digserro.m

此程序给出了不同情况的雷达距离测量仿真平台

% Digital Phase Shifter Serrodyning
% ---------------------------------

clf;clf;clear;

% Set Input Parameters

b=4;		% Quantizing Bits
N=128;	% Sample Points

% Define time vector 0 to tmax

tmax=1;
t=tmax*(0:N-1)/N;

% Sample frequency fs

fs=N/tmax;

% Define step ramp z which runs
% from 0 to tmax with amplitude 1

B=2^b;
y=B*t/tmax;
z=floor(y)/B;

% Define Phase Modulated Signal

j=sqrt(-1);
fo=0;
x=exp(j*2*pi*(fo*t+z));


% Find x for M steps

M=64;A=[];
for m=1:M;
A=[A x];end;
x=A;

% Extend for t vector

N=N*M;
t=tmax*(0:N-1)/N;

% Spectrum for x(t)

X=fft(x);
Px=X.*conj(X);
Px=fftshift(Px);

% Select central frequency axis

Px(3*N/4+1:N)=[];
Px(1:N/4)=[];
fax=fs*(-N/4:N/4-1)/N;

% Normalize amplitude

Px=Px/max(Px);
Pxdbm=10*log10(Px+1e-6);

plot(fax,Pxdbm);grid;
xlabel('Frequency - Hz');ylabel('Amplitude - dbm');
title(['Digital Phase Shifter Serrodyning' ...
'   ( Bits =',num2str(b),')']);
axis([-40 40 -60 0]);