Phase Shift Keying (PSK) : Types and Its Applications

The term PSK or Phase shift keying is broadly used in a radio communication system. This kind of technique is mostly compatible with data communications. It allows information in a more efficient way to be carried over a radio communications signal compare with other modulation forms. Data communication is rising with different forms of communication formats like analog to digital to carry data along with different modulation forms. There are different types of PSK where each one has its own benefits and drawbacks. An option of the optimum format has to be prepared for every radio communication system. To make the correct option, it is essential to have knowledge of how PSK works.

What is Phase Shift Keying (PSK)?

The Phase Shift Keying is one kind of digital modulation method. This kind of method is used to transmit data by modulating otherwise changing the phase of the carrier signal which is known as a reference signal. The digital data can be represented with any kind of digital modulation method by using a limited number of separate signals. This kind of modulation method uses a limited number of phases where each phase can be assigned with binary digits. Generally, every phase encodes an equivalent number of bits. Every bits pattern forms the symbol that is denoted by the exact phase.

The PSK method can be represented by a convenient method namely constellations diagram. In this kind of communication, the points of the constellation can be selected are generally placed by uniform angular spacing in the region of circle. So that utmost phase separation can be offered among nearby points & therefore the best protection to corruption. These are arranged in a circle so that they can all be transmitted by similar energy. Please refer to this link to know more about FSK Modulation and Demodulation With Circuit Diagram

Digital Modulation

The digital modulation or DM is one kind of modulation, which utilizes discrete signals to change a carrier wave. This kind of modulation eliminates the noise of communication and provides superior power for the signal interruption.  This modulation provides additional data capacity and security for high & easy system accessibility by huge communication quality. So, this kind of modulation has a vast demand than analog modulation.

Types of PSK

The PSK can be classified into two types which include the following.

• BPSK – Binary Phase-Shift Keying
• QPSK – Quadrature Phase-Shift Keying

1). BPSK – Binary Phase-Shift Keying

The term BPSK stands for Binary Phase-Shift Keying. Sometimes, it is also called as PRK (phase reversal keying) or 2PSK. This kind of phase-shift keying utilizes 2-phases which are separated with 180 degrees. So this is the reason to call as 2-PSK.

In this method, the arrangement of constellation points is not a matter where exactly they are placed. This type of modulation is strong to all the PSKs as it takes the maximum level of noise otherwise to distortion to make the demodulator attain an incorrect decision. However, it is only able to modulate at 1 bit per symbol and is not suitable for applications like high data rate.

2). QPSK – Quadrature Phase-Shift Keying

The bit rate can be enhanced by adding more bits on one single segment. In this kind of PSK, the bitstream can be parallelized so that every two incoming bits can be split up & phase shift keying a carrier frequency. One carrier frequency can be phase-shifted with 90 degrees from the other within quadrature. Then the 2 phase-shift keying signals are added to generate one of four signal elements.

Some Other Forms of PSK

Some of the more frequently used forms of PSK mainly include the following.

• Phase-Shift-Keying (PSK)
• Binary-Phase-Shift-Keying (BPSK)
• Quadrature-Phase-Shift-Keying (QPSK)
• Offset-Quadrature-Phase-Shift-Keying (O-QPSK)
• 8 Point-Phase-Shift-Keying (8 PSK)
• 16 Point-Phase-Shift-Keying (16 PSK)

The above-listed forms are the main PSK forms which are frequently used in the applications of radio communication. Each form of PSK includes advantages as well as disadvantages. Generally, the high order modulation forms will allow high data rates to transmit in a given bandwidth. But the problem is high data rate which needs a superior S/N ratio previous to the error rates begin to increase & this counter works to improve the performance of data rate. The form of modulation can be selected by the radio communications systems can depend on the existing conditions and requirements.

Advantages and Disadvantages of Phase Shift Keying

The advantages of phase-shift keying include the following.

• This type of PSK allows information to be carried with a radio communications signal more efficiently compare with FSK.
• QPSK is another kind of data transmits wherever 4 phase states are utilized, all in 90 degrees of one another.
• It is less vulnerable to faults when we evaluate with ASK modulation & occupies similar bandwidth like ASK.
• By using this, the high transmission data rate can be attained with the help of high-level PSK modulations like QPSK, 16-QAM. Here QPSK signifies 2-bits for each constellation and 16-QAM signifies 2-bits for each constellation.

The disadvantages of phase-shift keying include the following.

• The bandwidth efficiency of this PSK is less compared with ASK type of modulation
• It is a non-coherent reference signal
• By estimating the phase states of the signal, the binary information can be decoded. Algorithms like recovery and detection are extremely difficult.
• High-level PSK modulations like QPSK, 16-QAM is more sensitive to phase differences.
• It generates wrong demodulations as the fault can combine with time because the reference signal for demodulation is not fixed.

Applications of Phase Shift Keying

The applications of PSK include the following.

• This method is broadly used for bio-metric, wireless LAN along with wireless communications like Bluetooth and RFID.
• Local Oscillator
• Optical Communications
• Multi-channel WDM
• Delay & add demodulator
• Nonlinear effects for WDM transmission

This is all about Phase Shift Keying. From the above information finally, we can conclude that this PSK is a digital modulation technique which transmits information by altering the phase of a stable frequency carrier signal. Generally, these modulation methods are superior to modulation techniques like FSK in terms of bandwidth. These modulation schemes provide better efficiency. But FSK modulation methods are power-efficient at a given signal-to-noise ratio (S/N). This method is broadly used for bio-metric, wireless LAN along with wireless communications like Bluetooth and RFID. Here is a question for you, What is “shift keying” technique?