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This lab report was submitted to Sir Bhanuprasad Venkatesan at Shree Ram Swarup College of Engineering and Management for Analog Communication course. It includes: Abstract, Theory, Angle, Modulation, Phase, Frequency, Code, Description, Message, Signal, Graph, Figure
Typology: Exercises
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1. Abstract 2. Objective of the report 3. Steps to follow 4. Theory a. Angle Modulation i. Phase Modulation ii. Frequency Modulation 5. Code Description a. Message Signal b. Frequency Modulation c. Phase Modulation 6. MATLAB Code 7. Generated Graphs (Results) a. Figure 1 b. Figure 2 c. Figure 3 d. Figure 4 e. Figure 5
Angle modulation is a class of analog modulation. These techniques are based on altering the angle (or phase ) of a sinusoidal carrier wave to transmit data, as opposed to varying the amplitude, such as in AM transmission.
Frequency modulation ( FM ) conveys information over a carrier wave by varying its frequency.
Phase modulation (PM) is a form of modulation that represents information as variations in the instantaneous phase of a carrier wave.
Here we have learned to implement these techniques on MATLAB using a modulating signal.
Message Signal: To generate the message signal, the values of amplitude A, frequency w (^) m, and time axis have been defined arbitrarily. t is chosen such that sampling frequency is 500 samples/sec.
eq (5) : m(t) = A cos (w (^) mt )
Frequency Modulation: Generates the corresponding frequency modulated signal for the input m(t) by using the relation mentioned in eq (4).
Phase Modulation: Generates the corresponding frequency modulated signal for the input m(t) by using the relation mentioned in eq (3).
% Frequency Modulation:
syms A t wm fs kf kp wc A1 % Constucted variables to integrate the message signal for FM
m = A1cos(wmt) % Message Signal
i = int(m,t) % Integrated Signal
% Arguments:
t = 0:0.002:2; % Time vector with values 0 to 2, taking 1000 samples
A = 1; % Amplitude of both message signal and of the expression of FM and PM
wm = 2pi0.5; % Frequency of message signal
fs = 500; % Sampling rate
kf = pi/4; % Constant
kp = pi/3; % Constant
wc = 2pi10; % Frequency of carrier signal
A1 = 10; % Amplitude of message signal
% After giving values:
m = A1cos(wmt);
i = A1/wmsin(wmt);
% Time Domain:
phiFM = Acos((wct)+(kf*i));
phiPM = Acos((wct)+(kp*m));
figure, plot(t,m), title('Original Signal'),xlabel('time'),ylabel('Amplitude')
figure, plot(t,phiFM), title('Frequency Modulated Signal'),xlabel('time'),ylabel('Amplitude')
figure, plot(t,phiPM), title('Phase Modulated Signal'),xlabel('time'),ylabel('Amplitude')
% Frequency Domain:
w=-250:(2*250)/1000:250;
PHIFM = fftshift(abs(fft(phiFM)));
PHIPM = fftshift(abs(fft(phiPM)));
% To show the frequencies produced:
figure, stem(w,PHIFM), title('Fourier Transform of FM signal that shows the frequencies produced'), xlabel('linear frequency'),ylabel('Amplitude')
figure, stem(w,PHIPM), title('Fourier Transform of PM signal that shows the frequencies produced'), xlabel('linear frequency'),ylabel('Amplitude')
Figure 3
Figure 4
Figure 5:
