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How are FM waves generated?
FM signals can be generated either by using direct frequency modulation, which is achieved by inputting a message directly into a voltage-controlled oscillator, or by using indirect frequency modulation, which is achieved by integrating a message signal to generate a phase-modulated signal, which is then used to …
Which component is used in the generation of an FM signal?
The direct generation of FM signals involves a voltage-controlled oscillator (VCO), in which the oscillation frequency varies linearly with the control voltage. When a message signal is used as the control voltage, the output signal of the VCO is frequency modulated.
What is RF carrier wave?
A carrier wave is a pure wave of constant frequency, a bit like a sine wave. This process of imposing an input signal onto a carrier wave is called modulation. In other words, modulation changes the shape of a carrier wave to somehow encode the speech or data information that we were interested in carrying.
What is direct FM generation?
In direct FM generation, the instantaneous frequency of the carrier is changed directly in proportion with the message signal. For this, a device called voltage controlled oscillator (VCO) is used. This will vary the frequency of the oscillator to produce FM. The devices used are FET, transistor or varactor diode.
What is direct method of FM generation?
Direct Method In this method, Voltage Controlled Oscillator (VCO) is used to generate WBFM. VCO produces an output signal, whose frequency is proportional to the input signal voltage. This is similar to the definition of FM wave. The block diagram of the generation of WBFM wave is shown in the following figure.
Which is the carrier wave of a radio signal?
Most radio systems in the 20th century used frequency modulation (FM) or amplitude modulation (AM) to add information to the carrier. The frequency spectrum of a modulated AM or FM signal from a radio transmitter is shown above. It consists of a strong component (C) at the carrier frequency
Which is a form of carrier wave modulation?
Frequency Modulation (FM) is a form of modulation in which changes in the carrier wave frequency correspond directly to changes in the baseband signal.
What is the direct method for FM wave generation?
In direct FM generation, the instantaneous frequency of the carrier is changed directly in proportion with the message signal. For this, a device called voltage controlled oscillator (VCO) is used. A VCO can be implemented by using a sinusoidal oscillator with a tuned circuit having a high value of Q.
How to generate a wide band FM Wave?
Indirect Method 1 This method is called as Indirect Method because we are generating a wide band FM wave indirectly. 2 In this method first we will generate NBFM wave and then with the help of frequency multipliers we will get WBFM wave. 3 The block diagram of generation of WBFM wave is shown in the following figure.