Digitla Communication pulse shaping filterDocument Transcript
Digital Communication Systems Homework # 6 Muhammad Irfan AnjumMatlab code is given in the Appendix.BPSK Modulation ±1Sampling frequency fs= 2000 HzSampling interval T=1/fsSymbol duration Ts=20/fsProblem # 1 Matlab script to design root raised cosine filter p(kTs) with roll-off factor 0.5 and convolution oftwo root raised cosine pulse is shown in fig. 1.The graphs shown in Fig.1 are obtained using oversampling. It is clear from Fig.1 (b) that convolution oftwo root raised cosine pulses is raise cosine pulse.Problem # 2 Fig. 2 shows the time and frequency plots of transmitted BPSK symbols before and after passingthrough pulse shaping filter shown in Fig.1.Problem # 3 Fig. 3 shows the time and frequency plots of transmitted BPSK symbols before and after passingthrough filter h(t), where h(t)=c(t)*p(t).
Fig. 3Problem # 4 Fig. 4 shows the BER graphs of BPSK and 4-QAM modulations schemes in case of MLSD. It isclear from the figure that BPSK performs better than 4-QAM in ISI channel.
Fig. 4Appendix:%% HomeWork#6, Digital Communication Systems...clcclearclose allroll_off_factor=0.5; % Rolloff factor.fs=2000; % Sampling rrequency.Ts=1/fs; % Sampling rate.T=20/fs; % Symbol durationM=10^5; % Number of symbolsinterval=-T/2:Ts:T/2;SNR=0:3:15;%% Problem #1Index=1;for t=interval if t==0 p(Index)=1-roll_off_factor+4*roll_off_factor/pi; elseif t== abs(Ts/(4*roll_off_factor))