In this post, Matlab Code for Computer Exercise C7.3 Monson H. Hayes Statistical Digital Signal Processing book and its simulation output is discussed. Please refer the question (C7.3) below.
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Open in new tab Matlab code for computer exercise 7.3 (a)
clc;
clear;
close all;
%Define the length of the simulation.
N = input('Please enter the number of iteration for discrete Kalman Filter, N = ');
%Transition matrix
A = 0.8; % State Transition Matrix
C = 1.0; % Obserbation Matrix
%Define the noise covariances.
Q = 0.36; % Variance of process noise
R = 1; % Variance of measurement noise
%% Generate AR(1) process
e = randn(100,1);
b = [1 0];
X = filter(b,0.8,e);
%Calculate the process and measurement noise.
w1 = randn(1,N); %This line and the next can be commented out after running
v1 = randn(1,N); %the script once to generate multiple runs with identical
%noise (for better comparison).
w = w1*sqrt(Q);
v = v1*sqrt(R);
%Initial condition on the state, x.
x_0 = X(1);
%Initial guesses for state and a posteriori covariance.
p_0 = 1;
%Calculate the first estimates for all values based upon the initial guess
%of the state and the a posteriori covariance. The rest of the steps will
%be calculated in a loop.
x(1)= A*x_0 + w(1);
y(1)= C*x(1)+ v(1);
%Predictor equations
x_pred(1) = A*x_0;
p_pred(1) = A*A*p_0 + Q;
residual(1) = y(1)- C*x_pred(1);
%Corrector equations
K(1)= C*p_pred(1)/(C*C*p_pred(1)+R);
p_est(1)= p_pred(1)*(1-C*K(1));
x_est(1)= x_pred(1)+K(1)*residual(1);
%Calculate the rest of the values.
for j=2:N
%Calculate the state and the output
x(j)= A*x(j-1)+ w(j);
y(j) = C*x(j)+ v(j);
%Predictor equations
x_pred(j)= A*x_est(j-1);
residual(j)= y(j)- C*x_pred(j);
p_pred(j) = A*A*p_est(j-1)+ Q;
%Corrector equations
K(j) = C*p_pred(j)/(C*C*p_pred(j)+ R);
p_est(j) = p_pred(j)*(1-C*K(j));
x_est(j) = x_pred(j)+ K(j)*residual(j);
x_pred(j) = x_est(j);
end
j=1:N;
disp('The Kalman gain for the given number of iterations is:');
disp('=====================================================');
disp(K(j));
plot(K);Matlab code for computer exercise 7.3 (b)
clc;
clear;
close all;
%Define the length of the simulation.
nlen = 11;
%Define the system.
A = 1; % a=1 for a constant,
C = 1;
%Define the noise covariances.
Q = 1;
R = 0.64;
%% Generate AR(3) process
e2 = randn(100,1);
b1 = [1 0];
y = filter(b1,[-0.1 -0.09 0.648],e2);
% initial estimates (guesses) for x
x_0 = y(1);
%Initial guesses for error covariance.
p_0 = 0.6;
%Calculate the process and measurement noise.
w1 = randn(1,nlen); %This line and the next can be commented out after running
v1 = randn(1,nlen); %the script once to generate multiple runs with identical
%noise (for better comparison).
w = w1*sqrt(Q);
v = v1*sqrt(R);
%Calculate the first estimates for all values based upon the initial guess
%of the state and the a posteriori covariance. The rest of the steps will
%be calculated in a loop.
%Calculate the state and the output
x(1) = A*x_0 + w(1);
z(1) = C*x(1) + v(1);
%Predictor equations
x_pred(1) = A*x_0;
p_pred(1) = A*A*p_0 + Q;
residual(1) = z(1)-C*x_pred(1);
%Corrector equations
k(1) = C*p_pred(1)/(C*C*p_pred(1) + R);
p_est(1) = p_pred(1)*(1-C*k(1));
x_est(1) = x_pred(1)+ k(1)*residual(1);
%Calculate the rest of the values.
for j = 2:nlen
%Calculate the state and the output
x(j)= A*x(j-1)+ w(j);
z(j)= C*x(j)+ v(j);
%Predictor equations
x_pred(j)= A*x_est(j-1);
residual(j) = z(j)-C*x_pred(j);
p_pred(j) = A*A*p_est(j-1)+ Q;
%Corrector equations
k(j) = C*p_pred(j)/(C*C*p_pred(j)+ R);
p_est(j) = p_pred(j)*(1-C*k(j));
x_est(j) = x_pred(j)+k(j)*residual(j);
x_pred(j) = x_est(j);
x_pred(j) = x_est(j);
%disp(k(j));
end
%j=1:nlen;
disp('The Kalman gain for n = 0 to n = 10 is:');
disp('=======================================');
disp(k);
%% plot Kalman gain for 10 iterations
plot(k);
title('Kalman Gain for 11 iterations');
xlabel('Number of iterations');
ylabel('Gain');
Matlab code for computer exercise 7.3 (c)
clc;
clear all;
%Define the length of the simulation.
nlen = 10;
%Define the system.
A = 0.8;
H = 1;
%Define the noise covariances.
Q = 1;
R = 0.64;
%% Generate AR(3) process
phi = 0;
e = randn(100,1);
b = [1 phi];
y = filter(b,[1.2728 -0.09 0.648],e);
% initial estimates (guesses) for
% 1) the state.
x_0 = y(1);
% 2) the error covariance.
p_0 = 0;
%Calculate the process and measurement noise.
w1 = randn(1,nlen); %This line and the next can be commented out after running
v1 = randn(1,nlen); %the script once to generate multiple runs with identical
%noise (for better comparison).
w = w1*sqrt(Q);
v = v1*sqrt(R);
%Calculate the first estimates for all values based upon the initial guess
%of the state and the a posteriori covariance. The rest of the steps will
%be calculated in a loop.
%
%Calculate the state and the output
x(1) = A*x_0 + w(1);
z(1) = H*x(1) + v(1);
%Predictor equations
x_pred(1) = A*x_0;
p_pred(1) = A*A*p_0 + Q;
residual(1) = z(1)-H*x_pred(1);
%Corrector equations
k(1) = H*p_pred(1)/(H*H*p_pred(1)+ R);
p_est(1) = p_pred(1)*(1-H*k(1));
x_est(1) = x_pred(1)+k(1)*residual(1);
%Calculate the rest of the values.
for j=2:nlen
%Calculate the state and the output
x(j) = A*x(j-1) + w(j);
z(j) = H*x(j)+ v(j);
%Predictor equations
x_pred(j) = A*x_est(j-1);
residual(j) = z(j)- H*x_pred(j);
p_pred(j) = A*A*p_est(j-1)+ Q;
%Corrector equations
k(j) = H*p_pred(j)/(H*H*p_pred(j)+ R);
p_est(j) = p_pred(j)*(1-H*k(j));
x_est(j) = x_pred(j) + k(j)*residual(j);
x_pred(j) = x_est(j);
end
disp(k);
j=1:nlen;
%% plot Kalman gain for 10 iterations
plot(k(j));
title('Steady state value of gain')
xlabel('Number of iterations');
ylabel('Gain');
Matlab code for computer exercise 7.3 (d)
clc;
clear;
close all;
%Define the length of the simulation.
nlen = 10;
%Define the system.
a = 0.8; % a=1 for a constant,
h = 2;
%Define the noise covariances.
Q = 1;
R = 0.64;
%% Generate AR(3) process
phi =0;
e = randn(100,1);
b = [1 phi];
y = filter(b,[-0.1 -0.09 0.648],e);
% initial estimates (guesses) for
% 1) the state.
x_0 = y(1);
% 2) the error covariance.
p_0 = 0.8;
%Calculate the process and measurement noise.
w1 = randn(1,nlen); %This line and the next can be commented out after running
v1 = randn(1,nlen); %the script once to generate multiple runs with identical
%noise (for better comparison).
w = w1*sqrt(Q);
v = v1*sqrt(R);
%Calculate the first estimates for all values based upon the initial guess
%of the state and the a posteriori covariance. The rest of the steps will
%be calculated in a loop.
%
%Calculate the state and the output
x(1) = a*x_0 + w(1);
z(1) = h*x(1) + v(1);
%Predictor equations
x_pred(1) = a*x_0;
residual(1) = z(1)- h*x_pred(1);
p_pred(1) = a*a*p_0 + Q;
%Corrector equations
k(1) = h*p_pred(1)/(h*h*p_pred(1)+ R);
p_est(1) = p_pred(1)*(1-h*k(1));
x_est(1) = x_pred(1)+ k(1)*residual(1);
%Calculate the rest of the values.
for j=2:nlen
%Calculate the state and the output
x(j) = a*x(j-1) + w(j);
z(j) = h*x(j) + v(j);
%Predictor equations
x_pred(j) = a*x_est(j-1);
p_pred(j) = a*a*p_est(j-1) + Q;
residual(j) = z(j)-h*x_pred(j);
%Corrector equations
k(j) = h*p_pred(j)/(h*h*p_pred(j)+ R);
p_est(j) = p_pred(j)*(1-h*k(j));
x_est(j) = x_pred(j)+k(j)*residual(j);
x_pred(j) = x_est(j);
end
disp(k);
j=1:nlen;
%% plot Kalman gain for 10 iterations
figure(1);
plot(k(j));
legend('kalman gain');
title('Steady state value of gain')
xlabel('Number of iterations');
ylabel('Gain');
figure(2);
plot(x(j)); hold on;
plot(x_est(j)); hold on;
%plot(z(j)); hold on;
title('True Measured and estimated value')
xlabel('Number of iterations');
ylabel('values');
legend('True','Estimated');
Matlab code for computer exercise 7.3 (e)
clc;
clear;
close all;
%Define the length of the simulation.
nlen = 11;
%Define the system. Change these to change the system.
A = -0.95;
H = 1;
%Define the noise covariances.
Q = 1; % Variance of process noise
R = 0.8; % Variance of measurement noise
%% Generate AR(3) process
phi = 0;
e1 = randn(100,1);
b = [1 phi];
y = filter(b,[-0.95 -0.9025],e1);
% initial estimates (guesses) for
% 1) the state.
x_0 = y(1);
% 2) the error covariance.
p_0 = 0.6;
%Calculate the process and measurement noise.
w1 = randn(1,nlen); %This line and the next can be commented out after running
v1 = randn(1,nlen); %the script once to generate multiple runs with identical
%noise (for better comparison).
w = w1*sqrt(Q);
v = v1*sqrt(R);
%Calculate the first estimates for all values based upon the initial guess
%of the state and the a posteriori covariance. The rest of the steps will
%be calculated in a loop.
%
%Calculate the state and the output
x(1) = A*x_0 + w(1);
z(1) = H*x(1) + v(1);
%Predictor equations
x_pred(1) = A*x_0;
p_pred(1) = A*A*p_0 + Q;
residual(1) = z(1)- H*x_pred(1);
%Corrector equations
k(1) = H*p_pred(1)/(H*H*p_pred(1)+ R);
p_est(1) = p_pred(1)*(1-H*k(1));
x_est(1) = x_pred(1)+k(1)*residual(1);
%Calculate the rest of the values.
for j= 2:nlen
%Calculate the state and the output
x(j) = A*x(j-1)+ w(j) - w(j-1);
z(j) = H*x(j) + v(j);
%Predictor equations
x_pred(j) = A*x_est(j-1);
residual(j) = z(j)- H*x_pred(j);
p_pred(j) = A*A*p_est(j-1)+ Q;
%Corrector equations
k(j) = H*p_pred(j)/(H*H*p_pred(j)+ R);
p_est(j) = p_pred(j)*(1 - H*k(j));
x_est(j) = x_pred(j)+ k(j)*residual(j);
end
disp(k);
%% plot Kalman gain for 10 iterations
j= 1:nlen;
figure(1);
plot(k(j));
legend('kalman gain');
title('Steady state value of gain')
xlabel('Number of iterations');
ylabel('Gain');
figure(2);
plot(x(j)); hold on;
plot(x_est(j)); hold on;
%plot(z(j)); hold on;
title('True Measured and estimated value')
xlabel('Number of iterations');
ylabel('values');
legend('True','Estimated');
Matlab Code Simulation Output:
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