How to make fm transmitter and receiver of the same frequency

[Ezugudor]

please I have been searching all over the internet to find a guide on how to make an fm transmitter and receiver of the same frequency range but what I saw was not encouraging.
I saw that for a transmitter that the creator of the signal is the oscillator while for the receiver is the resonator that resonates to the signal generated by the transmitter but still am confuse on the difference between the oscillator and the resonator.
please someone should help me here am an electronic student in one of the Nigeria universities.

 

[davenn]

hi there

here is a basic block diagram of a transmitter and a receiver the transmitter at the top and the receiver below it....



The Oscillator in the transmitter could be a crystal or maybe a synthesiser
lets say it oscillates at 25MHz. So the transmitted signal is 25MHz. For a FM transmission commonly used for digital or voice, the modulation is applied to the oscillator as shown. In an AM transmitter, the modulation is usually applied to the final amplifier stage of the transmitter.

At the receiver, the received signal is very weak so first it is amplified and then it is mixed with the Local Oscillator (L.O.) signal. Again, like in the transmitter the L.O. could be a crystal or maybe a synthesiser. When you mix the incoming 25MHz with an appropriate L.O. signal you end up with a low frequency signal that you can Demodulate the audio from to send to a speaker.
The principals are the same if it was say a digital signal rather than an audio signal.

This is the basic system and there are many more complex variations. Some receivers may have 2 or 3 different Local Oscillators in them, quite common for very high frequency transmitters

cheers
Dave

 

[Ezugudor]

Thanks Daven but may be I should tell you the project am working on right now. I want to make a radio controlled toy but my problem is how LC circuit works. If am not mistaking i think that is the main part of the oscillator.

Thanks

 

[Jugurtha]

Hello,

Maybe you should use an FM transmitter IC. It's basically a single chip which handles everything. Since you want to control the toy, you might want to save on part count and PCB space, etc..