Matlab help ! need to digitally modulate a sine wav

[jess17]

ok i need to do FSK on a sine wave, but i keep getting an error saying

" ??? Error using ==> dpskmod at 41
Elements of input X must be integers in the range [0, M-1].

Error in ==> dpskmodulation at 15
sig = dpskmod(x,M,pi / 8 ) ; "


my code is as follows:


M = 4; % Use DQPSK in this example, so M is 4.
Fs = 100;
t = [0:2*Fs+1]'/Fs;
Fc = 10; % Carrier frequency
x = sin(2*pi*t); % Sinusoidal signal
figure(1)
plot(t, x);

sig = dpskmod(x,M,pi / 8 ) ;
figure(2)
plot % Plot all points, using lines to connect them.

 

[blooz]

ok i need to do FSK on a sine wave, but i keep getting an error saying

" ??? Error using ==> dpskmod at 41
Elements of input X must be integers in the range [0, M-1].

Error in ==> dpskmodulation at 15
sig = dpskmod(x,M,pi / 8 ) ; "


my code is as follows:

[COLOR="blue"]M = 4; % Use DQPSK in this example, so M is 4.
Fs = 100;
t = [0:2*Fs+1]'/Fs;
Fc = 10; % Carrier frequency
[COLOR="red"][U][B]x = sin(2*pi*t); % Sinusoidal signal[/B][/U][/COLOR]
plot(t, x);

[B][U]sig = dpskmod(x,M,pi / 8 ) ;[/U][/B][I][COLOR="red"]%here x must be an integer below m-1[/COLOR][/I]
figure(2)
plot(y) % Plot all points, using lines to connect them.

[/COLOR]

i think the problem is in the highlighted portion .
Instead of integers you have non integer array

 

[jess17]

well, i tried multiplying bi 1000, and then plotting the abs values, so I get only 0's and 1's for x, I am still getting the same error

 

[blooz]

well, i tried multiplying bi 1000, and then plotting the abs values, so I get only 0's and 1's for x, I am still getting the same error

Hi

jess

one solution is to generate a sine wave then sample the sine wave then Quantize the sample output.After Quantization the output will be just binary sequence Then you can apply the matlab function dpskmod() or fskmod() .


this link got a good explanation on Quantization
h**p://www.mathworks.com/matlabcentral/answers/2952-quantisation-using-matlab

 

[jess17]

ok here is what i did to quantize:

>> t = [0:.1:2*pi]; % Times at which to sample the sine function
sig = sin(t); % Original signal, a sine wave
partition = [-1:.2:1]; % Length 11, to represent 12 intervals
codebook = [-1.2:.2:1]; % Length 12, one entry for each interval
[index,quants] = quantiz(sig,partition,codebook); % Quantize.
plot(t,sig,'x',t,quants,'.')
legend('Original signal','Quantized signal');
axis([-.2 7 -1.2 1.2])
>>
>> M = 4;
>> y = dpskmod(quants,M,pi / 8 ) ;

but i still keep getting the error
??? Error using ==> dpskmod at 41
Elements of input X must be integers in the range [0, M-1].

 

[blooz]

[/B Let me ask one Question ,What's your Exact need FSK or PSK ....
here as per the problem given i infer two things

1.Your Carrier is Sinusoidal 100hz
2.Modulating Signal 10hz Sinusoidal

I think this thread can solve your problem it's quite similar to what you specified .
h**p://https://www.edaboard.com/threads/133432/


Here is another good material on FSK Containing Matlab Code

h**p://www.ece.udel.edu/~barner/courses/eleg212/laboratories/Lab_05.pdf