QPSK fundamental

1. What is QPSK technique?
2. Why is QPSK used?
3. How many levels are in QPSK?
4. Is QPSK digital or analog?

What is QPSK technique?

Quadrature Phase Shift Keying (QPSK) is a form of Phase Shift Keying in which two bits are modulated at once, selecting one of four possible carrier phase shifts (0, 90, 180, or 270 degrees).

Why is QPSK used?

Binary Phase-shift keying (BPSK) is a digital modulation scheme that conveys data by changing, or modulating, two different phases of a reference signal (the carrier wave). The constellation points chosen are usually positioned with uniform angular spacing around a circle.

How many levels are in QPSK?

We have 360° of phase to work with and four phase states, and thus the separation should be 360°/4 = 90°. So our four QPSK phase shifts are 45°, 135°, 225°, and 315°.

Is QPSK digital or analog?

Digital Phase Modulation: BPSK, QPSK, DQPSK.