Decode sine graph into binary N then convert 2 ASCII MATLAB

[commandar88]

I have to transfer a character (example the letter A) into binary, and using the sound card in my laptop, play the binary sound (of 1,s and 0,s) into the microphone of a second laptop. The second laptop will read the binary and display a sine graph accordingly.

I am stuck at the part where I have to decode the sine wave graph back into binary and then to ASCII code, so that the second laptop can display the character I pressed. (Example the letter A).

All of this has to be done using the MATLAB program.

So far for the Audio Input file, i have:

if (~isempty(daqfind))
stop(daqfind)
end
ai = analoginput('winsound');
addchannel(ai, 1);
ai.SampleRate = 8000;
ai.SamplesPerTrigger = 56000;
ai.TriggerType = 'Immediate';
start(ai)
[d,t] = getdata(ai);
plot(t,d);
zoom on

I need to add more so that after it Inputs the sine wave depending on the binary coding, I need to decode the sine graph into binary and then convert to ASCII code and display the character I pressed from the first laptop.

Your help would be greatly appreciated.
Thanks in advance.