GENERATION AND DETECTION OF FSK AND PSK

PRENSENTED BYK.DEEPAK REDDY

OUTLINE

• Introduction• • Coherent Digital modulation Techniques• • PSK• • FSK• • Non-Coherent Digital modulation Techniques• • FSK• • Applications of ASK,FSK and PSK

INTRODUCTION• •

In digital communication, the modulation process involves switching or keying the amplitude, frequency or phase of the carrier in accordance with the input data.

• • There are three basic modulation techniques for the transmission of digital data. i.e.

• • Amplitude Shift Keying• • Frequency Shift Keying• • Phase Shift Keying

BINARY PHASE SHIFT KEYING(BPSK)

• The most basic (binary) form of PSK involves the process of switching the carrier either in phase or out of phase, correspondence to a sequence of digital pulses that constitute the information signal.

• • One binary digit is represented by the carrier wave and the other binary digit is represented by the 1800 out of phase of the original carrier whereas the Frequency remains fixed

BINARY PHASE SHIFT KEYING(BPSK)

Product Modulator

DETECTION OF PSK SIGNAL

DISADVANTAGES OF PSK SIGNAL

• • To regenerate the carrier in the receiver we perform the squaring of the received signal.

• • The recovered carrier is unchanged whether the input signal is (+ve) or (-ve)(even if the input signal has changed its sign.)

• • It is not possible to find that whether the transmitted bit was +b(t) or –b(t) hence Phase ambiguity is a problem in the demodulation of a BPSK signal.

• • This problem can be removed with the use differential phase shift keying.

BINARY FREQUENCY SHIFT KEYING(BFSK)

• The most basic (binary) form of FSK involves the process of varying the frequency of a carrier wave by choosing one of the two frequencies (binary FSK) in correspondence to a sequence of digital pulses that constitute the information signal.

• • Two binary digits are represented by two frequencies around the carrier frequency whereas the Amplitude remains fixed.

BINARY FREQUENCY SHIFT KEYING(BFSK)

DETECTION OF FSK SIGNAL

DISADVANTAGES OF BFSK SIGNALS

• The generation of BFSK is easier but it has many disadvantages compared to BPSK signal.

• • Bandwidth is greater in comparison to BPSK and is almost double the bandwidth of BPSK.

• • The error rate of BFSK is higher

NON-COHERENT FSK DETECTION

APPLICATIONS OF FSK AND PSK

• FSK signal can be transmitted via telephone lines, fiber• optics or wireless media. FSK is commonly used for• caller ID and remote metering applications.• • PSK is typically applied in wireless local area networks• (WLAN), Bluetooth technology and radio frequency• identification (RFID) standards used in biometric,• passport and contactless payment systems.

REFERENCES

• • Lathi B.P. “Modern Digital and Analog Communication Systems” Oxford Publications, Fourth Edition

• • J.S. Chitode “ Digital Communication ” Technical • Publications, First Edition. • • Taub H.,Schilling D.L.,Saha G. “Taub’s Principle of Communication Systems”,

McGraw-Hill, Third edition • • Forouzan B. A, “Data Communications and Networking”, McGraw-Hill, 2nd

Ed., 2000 • • https://www.techopedia.com/definition/3004/frequency -shift-keying-fsk