Circuits for Mapping Voice and Digit Voltage Levels to 30kHz-300kHz Frequency Range

My project is about creating a transmitter using the low frequency range (30kHz -300kHz), I am in need of the right circuits to put together that would map both the voice and digits to frequency, that is, for every sample inputted into the system through a mic condenser for example, frequency is being generated and for the digits, for every key pressed, the voltage levels are converted to frequency and can be transmitted at low frequency range. I hope the little explanation given gives an idea of what I am trying to talk about and any help what so ever will be really appreciated.

Look at the LM331 voltage to frequency converter
http://www.ti.com/product/LM331There are other parts that will do this as well.

Maleek. I would guess that English is your second language, but if I understand you correctly you want to send voice or data information down a low frequency 30-300 KHz) radio link?  The "Mapping" you are referring to I think means "Modulation"?  There are different ways of modulating a radio signal, the two most often used are Amplitude Modulation (AM) and Frequency Modulation (FM), for digital signals they would be called Amplitude shift keying (ASK) and Frequecy shift keying (FSK).  I'd suggest you look these terms up and find out more about them.
You talk about "every sample inputted into the system through a mic condenser".  A condenser mic is basically an analogue device and does not put out samples directly.  Are you going to sample your mic with an ADC (Analogue to Digital Converter) and work digitally thereafter?A bit more idea about what you are trying to do, and how, would enable us to advise you better?

I think I understand what he's getting at. He wants to use Low Frequencies for voice communication, presumably for underground or underwater applications. At low frequencies, the audio bandwidth is severely restricted, which normally precludes the use of voice communication at such low frequencies, especially if the available frequency allocation is narrow. If there was a way (digital or other) to down-convert the voice modulation frequencies from a normal communication range of 300-3000Hz to say 30-300Hz, the Low Frequency carrier could then be successfuly modulated with this down-converted audio, then upconverted by the receive station. Whether or not the resulting speech would be sufficiently intelligible is another matter.