how to solve Index exceeds the number of array elements (1)?

clear, clc

% Set up time and frequency vectors
Ts = 1e-6; t = 0:Ts:1-Ts; N = length(t); % Time vectors
fs = 1/Ts; F = fs/N; f = (-fs/2):F:(fs/2)-F; % Frequency vectors


% Signal to be processed
A1 = 1.1;
A2 = 0.5;
f1 = 500;
f2 = 1500;
x = A1*cos((2*pi*f1*t)-(pi/6))+A2*cos((2*pi*f2*t)+(pi/4)); % Original signal


% Plot original signal
figure(1)
subplot(2,1,1), plot(t, x)
xlabel('Time, sec', 'Fontsize', 14)
ylabel('x(t)', 'Fontsize', 14)
hold on


% Simulate sampling this signal
fsamp = 4000; % sampling rate, choose Nyquist rate and 2 x Nyquist rate


% Simulate sampling this signal
Tsamp = 1/fsamp; % Sampling period
y = x(1:round(Tsamp/Ts):end); % This is the sampled signal!!

% Plot this on top of original signal
tsamp = t(1:round(Tsamp/Ts):end); % Set up new time array to plot samples against
stem(tsamp, y), axis([0 0.02 min(x)*1.5 max(x)*1.5])
grid on
hold off


% Quantiser information
n = 4; % Number of bits (n-bit quantiser)
L = 16; % Total number of quantisation levels
V_range = 3; % Total voltage range of quantiser (max p-p amplitude of incoming signal)
D = 0.1875; % Voltage spacing between quantisation levels
Vo = -1.40625; % Initial quantisation level
codebook = 0; % Vo + all remaining quantisation levels in an array e.g. codebook = [Vo V1 V2 V3 etc...];

% Quantise signal
encoded = myQuantiser(y, codebook); % Call function to perform quantisation on signal
% myQuantiser() requires the signal to be quantised (y) and the codebook
% which is all the quantisation levels in an array 
% e.g. codebook = [Vo V1 V2 V3 etc...];

subplot(2,1,2), stairs(tsamp, encoded), hold on
plot(t, x), hold off
xlabel('Time, sec', 'Fontsize', 14)
ylabel('x(t)', 'Fontsize', 14)
axis([0 0.02 min(x)*1.5 max(x)*1.5])
grid on

I got a problem about Index exceeds the number of array elements (1) in line 51. How to solve it? Thanks.

[DGM]

Include the function myQuantiser.

Answer 1

[Walter Roberson]

codebook = 0; % Vo + all remaining quantisation levels in an array e.g. codebook = [Vo V1 V2 V3 etc...];

Look at the comments. codebook is expected to be a vector of all of the quantization levels, but instead you have made it the scalar 0.

You should be using V0 and D and V_range to calculate the quantization levels.