## What is FSK?

Introduction:
It is a digital modulation technique which shifts the frequency of the carrier with respect to binary data signal. FSK stands for Frequency Shift Keying. The FSK modulation technique uses two different carrier frequencies to represent binary 1 and binary 0.

As shown in the figure-1, carrier frequency f1 represents binary data one and carrier frequency f2 represents binary data zero. Here amplitude and phase of the carrier remain constant while carrier frequency is changed. Binary FSK (BFSK) can be represented by following mathematical equation:
s(t) = A* cos(2*π*f1*t) for Binary 1
s(t) = A* cos(2*π*f2*t) for Binary 0
In this equation, f2 and f2 are offset from carrier frequency (Fc) by equal but opposite amounts.

Following are the typical applications of FSK modulation.
• It is used on voice grade lines for data rates upto 1200 bps.
• It is used for high frequency radio transmission from 3 to 30 MHz.
• It is also used in coaxial cable based LAN (Local Area Network) at higher frequencies.

## Benefits or advantages of FSK

Following are the benefits or advantages of FSK:
➨It offers lower probability of error (Pe) due to higher SNR (Signal to Noise Ratio).
➨It has higher immunity to noise due to constant envelope compared to ASK modulation. Hence it is robust against variation in attenuation through channel. This makes it favorable choice in certain practical applications.
➨The demodulation process for FSK signals is relatively simple, often requires frequency discriminators or filters. FSK transmitter and FSK receiver implementations are simple for low data rate application.

## Drawbacks or disadvantages of FSK

Following are the disadvantages of FSK:
➨It uses larger bandwidth compare to other modulation techniques such as ASK and PSK. Hence it is not bandwidth efficient.
➨The BER (Bit Error Rate) performance in AWGN channel is worse compare to PSK modulation.
➨FSK may not be the ideal choice for mobile communication systems due to its potential vulnerability to frequency-selective fading, a common occurrence in wireless channels.
➨FSK modulation may exhibit reduced power efficiency compared to some other modulation schemes, especially in scenarios where power consumption is a critical consideration.
➨FSK systems may require accurate frequency synchronization between the transmitter and receiver to maintain proper communication. Achieving and maintaining synchronization can be challenging in some environments.

In order to overcome drawbacks of binary FSK, multiple FSK modulation techniques with more than two frequencies have been developed. In MFSK (Multiple FSK), more than one bits are represented by each signal elements. Refer 2FSK and 4FSK Modulation types>>.

Conclusion : In summary, FSK modulation offers advantages in terms of noise immunity, simplicity of demodulation, and suitability for noisy environments. However, it has limitations in terms of spectral efficiency and may not be the best choice for high-data-rate or mobile communication applications.

## Modulation types

AM vs FM vs PM
AM FM PM MATLAB Code
What is modulation