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Man comm MCQ
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International Business Communication
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Mine Hauling System Tools
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ophthalmology
Experiment No. 1 Aim: To simulate AM Modulation. Software Used: VisSim Comm 6.0 Theory:Amplitude modulation is a process in which the amplitude of a carrier signal is varied in accordance with modulating signal. Amplitude modulation (AM) is a method of impressing data onto an alternating-current carrier waveform. The highest frequency of the modulating data is normally less than 10 percent of the carrier frequency. The instantaneous amplitude(overall signal power) varies depending on the instantaneous amplitude of the modulating data.
= initial phase of Carrier , A= Amplitude of Wave
Block Diagram:
Fig:- 1 Amplitude Modulation
Waveform:-
Result:- The Amplitude Modulation has been studied & Designed.
Experiment no. 2 Aim: To simulate FM Modulation . Software Used: VisSim. Comm 6.0 Modulation is type of continuous wave modulation. FM may be defined Theory: Frequency Modulation as the the proce process ss in which which a freq frequen uency cy of a sign signal al call called ed carr carrie ierr is varie varied d in acco accord rdan ance ce to instantaneous value of another signal called modulating signal. The signal resulting from the process of frequency modulation is called frequency modulated signal. Modulation index: As with other modulation indices,this quantity indicates by how much the modulated variable varies varies around its unmodulat unmodulated ed level. It relate to the variations variations in the frequency frequency of the carrier signal. Frequency modulation is a technique of modulating the frequency of the carrier signal in accordance accordance with the frequency of the modulating modulating or the informatio information n signal. signal. As the informati information on signal has a very low frequency, therefore it cannot be transmitted over long distances. To increase the efficiency of the modulating signal it is fed upon a carrier signal which has a very high high frequen frequency. cy. Now, Now, this this freque frequency ncy of carri carrier er signal signal is changed changed in accord accordance ance with with the information signal.
ω = instantaneous frequency ω = carrier frequency Δω = carrier deviation ω = modulation frequency i
c
m
Block Diagram:
Plot 1 -1 1 FM Mod s ig Fc= 2 Hzph
-1 0
2. 5
5
Fig :- 2(a) FM Modulation
Waveforms:
Result : The Frequency Modulation has been simulated and verified .
Experiment No. 3 Aim: To study and simulate the Amplitude shift keying(ASK) modulation and demodulation. Software Used: VisSim. Comm 6. Theory: Basica Basically lly digit digital al modula modulati tion on techni techniques ques may be classi classifie fied d into into coheren coherentt and non -coher -coherent ent techniques ,depending upon whether the receiver is equipped with phase recovery circuit or not. They are:
1. Coheren Coherentt digital digital modul modulati ation on techni technique ques. s. 2. non- coher coherent ent digit digital al modulat modulation ion techni technique ques. s.
Coherent Digital Modulation Techniques :
These are those techniques which employ coherent detection .In coherent detection ,the local carrier generated at receiver is phase locked with carrier at transmitter.
Non – Coherent Digital Modulation Techniques :
These are those techniques in which the detection process does not need the receiver carrier to be phase locked with transmitter.
Amplitude Shift Keying :
It is a coherent digital modulation technique. In this method there is only one energy carrier and it is switched on or off depending upon the input binary sequence. It is also known as on –off keying.
Block diagram
ASK MODULATION
ASK DEMODULATION
Waveforms:
Result: The Amplitude shift keying (ASK) has been simulated and studied.
Experiment No. 4
Frequency shift keying (FSK) Modulation and and AIM : To study and stimulate the Frequency demodulation Software Used: VisSim Comm. 6.0. Theory: Frequency – Shift Keying (FSK) is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier wave. The simplest FSK is binary FSK (BFSK). BFSK literally implies using a pair of discrete frequencies to transmit binary (0s and 1s) informati information on . With this this scheme , the “1” is called the mark frequency frequency and the “0” is called the space frequency.
BlockDiagram:
Fig:- 5 (Frequency Shift Keying modulation and Demodulation)
Waveform:
Result: The Frequency Shift Keying (FSK) Modulation and Demodulation has been studied & Simulated.
Experiment No. 5
Aim:- To study and simulate Phase Shift Keying(PSK). Simulator Used:- Vis Sim Version 6.0 modulation technique, technique, the modulated modulated output switches switches Theory:- In Phase Shift Keying (PSK) modulation between in-phase and out-of phase component of the carrier for every “one” to “zero” transitions of modulating signal. The carrier frequency chosen for PSK modulation are 1MHZ (0 Degree) and 1 MHZ (180 Degree).The phase detector works ion the principle of squaring loops. First step in PSK detection is the square wave conversion using a Schmitt trigger. This enables the PSK detector to be built around digital IC’s. BPSK (also sometimes called PRK, Phase Reversal Keying, or 2PSK) is the simplest form of phase shift keying (PSK). It uses two phases which are separated by 180° and so can also be termed 2-PSK. A binary phse shift keying signal can be given as:
s(t) = A m(t) cos 2πfct Block Diagram:
Fig. 5(a) Phase Shift Keying Modulation and Demodulation
Waveforms:-
Fig. 5(b) Carrier Signal
Fig. 5(c) Modulating Signal
Fig. 5(d) Modulated Signal
Fig. 5(e) Demodulated Signal
Keying(PSK) modulation and demodulation has has been Result:- The Phase Shift Keying(PSK) studied and simulated .
Experiment-6 Aim: To study and simulate Pulse Amplitude Modulation. Software used: VisSim Comm. Version 6.0 Theory:Pulse-amplitude modulation , acronym PAM, is a form of signal modulation where the message
information is encoded in the amplitude of a series of signal pulses.. In this the signal is sampled at regular intervals and each sample is made proportional to the magnitude of the signal at the instant of sampling.These sampled pulses may then be sent either directly by a channel to the receiving end or may be made to modulated using a carrier wave before transmission.
Block Diagram:-
Fig:- 8 (Pulse Amplitude Modulation )
Waveforms:-
Result: The Pulse amplitude Modulation has been studied and simulated.
Experiment-7
Aim: To study and simulate Pulse Position Modulation. Software used: VisSim Comm. Version 6.0 Theory:Pulse-position modulation (PPM) is a form of signal modulation in which M message bits are
encoded by transmitting a single pulse in one of 2M possible time-shifts. This is repeated every T seconds, such that the transmitted bit rate is M/T bits per second. It is primarily useful for optical for optical communications systems.
Block Diagram:-
Fig:- 8 Pulse Position Position Modulation
Waveforms:-
Result : The Pulse Position Modulation has been studied and and simulated.
Experiment No. 8
Aim: To simulate DPSK Modulation. Software Used: VisSim. Comm 6.0 Theory: Differential phase shift keying (DPSK), a common form of phase modulation conveys data by changing the phase of carrier wave. In Phase shift keying, High state contains only one cycle but DPSK contains one and half cycle. High state is represented by a M in modulated signal and low state is represented by a wave which appears like W in modulated signal DPSK encodes two distinct signals of same frequency with 180 degree phase difference between the two. This experiment requires two 180 degree out of phase carrier and modulating signals. Sine wave from oscillator is selected as carrier signal. DSG converts DC input voltage into pulse trains. These pulse trains are taken as modulating signals. In actual practice modulating signal is digital form of voice or data. Sine wave is selected as carrier and 180 degree phase shift is obtained using Opamp as shown in figure below.
Block Diagram:
Fig 9-1 DPSK modulation
Waveforms:
Result :- The DPSK modulation has been studied studied and stimulated. stimulated.
Experiment No. 9
Aim: To simulate DPSK Demodulation. Software Used: VisSim. Comm 6.0 Theory: Differential phase shift keying (DPSK), a common form of phase modulation conveys data by changing the phase of carrier wave. In Phase shift keying, High state contains only one cycle but DPSK contains one and half cycle. High state is represented by a M in modulated signal and low state is represented by a wave which appears like W in modulated signal DPSK encodes two distinct signals of same frequency with 180 degree phase difference between the two. This experiment requires two 180 degree out of phase carrier and modulating signals. Sine wave from oscillator is selected as carrier signal. DSG converts DC input voltage into pulse trains. These pulse trains are taken as modulating signals. In actual practice modulating signal is digital form of voice or data. Sine wave is selected as carrier and 180 degree phase shift is obtained using Opamp as shown in figure below.
Block Diagram:
Fig 9-1 DPSK Demodulation
Waveforms:
Result: - The DPSK Demodulation has been studied and stimulated.
