QPSK (Quadrature Phase-Shift Keying) is a kind of Phase Shift Keying. Here quadrature is added to the standard PSK where 2 bits are modulated at one time by choosing one among the four probable carrier phase shifts (0, 90, 180, or 270 degrees).

2016年12月27日 · There are different types of QPSK: Offset (staggerd) QPSK, $\pi/4$-QPSK, etc. In its most known form, QPSK is identical to $4$-QAM or $4$-PSK. That is, the same constellation can be referred to by different names.

QPSK (Quadrature Phase Shift Keying) and 4-PSK (4-Phase Shift Keying) are related but not exactly the same. QPSK (Quadrature Phase Shift Keying): In QPSK, each symbol represents 2 bits of data. It modulates the carrier signal by changing its phase with four possible values (0°, 90°, 180°, 270°) corresponding to four different states.

2021年6月9日 · Yes, QPSK and 4-QAM are effectively the same. Higher order PSK and QAM would be different, but they reduce to the same thing if you only have 4 constellation points. For more information about digital modulation, see Digital Modulation.

2013年1月8日 · Both 4QAM and QPSK apparently produce the same waveform, but are they the same mathematically? In a QPSK constellation, are the mapping points at 45, 135, 225 and 315 degrees while the 4QAM is at 0, 90, 180 and 270? I also struggle to understand the I/Q components of such a constellation diagram.

ACHIEVEMENTS: review of the quadrature amplitude modulator (QAM) in digital communications; as a generator of a quadrature phase shift keyed (QPSK, or 4-PSK) signal. Demodulation of QPSK.

2024年1月15日 · QAM is a modulation scheme using amplitude and phase variations, whereas QPSK is a phase modulation technique using four distinct phase angles.

qpsk是通过改变相位来传递信息，信号的幅度相同。 QAM是正交幅度相位调制，幅度、相位可能不同。 在M=4的情况下，QPSK和4QAM的信号星座图可以相同。

Quadrature Phase Shift Keying (QPSK) and 4-QAM (Quadrature Amplitude Modulation) are both digital modulation techniques used in communication systems, but they differ in their modulation schemes and the way they represent information.

QPSK, or Quadrature Phase Shift Keying, is a modulation method that can encode two bits per symbol. Each of the four resultant phase shifts previously mentioned—45°, 135°, 225°, and 315°—is mapped to a 2-bit value.