Skip to main content

ASK, FSK, and PSK (with MATLAB + Online Simulator)



ASK or OFF ON Keying

ASK is a simple (less complex) Digital Modulation Scheme where we vary the modulation signal's amplitude or voltage by the message signal's amplitude or voltage. We select two levels (two different voltage levels) for transmitting modulated message signals. For example, "+5 Volt" (upper level) and "0 Volt" (lower level). To transmit binary bit "1", the transmitter sends "+5 Volts", and for bit "0", it sends no power. The receiver uses filters to detect whether a binary "1" or "0" was transmitted.

Output of ASK, FSK, and PSK modulation using MATLAB
Fig 1: Output of ASK, FSK, and PSK modulation using MATLAB for a data stream "1 1 0 0 1 0 1 0" (Get MATLAB Code)

FSK

In Frequency Shift Keying (FSK), the message signal is modulated using a high-frequency carrier. Binary "1" and "0" are represented by two different frequencies close to the carrier frequency.

For example, using two frequencies f1 and f2 (where f1 > f2), binary "1" is modulated with f1 and binary "0" with f2. 

S₁(t) = A cos(2Ï€fc1t)      for binary 1
S₂(t) = A cos(2Ï€fc2t)      for binary 0

Here, fc1 is different from fc2.


PSK

In Phase Shift Keying (PSK), the phase of the carrier signal is changed to represent data bits. Binary "1" is transmitted by shifting the signal’s phase by 180°, while binary "0" keeps the same phase. 

s(t) = A cos(2πfct + π)        for binary 1
s(t) = A cos(2Ï€fct)            for binary 0

Which Modulation Technique Achieves Higher Bit Rates?

PSK (Phase Shift Keying)

PSK can use various phase shifts to encode more bits per symbol. For example, QPSK doubles the data rate of BPSK. Higher-order PSK (like 8-PSK, 16-PSK) further increases bit rate.

FSK (Frequency Shift Keying)

FSK generally requires more bandwidth, and symbol separation makes it less bit-efficient than PSK.

ASK (Amplitude Shift Keying)

ASK is more susceptible to noise and less bit-efficient. While higher-order schemes (like QAM) can help, pure ASK is typically less effective than PSK.

Conclusion: PSK can achieve the highest bit rates, especially using higher-order modulation techniques.


Simulator for Binary ASK, FSK, and PSK Modulation

Further Reading

  1. Amplitude, Frequency, and Phase Modulation
  2. Online Simulator for AM
  3. Digital Communication System Simulator
  4. Comparison of ASK, PSK, and FSK
  5. Simulation of ASK, FSK, and PSK
  6. MATLAB Code for ASK, FSK, and PSK
  7. Constellation Diagrams of ASK, PSK, and FSK
  8. BER vs. SNR for ASK, FSK, and PSK
  9. MATLAB Code for Constellation Diagrams

People are good at skipping over material they already know!

View Related Topics to







Contact Us

Name

Email *

Message *

Popular Posts

BER vs SNR for M-ary QAM, M-ary PSK, QPSK, BPSK, ...(MATLAB Code + Simulator)

📘 Overview of BER and SNR 🧮 Online Simulator for BER calculation of m-ary QAM and m-ary PSK 🧮 MATLAB Code for BER calculation of M-ary QAM, M-ary PSK, QPSK, BPSK, ... 📚 Further Reading 📂 View Other Topics on M-ary QAM, M-ary PSK, QPSK ... 🧮 Online Simulator for Constellation Diagram of m-ary QAM 🧮 Online Simulator for Constellation Diagram of m-ary PSK 🧮 MATLAB Code for BER calculation of ASK, FSK, and PSK 🧮 MATLAB Code for BER calculation of Alamouti Scheme 🧮 Different approaches to calculate BER vs SNR What is Bit Error Rate (BER)? The abbreviation BER stands for Bit Error Rate, which indicates how many corrupted bits are received (after the demodulation process) compared to the total number of bits sent in a communication process. BER = (number of bits received in error) / (total number of tran...
Read more

Shannon Limit Explained: Negative SNR, Eb/No and Channel Capacity

Understanding Negative SNR and the Shannon Limit Understanding Negative SNR and the Shannon Limit An explanation of Signal-to-Noise Ratio (SNR), its behavior in decibels, and how Shannon's theorem defines the ultimate communication limit. Signal-to-Noise Ratio in Shannon’s Equation In Shannon's equation, the Signal-to-Noise Ratio (SNR) is defined as the signal power divided by the noise power: SNR = S / N Since both signal power and noise power are physical quantities, neither can be negative. Therefore, the SNR itself is always a positive number. However, engineers often express SNR in decibels: SNR(dB) When SNR = 1, the logarithmic value becomes: SNR(dB) = 0 When the noise power exceeds the signal power (SNR < 1), the decibel representation becomes negative. Behavior of Shannon's Capacity Equation Shannon’s channel capacity formula is: C = B log₂(1 + SNR) For SNR = 0: log₂(1 + SNR) = 0 When SNR becomes smaller (in...
Read more

Amplitude, Frequency, and Phase Modulation Techniques (AM, FM, and PM)

📘 Overview 🧮 Amplitude Modulation (AM) 🧮 Online Amplitude Modulation Simulator 🧮 MATLAB Code for AM 🧮 Q & A and Summary 📚 Further Reading Amplitude Modulation (AM): The carrier signal's amplitude varies linearly with the amplitude of the message signal. An AM wave may thus be described, in the most general form, as a function of time as follows: When performing amplitude modulation (AM) with a carrier frequency of 100 Hz and a message frequency of 10 Hz, the resulting peak frequencies are as follows: 90 Hz (100 - 10 Hz), 100 Hz, and 110 Hz (100 + 10 Hz). Figure: Frequency Spectrums of AM Signal (Lower Sideband, Carrier, and Upper Sideband) A low-frequency message signal is modulated with a high-frequency carrier wave using a local oscillator to make communication possible. DSB, SSB, and VSB are common amplitude modulation techniques. We find a lot of bandwidth loss in DSB. The bandwidth of S...
Read more

Analog vs Digital Modulation Techniques | Advantages of Digital ...

Modulation Techniques Analog vs Digital Modulation In our previous discussion, we explored the necessity of modulation. In this article, we focus on the fundamental differences between analog and digital modulation. The primary distinction is that digital modulation uses a discrete digital signal to modify the carrier, whereas analog modulation uses a continuous analog signal. Advantages of Digital Modulation over Analog Modulation Bandwidth Efficiency: Digital techniques (like QAM) can transmit more data within a limited frequency range. Noise Resistance: Digital signals have superior resistance to noise because they can be perfectly regenerated. Multiplexing: It is much easier to multiplex various data types (audio, video, text) into a single digital stream. Higher SNR: Better noise immunity leads to a higher Signal-to-Noise Ratio (SNR). Increased Throughput: Modern digital techniques provide significantly higher data ...
Read more

Comparing Baseband and Passband Implementations of m-ary QAM

  Let's assume your original digital message bitstream is: 0, 0, 1, 0, 0, 0, 1, 0, 1, 1 In 4-QAM, we group them into pairs: (00), (10), (00), (10), (11). Your baseband symbols are: Symbol 1 (Bits 00): -1.00 - j1.00 Symbol 2 (Bits 10): 1.00 - j1.00 Symbol 3 (Bits 00): -1.00 - j1.00 Symbol 4 (Bits 10): 1.00 - j1.00 Symbol 5 (Bits 11): 1.00 + j1.00   To transmit these symbols over a wireless medium, we modulate this baseband signal onto a high-frequency carrier (e.g., 50 Hz). This process creates the passband signal , where the information is stored in the phase and amplitude of the sine wave. Fig 1: 4-QAM Baseband I and Q Components Fig 2: 4-QAM Passband Modulated Signal   In this example, the symbol rate is 5 symbols per second. Detailed Explanation 4-QAM Constellation Mapping In standard 4-QAM mapping, bits are converted to complex points on a grid: Bits...
Read more

Comparing Baseband and Passband Implementations of ASK, FSK, and PSK

📘 Overview 🧮 Baseband and Passband Implementations of ASK, FSK, and PSK 🧮 Difference betwen baseband and passband 📚 Further Reading 📂 Other Topics on Baseband and Passband ... 🧮 Baseband modulation techniques 🧮 Passband modulation techniques   Baseband modulation techniques are methods used to encode information signals onto a baseband signal (a signal with frequencies close to zero). Passband techniques shift these signals to higher carrier frequencies for transmission. Here are the common implementations: Amplitude Shift Keying (ASK) [↗] : In ASK, the amplitude of the signal is varied to represent different symbols. Binary ASK (BASK) is a common implementation where two different amplitudes represent binary values (0 and 1). ASK is simple but susceptible to noise. ASK Baseband (Digital Bits) ASK Passband (Modulated Carrier)     Fig 1:  ASK Passband Modulation (...
Read more

Online Simulator for ASK, FSK, and PSK

Try our new Digital Signal Processing Simulator!   Start Simulator for binary ASK Modulation Message Bits (e.g. 1,0,1,0) Carrier Frequency (Hz) Sampling Frequency (Hz) Run Simulation Simulator for binary FSK Modulation Input Bits (e.g. 1,0,1,0) Freq for '1' (Hz) Freq for '0' (Hz) Sampling Rate (Hz) Visualize FSK Signal Simulator for BPSK Modulation ...
Read more

Theoretical vs. simulated BER vs. SNR for ASK, FSK, and PSK (MATLAB Code + Simulator)

📘 Overview 🧮 Simulator for calculating BER 🧮 MATLAB Codes for calculating theoretical BER 🧮 MATLAB Codes for calculating simulated BER 📚 Further Reading BER vs. SNR denotes how many bits in error are received for a given signal-to-noise ratio, typically measured in dB. Common noise types in wireless systems: 1. Additive White Gaussian Noise (AWGN) 2. Rayleigh Fading AWGN adds random noise; Rayleigh fading attenuates the signal variably. A good SNR helps reduce these effects. Simulator for calculating BER vs SNR for binary ASK, FSK, and PSK Calculate BER for Binary ASK Modulation Enter SNR (dB): Calculate BER Calculate BER for Binary FSK Modulation Enter SNR (dB): Calculate BER Calculate BER for Binary PSK Modulation Enter SNR (dB): Calculate BER BER vs. SNR Curves MATLAB Code for Theoretical BER % The code is written by SalimWireless.Com clc; clear; close all; % SNR va...
Read more