Method and apparatus for simultaneous transmission of digital telephony and analog video over a single optic fiber using wave division multiplexing

摘要

Downstream digital telephony signals are transmitted over the 1310 nm transmission band of a silica optic fiber. Upstream digital telephony signals are transmitted over a "short wavelength" portion of the 1550 nm transmission band of the optic fiber, i.e. within a portion of the 1550 nm transmission band having wavelengths less than a predetermined threshold wavelength of 1550 nm. Simultaneously, downstream analog video signals are transmitted over a "long wavelength" portion of the 1550 nm transmission band of the optic fiber, i.e. within a portion of the 1550 nm transmission band having wavelengths exceeding the predetermined threshold wavelength of 1550 nm but still within an erbium- doped fiber amplifier gain profile. Thus, the upstream digital telephony signals are always transmitted at wavelengths shorter than the threshold wavelength and the downstream analog video signals are always transmitted at wavelengths longer than the threshold wavelength. Accordingly, no significant signaling conflicts occur between the upstream digital telephony signals and the downstream analog video signals, and both upstream and downstream digital telephony signals and analog video signals are reliably carried over the single optic fiber.