What Is Frequency Modulation And Different Methods To Generate FM:
The Purpose of this article is to explain What Is Frequency Modulation And Different Methods To Generate FM. Hope so this help the reader about Frequency Modulation And Different Methods To Generate FM. So, few of basic terms are also given for better explanation about Frequency Modulation And Different Methods To Generate FM.
It is defined as a transmitted electromagnetic pulse or wave at a steady base frequency of alternation on which information can be imposed by increasing signal strength, varying the base frequency, wave phase or other means.
It is defined as the information carrying or input signal to communication system which causes a variation of some characteristics of a carrier.
Modulation is defined as the process in which parameters of carrier wave are varied n accordance with the modulating signal & it is performed in a transmitter by a circuit called MODULATOR.
Demodulator is the reverse process of modulation and converts the modulated signal back to original information and it is performed in the receiver by a circuit called DEMODULATOR.
In frequency modulation method, the frequency of the carrier is changed in proportion with the amplitude of the modulating signal. The FM signal is transmitted by the transmitter and it carries the information in the frequency variation. The amplitude of the carrier remains constant.FM is used for TV sound and radio broadcasting and police wireless transmission.
Classification of FM Modulators:
There are two basic methods of generating FM waves as follows:
1. Direct methods.
2. Indirect methods
Direct Method Of FM Generation By Varactor Diode Or Varicap:
Direct FM is angle modulation in which the frequency of the carrier is varied directly by the modulating signal. With direct FM, the instantaneous frequency deviation is directly proportional to the amplitude of the modulating signal. The tank circuit (L and C) is the frequency determining section for a standard LC oscillator. The capacitor microphone is a transducer that converts acoustical energy to mechanical energy, which is used to vary the distance between the plates of C and consequently, change its capacitance. As C is varied, the resonant frequency is varied. Thus, the oscillator output frequency varies directly with the external sound source. This is direct FM because the oscillator frequency is changed directly by the modulating signal, and the magnitude of the frequency change is proportional to the amplitude of the modulating signal voltage (Frequency Modulation And Different Methods To Generate FM) .
Advantages Of FM Generation:
- More Efficiency rather Amplitude Modulation.
- Effect of noise can be reduced by using Clipper Circuits.
- More S/N ratio.
Disadvantage Of FM Generation:
- More Complex Transmission or Receiver Ckts.
- No. of sidebands are more more bandwidth required.