Abstract:
A multi-port optical node is disclosed. The optical node is configured to send and receive optical and radio frequency data signals over a data distribution network. The data signals enter and exit the node through cables connected to ports of the main housing of the node. The main housing has a plurality of slots configured to accept a plurality of electronic modules. The electronic modules provide the basic functionality of the optical node including the power supply and transmitters and receivers for sending, receiving and converting of data signals. The electronic modules are approximately all the same size thus they can occupy any of the slots of the main housing. The modules further can be monitored and controlled via a serial system bus.

Description:
FIELD OF THE INVENTION 
     This invention relates to an improved method and apparatus for receiving and transmitting data signals over a multi-port optical node. 
     BACKGROUND OF THE INVENTION 
     In recent years, the Cable Television (“CATV”) industry has been extending its traditional mandate by providing new television-based entertainment applications to even more and more subscribers. The new applications include for example, broadband telecommunications, interactive multimedia, and video on demand (“VOD”). As the variety of new applications and the number of subscribers continue to increase, the distribution systems for CATV plants (the physical implementation of the system) must be continually modified and upgraded. To handle the growth, the CATV equipment must be reliable and rapidly configurable. Such growth has led the CATV operators to change the implementation of distribution systems from an all coaxial tree-and-branch architecture to the multi-port optical node design used, for example, with fiber optic networks. 
     Optical nodes are the point of connection and conversion between the fiber optic cable and coaxial cable of a distributed network. The data from the headend service provider is usually sent over the fiber cable of the network to a plurality of preconfigured optical nodes for broadcast via the coaxial cable into a plurality of homes serviced by each of the optical nodes on the network. Depending on network architecture, each optical node has a plurality of ports for providing a direct connection between the optical node and the external network for converting an optical signal back to a Radio Frequency (“RF”) signal for distribution in the CATV coaxial plant. 
     The major components of an optical node include an optical receiver which receives information-modulated light from an optical fiber and converts that information into an electrical signal, an optical transmitter which converts electrical signals that originate from the subscriber to information-modulated optical signals that are transported by optical fiber to a central location, a RF amplifier which provides additional gain and filtering for the electrical signals for distribution to subscribers, and a power supply which receives AC/DC electrical power for the optical node from the main cable or through a dedicated power line. 
     The typical optical node has its major components configured among electronic modules, fixed into specific slots in the node. The most prevalent optical node configuration in the market today has a total of four to six RF ports on the left and right sides of the optical node and which are serviced by a single RF amplifier module. One of the limitations of this configuration is that in the event of a failure of the circuitry driving one of the four ports, all four ports need to be removed from service to replace the offending RF module. As CATV delivery system reliability becomes increasingly important to be competitive with other telecommunication service providers, the up time of a system, as well as the number of subscribers affected by a given outage of service, become mission critical. 
     Another critical shortcoming with typical optical node implementation today is the ability of the system operators to have optical nodes that are field configurable. When modules are preconfigured and fixed into slots in an optical node, system planners have limited flexibility in how to configure the cables leading to the ports. A variety of environmental and space factors control how a node is ultimately installed at a location. This lack of flexibility in where the ports are on the node causes difficult installation requirements and, therefore, increases installation time. Little or no flexible expansion or configuration capability is typically available for an optical node installation today. 
     In yet another limitation of a typical configuration of an optical node, the electronic modules and slots of the optical node lack uniformity in size. Thus, electronic modules are limited to the slots of the node specifically built to house that particular module. This limits the system operator&#39;s ability to configure optical nodes for future expansion and forces them to over-configure individual nodes or add more nodes to the distribution network, both costly alternatives. 
     In still yet another limitation of a typical configuration of an optical node, power supplies that are rated for a fully loaded version of the optical node must be configured for each optical node. While this serves the long-term plans of a system build, the system operator is forced to buy much more capacity than is necessary for his short to intermediate term needs. 
     Therefore the intention of the present invention addresses inherent problems with current optical node design and deployment and presents the solution in a multi-port optical node that is scaleable, highly modular, and field configurable. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, an improved multi-port optical node is described. 
     Multi-Port Optical Node 
     The optical node is integrated into a data distribution network with the optical node configured to send and receive data of the distribution network. The optical node comprises a main housing. The main housing provides environmental protection and a thermal path to the ambient environment sufficient to allow all components internal to the main housing to operate below their specified limits in the maximum ambient temperature. The main housing further comprises a plurality of slots for the coupling of a plurality of electronic modules to the main housing. The modules are connected to the main housing node through a module interface connector of the node. The electronic modules are system components of the main housing that control the electronic aspects of the optical node. The main housing further comprises a plurality of ports. The ports provide data connectivity between the optical node, the electronic modules and the distribution network. 
     In another aspect of the invention, the optical node is comprised of control interfaces for routing of the data of the distribution network over the optical and RF components of the optical node. Additionally, the optical node has an interface for the routing of power from the main power connector of the optical node to a plurality of electronic modules that comprise the optical node. 
     In another aspect of the invention, the optical node is comprised of a plurality of optical receiver modules, which receiver module receives information-modulated light from an optical fiber of the fiber management system and converts that information into an electrical signal for distribution over the data network. 
     In another aspect of the invention, the optical node comprises a plurality of optical transmitter modules, which transmitter modules convert electrical signals that originate primarily from the subscriber of the data services to information-modulated optical signals that are transported by optical fiber of the distribution network to a central location of the head end data service provider. 
     In another aspect of the invention, the optical node comprises a plurality of RF output modules, which RF output modules comprise the RF interface to the coaxial cable plant of the data distribution network via an AC/DC entry module and the main housing. 
     In another aspect of the invention, the optical node comprises at least one power supply module, which power supply module receives AC/DC electrical power for the optical node from the main cable or through a dedicated power line. The AC/DC power is converted to DC at regulated levels for distribution to any of the optical receivers, optical transmitters, and RF output modules deployed in the optical node. 
     In yet another aspect of the invention, return and transmit functions of the RF output, transmitter and receiver modules incorporate status monitoring for the purpose of controlling any of the plurality of the electronic modules via the external data cable and internally via the serial data bus of the optical node. 
     In yet another aspect of the invention, the optical node comprises at least one AC/DC entry module, which entry module provides the diplexing of the power and RF signals. 
     In still yet another aspect of the invention, the multi-port optical node comprises a uniform footprint of all modules. Thus, any module can be placed in any of the appropriate ports of the node. 
     In still yet another aspect of the invention, power supply modules can be added as needed to the optical node, including adding power modules to the node when the node has been activated on the distribution network. 
     In an alternative embodiment of the invention, there are two half-duplexed power supply modules of the optical node so that a plurality of power supply modules in parallel can power a plurality of electronic modules of the optical node. 
     Serial Data Bus 
     In another aspect of the present invention, there is provided a system and method for monitoring and controlling electronic module functions via a synchronous serial data bus of the optical node firmware. In the preferred embodiment of the invention, the serial data bus consists of wired and bi-directional, data and clock lines. The lines are connected to an electronic module via a module connector on the module controller. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The many features and advantages of this invention are better understood with reference to the following detailed description of the preferred embodiment, along with the following drawings. 
     FIG. 1 is a top view of an embodiment of a main housing of the multi-port optical node; 
     FIG. 2 is a block diagram of a data communications subsystem of the present invention; and 
     FIG. 3 is a functional diagram of a module controller used with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention is a multi-port optical node that is integrated into a data distribution network. The optical node is configured to send and receive distribution network data between a data provider and a data subscriber. The data distribution network data is sent over the network from a service provider as optical data signals to the optical node, where the optical node receives the optical data signals and converts them to RF signals for distribution over a coax cable plant to the subscriber&#39;s equipment. 
     FIG. 1 is a top view of the preferred embodiment of the multi-port optical node. The optical node has a main housing assembly  10  that is constructed into two sides, a main housing base  105  and a main housing lid  110 . Each side of the optical node accommodates a plurality of slots  20 - 95 . The slots are capable of accommodating an electronic module. The electronic module is a device that provides power supply to the optical node or sends and receives data signals through the node. The electronic modules are of a fixed dimension to ensure modularity. Both the housing base  105  and the housing lid  110  accommodate a plurality of modules. While the preferred embodiment is illustrated with a fixed plurality of slots for each of the sides of the main housing for the accommodation of the electronic modules, the number of slots is flexible to meet the installation requirements of a particular optical node. 
     The main housing  10  includes at least one main optical connector port  12  that provides the point of entry and exit for the optical data signals of the distribution network, and at least one coax cable plant port  14  that provides the point of exit for the converted optical data signals to RF data signals compatible with the receiving devices of the subscribers of the data distribution network. While the preferred embodiment is illustrated with a fixed plurality of ports for each of the sides of the main housing for the incoming and outgoing of data signals, the number of ports is flexible to meet the installation requirements of a particular optical node. 
     The electronic modules include but are not limited to an RF output module, power supply module, and optical transmitter and receiver module. The RF output module provides additional gain of the electronic data signals that are distributed to subscribers of the data services of the distribution network. The power supply module receives AC/DC electrical power for the optical node from the main cable or through a dedicated power line. The AC/DC power is converted to DC power at regulated levels for distribution to the RF output module, optical transmitter and receiver module, and other electronic components of the optical node. The transmitter module converts electrical signals to information-modulated optical signals that are transported by at least one optical fiber of the data distribution network back through the optical port  12 . The receiver module receives the optical data signal from the optical fiber connected to the optical port  12  and converts that information into an electronic signal for distribution through the coax cable connected at the RF port  14 . 
     The main housing slots are highly modular and configurable to accommodate multiple electronic module configurations in any of the plurality of the slots of the main housing  10 . The housing base  105  and the housing lid  110  include a plurality of slots having approximately the same dimensions. An advantage of the present invention allows any of the electronic modules to be housed in any of the slots of the main housing  10 . This allows the optical node to be configured at the site of installation by allowing modules to be added as needed. An additional advantage is that the modularity of the electronic modules allows the optical nodes to be more easily installed because the modules can be placed in a main housing slot in a location that is advantageous for positioning the node for cable connections. 
     The present invention monitors and controls node functions of the multi-port optical node. FIG. 2 is a block diagram of the preferred embodiment of a data communications system  220  to monitor and control the internal functions of the modules housed in the optical node. The system is preferably implemented through a 2-wire synchronous serial data bus  225 . All control and data signals are routed through the electronic modules  245  over the synchronous serial data bus  225  through a connector on a module controller  230  included with each electronic module and through a node controller  235  included in the main housing  10 . A serial interface  240 , for example RS485, is implemented between an RF modem  250  included in the main housing  10  and the node controller  235  to support the addition of, and communication with network monitoring equipment. The node controller  235  provides the management for monitoring and controlling modules  245  of the data communication system  220 . Furthermore, the node controller  235  includes a processor that is preprogrammed to view all modules  245  as having the same logical monitor and control capability. Thus, any module  235  in a slot can accept any system monitoring or control function carried out by the node controller  235 . If the monitoring or control function is not applicable to a module  245 , the module ignores the function. For example, if the node controller  235  sends out a data signal to power up a power supply, all modules receive the data but only the power supply module actually acts upon the data command. Further managed functions include, for example, the power to each module, the occupancy of a slot by a module, and other like functions. While the preferred embodiment of the present invention implements the monitoring and control system discussed below through firmware stored in non-volatile memory associated with an electronic module, the system can be implemented in other ways known in the art including, for example, via RAM chips, or EEPROMs or other comparable devices. 
     Referring to FIGS. 1 and 2, when a module is inserted in a slot, the module  245  is assigned by the module controller  230 , by a processor included in the module, a unique identification code that is easily identifiable to the node controller  235  for monitoring and controlling the module. The node controller  235  uses this data for example, to detect a data signal, thereby sensing that a module is connected to a slot. When a module has been identified as being connected to a slot, it is further monitored over the data bus  225  to ascertain module problems and provide remote control of module functions via the node controller. 
     FIG. 3 is a functional diagram of a preferred embodiment of a module controller  230  used with the present invention. Each module controller  230  provides non-volatile volatile storage memory for storing an electronic module model number, serial number, date of manufacture, and any calibration data required for module operation of the modules referred to earlier in FIG.  1  and any other module housed in the main housing  10  of the optical node. Referring to FIG. 2 and 3, the data routed over the serial bus  225  through the module controllers  230  is digital or analog and is appropriately converted as discussed below to its necessary signal for interpretation by the module controller  230 . The module controller comprises a plurality of components that include analog-to-digital-converters (“ADCs”)  255 - 270 , at least one 8-bit digital-to-analog-converter (“DAC”)  275 , at least one 8-bit digital sense line  280 , at least one 8-bit digital control line  285 , and at least 4-bits for slot ID  295 . Data representing measurements or the states of the slots are maintained in an appropriate input or output data buffer  300  and  305 . The module controller  230  includes a control register  310  and a configuration register  315 . The state of the module controller  230  (for example, on/off) and the nature of the data transfer expected for the monitoring and control of the optical node (for example, the data to be sent is a control function for modules  245 ) are provided by the control register  310  and the configuration register  315 . Additionally, a module data records file  320  provides to the control register  310  and configuration register  315 , a physical location and information about the module controller  230 . An address register  325  holds the module controller&#39;s read/write address for receiving particular controlling data from the node controller  235 . An advantage of the present invention is to use the slot location data of modules to move the modules to other slots when necessary with little or no downtime of the optical node. 
     While the preferred embodiment of the system to monitor and control the modules of the optical node is described above, the system can be implemented with a variety of permutations of the components described. 
     While this invention has been described in terms of preferred embodiments, there are alterations, permutations, and equivalents that fall within the scope of this invention. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow, including all such alterations, permutations, and equivalents as fall within the true spirit and scope thereof.