Frequency Modulation

FM or frequency modulation is applied in a variety of applications ranging from television to telecommunications and has several advantages over other modes. While modulating a radio signal by changing its amplitude is the most common method we all know. But it is far from the only reason for frequency modulation to be this famous. Frequency modulation is another way to modulate the frequency of transmission. It is commonly used on frequencies above 30 MHz. VHF FM broadcasts are one of the most well-known applications. In this article, you will learn more about frequency modulation.

What is frequency modulation in physics? 

Frequency Modulation is a form of modulation in which the carrier’s wavelength is changed by the modulating signal’s instantaneous amplitude. It also retains the phase and amplitude at constant. The objective of changing the carrier wave frequency is to transmit data or information over short ranges.

The Frequency Modulation index is generally higher than one. That’s why it requires a wide bandwidth of 200 kHz. It also operates in a very high-frequency range of 88 to 108 Megahertz. FM is a complex circuit with an endless number of sidebands that receives a high signal with good sound quality. Angle modulation is a type of carrier frequency modulation. This type of modulation is particularly used in telecommunications and transmission systems. 

Direct frequency modulation comprises a system that is trying to feed a direct message into a voltage-controlled modulator or indirect frequency modulation. It also involves integrating a message signal to start generating a phase-modulated output. This phase modulation is then used to modify a crystal-controlled oscillator and the output is transferred through a frequency multiplier to start the generation of an FM signal.

Even though it is not as simple as amplitude modulation, frequency modulation has several distinct advantages. It is also capable of providing near-interference-free reception. That’s why we use this for VHF sound transmissions. 

Frequency modulation is more frequently used in older broadcasts on the long, medium, and short wavebands. This is because these transmissions could provide high-fidelity audio.

FM is used in various two-way radio communication technologies and is also used extensively for high-quality audio broadcasts. FM systems are extremely popular for permanent or mobile radio communication systems. 

What is frequency demodulation? 

When we modulate any signal, we need to demodulate it. So it is important to effectively demodulate and recover the original signal, as with any form of modulation. FM demodulator, FM sensor, or FM voltage divider are all terms used to describe the FM demodulator. 

There are different types of FM demodulators. They only allow the incoming signal’s frequency variations to be transformed into amplitude variations on the output. If data is being transferred across the system, these are usually fed into an audio amplifier or a digital interface. 

Different types of FM modulators

There are so many types of modulators used for frequency modulation signals: 

• Varactor diode oscillator – A varactor diode is installed within the tuned circuit of an oscillator circuit. A varactor diode can also be used as part of a crystal oscillator circuit. When crystal oscillators are used for signals, they are doubled in frequency. This narrow band is possible in frequency modulation.

• Phase-locked up: Frequency modulation can be easily produced using phase-locked loops. If you want to carefully manage limitations within the loops, you can use this.   

Advantages and disadvantages of frequency modulation 

There are various advantages and drawbacks of using frequency modulation, as there are with any other type of modulation system. But before making final decisions, you need to keep the following things in mind. You can learn what frequency modulation is? Examples are through its advantages. 

Advantages of using frequency modulation: 

Frequency modulation has been widely employed for high-quality audio broadcasting, two-way radio communications, and a variety of other applications due to its many advantages.

• Resistance to noise:

Frequency modulation has several advantages, one of which is its resistance to signal level changes. The modulation is simply carried as frequency fluctuations. This means that any changes in signal level will not affect the audio output, as long as the signal does not dip below the receiver’s ability to receive.

 Due to these advantages, FM is appropriate for mobile radio communication, which uses two-way radio or portable applications where signal levels are expected to vary significantly. FM can resist noise and interference in between a network.

• Easy to use modulation: 

Another benefit of frequency modulation is connected with transmitters. It is simple to apply modulation at a reduced power phase of the transmitter. It is possible to apply modulation to a low-power transmitter phase. A  quadratic form of amplification is not required to raise the signal’s power level to achieve its final value.

• RF amplifiers: 

With frequency modulated signals, you can use RF amplifiers. Non-linear RF amplifiers can also be used to amplify FM signals in a transmitter as they are much more efficient than linear ones. RF amplifiers are necessary for signals with any amplitude fluctuations. By using this, you need less power for achieving the desired output. This system makes frequency modulation systems more practical for portable two-way radio applications.

With so many advantages and uses of frequency modulation, some drawbacks overpower this modulation. 

Some of the disadvantages of using frequency modulation are : 

Frequency modulation, like all schemes and approaches, has several drawbacks that must be considered when you want to apply frequency modulation in any system. 

• Poorer spectral efficiency: 

The spectral efficiency of FM is lower than that of other modulation systems.  Frequency shift keying is a kind of frequency modulation that has lower spectral efficiency for data transmission. It has low efficiency as compared to other phase modulation and quadrature phase shift modulation systems. Due to this, many people use PSK and QAM for transmission.

• Demodulator that is complicated: 

One of the small drawbacks of using frequency modulation is its demodulator. This system uses a complicated demodulator which is expensive plus not easy to understand. However, because many radio integrated circuits now include a built-in frequency demodulator, this is no longer an issue. 

Conclusion 

Frequency modulation, or FM as it’s more commonly known by all of us. Frequency modulation is frequently used in radio communication and broadcasting nowadays. But have we ever questioned what FM is or what the technology and process behind it is? But, now we have all the information about frequency modulation.