Hybrid fiber-coax system having at least one digital fiber node

DETAILED DESCRIPTION Briefly, in accordance with a preferred embodiment of the invention, ingress noise in a shared hybrid fiber-coax system in which upstream information is transmitted from the subscribers to the head end, can be reduced by regenerating the subscriber-generated upstream information through uplink regenerators, as taught in my copending patent application Ser.
No.
08/650,683 (incorporated by reference herein).
However, at the fiber node, the upstream signal, previously digitized by the regenerator, is not reconverted to an analog signal.
Instead, the digital received signal is transmitted in a digital baseband, optical format across an optical fiber to the head end.
In comparison to modulating the upstream by analog techniques at the Fiber Node, as taught by the prior art, digital modulation affords several advantages.
First, digital electrical-to-optical converters for accomplishing digital modulation are less expensive than their analog counterparts.
Additionally, digital modulation provides a more robust signal quality.
Moreover, use of such modulation techniques as Wavelength Division Multiplexing permits digitally modulated optically-formatted signals to share a common optical fiber link with signals that are modulated by analog techniques.