Constellation Diagrams: ASK, FSK, and PSK
Comprehensive guide to signal space representation, including interactive simulators and MATLAB implementations.
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: +√Eb or -√Eb (they differ by 180 degree phase shift), where Eb is the energy per bit. These signals represent binary 0 and 1.
Signal Space Simulator
Visualize BASK, BPSK, and BFSK Constellation Diagrams with Noise Control.
Theory & Key Points
- ✔ BASK: Bit '0' is low voltage/no signal; bit '1' is high level voltage.
- ✔ BFSK: Maps bit '0' to 'j' and bit '1' to '1'. Signals are orthogonal.
- ✔ BPSK: 0° shift for binary '1' (+1) and 180° shift for binary '0' (-1). Read more [↗]
Figure 1: Constellation diagrams of ASK, PSK, and FSK. The x-axis shows the real part, y-axis shows the imaginary part.
The spacing between signaling points determines the Probability of Error (Pe). ASK is prone to bit errors due to shorter distances ($\sqrt{E_b}$). PSK performs better in noisy channels with a distance of $2\sqrt{E_b}$.
