%function rate=digask(M, SNR) 
M = 4;     % Use 4-ary modulation.
Fd = 1;     % Assume the original message is sampled
            % at a rate of 1 sample per second.
Fs = 1;     % The modulated signal will be sampled
            % at a rate of 1 samples per second.
N =10000;    %number of bits generated

SNR = 10;    %signal-to-noise ratio in dB

x = randint(N,1,M);   % Random digital message
            
y = dmodce(x,Fd,Fs,'ask',M);    % Use M-ary PSK modulation to produce y.

ynoisy = y + (1/SNR)*randn(Fs*N,1) + (1/SNR)*j*randn(Fs*N,1); % Add some Gaussian noise.

scatterplot(ynoisy,1,0,'b.');   % Create scatter plot from noisy data.

z = ddemodce(ynoisy,Fd,Fs,'ask',M);     % Demodulate y to recover the message.

[s, rate] = symerr(x,z);         % Check symbol error rate.