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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.

Signal Space Simulator (Constellation)

Real-time Constellation Visualization with Noise Control

Theory & Key Points

  • ✔BASK: Bit '0' is low voltage; bit '1' is high. Distance between points is $\sqrt{E_b}$.
  • ✔BFSK: Bit '0' and '1' are orthogonal. Distance between points is $\sqrt{2E_b}$.
  • ✔BPSK: Antipodal signaling. Distance between points is $2\sqrt{E_b}$. Detailed Theory [↗]
Constellation

Figure 1: Typical Constellation diagrams (Real vs Imaginary).

Comparison Table (Distance Between Constellation Points)

Scheme Distance Immunity
BPSK $2\sqrt{E_b}$ Highest
BFSK $\sqrt{2E_b}$ Medium
BASK $\sqrt{E_b}$ Low

Comparison Table (Q-funtion)

ParameterBASKBFSKBPSK
Noise ImmunityVery LowMediumHighest
BER Formula$Q(\sqrt{E_b/2N_0})$$Q(\sqrt{E_b/N_0})$$Q(\sqrt{2E_b/N_0})$

Read More: about Q-function How to calculate BER vs SNR from Constellation

📖 Detailed Theory

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