With this speed this may take very long time. I suggest to tell us what you have done so far, and why and how you struggle. This can be done by posting your schematic and your code.
i know its hard to tell, but the idea is to transmit alphanumeric characters using the dtmf tones, and this tones will be decoded in the receiver that will be displayed in the lcd
from what is on my mind, the alphanumeric characters from the keypad will be converted into binary. ( 8 bits) then this 8 bits will be represented by the dtmf tones, in the receiver, the tones will be converted to back to binary and finally be displayed in LCD.
If you wanted to do something neat, you could convert the characters to binary like you suggested, then convert that into tones.
For instance START transmission would be the tone for the number '1'
then binary 0 would be tone '2'
binary 1 would be tone '3'
Done Transmission would be tone '4'
That would be rather straight forward..ish..
That allows you to send:
1(start TX) 2333232323222232333233323232323232322233332000 4(end TX)
The 2s and 3s would equate to:
01110101 01000010 11101110 10101010 10101000 11110111
That would be grabbed by the receiving in 8 bit chunks and converted to the letter you want and displayed onscreen.
This also gives you tones for 5,6,7,8,9,and 0 to do other communications stuff.
For instance if you wanted to have the other end talk back,
Then transceiver 'A' would use tones 1,2,3,4 as noted above, but transceiver 'B' would use 5,6,7,8 for (start TX, 0, 1, and end TX)
You would also be able to have 'b' respond to 'a' to let it know it is online.
For instance 'a' send the tone '1' for start then waits for 'b' to send : 5,8 which would be start-stop and 'a' would then know it could send the bit-stream.
so meaning, the equivalent tone (w/c is the 8 bit ) will be decoded by dtmf decoder into 8bit equivalent, w/c will be displayed in lcd as characters, right?