Create a digital FM transmitter

hello
i want to design a FM transmitter that send digital signal between start point to destination.my main question is
if i want to send a digital signal to environment it waist a big Bandwidth.so if i want to send another signal such as sinusoidal with different frequency i have a more and difficult signal processing to count the frequency and detect my bits.so whats your suggestion
?

have a look at this
http://en.wikipedia.org/wiki/Frequency-shift_keying

Yes, i know the FSK modulation. could you introduce me an example receiver circuit?

No one can't help me how can i demodulate the input signal to 0 and 1? because if i know it i could work on QAM modulation

Dear baby_1
Hi
As i understood , your problem is how to detect an FSK signal , right ?
So , if yes , it is simple . as you probably know , FSK , is pretty similar with FM , but with this difference that the message signal is coded , and it is , just a pulse , so , if you use the usual ways that we will use for FM detection , the message signal that will given , will be an square wave ! ( coded signal ) so , you'll need a decoder , ( according to the coder ) , to change it to an analog signal , and then you should amplify it and ........ .
Best Wishes
Goldsmith

Dear Goldsmith
could you tell me more about FM receiver and give me some reference and example circuits to know how they works?

Hi again
You can find about fm detectors , in each telecommunication textbook , simply .
There are many ways , such as coincidence , or quadrature or foster seely or slope , or travis or PLL detector or ........ but there are many integrated circuits available too for this aim , too .
Best Lucks
Goldsmith

Your intention isn't quite clear. Do you want to detail the broad idea of a data FM radio link, make a principle demonstration circuit or build transmitters and receivers with some range performance? In the latter case, you should look for existing IC solutions from TI, HopeRF, SiliconLabs and others. Or use ready-made FM modules.

Could you introduce me some good reference about fm modulator and receiver?
Thanks

Sure . there are several books available . such as solid state radio engineering by herbert l kraus , or telecommunications of george kennedy or ........ !