Abstract:
In one embodiment, a method for electrically connecting a stinger into a network node may include installing a non-conductive force exerting means through a port of a closed node housing of a network node. The method may include extending the force exerting means from outside the node housing to within the interior of the network node and adjusting the force exerting means without accessing the interior of the node housing to exert a force on the conductor of a stinger installed within the interior of the network node to contact and forcibly bring the conductor of the stinger into electrical contact with an interface means installed within the interior of the network node to establish an electrical interface and seize the conductor of the stinger within the interior of the network node.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application is a divisional application of U.S. patent application Ser. No. 10/947,586, filed Sep. 22, 2004, which is a divisional application of U.S application Ser. No. 10/319,128, now U.S. Pat. No. 6,811,447, filed Dec. 13, 2002, which claims priority to U.S. provisional patent application No. 60/340,403, filed Dec. 14, 2001, which is incorporated herein by reference. 

   FIELD OF THE INVENTION 
   This invention relates, generally, to communication networks having radio frequency (“RF”) amplifiers, and, more particularly, to connections at network nodes. 
   BACKGROUND 
   As broadband networks continue to move from the experimental realm to the order of the day for network and service providers, the competition-driven need for providers to reduce costs of implementation increases proportionally. Community Antenna Television (“CATV”) has traditionally relied on metallic coaxial (“coax”) cabling to deliver video signals. The conductors that transport the signals through the network may be typically connected at various points within the network, such as head ends, or central offices, nodes and subscriber premise equipment (“SPE”) devices. The conductors are typically connected at the various types of equipment with connectors that are typically designed to minimize signal loss and to have impedance that matches that of the conductor(s) being connected. 
   The nodes may include electrical devices that are located outdoors and may be aerially hung from a conductor strand. Whether a node is mounted inside a cabinet affixed to the ground, or installed aerially, a technician typically installs a stinger, a device known in the art for providing an RF connection through a penetration into a housing. The stinger may comprise a hollow metallic shell threaded on the outside, a center conductor and a dielectric interposed between the conductor and the inner surface of the shell. The center conductor projects axially from the stinger such that the device resembles a bee stinger, hence the name. There are various types and styles of stingers known in the art, some designed for lab testing and some designed for field-use. In a lab-test style stinger, the end opposing the projecting conductor typically has a RF terminal. The field-use stinger typically has a mechanism for capturing and transferring electrical signals to the shield and conductor of a coaxial cable. The stinger is threaded into the node housing penetration, which is typically threaded to receive the stinger. When the stinger is in the installed position, the conductor projection into the node housing is guided into a predetermined position. The stinger conductor is guided by a guide device that may include a narrow channel to locate the conductor such that the nail head of a threaded seizure connector device may contact the center conductor when the seizure connector is screwed into place towards the guide, the axis of the seizure connector being perpendicular to the stinger conductor. Moreover, the seizure connector is typically screwed into place with a predetermined torque, the torque value determined to cause the center conductor to be “seized,” or clamped, between the nail head and a metallic button that is located on the surface of the guide device underneath the center conductor. 
   To guide an RF signal from the stinger conductor through the seizure connector, the nail head penetrates the seizure connector through a dielectric device and terminates with a conducting pin inside a barrel defined by the seizure connector. This forms the male end of an RF connector such that the center conductor penetrates a matching female RF connector affixed to an amplifier assembly that houses node-processing circuitry. Although this arrangement provides acceptable transfer of RF signal power into or out of a node, the process of installing a node or performing maintenance is cumbersome because the stinger must be installed before the seizure connector is screwed into place using a torque wrench. 
   The seizure connector is screwed into place before the amplifier is located within the housing and the connection between the network conductor and the node circuitry is made. Furthermore, if the torque value for installing the seizure connector is exceeded, the stinger center conductor may be deformed, possibly causing degradation of the transfer of the RF signal power from the stinger to the seizure connector. On the other hand, if the torque value is too low, the connection between the nail head of the seizure connector and the stinger conductor may not be sound, thus resulting in poor signal power transfer as well. In addition, even if the torque applied in installing the seizure connector is proper, the nail head surface, as well as the stinger conductor, may nevertheless become deformed. This is because the nail head is turning against the stationary stinger conductor as the force imparted to the conductor is increasing, thus gouging the contact surfaces, which may result in decreased transfer of signal power at RF signal frequencies. 
   To replace a stinger or remove a node, especially a node that is aerially hung from a strand, the amplifier, which may be secured into the node with a plurality of screws or other fasteners known in the art, must be removed. This typically requires opening the node housing, which may typically be a hinged, clamshell housing fastened with screws or other known fasteners. After the amplifier has been removed from the housing, the seizure connector is unscrewed so that the seizing, or clamping force, exerted by the seizure connector nail head towards stinger conductor and opposed by the guide button, is relieved so that the stinger can be unscrewed from the node housing. 
   Thus, there is a need for a method and system that reduces the number of steps for installing or removing a stinger from a node, thus resulting in a less cumbersome method of installing a node in a network. Furthermore, there is a need for a method and system for providing an even and constant exertion of force for maintaining contact between the stinger conductor and the nail head. There is also a need for a method and system for minimizing damage that may occur to the stinger conductor and nail head contact surface areas due to gouging as the seizure connector is screwed towards the stinger conductor. 
   SUMMARY 
   An objective of the invention is to provide a simplified method and system for seizing a stinger center conductor between a force exerting means and the end of a conducting pin, the pin being part of a connector means having an axis perpendicular to the axis of the center conductor, to facilitate transferring of electrical energy from the stinger to the connector. 
   It is another objective to provide a means of exerting said for such that a unique torque is not specified for providing contact between the stinger conductor and the pin. Furthermore, it is an object to provide a method and system for exerting said force in a substantially constant amount regardless of slight tolerance variations in the alignment among the stinger center conductor, the force exerting means and the pin of the connector. 
   It is yet another object to provide a method and system for exerting a force on the stinger conductor, thereby bringing it into contact with the center pin of the connector, but without gouging the surfaces of contact of the pin or the stinger conductor. 
   Generally described is a system for connecting an RF node into a network comprising means for electrically interfacing with a stinger signal conductor and means for exerting a resilient force opposing the interfacing means, the exerted force maintaining the stinger conductor in positive contact with the interface means. The exerting means may include a non-conductive plunger having a distal face for applying the exerted force towards the electrical interface means. A transition between the distal face and a side face of the plunger may be chamfered. The interface means may include a conductor button, also referred to as a nail head, for contacting the stinger conductor at a contact area, the button being at the end of a pin that functions as the center conductor through a dielectric. 
   The exerting means may be rigidly installed into a housing, the housing defining mounting holes for the exerting means and the stinger such that an axis of the exerting means and the interface means are coaxial. The interface means may be rigidly mounted and located to a circuit amplifier such that when the amplifier is installed into the housing, the stinger conductor may be interposed between the exerting means and the electrical interface means at a right angle to the axis of the opposing interface and exerting means when the stinger is installed into the housing. 
   Also generally described is a method for installing a node comprising the steps of rigidly attaching at a predetermined location on a circuit board of an amplifier an RF connector having an electrical interface, installing a stinger into a housing of the node and installing a force exerting means for resiliently forcing the center conductor of the stinger against the electrical interface of the RF connector. The amplifier may also be installed into the node housing before or after the exerting means has been installed. 
   A process to remove the node comprises the steps-of partially removing the exerting means from the housing to reduce or remove the force exerted against the stinger conductor and removing the stinger from the housing. The amplifier may also be removed from the node housing if the exerting means has not been removed. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  illustrates a typical outdoor strand mounting of a node. 
       FIG. 2  illustrates a typical node housing with modules installed. Two stingers are shown, one installed and the other before installation. 
       FIG. 3  illustrates an electrical interface aspect that penetrates an amplifier chassis and is attached to a printed circuit board. 
       FIG. 4  illustrates a plunger aspect for forcing a stinger conductor into contact with an electrical interface aspect. 
       FIG. 5  illustrates an installation of as electrical interface and a plunger, the plunger partially installed, into a node housing before electrical contact between the electrical interface and a stinger center conductor is made. 
       FIG. 6  illustrates an installation of as electrical interface and a plunger into a node housing such that electrical contact between the electrical interface and a stinger center conductor is made. 
   

   DETAILED DESCRIPTION 
   As a preliminary matter, it readily will be understood by those persons skilled in the art that the present invention is susceptible of broad utility and application. Many methods, embodiments and adaptations of the present invention other than those herein described, as well as many variations, modifications, and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the following description thereof, without departing from the substance or scope of the present invention. 
   Accordingly, while the present invention has been described herein in detail in relation to preferred embodiments, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for the purposes of providing a full and enabling disclosure of the invention. The following disclosure is not intended nor is to be construed to limit the present invention or otherwise to exclude any such other embodiments, adaptations, variations, modifications and equivalent arrangements, the present invention being limited only by the claims appended hereto and the equivalents thereof. Furthermore, while some aspects of the present invention are described in detail herein, no specific metallic, plastic or other material, housing or chassis shape, or connector size, for example, is required to be used in the practicing of the present invention. 
   Turning now to the figures,  FIG. 1  illustrates a typical architectural scenario  2  of a broadband network where a network node  4  is strand-mounted from a support wire  6 . Cables  10 ,  11 ,  12  and  13  may typically be coaxial cables for transmitting RF signal information as well as AC power. Information signals may be provided to and transmitted from node  4  via multiple optical fiber inputs in line bundle  8  and returned to the network via output lines  10 ,  11 ,  12 , and  13 . Node  4  typically provides information signals to subscribers via subscriber drop line. Coaxial cables may each be connected to a connector means at the outside of the housing of node  4 , the connector means typically passing the signal through a penetration in the outer wall of the housing. The connector means that passes are typically designed to provide a watertight seal, since node  4  is exposed to the elements, as opposed to merely passing a cable through a hole in the side of the housing and directly connecting the cable to a circuit board inside. 
   Turning now to  FIG. 2 , a node housing  14  is shown in an open state. As shown in the drawing, housing  14  may typically be a hinged clamshell enclosing various components, such as modules  15  A-n, in the lower portion, or lid  16  of the housing. The upper portion  18 , or base, of node housing  14  may typically contain an amplifier chassis  19  shown in the drawing as a chassis outline for clarity, the chassis typically being a rigid frame like structure for mounting a printed circuit board (“PCB”). The term “amplifier” and function thereof are known in the art and the PCB circuitry typically includes means for providing RF signal interface functionality. For example, this functionality may include separating or isolating a low frequency power supply signal from a high frequency RF signal, before the separated or isolated signals are further processed and then provided to or received from modules  15  and other circuitry contained in lid  16 . It will be appreciated that only the outline of amplifier  19  is shown, although the edges hidden by base  18  are shown as dashed lines. Otherwise, as amplifier  19  would obscure their view, some items to be described hereafter in connection with  FIG. 2  would have to be shown with dashed lines, thereby reducing clarity. Similarly, the PCB is not shown in the drawing for clarity so as not to obscure the view of items to be discussed hereafter. However, amplifier  19  as used in the illustrated embodiment may be thought of as a rectangular baking dish oriented so that the viewer of the figure is looking into the dish with the PCB being inside the dish, the bottom of the “amplifier” being oriented into the drawing when placed within base  18 . 
   As discussed above, a watertight connection is provided to pass the RF and power signal from a coaxial line through node base  18 . The signal typically penetrates base  18  via a stinger  20 , stingers being known in the art. Stinger  20  may be threaded so that matching threads in port  22  receive the stinger, which may also locate a sealing o-ring or gasket between nut  24  and port  22 . Stinger  10  typically has a capture and locking mechanism at network side  26  for transferring electrical signals to connecting lines, such as lines  10 ,  11 ,  12 , and  13  shown in  FIG. 1 . The housing side of stinger  20  typically includes a center conductor  28  that transfers a non-grounded signal received at network side  26  to the inside of housing  14 . The stinger conductor  28  is typically forced into contact with another connecting means inside housing  14 , the other connecting means having an axis substantially perpendicular to the axis of stinger  20 , which runs coaxially with center conductor  28 . The other connecting means is typically part of a system of two assemblies, which will be described infra, the system being referred to as a seizure mechanism. 
   One of the assemblies, a force exerting means  30 A-n, typically is installed into the into ports  32 A-n of base  18 . The force from exerting assembly  30  is opposed by an RF electrical interface means  34 , which is typically mounted rigidly to a PCB that is located by amplifier chassis  19 . Amplifier chassis  19  locates interface means  34  such that the coaxial axis of the interface means and exerting means  30  is substantially perpendicular to the axis of stinger  20 , such that conductor  28  intersects said coaxial axis. It will be appreciated that there will typically be a like number of interface means  34  as there are exerting means  30  and stingers  20 . However, only one interface means  34  is shown in  FIG. 2  for clarity. Furthermore, all ports  22  and  32 , and hence stingers  20  and exerting means  30  respectively, need not be located at one end of housing  16 , as those skilled in the art can determine the best location of these items, based on particular installation needs. It will further be appreciated that housing  16  may be manufactured with a plurality of ports  22  and  32 , in number greater than the number actually used, in which case the unused ports could be sealed with a blind plug known in the art, such as a port plug, for example. 
   Turning now to  FIG. 3 , the electrical interface means  34  of the connector system is illustrated in detail. The interface assembly  34  is attached to PCB  36 , which is mounted to amplifier chassis  19 . The body of interface  34  may typically be made out of a conducting material, such as brass, for example, and may comprise a castellated ring section  38 , the castellations  40  defining PCB mounting prongs  42  projecting from said castellations. It will be appreciated that although two castellations  40  and prongs  42  are shown, the number of castellations and prongs may be more or less than two. 
   The body of interface  34  further includes barrel  44 , which extends from ring section  38 . Barrel  44  extends from ring  38  to the extent that it passes through and beyond amplifier chassis  19 . Furthermore, barrel  44  may typically be threaded around the outside to receive retaining nut  46 . Thus, barrel  44  extends beyond outer face  48  of amplifier chassis  19  to provide enough threads for securing interface  34  and chassis  19  with nut  46 . It is noted that the cross section of ring section  38 , as well as nut  46  will typically be larger that the hole in chassis  19  through which barrel  44  passes. Thus, interface assembly  34  may be rigidly attached to chassis  19  for mechanical stability, and, in addition, to provide system ground interconnection from the chassis to the interface assembly. This also bolsters the ground interconnection between chassis  19  and PCB  36  if prongs  42  are attached to ground traces, such as with solder, for example. 
   To provide RF signal transfer, dielectric  50  is forcefully retained within barrel  44  and extends through and past the projected extent of the barrel. Within dielectric  50 , conducting pin  52  is forcefully retained, and may be soldered to PCB  36  at solder ball  54 . Conducting pin  52  extends past the dielectric projection approximately 0.125″, for example, whereupon the pin flares slightly to create a nail head surface  56  that provides a contact surface for the stinger center conductor, as described above. 
   Turning now to  FIG. 4 , exerting means  30  is shown in the preferred embodiment as a plunger arrangement. The body of exerting means  30  includes barrel  58 , plunger  60  and spring  62 . Spring  62  is compressed within barrel  58  such that plunger  60  is motivated away from flange  64  and hexagonal head  66 . Plunger  60  is restrained from being expelled from the barrel as plunger base  68  is forced into contact with stop lip  70 . Barrel  58  is threaded so that after a stinger has been installed into a node housing, a technician may install the exerting means  30  into the node housing by turning hexagonal head  66  with a wrench. Application to exerting device  30  of a unique and specifically narrow unique torque value, or range of values, is not required when installing it to ensure that the force exerted against a stinger conductor is within a narrow range. This is because plunger  60  is spring loaded with spring  62 , which is preferably a coil or other type of spring having a typically linear force versus displacement curve. 
   Thus, manufacturing tolerance of the distance between flange  64  and plunger end  72  need not be extremely precise to ensure that a predictable force is applied to the stinger conductor. If spring  62  is manufactured to have sufficient deflection (preferably on the order of approximately four or five times the diameter of the stinger center conductor, but can be more or less, depending upon criteria determined by one skilled in the art), a field technician may turn hexagonal head  66 , which is rigidly connected to barrel  58 , until flange  64  is stopped against the outside of the node housing. An additional quarter turn for example, may be applied to hexagonal head  66  to ensure that it is adequately seated against the housing. Thus, installation is quick and easy, without the requirement of using a torque wrench, or other special tools. The nominal excess deflection designed into the compression length of spring  62  compensates for differences in length between plunger end  72  and flange  64 , as well as other slight manufacturing differences, such as, for example, the distance between the housing face against which flange  64  stops and the centerline of the penetration into which a stinger is installed. 
   Along with the even exertion of force provided by the spring loaded characteristic of plunger  60 , chamfering of plunger end  72  may further facilitate installation of a stinger into a node for a new installation, or even an existing node upon which coaxial line maintenance is being performed. To reinstall the stinger, the plunger  60  will typically be loosened a few turns to provide clearance between plunger end  72  and the nail head. 
   Turning now to  FIG. 5 , housing base  18  is shown with amplifier assembly  19  and stinger  20  installed. Amplifier chassis  19  is shown with support legs dashed for clarity, although the legs would be as visible as the rest of the chassis as shown in the figure. Exerting device  30  is shown partially installed; it will be appreciated that as hexagonal head  66  is turned clockwise (for right hand threads), the exerting device will move closer and closer to interface  34  until plunger end  72  contacts stinger conductor  28 . This contact forces stinger conductor  28  into contact with nail head  56  to result in electrical connection between RF path  74  of stinger  20  and solder ball  54  on PCB  54 . After plunger  72  contacts conductor  28  and pushes it against nail head  56 , turning of hexagonal head  66  may continue without damage occurring to the stinger center conductor, because spring  62  compresses as flange  64  moves closer to housing  16 . If spring  62  is a properly designed coil spring, for example, its characteristics should obey Hooke&#39;s Law, which is F=k*x. F is the force exerted by a linear spring, x is the amount of distance a spring has deflected from its rest state and k is known as the spring constant. If exerting device  30  is manufactured such that spring  62  is in a partially compressed state, a force in accordance with Hooke&#39;s Law will be exerted against plunger base  68  and flange  64 , which is rigidly attached to barrel  58 . This force may be referred to as the preload (P) of spring  62 . Thus, the as-installed force equation representing the force exerted by plunger  72  when it forces conductor  28  into contact with nailhead  56  is F=P+k*x. 
   If device  30  is manufactured such that k is low and preload P is less than the force that could cause damage to either conductor  28  or interface  34 , then the force applied by plunger  72  will be essentially the preload force P regardless of how many turns ofas hexagonal head  66  are used to bring flange stop  64  into contact with the node housing, the final position of the plunger for forcing the conductor into contact with nailhead  56 . Those skilled in the art will appreciate that although the force will increase proportionally with deflection of spring  62  (caused by continued turning of hexagonal head  66  after plunger  72  has motivated conductor  28  into contact with nail head  56 ), if the spring constant k is kept low, the increase will be slight. Accordingly, for all practical purposes, the changes in force pushing conductor  28  against nail head  56  will be negligible as hexagonal head  66  is turned after plunger  72  contacts conductor  28  and conductor  28  subsequently contacts nail head  56 . 
   Turning now to  FIG. 6 , housing base  18  is shown with amplifier assembly  19  and stinger  20  installed. Exerting device  30  is shown fully installed with plunger  72  exerting force against conductor  28 , the exerted force pushing conductor  28  against nail head  56 . It is noted that hexagonal head  66  has been turned until flange  64  seated against port  32 . It is also noted that plunger  72  extends a smaller distance beyond the top of device  30 , and that plunger  68  (shown in dashed lines behind the threads of barrel  58 ) is recessed into the barrel, as compared to the same items as shown in  FIG. 5 . It is further noted that the coils of spring  62  are closer together, indicating that the spring has deflected to accommodate the seating of flange  64  against port  32 . As discussed above, if spring  62  has a properly designed spring factor k, the force exerted by plunger  72  against conductor  28  will fall within a range between zero, when the plunger first contacts the conductor, and possibly up to a value slightly higher than preload P. Thus, regardless of manufacturing tolerances of the dimensional relationship between the centerline of port  22  and the plane of housing  18  in which port  32  lies, or the dimensional relationship of nail head  56  thereto, stinger  20  may be installed and reliably connected to the nail head by screwing exertion device  30  into port  32  until flange  64  bottoms thereon. Therefore, a field technician need not have to remove amplifier chassis  19  in order to install stinger  20  into housing  16 , nor have to apply a predetermined torque to device  30  to ensure positive electrical contact between conductor  28  and nail head  56  while preventing damage from over tightening. Accordingly, time needed for a technician to install or maintain a node is reduced. The spring may also be designed not to exert too much force that would damage the stinger in the case that the amplifier is removed for maintenance while the plunger is still installed from the initial installation. This design provides an additional benefit to the technician when servicing the amplifier. The amplifier may be removed and replaced without removing the stinger from the housing. 
   These and many other objects and advantages will be readily apparent to one skilled in the art from the foregoing specification when read in conjunction with the appended drawings. It is to be understood that the embodiments herein illustrated are examples only, and that the scope of the invention is to be defined solely by the claims when accorded a full range of equivalents.