Interactive video distribution systems – Video distribution system with upstream communication – Transmission network
Reexamination Certificate
1998-03-17
2002-09-24
Faile, Andrew (Department: 2611)
Interactive video distribution systems
Video distribution system with upstream communication
Transmission network
C725S129000, C725S149000, C359S199200, C359S199200
Reexamination Certificate
active
06457178
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to cable television systems, and more specifically to nodes that are used within such systems to process both optical and radio frequency signals.
BACKGROUND OF THE INVENTION
Cable television systems typically include a head end section that receives satellite signals and demodulates the signals to baseband. The baseband signal is then converted to an optical signal for transmission from the head end section, such as over fiber optic cable. Cable systems also usually include one or more hubs for splitting the signals into a plurality of branches for transmission to various geographical regions within a system. Optical nodes situated within the system convert the optical signals to radio frequency (RF) signals for further transmission, such as over coaxial cables, to system subscribers. Taps are situated along the coaxial cable to provide subscriber “drops” that tap off signals to subscriber premises.
In cable television systems having two-way communication capabilities, RF signals are transmitted in the reverse direction from system subscribers. These signals can include any or all of voice, video, or data information, resulting in a composite broadband RF signal that is received by an optical node. The node must then convert this RF signal into an optical signal for transmission back to the head end section.
Typically, the optical nodes that, in the forward direction, split the outgoing optical signal into a number of RF signals also contain a relatively inexpensive, robust laser for such reverse transmissions. Such optical nodes can, for instance, be mounted on utility poles and exposed to a range of environmental conditions; therefore the laser must be suitable for outdoor use. These simple lasers ordinarily use linear modulation to process the RF signals that are to be transmitted in the reverse direction. However, linear modulation of broadband RF signals can cause clipping of the signal and overloading of the laser, resulting in an excessively noisy signal that may be erroneously decoded at the head end section.
Thus, what is needed is a better way of optically processing a broadband RF signal for transmission to the head end section in the reverse direction.
REFERENCES:
patent: 3590250 (1971-06-01), Witkover
patent: 4140980 (1979-02-01), Cummings
patent: 4470068 (1984-09-01), Plume
patent: 4669089 (1987-05-01), Gahagan et al.
patent: 4694504 (1987-09-01), Porter et al.
patent: 4713841 (1987-12-01), Porter et al.
patent: 4776036 (1988-10-01), Hulsey et al.
patent: 4896372 (1990-01-01), Weaver
patent: 5040242 (1991-08-01), Tsuchiya et al.
patent: 5052037 (1991-09-01), Perelman
patent: 5349461 (1994-09-01), Huynh et al.
patent: 5373387 (1994-12-01), Bosch et al.
patent: 5408351 (1995-04-01), Huang
patent: 5448629 (1995-09-01), Bosch et al.
patent: 5469287 (1995-11-01), Iwakuni
patent: 5544161 (1996-08-01), Bigham et al.
Barnhardt III Hubert J.
Couturier Shelley L.
Faile Andrew
Koenig Andrew Y.
Massaroni Kenneth M.
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