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

Electricity policies, Electricity Policies: The National Electricity P...

Electricity Policies: The National Electricity Policy is a main policy instrument having the force of law under the Electricity Act, 2003. The Central and State Electricity Re

Introduction to electronics, Explain the difference between a microprocesso...

Explain the difference between a microprocessor and an embedded microcontroller

What is a differentiator circuit, Q. What is a differentiator circuit? ...

Q. What is a differentiator circuit? By introducing electrical reactance into the feedback loops of op-amp amplifier circuits, we can cause the output to respond to changes in

Determine the bandwidth required for transmission, 1. A PCM system uses 8 b...

1. A PCM system uses 8 bits per sample and the analog signal is limited to 4.3 kHz. The PCM data is transmitted using (a) BFSK and (b) ASK. Determine the bandwidth required for tra

Describe the two core-excited states, Using the optimized 6-311G(d,p) geome...

Using the optimized 6-311G(d,p) geometry determined in question 1, perform the following equivalent core calculations for any two inequivalent carbons of butadiene: (a) Equivale

Explain the working of electronic multimeter, Q.  Give suitable block diag...

Q.  Give suitable block diagram to explain the working of electronic multimeter. Sol. An electronic multimeter is a laboratory instrument which is capable of measurement of

Explain the tap changing transformers, Explain the Tap Changing Transformer...

Explain the Tap Changing Transformers? This is the most popular form of voltage control at all voltage levels. It is based on changing the turns ratio of the transformer, hence

Find largest of n numbers stored in t memory, To determine the largest of n...

To determine the largest of n numbers stored into t memory, write a program in assembly language. A program of the largest of n numbers stored into t memory in assembly languag

Design a pulse generator, To design a VI that can also be used as a Sub VI ...

To design a VI that can also be used as a Sub VI in another VI. The title of the VI will be Pulse Generator. The output from the VI will be of the type Analogue Waveform and

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