error in ASK-4 Matlab code

Hello All,

The code for ASK-4 is as follows:

N = 8; % The number of bits to send - Frame Length
bit_stream = round(rand(1,N)) % Random bit stream
A1 = 3; % Amplitude for 0 bit
A2 = 5; % Amplitude for 1 bit
f = 3; % Frequency of Modulating Signal
fs = 100; % Sampling rate
t = 0:1/fs:1; % Time for 1 bit
% This time variable is just for plot
time = [];
ASK4_signal = [];
for ii = 1: 1: length(bit_stream)
ASK4_signal = [ASK4_signal (bit_stream(ii)==0)&&(bit_stream(ii)==0)*A1*sin(2*pi*f*t)+(bit_stream(ii)==0)&&(bit_stream(ii)==1)*A2*sin(2*pi*f*t)+(bit_stream(ii)==1)&&(bit_stream(ii)==0)*-A2*sin(2*pi*f*t)+(bit_stream(ii)==1)&&(bit_stream(ii)==1)*-A1*sin(2*pi*f*t)];
time = [time t];
t = t + 1;
end
subplot(2,1,1);
plot(time,ASK4_signal,'LineWidth',2);
xlabel('Time (bit period)');
ylabel('Amplitude');
title('ASK4');
%axis([0 time(end) 1.5 1.5]);
grid on;

When I run the above code, it gives me following error as
Operands to the || and && operators must be convertible to logical scalar
values.

Error in Untitled3 (line 12)
ASK4_signal = [ASK4_signal
(bit_stream(ii)==0)&&(bit_stream(ii)==0)*A1*sin(2*pi*f*t)+(bit_stream(ii)==0)&&(bit_stream(ii)==1)*A2*sin(2*pi*f*t)+(bit_stream(ii)==1)&&(bit_stream(ii)==0)*-A2*sin(2*p

I am not able to understand what is wrong in the code. Kindly help me.

Regards,
Shruti

it seems that a comma is missing in: (bit_stream(i i)

Try the following:

N = 8; % The number of bits to send - Frame Length
bit_stream = round(rand(1,N)) % Random bit stream
A1 = 3; % Amplitude for 0 bit
A2 = 5; % Amplitude for 1 bit
f = 3; % Frequency of Modulating Signal
fs = 100; % Sampling rate
t = 0:1/fs:1; % Time for 1 bit
% This time variable is just for plot
time = [];
ASK4_signal = [];
for ii = 1: 1: length(bit_stream)
ASK4_signal = [ASK4_signal (bit_stream(ii)==0)&&(bit_stream(ii)==0)*A1*sin(2* pi*f*t)+(bit_stream(ii)==0)&&(bit_stream(ii)==1)*A 2*sin(2*pi*f*t)+(bit_stream(ii)==1)&&(bit_stream(i,i)==0)*-A2*sin(2*pi*f*t)+(bit_stream(ii)==1)&&(bit_stream( ii)==1)*-A1*sin(2*pi*f*t)];
time = [time t];
t = t + 1;
end
subplot(2,1,1);
plot(time,ASK4_signal,'LineWidth',2);
xlabel('Time (bit period)');
ylabel('Amplitude');
title('ASK4');
%axis([0 time(end) 1.5 1.5]);
grid on;

send you my code:
close all
clear all
clc
%ASK..............
SNR=linspace(10,30,10);%dB
N=10^6;% number of bit
a1=3;a2=8; %amplitude for 0 bit & 1 bit.
A=[3 8];
f=3; % carrier frequency.
n=30;% number sample of bit.
bit_stream= round(rand(1,N));
fres=A(bit_stream+1);
bit_stream_sig= rectpulse(bit_stream,n);
t=linspace(0,1,30);carrier0=3*sin(2*pi*f*t);carrier1=a2*sin(2*pi*f*t);
% ask signal
for i=1:length(bit_stream)
if bit_stream(i)==0
ask_signal((i-1)*30+1:i*30)=carrier0;
else
ask_signal((i-1)*30+1:i*30)=carrier1;
end
end
plot(bit_stream_sig(1:8*30));hold on;plot(ask_signal(1:8*30),'r');
for ii=1:length(SNR)
ask_receive=awgn(ask_signal,SNR(ii),'measured');
%recover ask signal
ask_receive=ask_receive';
ask_receive = reshape(ask_receive,n,N);
[a b]= size(ask_receive);
for i=1:b
ask_receive,i)=ask_receive,i).*sin(2*pi*f*t)';
end;
ask_receive=round(mean(ask_receive,1)*2);
%bit error
N_err=biterr(ask_receive,fres);
BER(ii)=N_err/N;
end
figure(2)
semilogy(SNR,BER)
grid on
I would like this code can help you!have fun