distortion of the signal.

1.4 Amplitude

Both these cycles are varied according to the information to be sent. The carrier then consists of sine waves whose amplitudes follow the amplitude variations of the modulating wave. The carrier is kept in an envelope formed by the modulating wave. From the figure,we can also see that the amplitude variation of the high frequency carrier is at the signal frequency and the frequency of the carrier wave is the same as the frequency of the resulting wave.

Fig. 1.4 Amplitude Modulation

1.4.1 Limitations of Amplitude Modulation, AM :

There are several advantages of amplitude modulation, and some of these reasons have meant that it is still in widespread use today: Since the effective power that present in the small bands is quite small, so the efficiency of AM system is low. The range of operation is small due to low efficiency. Thus, transmission of signals is difficult. As the radio receiver finds it difficult to characterize between the amplitude variations that represent noise and those with the signals, heavy noise is occur in its reception.

To obtain high fidelity reception, all audio frequencies till 15 KiloHertz must be replicated and this require the bandwidth of 10 KiloHertz to minimize the interference from the neighboring broadcasting stations. Therefore in AM broadcasting stations audio quality is known to be