Interactive video distribution systems – Video distribution system components – Transmission network
Reexamination Certificate
1999-02-11
2001-03-06
Faile, Andrew (Department: 2611)
Interactive video distribution systems
Video distribution system components
Transmission network
C725S127000, C330S051000, C330S151000, C333S101000, C439S119000, C439S225000, C439S192000
Reexamination Certificate
active
06199207
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to circuit apparatus for routing signals to multiple CATV distribution amplifiers, and more particularly to a method and apparatus for internally dividing radio frequency and alternating current power signals from the input (upstream) port of an amplifier circuit and then routing the signals to both an output port of the amplifier circuit and an additional port for coupling to a second amplifier circuit or a power inserter input.
BACKGROUND
Cable television signal distribution systems comprise signal delivery systems that are analogous, to the trunk and limbs of a tree. As cable television systems grow, new limbs and branches must be provided to reach new subscribers, for example, in new subdivisions, apartment building complexes and the like or to reach further into the territory served by the cable television service provider. In order to facilitate delivery of services to potential subscribers from the serving CATV facility, typically referred to as a headend, CATV (community antenna, television/cable television) systems may require the installation of either two co-located distribution amplifiers for a new branch of the tree or that the signal be split at a point along the coaxial cable prior to entering the distribution amplifier. If the signal is to be split it has been necessary to accomplish this by installing an external power passing splitter or coupler at or near the location of the amplifier, an implementation of which is shown in FIG.
1
. An external power passing splitter
16
a
may require its own housing or additional space within a pedestal at the amplifier location, not only for the splitter, but also for the routing of the coaxial cable into and out of the splitter. In underground or buried cable installations, pedestals are used to house amplifiers and in overhead cable environments, amplifier casings and the like are mounted on poles or hung from strands supporting the cable. In both of these environments, and particularly in a pedestal (buried) environment, space for additional splitters and amplifiers and the like is at a premium. The alternative of providing a larger pedestal is not only economically undesirable but may be unattractive and run afoul of local utility or environmental regulations. Additionally, AC (alternating current) power to the CATV system must be interrupted in order to splice an external splitter into the coaxial cable for provision of service to feed a new branch of subscribers. This can cause disruption of service to all subscribers downstream of the amplifier location. Creation of such a splice also requires a fair amount of work by a specialized craftsperson resulting in down time. Moreover, the resulting splice may require additional shielding when completed to prevent serving signal loss or noise ingress, for example, from power, broadcast radio frequencies or telecommunications lines located nearby.
OBJECTS OF THE INVENTION
Accordingly, a primary object of the present invention is to provide a relatively simple, plug-in method for dividing a CATV signal at a desired point along the serving CATV distribution plant.
In particular, an object of the present invention is to split CATV signals via an internal signal divider located on an amplifier motherboard within an amplifier housing for containment within a pole or strand mounted casing or pedestal.
A further particular object of this invention is to reduce the work, system downtime, and space requirements for extending a cable distribution system to reach additional subscribers of a cable television system or for adding a power inserter into the system.
SUMMARY
In accordance with the principles of the present invention, a connector is provided on an amplifier motherboard for receiving at least one removable plug-in board for tapping off incoming RF and AC signals to provide an external output or for permitting power insertion to the amplifier. The motherboard and plug-in board, when installed, are both contained within an amplifier housing. The plug-in board in one embodiment contains a power passing, radio frequency choke or inductor and either a directional coupler or a splitter, along with an input (upstream) port and two output (downstream) ports. By input port here and throughout the following description is meant the upstream signal input from a headend and such an input as so defined permits both downstream and upstream signal flow, for example, for bidirectional telecommunications signals including digital data (for example, CATV system status monitoring), voice (for example, telephony) or video (for example, for remote broadcast feeds upstream or for video conferencing). Also, by output port is intended the downstream side of the element and such an output port permits both downstream and upstream signal flow. By distribution amplifier, whenever used herein, is intended the provision of amplification circuitry permitting a single input and a single or multiple outputs for serving multiple branches of the CATV distribution plant.
This plug-in board of the present invention is intended to be inserted into a receiving connector of a motherboard on which is mounted amplification circuitry and may be inserted either in the field or at the factory. The connector passes signals directly to the amplification circuitry when the plug-in card is not plugged into the connector and, when the plug-in is installed, the plug-in board routes radio frequency (RF) signals arriving on a coaxial or other cable input port of the amplifier motherboard through a directional coupler to the amplification circuitry, from which the signals are further routed to the main amplifier output port. The plug-in board additionally taps off and feeds the incoming RF signals to a second output port of the amplifier motherboard. In this manner, potential subscribers of new branches of a CATV distribution plant may be served with minimal disruption of service to existing downstream customers. Also, the additional external port may be utilized, not only for serving new customers, but as a power insertion point for providing power to the amplifier if, for example, insufficient power is available at either its input or output.
When the plug-in is installed, AC power signals arriving on the coaxial input port are fed through alternating current passing inductors (radio frequency choke coils) to the new second, tapped off, port, as well as through another radio frequency choke to the main amplifier output port via power supply and divider circuitry for providing power for the amplification circuitry of the motherboard and any other upstream or downstream amplifiers as desired. If the plug-in board is removed, the RF signals arriving at the input port are fed directly through the amplification circuitry of the motherboard to the main amplifier output port and the AC signals are fed directly through the radio frequency choke to power supply and divider circuitry for powering the amplification circuitry and to the main amplifier output port.
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Jelinek Catherine W.
Palazzo Mark A.
Vogt Stephan W.
Barnhardt III Hubert J.
Faile Andrew
Gardner Kelly A.
Massaroni Kenneth M.
Scientific-Atlanta, Inc.
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