Hi,
I am designing a circuit which I can use to transmit simple tones (sine waves, Vpp is variable) using FM over short distances (<50m) . I have used an op-amp RC oscillator to generate the tone. I want to modulate the carrier (HF range <30MHz. Also to avoid the commercial FM range (85-105MHz)) with these tones, so I can transmit signals over this range. I am facing problems with my RF stage as I cannot get a design that is stable and can be modulated. Can anyone help me with the design /stage? At the receiving end, I intend to demodulate this and use a bandpass filter bank to separate the tones (which is essentially signalling using tones). Any help with the modulation / demodulation theory and/or design will be appreciated.
Thanks
Wormgear