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

MATLAB Code for Rms Delay Spread

RMS delay spread is crucial when you need to know how much the signal is dispersed in time due to multipath propagation, the spread (variance) around the average. In high-data-rate systems like LTE, 5G, or Wi-Fi, even small time dispersions can cause ISI. RMS delay spread is directly related to the amount of ISI in such systems. RMS Delay Spread [↗] Delay Spread Calculator Enter delays (ns) separated by commas: Enter powers (dB) separated by commas: Calculate   The above calculator Converts Power to Linear Scale: It correctly converts the power values from decibels (dB) to a linear scale. Calculates Mean Delay: It accurately computes the mean excess delay, which is the first moment of the power delay profile. Calculates RMS Delay Spread: It correctly calculates the RMS delay spread, defined as the square root of the second central moment of the power delay profile.   MATLAB Code  clc...
Read more

LDPC Encoding and Decoding Techniques

📘 Overview & Theory 🧮 LDPC Encoding Techniques 🧮 LDPC Decoding Techniques 📚 Further Reading 'LDPC' is the abbreviation for 'low density parity check'. LDPC code H matrix contains very few amount of 1's and mostly zeroes. LDPC codes are error correcting code. Using LDPC codes, channel capacities that are close to the theoretical Shannon limit can be achieved.  Low density parity check (LDPC) codes are linear error-correcting block code suitable for error correction in a large block sizes transmitted via very noisy channel. Applications requiring highly reliable information transport over bandwidth restrictions in the presence of noise are increasingly using LDPC codes. 1. LDPC Encoding Technique The proper form of H matrix is derived from the given matrix by doing multiple row operations as shown above. In the above, H is parity check matrix and G is generator matrix. If you consider matrix H as [-P' | I] then matrix G will be...
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 is a Chirp Signal?

📘 Overview & Theory 🧮 MATLAB Code 🧮 Chirp Signal Simuator 📚 Further Reading   Chirp signals are often used to find target objects. In a chirp signal, the frequency varies with time. For up-chirp signals, frequency increases with time. Oppositely, for down-chirp signals, the frequency decreases with time. Advantages of a chirp signal over a single-toned signal Better resolution Better Security The wide bandwidth of a chirp signal allows for capturing more detailed info about the target or object In a chirp signal, pulse compression enhances resolution by concentrating the signal energy into a shorter duration of time It is less susceptible to noise  It improves signal to noise ratio Up-Chirp Signal A sinusoidal up-chirp signal is denoted as Where A is the amplitude of this signal             f0 is the starting frequency of the chirp at t=0             Î± is the chirp rate or the...
Read more

Alamouti Scheme for 2x2 MIMO in MATLAB

📘 Overview & Theory 🧮 MATLAB Code for Alamouti Scheme 🧮 MATLAB Code for BER vs. SNR for Alamouti Scheme 🧮 Alamouti Scheme Transmission Table 📚 Further Reading    Read about the Alamouti Scheme first MATLAB Code for Alamouti's Precoding Matrix for 2 X 2 MIMO % Clear any existing data and figures clc; clear; close all; % Define system parameters transmitAntennas = 2; % Number of antennas at the transmitter receiveAntennas = 2; % Number of antennas at the receiver symbolCount = 1000000; % Number of symbols to transmit SNR_dB = 15; % Signal-to-Noise Ratio in decibels % Generate random binary data for transmission rng(10); % Set seed for reproducibility transmitData = randi([0, 1], transmitAntennas, symbolCount); % Perform Binary Phase Shift Keying (BPSK) modulation modulatedSymbols = 1 - 2 * transmitData; % Define Alamouti's Precoding Matrix precodingMatrix = [1 1; -1i 1i]; % Encode and transmit data using Alamouti scheme transmittedSym...
Read more