Yes, it is possible to modulate a wave with an audio signal using frequency modulation (FM) at lower frequencies than those typically used for broadcast radio stations. FM is a modulation technique where the frequency of a carrier wave is varied in accordance with the modulating signal. In the case of audio FM modulation, the modulating signal is an audio waveform.
The primary difference between lower-frequency FM and broadcast radio stations is the range of frequencies involved. Broadcast radio stations typically operate in the megahertz (MHz) range, while lower-frequency FM modulation can be done in the kilohertz (kHz) range or even lower.
To implement FM modulation at lower frequencies, you would need an FM modulator circuit or software that allows you to vary the frequency of a carrier wave based on the audio signal. This can be achieved using various techniques and components such as voltage-controlled oscillators (VCOs) or software-based algorithms.
The modulating audio signal would typically be an analog waveform representing the desired audio content. This audio signal would be used to control the frequency of the carrier wave, resulting in the FM-modulated signal. The FM-modulated signal can then be transmitted or used for other purposes, such as audio synthesis or communication.
Keep in mind that transmitting FM-modulated signals may be subject to regulations and legal considerations depending on the frequency range and jurisdiction. It's important to research and comply with any applicable laws and regulations before engaging in any form of radio transmission.