In trying to figure out the difference between QPSK and QAM, we should understand that QPSK is the same as 4-QAM or 4-PSK in its most common version. That is, several names might be given to the same constellation. As a result, there are little or no differences.

QPSK modulators are often developed utilizing the QAM concept; they are not termed QAM since the modulated carrier signal’s amplitude remains constant. For digital telecommunication systems, QAM is widely used as a modulation method. QAM has a strong noise immunity.

Two distinct modulation methods are QPSK and QAM. Since QAM translates two digital bit streams by altering the amplitudes of two carrier waves using the ASK while the carrier waves are 90 degrees out of phase with each other, QAM may be regarded as a mix of amplitude-shift keying and phase-shift keying.

What is the purpose of QPSK? QPSK QPSK enables a signal to convey twice as much data in the same bandwidth as regular PSK. QPSK is a digital communication protocol used for satellite transmission of MPEG2 video, video conferencing, cable modems, cellular phone systems, and other digital communication via an RF carrier.

Please continue reading to find out the difference between QPSK and QAM, but it is vital to know their meanings before we get there.

Read Also:聽ADSL Modem vs Cable Modem [With Comparison Table]

QAM (Quadrature Amplitude Modulation) is a hybrid modulation technology that combines analogue and digital techniques. Quadrature carriers are two sinusoid carrier waves that do not stay in phase with each other and have a 90掳 difference in degree. The modulated waves are combined, resulting in a hybrid waveform of PSK and ASK methods.

A fixed number of minimum two phases and at least two amplitudes are used in digital QAM. Because the modulated carrier’s amplitude is constant, PSK modulators are designed using QAM principles but are not called QAM.

In digital communications networks, the QAM modulation method is widely employed. The appropriate constellation size is determined and limited by the linearity of the communication channels and the degree of noise in QAM to obtain higher spectral efficiency. QAM modulations have a variety of uses, including boosting bit rates in optical fibre systems, and QAM 16 and 64 may be visually stimulated via a 3-path interferometer.

In this case, quadrature is added to the typical PSK, which modulates two bits at once by selecting one of four possible carrier phase shifts (0, 90, 180, or 270 degrees). It can transport double the amount of data as normal PSK while utilizing the same bandwidth.

QPSK is often referred to as quaternary PSK, quadriphase PSK, 4-PSK, or 4QAM. The QPSK diagram is created by placing four points evenly spaced around the circle above the constellation diagram. In QPSK, the encoding is done in four stages, with two bits in each symbol and grey coding to lower the bit error rate (BER).

Furthermore, the primary difference between QPSK and QAM is that the latter has a shorter spectral breadth than QPSK. Also, the QAM has a greater BER (Bit Error Rate) than the QPSK. Suppose you use an analogue transmission medium to transport digital data. In that case, you will need a technique to transform digital data into analogue signals, similar to what is used in telephone networks. A modem (modulator/demodulator) is used, which performs signal demodulation and modulation.

The QPSK is comparable to the PSK in many ways. The sole difference between PSK and QPSK is that in basic PSK, phase shifts happen every 180 degrees, but in QPSK, phase shifts happen every 90 degrees. On the other hand, QAM is a combination of ASK and PSK.

The proportion of erroneous bits concerning the total amount of sent, received and processed bits in a certain period is known as BER, analogous to the signal-to-noise ratio.

The bit error rate, bandwidth efficiency, performance, and other parameters are considered while evaluating the modulation schemes and the difference between QPSK and QAM. QPSK, however, outperforms QAM in several ways in this scenario.