amplitude modulation circuit-manuals
DESCRIPTION
i have this for my communication system manuals.if any one want them he/she is welcome to get it.it contains Simulink circuit with constant and without constant also it contains a Matlab coding for AM signal output with their resulting wave forms pasted..TRANSCRIPT
![Page 1: Amplitude Modulation Circuit-manuals](https://reader036.vdocument.in/reader036/viewer/2022082804/546b0d97af795985298b49b4/html5/thumbnails/1.jpg)
AMPLITUDE MODULATION CIRCUIT
SOFTWARE: THE MATHWORKS™ SIMULINK®
Circuit Diagram:
A.M. circuit
Components:
Signal Generators, Constant, Adder, Multiplier, Oscilloscopes.
Working:
First of all we take the signal generator and add a constant 2 to its output sinusoidal signal using an ADDER. The constant here acts as a Bias to distinguish between to important types of amplitude modulation called DSB-SC and DSB-with large carrier. Then we will multiply the output of the adder circuit with the carrier. The output of the multiplier will be our final Amplitude Modulated Wave ready to be transmitted. As shown in the figure we have placed 3 Scopes at three different points. There output are shown the following figures using Simulink®.
![Page 2: Amplitude Modulation Circuit-manuals](https://reader036.vdocument.in/reader036/viewer/2022082804/546b0d97af795985298b49b4/html5/thumbnails/2.jpg)
Outputs:
Output of Scope2 i.e. actual Message
Output of Scope1 i.e. Carrier
![Page 3: Amplitude Modulation Circuit-manuals](https://reader036.vdocument.in/reader036/viewer/2022082804/546b0d97af795985298b49b4/html5/thumbnails/3.jpg)
Output of the multiplier Amplitude Modulated Wave
The output we have just seen is the type of A.M. that contains a double side band with Large Carrier because a constant is used here.
Now if we remove the constant then the circuit will become
![Page 4: Amplitude Modulation Circuit-manuals](https://reader036.vdocument.in/reader036/viewer/2022082804/546b0d97af795985298b49b4/html5/thumbnails/4.jpg)
Then the output of the multiplier will be like this:
Amplitude Modulated Wave with Suppressed Carrier (DSB-SC).
![Page 5: Amplitude Modulation Circuit-manuals](https://reader036.vdocument.in/reader036/viewer/2022082804/546b0d97af795985298b49b4/html5/thumbnails/5.jpg)
Simulation in MATLAB™
Source Code:
t=0:0.001:1;
vd=8*cos(2*pi*5*t);
vc=0.1*cos(2*pi*15*t);
ft=vc.*vd;
am=ft+vc;
figure(1)
plot(t,vd);
figure(2)
plot(t,vc);
figure(3)
plot(t,am);
Outputs:
Message Signal.
![Page 6: Amplitude Modulation Circuit-manuals](https://reader036.vdocument.in/reader036/viewer/2022082804/546b0d97af795985298b49b4/html5/thumbnails/6.jpg)
Carrier Signal.
Amplitude Modulated Signal.
![Page 7: Amplitude Modulation Circuit-manuals](https://reader036.vdocument.in/reader036/viewer/2022082804/546b0d97af795985298b49b4/html5/thumbnails/7.jpg)
Notes:
To recover the original message found in DSB-SC AM will require some sophisticated circuitry like phased-locked loops PLL). PLL is used to implement the concept of coherent detection since it requires precise knowledge of how the transmitted carrier behaves.
On the other hand, to recover DSB-LC AM, only a simple envelope detector is needed. Envelope detection requires a simple diode, a resistor and capacitor. It does not require the phase information of the transmitted carrier. Envelope detection is also known as non-coherent detection.