Skip to main content

Menu

Home 📘 Wireless Communication (Main Page) Constellation Diagrams BER vs SNR GMSK MSK Channel Impulse Response Modulation Schemes MIMO Technology OFDM MATLAB Machine Learning Contact
Login Try App

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



 

Baseband modulation techniques are methods used to encode information signals onto a baseband signal (a signal with frequencies close to zero), allowing for efficient transmission over a communication channel. These techniques are fundamental in various communication systems, including wired and wireless communication. Here are some common baseband modulation techniques:

Amplitude Shift Keying (ASK) [↗] :

In ASK, the amplitude of the baseband 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







ASK Passband 

 
 
 
Fig 1:  Amplitude Modulation and Demodulation (Get MATLAB Code)

In Figure 1 above, you can see binary information bits are simply represented by carrier signals in the case of binary information '1'. That's why it is called baseband signal.


Frequency Shift Keying (FSK) [↗] :

FSK modulates the frequency of the baseband signal to represent digital data.
In binary FSK (BFSK), two different frequencies represent binary values.
FSK is less susceptible to noise compared to ASK but requires more bandwidth.


FSK Baseband







FSK Passband

 
 

For baseband FSK modulation, we can map the binary bit '0' to 'j' and bit '1' to '1'. When transmitting the signals through a wireless medium, we can modulate bit '0' with a lower frequency carrier signal and bit '1' with a higher frequency carrier signal

 

 
Fig 2: Frequency Modulation and Demodulation (Get MATLAB Code from here)

In Figure 2 above, you can see binary information bits '1's and '0's are represented by higher frequency carrier signal and lower frequency carrier signal, respectively. So this is also an example of the baseband signal.

Phase Shift Keying (PSK) [↗] :

PSK varies the phase of the baseband signal to represent symbols. For example, we can map binary bit '0' to '-1' and bit '1' to '+1'.
Binary PSK (BPSK) uses two different phase shifts to represent binary values.
Quadrature PSK (QPSK) uses four phase shifts for higher data rates.
PSK is robust against noise and more bandwidth-efficient than ASK and FSK.

PSK Baseband







PSK Passband 






Baseband vs. Passband QAM

Quadrature Amplitude Modulation (QAM) [↗] :

QAM combines ASK and PSK by varying both amplitude and phase of the baseband signal.
In QAM, each symbol represents a combination of amplitude and phase, allowing for higher data rates.
Higher-order QAM (e.g., 16-QAM, 64-QAM) increases the number of symbols and data rates but requires more complex receiver designs.

Pulse Amplitude Modulation (PAM) [↗] :

PAM encodes information in the amplitude of pulses in the baseband signal.
PAM is often used in digital communication systems where digital data is encoded into pulse amplitudes.

Orthogonal Frequency Division Multiplexing (OFDM) [↗] :

OFDM divides the baseband signal into multiple narrowband subcarriers, each modulated using PSK or QAM.


OFDM is widely used in modern communication systems such as Wi-Fi, LTE, and digital television (DVB, ATSC) due to its robustness against frequency-selective fading and ability to mitigate intersymbol interference.

These modulation techniques play crucial roles in various communication systems, each with its advantages and limitations depending on the specific application requirements such as bandwidth efficiency, spectral efficiency, robustness against noise, and complexity of implementation. 

 

Further Reading

  1.  Comparing Baseband and Passband Implementations of m-ary QAM

People are good at skipping over material they already know!

View Related Topics to







Contact Us

Name

Email *

Message *

Popular Posts

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

Constellation Diagrams of ASK, PSK, and FSK

📘 Overview of Energy per Bit (Eb / N0) 🧮 Online Simulator for constellation diagrams of ASK, FSK, and PSK 🧮 Theory behind Constellation Diagrams of ASK, FSK, and PSK 🧮 MATLAB Codes for Constellation Diagrams of ASK, FSK, and PSK 📚 Further Reading 📂 Other Topics on Constellation Diagrams of ASK, PSK, and FSK ... 🧮 Simulator for constellation diagrams of m-ary PSK 🧮 Simulator for constellation diagrams of m-ary QAM BASK (Binary ASK) Modulation: Transmits one of two signals: 0 or -√Eb, where Eb​ is the energy per bit. These signals represent binary 0 and 1.    BFSK (Binary FSK) Modulation: Transmits one of two signals: +√Eb​ ( On the y-axis, the phase shift of 90 degrees with respect to the x-axis, which is also termed phase offset ) or √Eb (on x-axis), where Eb​ is the energy per bit. These signals represent binary 0 and 1.  BPSK (Binary PSK) Modulation: Transmits one of two signals...
Read more

BER vs SNR for M-ary QAM, M-ary PSK, QPSK, BPSK, ...

📘 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

Power Spectral Density Calculation Using FFT in MATLAB

📘 Overview 🧮 Steps to calculate the PSD of a signal 🧮 MATLAB Codes 📚 Further Reading Power spectral density (PSD) tells us how the power of a signal is distributed across different frequency components, whereas Fourier Magnitude gives you the amplitude (or strength) of each frequency component in the signal. Steps to calculate the PSD of a signal Firstly, calculate the first Fourier transform (FFT) of a signal Then, calculate the Fourier magnitude of the signal The power spectrum is the square of the Fourier magnitude To calculate power spectrum density (PSD), divide the power spectrum by the total number of samples and the frequency resolution. {Frequency resolution = (sampling frequency / total number of samples)} Sampling frequency (fs): The rate at which the continuous-time signal is sampled (in Hz). ...
Read more

Comparisons among ASK, PSK, and FSK | And the definitions of each

📘 Comparisons among ASK, FSK, and PSK 🧮 Online Simulator for calculating Bandwidth of ASK, FSK, and PSK 🧮 MATLAB Code for BER vs. SNR Analysis of ASK, FSK, and PSK 📚 Further Reading 📂 View Other Topics on Comparisons among ASK, PSK, and FSK ... 🧮 Comparisons of Noise Sensitivity, Bandwidth, Complexity, etc. 🧮 MATLAB Code for Constellation Diagrams of ASK, FSK, and PSK 🧮 Online Simulator for ASK, FSK, and PSK Generation 🧮 Online Simulator for ASK, FSK, and PSK Constellation 🧮 Some Questions and Answers Modulation ASK, FSK & PSK Constellation MATLAB Simulink MATLAB Code Comparisons among ASK, PSK, and FSK    Comparisons among ASK, PSK, and FSK Comparison among ASK, FSK, and PSK Parameters ASK FSK PSK Variable Characteristics Amplitude Frequency ...
Read more

What are the main lobe and side lobes in Beamforming

    What are the main lobe and side lobes in Beamforming? You've probably noticed that in the diagram of  beamforming , there are two types of lobes in beamforming patterns. One is the main lobe, while the others are side lobes. We intend to communicate with receivers with a stronger directional path from the transmitter when we produce beams for wireless communication. We can also see side lobes in this scenario. These side lobes, on the other hand, are not necessary for effective communication. As a result, we take various procedures to remove those side lobes or to reduce the number of side lobes as much as feasible; otherwise, inter-symbol interference  occurs, and signal quality suffers. Figure: Illustration of Main Lobe and Side lobes, where the x-axis denotes the angle of arrival (AOA) and angle of departure (AOD), respectively, while, the y-axis denotes the gain/power in dB (decibel).     In the case of MIMO antennas, our major goal is to reduce int...
Read more

Coherence Bandwidth and Coherence Time

🧮 Coherence Bandwidth 🧮 Coherence Time 🧮 MATLAB Code s 📚 Further Reading For Doppler Delay or Multi-path Delay Coherence time T coh ∝ 1 / v max (For slow fading, coherence time T coh is greater than the signaling interval.) Coherence bandwidth W coh ∝ 1 / Ï„ max (For frequency-flat fading, coherence bandwidth W coh is greater than the signaling bandwidth.) Where: T coh = coherence time W coh = coherence bandwidth v max = maximum Doppler frequency (or maximum Doppler shift) Ï„ max = maximum excess delay (maximum time delay spread) Notes: The notation v max −1 and Ï„ max −1 indicate inverse proportionality. Doppler spread refers to the range of frequency shifts caused by relative motion, determining T coh . Delay spread (or multipath delay spread) determines W coh . Frequency-flat fading occurs when W coh is greater than the signaling bandwidth. Coherence Bandwidth Coherence bandwidth is...
Read more

MATLAB Code for Pulse Amplitude Modulation (PAM) and Demodulation

Pulse Amplitude Modulation (PAM) & Demodulation 📘 Overview & Theory of Pulse Amplitude Modulation (PAM) 🧮 MATLAB Code for Pulse Amplitude Modulation and Demodulation of Analog Signal and Digital Signal 🧮 Simulation Results for Comparison of PAM, PWM, PPM, DM, and PCM 📚 Further Reading 📂 Other Topics on Pulse Amplitude Modulation ... 🧮 MATLAB Code for Pulse Amplitude Modulation and Demodulation of an Analog Signal (2) 🧮 MATLAB Code for Pulse Amplitude Modulation and Demodulation of Digital Data 🧮 Other Pulse Modulation Techniques (PWM, PPM, DM, PCM) Pulse Amplitude Modulation (PAM) & Demodulation of an Analog Message Signal MATLAB Script clc; clear all; close all; fm = 10; % frequency of the message signal fc = 100; % frequency of the carrier signal fs = 100...
Read more