Skip to main content

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


📘 ASK Theory 📘 FSK Theory 📘 PSK Theory 📊 Comparison 🧮 MATLAB Codes 🎮 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.

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 (Frequency Shift Keying)

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 frequencies f1 and f2 (where f1 > 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 (Phase Shift Keying)

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

Bit Rate Comparison

PSK (Phase Shift Keying)

PSK can use various phase shifts to encode more bits per symbol (e.g., QPSK, 16-PSK). It is the most efficient for high bit rates.

FSK (Frequency Shift Keying)

FSK requires more bandwidth, making it less bit-efficient than PSK for high-speed applications.

ASK (Amplitude Shift Keying)

ASK is highly susceptible to noise and is typically less effective than PSK for high-speed transmission.

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

MATLAB Code: ASK, FSK, and PSK

This single script generates a random binary sequence and applies all three digital modulation techniques (Amplitude, Frequency, and Phase Shift Keying) for side-by-side comparison.

% DIGITAL MODULATION (ASK, FSK, PSK) 
% Source: SalimWireless.Com 

clc; clear all; close all;

% --- 1. Parameters Configuration ---
Fs = 1000;              % Sampling Frequency
Tb = 1;                 % Bit Duration (seconds)
N_bits = 8;             % Number of bits to transmit
fc = 10;                % Base Carrier Frequency (Hz)
fc2 = 30;               % Secondary Frequency for FSK (Hz)
Ts = 1/Fs;              % Sampling Period
t_bit = 0:Ts:Tb-Ts;     % Time vector for one bit
rng(42);                % For reproducible results

% Generate Random Binary Data
binary_data = randi([0, 1], 1, N_bits);

% --- 2. Signal Generation ---
message_sig = [];
ask_sig = [];
fsk_sig = [];
psk_sig = [];

for bit = binary_data
    % Message Signal (Square wave)
    m_segment = bit * ones(1, length(t_bit));
    message_sig = [message_sig m_segment];
    
    % ASK Logic: Bit 1 = Carrier ON, Bit 0 = Carrier OFF
    ask_seg = bit * sin(2*pi*fc*t_bit);
    ask_sig = [ask_sig ask_seg];
    
    % FSK Logic: Bit 1 = fc2 (High), Bit 0 = fc (Low)
    if bit == 1
        fsk_seg = sin(2*pi*fc2*t_bit);
    else
        fsk_seg = sin(2*pi*fc*t_bit);
    end
    fsk_sig = [fsk_sig fsk_seg];
    
    % PSK Logic: Bit 1 = 180 deg phase, Bit 0 = 0 deg phase
    if bit == 1
        psk_seg = sin(2*pi*fc*t_bit + pi);
    else
        psk_seg = sin(2*pi*fc*t_bit + 0);
    end
    psk_sig = [psk_sig psk_seg];
end

% Total Time Vector for Plotting
t_total = 0:Ts:(N_bits*Tb)-Ts;

% --- 3. Visualization ---
figure('Name', 'Digital Modulation Comparison', 'Color', 'w');

subplot(4,1,1);
plot(t_total, message_sig, 'LineWidth', 2, 'Color', 'k');
title(['Binary Message: ', num2str(binary_data)]); grid on; axis([0 N_bits*Tb -0.5 1.5]);

subplot(4,1,2);
plot(t_total, ask_sig, 'LineWidth', 1, 'Color', 'b');
title('ASK (Amplitude Shift Keying)'); grid on;

subplot(4,1,3);
plot(t_total, fsk_sig, 'LineWidth', 1, 'Color', 'r');
title('FSK (Frequency Shift Keying)'); grid on;

subplot(4,1,4);
plot(t_total, psk_sig, 'LineWidth', 1, 'Color', [0 0.5 0]);
title('PSK (Phase Shift Keying)'); grid on;
xlabel('Time (seconds)');

Interactive Modulation Simulator

Test your binary data (1,0,1,0) and adjust carrier frequencies in our web-based simulator tool.

Launch Full Simulator →

📚 Try Online Interactive Simulators

📚 Further Reading

📊 MATLAB & ONLINE SIMULATIONS (Web-Based)
🎓 GATE & UGC - NET SOLUTIONS
📡 WIRELESS & SIGNAL PROCESSING


Contact Us

Name

Email *

Message *

Popular Posts

RMS Delay Spread, Excess Delay Spread and Multi-path ...(with MATLAB + Simulator)

📘 Overview of Delay Spread and Multi-path 🧮 Excess Delay spread 🧮 Power delay Profile 🧮 RMS Delay Spread 📚 Further Reading 📂 Other Topics on RMS Delay Spread, Excess Delay ... 🧮 Multipath Components or MPCs 🧮 Online Simulator for Calculating RMS Delay Spread 🧮 Why is there significant multipath in the case of very high frequencies? 🧮 Why RMS Delay Spread is essential for wireless communication? 🧮 Why the Power Delay Profile is essential? 🧮 MATLAB Codes for Calculating Different Types of delay Spreads Delay Spread, Excess Delay Spread, and Multipath (MPCs) The fundamental distinction between wireless and wired connections is that in wireless connections signal reaches at receiver thru multipath signal propagation rather than directed transmission like co-axial cable. Wireless Communication has no set communication path between the transmitter and the receiver. The line...
Read more

Online Simulator for ASK, FSK, and PSK Signal Generation

Interactive Digital Signal Processing (DSP) Tutorial and Simulator for ASK, FSK, and BPSK modulation techniques. Try our new Digital Signal Processing Simulator!   •   Interactive ASK, FSK, and BPSK tools updated for 2025. Start Now Digital Modulation Visualizer: ASK, FSK, & BPSK Simulator Learn and visualize binary modulation techniques (ASK, FSK, BPSK) in real-time with adjustable carrier and sampling parameters. Perfect for DSP students and engineers. 📡 ASK Simulator 📶 FSK Simulator 🎚️ BPSK Simulator 📚 More Topics ASK Modulator FSK Modulator BPSK Modulator More Topics 1. ASK (Amplitude Shift Keying) Simulat...
Read more

Amplitude Shift Keying (ASK) Modulation & Demodulation (with Simulation)

Amplitude Shift Keying (ASK): Signal Analysis and Characterization Theoretical Overview: Amplitude Shift Keying (ASK) represents a primary digital modulation technique wherein information is encoded through discrete variations in the carrier signal's instantaneous amplitude. In a Binary ASK (BASK) framework, the modulation process maps binary data onto two distinct amplitude levels. Specifically, the binary '1' (mark) is conveyed by a sinusoidal carrier with amplitude A c and frequency f c over a bit interval T b , while the binary '0' (space) is represented by a null signal state. This particular signaling method is widely recognized as On-Off Keying (OOK) . It is technically realized by gating a carrier oscillator with a unipolar baseband sequence, effectively performing a product modulation that shifts the baseband spectrum to the carrier frequency. ASK Transmitter Architecture: ...
Read more

Frequency Shift Keying (FSK) Modulation & Demodulation (with Simulation)

Frequency Shift Keying (FSK) Theoretical Foundations: Frequency Shift Keying (FSK) is a discrete frequency modulation scheme wherein the digital information is encoded via instantaneous shifts in the carrier signal's frequency. The fundamental implementation is Binary FSK (BFSK), which maps binary data onto two distinct, discrete spectral states. A binary '1' (the "mark" state) is represented by a carrier frequency \( f_1 \), while a binary '0' (the "space" state) corresponds to frequency \( f_2 \). Each symbol is sustained for a bit interval denoted by \( T_b \). FSK Transmitter Characterization: The mathematical model for the modulated BFSK output \( s(t) \) is defined as: \[ s(t) = \begin{cases} A_c \cos(2\pi f_1 t), & \text{for } m = 1 \\ A_c \cos(2\pi f_2 t), & \text{for } m = 0 \end{cases} \] ...
Read more

Constellation Diagrams of ASK, PSK, and FSK (with MATLAB Code + Simulator)

Constellation Diagrams: ASK, FSK, and PSK Comprehensive guide to signal space representation, including interactive simulators and MATLAB implementations. 📘 Overview 🧮 Simulator ⚖️ Theory 📈 Q-function 📚 Resources BASK Modulation Transmits one of two signals: 0 or $\sqrt{E_b}$, representing binary 0 and 1. Simple but sensitive to noise. BFSK Modulation Transmits one of two signals: $\sqrt{E_b}$ on the Y-axis or $\sqrt{E_b}$ on the X-axis. These are orthogonal signals. BPSK Modulation Transmits $+\sqrt{E_b}$ or $-\sqrt{E_b}$ (antipodal signaling). Most efficient binary scheme. ...
Read more

Design of CMOS XOR/XNOR Gates

Design of CMOS XOR/XNOR Gates The semiconductor industry has experienced rapid integration of multimedia applications into mobile electronics, leading to very high integration density in CMOS VLSI. As operating frequencies increase, power consumption, speed, silicon area, and reliability become critical considerations. The XOR-XNOR circuits are fundamental building blocks in arithmetic circuits (Full Adders, Multipliers), compressors, comparators, parity checkers, code converters, error-detecting/correcting codes, and phase detectors. Their performance directly impacts the complex circuits they are used in. Design goals include full output voltage swing, low power consumption, reduced transistor count, minimal delay, and simultaneous non-skewed outputs. Static Logic (Static CMOS) Stat...
Read more

MATLAB code for BER vs SNR for M-QAM, M-PSK, QPSK, BPSK (with Simulation)

🧮 MATLAB Code for BPSK, M-ary PSK, and M-ary QAM Together 🧮 MATLAB Code for M-ary QAM 🧮 MATLAB Code for M-ary PSK 📚 Further Reading MATLAB Script for BER vs. SNR for M-QAM, M-PSK, QPSK, BPSK % Written by Salim Wireless clc; clear; close all; snr_db = -5:2:25; psk_orders = [2, 4, 8, 16, 32]; qam_orders = [4, 16, 64, 256]; ber_psk_results = zeros(length(psk_orders), length(snr_db)); ber_qam_results = zeros(length(qam_orders), length(snr_db)); for i = 1:length(psk_orders) ber_psk_results(i, :) = berawgn(snr_db, 'psk', psk_orders(i), 'nondiff'); end for i = 1:length(qam_orders) ber_qam_results(i, :) = berawgn(snr_db, 'qam', qam_orders(i)); end figure; semilogy(snr_db, ber_psk_results(1, :), 'o-', 'LineWidth', 1.5, 'DisplayName', 'BPSK'); hold on; for i = 2:length(psk_orders) semilogy(snr_db, ber_psk_results(i, :), 'o-', 'DisplayName', sprintf('%d-PSK', psk_or...
Read more