Illustrate differential phase-shift keying, Electrical Engineering

Assignment Help:

Q. Illustrate Differential phase-shift keying?

In order to eliminate the need of a local carrier, DPSK has been developed in which the receiver uses the received signal to act as its own carrier. Figure shows the functions of a DPSK system in which the leftmost product operation along with 1-bit delay is the differential encoder. The digital signal d(t) is a polar waveform of levels ±1, corresponding to binary digits 1 and 0, respectively. The output signal a(t) from the differential encoder PSK-modulates a carrier to produce the DPSK signal sDPSK(t). The product device followed by the wide-band low-pass filter acts as the coherent detector. The two inputs to the product device are obtained from the output of a filter matched to the input pulse in a single bit interval. Note that the 1-bit delayed input to the product device serves the purpose of the local oscillator for the coherent detector; that is to say, the DPSK waveform in a given bit interval serves as its own local-oscillator signal in the following bit interval.

870_Differential phase-shift keying.png

In Figure, si(t) is the signal component of the matched filter output, and sd(t)isthe signal component of the detector output. If the phases of both si(t) and si(t - Tb) are the same, sd(t) is then a positive voltage; if their phases differ by π radians, sd(t) will then be a  negative voltage. These voltages will have maximum amplitudes at the sample time at the end of the bit interval. Because the sign of the voltage at the sampler depends upon the phase relationship between si(t) and its delayed replica, and the sign of sd(t) is of the same form as d(t), the original digital bit sequence can be determined by sampling to decide the sign of the detector output. Figure illustrates an example sequence of message binary digits, modulator wave- forms in DPSK, and phase and polarity relationships as applied to DPSK message recovery.


Related Discussions:- Illustrate differential phase-shift keying

Components of plc - stepper motor , Components of PLC There are follow...

Components of PLC There are followings  three main  components of PLC : a.The power supply and rack. b.The central  processing  unit ( CPU) c.The input / output  (I/O

Eeprom, advantages and disadvantages

advantages and disadvantages

What do you mean by insurance, Q. What do you mean by Insurance? This i...

Q. What do you mean by Insurance? This is done by creating a common fund out of the contribution (known as premium) from several persons who are equally exposed to the same los

Stator current control methods - motor control , Stator  Current Control ...

Stator  Current Control Methods The torque  and speed  of an induction motor  can be  controlled  by the  stator  current  the motor  behaviour  is different from that with VS

Advanced mobile phone system, Q. Advanced Mobile Phone System? Cellular...

Q. Advanced Mobile Phone System? Cellular systems employed cells with a radius in the range of 5-18 km. The base station usually transmitted at a power level of 35 W or less, a

Modern AC Generators, What are the advantages of modern ac generators and I...

What are the advantages of modern ac generators and Integrated Drive Generators? There are two questions here. I''d really like it if somebody could help me. I''m an AE student.

Increase in ht and lt ratio, Increase in HT and LT Ratio It is well kn...

Increase in HT and LT Ratio It is well known that for high HT/LT ratio, the losses will be low. The losses for a given quantum of power supplied through a line are inversely p

Mention the desirable properties of fuse materials, Mention the desirable p...

Mention the desirable properties of fuse materials. A fuse material must possess the properties as follows: Low resistivity - It means, thin wires can be used that will of

Explain cwd instructions in 8086 family, Explain CWD instructions in 8086...

Explain CWD instructions in 8086 family with example and their effect on flag. Convert signed word to signed double word: CWD instruction enlarges the sign bit of a word int

Explain a miller sweep generator, Q. With the help of circuit diagram expla...

Q. With the help of circuit diagram explain a Miller Sweep generator Figure given below shows the circuit of a Miller integrator or a sweep circuit. Transistor Q1 acts as a swi

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd