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Comparisons among ASK, PSK, and FSK (with MATLAB + Simulator)


  

Comparisons among ASK, PSK, and FSK

Comparison among ASK, FSK, and PSK
Parameters ASK FSK PSK
Variable Characteristics Amplitude Frequency Phase
Bandwidth The minimum theoretical bandwidth for BASK is equal to the bit rate, Nb. The bandwidth requirement is approximately (fc2 - fc1) + Nb. The bandwidth is always greater than ASK. The minimum theoretical bandwidth for BPSK is equal to the bit rate, Nb. It is more bandwidth-efficient than FSK.
Noise Immunity Poor. Amplitude is highly susceptible to noise interference. Good. Less affected by noise than ASK as information is in frequency, not amplitude. Excellent. Offers the best noise immunity of the three for the same signal power.
Complexity Simple to implement. More complex than ASK. Most complex, as it requires a phase-synchronous (coherent) detector.

 

Simulator for Calculating Bandwidth of ASK, FSK, and PSK

The baud rate represents the number of symbols transmitted per second. Both baud rate and bit rate are same for binary ASK, FSK, and PSK.











Comparison among ASK, FSK, and PSK

Performance Comparison:

1. Noise Sensitivity:

   - ASK is the most sensitive to noise due to its reliance on amplitude variations.
   - PSK is less sensitive to noise compared to ASK.
   - FSK is relatively more robust against noise, making it suitable for noisy environments.

2. Bandwidth Efficiency:

   - PSK is the most bandwidth-efficient, requiring less bandwidth than FSK for the same data rate.
   - FSK requires wider bandwidth compared to PSK.
   - ASK's bandwidth efficiency lies between FSK and PSK.

3. Complexity:

   - ASK and FSK are relatively simpler to implement and demodulate.
   - Coherent PSK demodulation can be more complex due to carrier synchronization requirements.

4. Fading and Multipath Resilience:

   - FSK performs well in fading and multipath scenarios due to its frequency diversity properties.
   - PSK can be affected by fading, especially in frequency-selective fading conditions.
   - ASK may experience significant performance degradation in fading and multipath channels.

5. Applications:

   - ASK is commonly used in simple applications such as remote controls, RFID, and binary communication.
   - FSK is suitable for applications where noise immunity is important, such as wireless communication and telemetry systems.
   - PSK is widely used in digital communication systems, including modems, Wi-Fi, and digital broadcasting.

The choice of modulation technique depends on the specific requirements of the communication system, including the channel characteristics, noise levels, data rate, and complexity constraints. Each modulation technique has its strengths and weaknesses, and the best choice will depend on balancing these factors for the given scenario. 

Graphical or plot representation of ASK, FSK, and PSK










The above figures show that the carrier frequency for ASK is 10 Hz. For PSK, that is 5 Hz. But for FSK, carrier frequencies are 10 Hz and 2 Hz


Summary

  • ASK is simple to generate, and it has a less complex circuitry in comparison to FSK and PSK
  • As noise is very sensitive to amplitude so it has poor noise immunity.  
  • FSK is less susceptible to errors than ASK
  • FSK is suitable for high-frequency communication as modulation deals with two different high carrier frequencies here. 
  • FSK circuitry is moderately complex
  • The bit rate in FSK is higher than in ASK 
  • In FSK, noise immunity is high
  • PSK circuitry is very complex 
  • PSK has a higher bit rate as compared to FSK
  • PSK has better noise immunity than FSK

Why are ASK, FSK, and PSK used? 


Electronic devices are sensitive to amplitude, frequency, and phase, so these three digital modulation techniques are used during wireless data transfer.

 

Comparison of BER vs SNR among ASK, FSK, and PSK in MATLAB







(Get MATLAB Code)

Fig 2: Comparison of BER vs SNR among ASK, FSK, and PSK



 Simulator for ASK, FSK, and PSK Generation







Some Questions and Answers (Q&As)

  1. In a coherent Frequency Shift Keying (FSK) system, what is the primary challenge in achieving coherent detection?
    Answer: Maintaining phase synchronization between transmitter and receiver.
    Explanation: Coherent detection requires maintaining phase synchronization to correctly demodulate the signal. 
  2. Which of the following is a major disadvantage of Amplitude Shift Keying (ASK)?
    Answer: Susceptibility to noise and interference.
    Explanation: ASK is highly susceptible to noise because it relies on amplitude changes.
  3. Which modulation scheme is typically more bandwidth-efficient?
    Answer: Phase Shift Keying (PSK).
    Explanation: PSK is more bandwidth-efficient because it encodes information in phase shifts.
  4. In Phase Shift Keying (PSK), what is the impact of increasing the number of phase states?
    Answer: Higher data rates.
    Explanation: More phase states allow higher data rates as more bits can be encoded per symbol.
  5. Which of the following is a key advantage of using Non-Coherent FSK over Coherent FSK?
    Answer: Simpler receiver design.
    Explanation: Non-Coherent FSK has a simpler receiver design because it does not require phase synchronization.
  6. Why is Phase Shift Keying (PSK) considered more power efficient than Frequency Shift Keying (FSK)?
    Answer: PSK can maintain performance at lower signal-to-noise ratios.
    Explanation: PSK is more power efficient because it can achieve good performance at lower signal-to-noise ratios.
  7. Which characteristic of FSK modulation makes it advantageous for certain applications?
    Answer: Its robustness in high-noise environments.
    Explanation: FSK is robust in noisy environments because the frequency changes are distinct.
  8. What is the primary disadvantage of using higher-order PSK modulation schemes?
    Answer: Increased sensitivity to noise.
    Explanation: Increased sensitivity to noise due to smaller phase differences between symbols.
  9. Which modulation scheme is typically used in radio broadcasting?
    Answer: Frequency Modulation (FM).
    Explanation: FM is commonly used in radio broadcasting due to its robustness to noise.
  10. In a PSK system, what can be used to improve error performance?
    Answer: Using error correction coding.
    Explanation: Error correction coding helps to detect and correct errors, improving performance.

Read Also

  2.  Modulation Indices for Amplitude Modulation, Frequency Modulation, and Phase Modulation
  3. Constellation Diagrams of ASK, FSK, and PSK 
  4.  MATLAB Code for ASK, FSK, and PSK 
  5.  Simulation of ASK, FSK, and PSK using MATLAB Simulink
  6.  Theoretical BER vs SNR for BPSK 
  7. Understanding the Q-function in BASK, BFSK, and BPSK
  8.  Comparisons among Amplitude, Frequency and Phase Modulation

 
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