FSK: Advantages and Disadvantages of Frequency Shift Keying

This page covers the advantages and disadvantages of FSK (Frequency Shift Keying). It discusses FSK benefits and drawbacks.

What is FSK? (Introduction)

FSK stands for Frequency Shift Keying. It’s a digital modulation technique where the frequency of the carrier signal is shifted according to the binary data signal. Essentially, it uses different frequencies to represent binary 1s and 0s.

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 above, carrier frequency f1 represents binary data one, and carrier frequency f2 represents binary data zero. The amplitude and phase of the carrier remain constant while the carrier frequency is changed.

Binary FSK (BFSK) can be represented by the 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, f1 and f2 are offset from the 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 up to 1200 bps.
• It is used for high-frequency radio transmission from 3 to 30 MHz.
• It is also used in coaxial cable-based LANs (Local Area Networks) at higher frequencies.

Benefits or Advantages of FSK

The following are the benefits or advantages of FSK:

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

Drawbacks or Disadvantages of FSK

The following are the disadvantages of FSK:

• It uses larger bandwidth compared to other modulation techniques such as ASK and PSK. Hence, it is not bandwidth efficient.
• The BER (Bit Error Rate) performance in the AWGN (Additive White Gaussian Noise) channel is worse compared 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 the drawbacks of binary FSK, multiple FSK modulation techniques with more than two frequencies have been developed. In MFSK (Multiple FSK), more than one bit is represented by each signal element.

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.