Demand-driven duplex

1 . An apparatus for implementing soft duplex operation of a communications network that transmits downstream signals from a service provider to a subscriber and upstream signals from the subscriber to the service provider, the apparatus comprising:

a pair of opposed triplexers defining a first signal path for a first frequency range through a first amplifier and for exclusively a downstream signal, a second signal path for a second frequency range through a second amplifier and for exclusively an upstream signal, and a third signal path for a third frequency range through a third, single amplifier, where said third frequency range is between said first frequency range and said second frequency range; and

at least one switch that selectively alternates a third signal through the third, single amplifier between an upstream signal and a downstream signal; and

including at least one gain and tilt module in the path of the third, single amplifier; and

further including different gain and tilt modules for the upstream and downstream directions, respectively.

2 . The apparatus of claim 1 implemented in an amplifier in a coaxial portion of the communications network.

3 . The apparatus of claim 1 implemented in a node of the communications network, the node receiving an optical signal and outputting an RF signal.

4 . The apparatus of claim 1 including at least one filter in the path of the third, single amplifier.

5 . The apparatus of claim 4 where the at least one filter filters a signal amplified by the third, single amplifier.

6 . The apparatus of claim 4 where the at least one filter includes a high pass filter and a low pass filter.

7 . The apparatus of claim 4 where the at least one filter isolates a mid-band signal from the exclusively downstream signal and the exclusively upstream signal, respectively.

8 . The apparatus of claim 1 where the at least one switch is a double throw switch.