HW4S - g=conv(s,h); % Convolve received pulse with matched...

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ps4_3a.m close all; clear all; f0 =100e6; % Starting frequency of chirp (Hz) N =32768; % Number of points to sample pulse tau=2e-6; % Pulse duration (seconds) B=10e6; % Student input: Bandwidth of chirp (Hz) dt=2*tau/N; % Setup time axis t=(-tau:dt:tau-dt); f=f0+B*t/tau; % Linear FM chirp frequency s=cos(2*pi.*f.*t); % Generate chirped waveform s(find(abs(t)>tau/2))=0; % Create pulse % Student formula #1: impulse response of matched filter goes here % It is not necessary to introduce any time delays into the filter % response h=???; % Student formula #2: Include doppler if desired % fd=???; % Doppler shift (Hz) % s=???; % Generate chirped waveform w/ Doppler shift % s(find(abs(t)>tau/2))=0; % Create pulse
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Unformatted text preview: g=conv(s,h); % Convolve received pulse with matched filter impulse response t2=(-2*tau+dt:dt:2*tau-dt); % Time axis for convolution % Demodulate pulse from IF to baseband gf=fft(fftshift(g.*exp(-j*2*pi*(f0+B/2).*t2))); % Low pass filter the output % filter cutoff set by either chirp (B>0) or pulse bandwidth (B=0) df=1/4/tau; if (B>0) N1=4*floor(B/df); else N1=8*floor(1/(df*tau)); end gf(N1:end-N1)=0; g2=fftshift(abs(ifft(gf))); % Transform back to time domain figure set(gca,'Fontsize',14) plot(t2/1e-9,g2./max(g2),'r','linewidth',2); % Plot results axis([-tau/1e-9 tau/1e-9 -0.1 1.2]) grid on hold on xlabel('Time (nsec)') ylabel('Matched filter output ')...
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This note was uploaded on 10/28/2009 for the course ECE 714 taught by Professor Johnson,j during the Spring '08 term at Ohio State.

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