Using fiber optics with analog RF signals

The use of a laser diode transmitter and a photodiode receiver allows radio signals, as high as 1 GHz in frequency, to be directly modulated onto fiber cable. The amplitude-modulated signal can then be transmitted along the fiber cable and coupled to a photodiode receiver. The receiver down-converts the optical modulated signal to the original radio frequency (RF) signal which can be amplified to a usable level. This concept can be used to carry low-level land mobile radio frequencies over long distances with little distortion and with relatively little loss. Typical applications for the system include tunnels, subways, large buildings, ships, and simulcast systems