Fiber Optic Signal Link Using Frequency Modulation

The patent replaces the conventional amplitude modulation electrical signal transmission with frequency modulation of optical signals. The transmitter converts electrical analog signals to optical signals using frequency modulation instead of amplitude modulation, and the receiver converts optical signals back to electrical signals. This substitution of the transmission medium and modulation method eliminates the degradation in signal to noise ratio that occurs with increased cable length in traditional amplitude modulation systems.

The patent introduces optical signals as an intermediary medium to transmit information from high electromagnetic field areas to low field areas. The transmitter converts electrical signals to optical signals, which are immune to electromagnetic interference during transmission through the fiber optic cable. The receiver then converts the optical signals back to electrical signals in the low field area, effectively isolating the signal path from electromagnetic interference that would otherwise compromise signal integrity.

The patent employs frequency modulation of optical signals rather than electrical signals, which fundamentally reduces electromagnetic interference. The transmitter uses a voltage-controlled oscillator to generate optical frequency modulated signals, and the receiver uses a phase locked loop to recover the modulating signal. While this introduces frequency conversion circuits, the use of optical frequencies and integrated photonic components keeps the overall system complexity manageable while achieving superior electromagnetic interference rejection compared to traditional electrical transmission systems.