siap_analysis and result _lab5

7/27/2019 Siap_analysis and Result _lab5

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ANALYSIS AND RESULT

1. Design a digital modulation signal for any 9-bit stream of data using

a) ASK Modulation

Coding for ASK Modulation

clc;clear all;close all;%GENERATE CARRIER SIGNALTb=1; fc=10;t=0:Tb/100:1;c=sqrt(2/Tb)*sin(2*pi*fc*t);

%generate message signalN=8;m=rand(1,N);t1=0;t2=Tbfor i=1:Nt=[t1:.01:t2]if m(i)>0.5m(i)=1;m_s=ones(1,length(t));else m(i)=0;m_s=zeros(1,length(t));end message(i,:)=m_s;%product of carrier and messageask_sig(i,:)=c.*m_s;t1=t1+(Tb+.01);t2=t2+(Tb+.01);%plot the message and ASK signalsubplot(5,1,2);axis([0 N -2 2]);plot(t,message(i,:),'r');title('message signal');xlabel('t--->');ylabel('m(t)');grid on hold on subplot(5,1,4);plot(t,ask_sig(i,:));title('ASK signal');xlabel('t--->');ylabel('s(t)');grid on hold on end hold off

%Plot the carrier signal and input binary datasubplot(5,1,3);plot(t,c);title('carrier signal');xlabel('t--->');ylabel('c(t)');grid on subplot(5,1,1);stem(m);title('binary data bits');xlabel('n--->');ylabel('b(n)');grid on



Output for ASK Modulation

Figure 1: ASK Modulation Output

Discussion

ASK (Amplitude shift keying) refers to a type of amplitude modulation that

assigns bit values to discrete amplitude levels. The carrier signal is then

modulated among the members of a set of discrete values to transmit information.

From figure, ASK is a modulation process, which imparts to a sinusoid two or

more discrete amplitude levels. These are related to the number of levels adopted

by the digital message. For a binary message sequence there are two levels, one of

which is typically zero. The data rate is a sub-multiple of the carrier frequency.

Thus the modulated waveform consists of bursts of a sinusoid. When the bit 0, the

ASK signal is none but when bit 1, the signal will produced.



b) BPSK Modulation

Coding for BPSK Modulation

clc; clear all; close all; %GENERATE CARRIER SIGNAL Tb=1; t=0:Tb/100:Tb; fc=2; c=sqrt(2/Tb)*sin(2*pi*fc*t); %generate message signal N=9; m=rand(1,N); t1=0;t2=Tb for i=1:N t=[t1:.01:t2]

if m(i)>0.5 m(i)=1; m_s=ones(1,length(t)); else m(i)=0; m_s=-1*ones(1,length(t)); end message(i,:)=m_s; %product of carrier and message signal bpsk_sig(i,:)=c.*m_s; %Plot the message and BPSK modulated signal subplot(5,1,2);axis([0 N -2 2]);plot(t,message(i,:),'r'); title('message signal(POLAR form)');xlabel('t---

>');ylabel('m(t)'); grid on; hold on; subplot(5,1,4);plot(t,bpsk_sig(i,:)); title('BPSK signal');xlabel('t--->');ylabel('s(t)'); grid on; hold on; t1=t1+1.01; t2=t2+1.01; end hold off %plot the input binary data and carrier signal subplot(5,1,1);stem(m); title('binary data bits');xlabel('n--->');ylabel('b(n)'); grid on; subplot(5,1,3);plot(t,c); title('carrier signal');xlabel('t--->');ylabel('c(t)'); grid on;



Output for BPSK Modulation

Figure 2: BPSK Modulation Output

Discussion

Binary phase shift keying (BPSK) shifts the carrier sine wave 180° for each

change in binary state. BPSK is coherent as the phase transitions occur at the zero

crossing points. It uses two opposite signal phases (0 and 180 degrees). The

digital signal is broken up time wise into individual bits (binary digits). The state

of each bit is determined according to the state of the preceding bit. If the phase of

the wave does not change, then the signal state stays the same (0 or 1) if the phase

of the wave changes by 180 degrees. If the phase reverses, then the signal state

changes (from 0 to 1 or from 1 to 0). Because there are two possible wave phases,BPSK is sometimes called bi-phase modulation.



c) QPSK Modulation

Coding for QPSK Modulation

lear; clc; b = input('Enter the bit stream = '); n = length(b); t = 0:0.01:n; x = 1:1:(n+2)*100; for i = 1:n if (b(i) == 0) u(i) = -1; else u(i) = 1; end for j = i:0.1:i+1 bw(x(i*100:(i+1)*100)) = u(i); if (mod(i,2) == 0) bw_e(x(i*100:(i+1)*100)) = u(i); bw_e(x((i+1)*100:(i+2)*100)) = u(i); else bw_o(x(i*100:(i+1)*100)) = u(i); bw_o(x((i+1)*100:(i+2)*100)) = u(i); end if (mod(n,2)~= 0) bw_e(x(n*100:(n+1)*100)) = -1; bw_e(x((n+1)*100:(n+2)*100)) = -1; end

end end bw = bw(100:end); bw_o = bw_o(100:(n+1)*100); bw_e = bw_e(200:(n+2)*100); cost = cos(2*pi*t); sint = sin(2*pi*t); x = bw_o.*cost; y = bw_e.*sint; z = x+y; subplot(3,2,1); plot(t,bw); xlabel('n ---->'); ylabel('Amplitude ---->'); title('Input Bit Stream'); grid on ; axis([0 n -2 +2]); subplot(3,2,5); plot(t,bw_o); xlabel('n ---->'); ylabel('Amplitude ---->'); title('Odd Sequence'); grid on ;



axis([0 n -2 +2]); subplot(3,2,3); plot(t,bw_e); xlabel('n ---->'); ylabel('Amplitude ---->'); title('Even Sequence'); grid on ;

axis([0 n -2 +2]); subplot(3,2,4); plot(t,x); xlabel('Time ---->'); ylabel('Amplitude ---->'); title('Odd Sequence BPSK Modulated Wave'); grid on ; axis([0 n -2 +2]); subplot(3,2,2); plot(t,y); xlabel('Time ---->'); ylabel('Amplitude ---->'); title('Even Sequence BPSK Modulated Wave'); grid on ; axis([0 n -2 +2]); subplot(3,2,6); plot(t,z); xlabel('Time ---->'); ylabel('Amplitude ---->'); title('QPSK Modulated Wave'); grid on ; axis([0 n -2 +2]);



Output for QPSK Modulation

Figure 3: QPSK Modulation Output

Discussion

QPSK is also known as quaternary PSK, quadriphase PSK, 4-PSK, or 4-QAM. It

is a phase modulation technique that transmits two bits in four modulation states.

Phase of the carrier takes on one of four equally spaced values such as π/4, 3π/4,

5π/4 and7π/4. In QPSK, four phases with each finite phase change representing

unique digital data are possible, so two binary digits, or “bits," of information can

be transmitted within each time period. In other words, the rate of change of the

signal in QPSK allows the carrier wave to transmit two bits of information rather

than one and effectively doubles the bandwidth, or transmission capacity, of the

carrier wave. QPSK transmits twice the data rate in a given bandwidth compared

to BPSK at the same BER.



2. Analyze the system in Figure

Figure

Figure 4: Block Diagram for System Communication Link for M-PSK

Modulator Baseband using Matlab



Output from figure 1

Figure 5: Eye Diagram Output



Figure 6: Signal Trajectory Output

Figure 7: Time Scatter Plot Output

Discussion

From the output, we can see the performance characteristic of M-PSK Modulator

Baseband with M=2. The eye diagram is obtained from the discrete-time eye

diagram scope that displays the trace of a modulated signal that is used to analyze

the modulation characteristics. There is no pulse shaping at the eye diagram

because it is a balance characteristic with no interference or noise. If no

interference happens and balance eye diagram, so there is no signal at the signal

trajectory scope. The signal constellation of a signal being modulated in its signal

space is display by plotting the graph between its in-phase component and

quadrature component. There is two points which is at -1(bit 0) and 1(bit 1). It

uses two opposite signal phases (0 and 180 degrees).



3. Investigate the input and output of the system in figure

Figure

Figure 8: Block Diagram for System Communication Link for M-PSK

Modulator Baseband using Matlab



Output from figure 2

Figure 9:Outputof Eye Diagram Scope

Figure 10: Output of Signal Trajectory Scope



Figure 11: Output of Scatter Plot Scope

Discussion

From the output, we can see the performance characteristic of M-PSK Modulator

Baseband with M=2 and added with AWGN channel. The function of this block

is to add White Gaussian noise to the modulated data. Noise is an unwanted

signal which is always present in the transmitted signal. It cannot be removed but

by using various techniques it can be minimized. Additive in AWGN means that

the noise is superimposed onto the signal which will mask the signal and it limits

the ability of the receiver to make its decision. The eye diagram is obtained from

the discrete-time eye diagram scope that displays the multiple traces of a

modulated signal that are used to analyze the modulation characteristics. Theseare pulse shaping or the characteristics as channel distortion of the various

signals. The scatter diagram show there is different after added with channel. The

variations experienced in the channel mean that occasionally the noise will be far

more significant. At these times the system will experience a large number of

errors.



4. Analyze the digital communication system in figure

Figure

Figure 12: Block Diagram for System Communication Link with Error

RateCalculation using Matlab



Table for Bit Error Rtae Versus Channel SNR

Channel SNR Bit Error Rate (BER)

1000 0

100 0

10 0.001998

1 0.2498

-1 0.3447

-10 0.6084

-100 0.7552

-1000 0.7552

Output from figure

a) SNR 1000 dB



Figure 13: Output of SNR 1000 dB

b) SNR 100 dB



Figure14 : Output of SNR 100 dB

c) SNR 10 dB



Figure 15: Output of SNR 10 dB

d) SNR 1dB



Figure 16: Output of SNR 1dB

e) SNR -1 dB



Figure 17: Output of SNR -1 dB

f) SNR -10 dB



Figure 18: Output of SNR -10dB

g) SNR -100 dB



Figure 19: Output of SNR -100dB

h) SNR -1000dB



Figure 20: Output of SNR -1000 dB

Discussion

From the table and output graph, the results are analyzed when the value of SNR

is higher, their bit error rate value is become smaller for the bit error rate versus

SNR that. The value of bit error rate is 0 is when the value of SNR is above then

10. The bit error rate is increasing when the value of SNR is below then 10. In

addition, SNR is still remains the same value which is zero for the SNR of

1000db. However, when the value of SNR is -1000db, their bit error rate is

0.7742. So, the higher the value of SNR is better because the error that produces

is 0.



CONCLUSION

As a conclusion of this experiment, we have learned to manipulate and solve practical

problem using MATLAB on communication link analysis. Next, we have learned the

application of communication link analysis using MATLAB simulink. Then, amplitude-shift

keying (ASK) is a form of amplitude modulation that represents digital data as variations in

the amplitude of a carrier wave. 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. In QPSK, the data bits to be modulated are grouped

into symbols, each containing two bits, and each symbol can take on one of four possible

values: 00, 01, 10, or 11. White Gaussian noise (AWGN) is a channel model in which the only

impairment to communication is a linear addition of wideband or white noise with a constant

spectral. Finally, we have successfully done our experiment and achieved the objectives.

http://en.wikipedia.org/wiki/Amplitude_modulation

http://en.wikipedia.org/wiki/Digital_data

http://en.wikipedia.org/wiki/Data

http://en.wikipedia.org/wiki/Amplitude

http://en.wikipedia.org/wiki/Carrier_wave

http://en.wikipedia.org/wiki/Channel_(communications)

http://en.wikipedia.org/wiki/Wideband

http://en.wikipedia.org/wiki/White_noise

http://en.wikipedia.org/wiki/White_noise

http://en.wikipedia.org/wiki/Wideband

http://en.wikipedia.org/wiki/Channel_(communications)

http://en.wikipedia.org/wiki/Carrier_wave

http://en.wikipedia.org/wiki/Amplitude

http://en.wikipedia.org/wiki/Data

http://en.wikipedia.org/wiki/Digital_data

http://en.wikipedia.org/wiki/Amplitude_modulation

siap_analysis and result _lab5

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