WO2005125112A2

WO2005125112A2 - Field configurable node return path

Info

Publication number: WO2005125112A2
Application number: PCT/US2005/020641
Authority: WO
Inventors: Kenneth E. Maricondo; Kenneth K. Richey
Original assignee: Db-Tronics, Inc.
Priority date: 2004-06-10
Filing date: 2005-06-10
Publication date: 2005-12-29
Also published as: WO2005125112A3

Abstract

A typical non-scalable node/amplifier has the all its return path ports combined into one common path prior to the optical return transmitter. With a typical return path bandwidth being only 5 MHz to 40MHz wide, the return path bandwidth gets allocated quickly with services such as cad a modems, telephony, and video on demand (VOD). In certain cases, the ability to segment the return path is desirable to increase the return path bandwidth; but unless the node/amplifier is replaced entirely with a scaleable node, segmentation of the return path ports for an existing node/amplifier is unattainable in present conditions. The return path segmenting circuit and dual return amplifier with a common heat sink presented allows the return path ports of node/amplifier to be configured in any number of combinations, thus allowing return path/ports segmentation depending upon the desired segmentation required by the CATV/Telecom operator.

Description

FIELD CONFIGURABLE NODE RETURN PATH

RELATED APPLICATION The present application relies on US Patent Application No 60/578,604 filed June 10, 2004 and entitled Field Configurable CATV Return Path Node Port Combiner/Splitter Network Using A Dual CATV Return Amphfer With A Common Heat Sink

BACKGROUND OF THE INVENTION A typical CATV node/amplifier that is return path non-segmented or non-scalable limits that amount of RF return traffic returning back to the headend With the addition of cable modems, telephony, and video on demand (VOD), return path traffic has increased greatly over the years In order for a CATV7 telecom operator to capitalize on the revenue generated by the return path traffic, a CATV/telecom operator must have sufficient bandwidth for the amount of given customers off a node/amplifier One way to increase the return path bandwidth is to replace entirely the current node/amplifier housing with a more expensive node/amplifier housing, e g , with scalable features that allow the node/amplifier to segment the return path within the node and by additional return path optical transmitter allow for the segmented path to be returned optically to the headend SUMMARY OF THE INVENTION The primary objective of the invention is to provide a CATV/Telecom operator with the flexible ability to segment the return path while still using an existing non-scalable node/amplifier It has been shown that a typical non-scalable node/amplifier has the all return path ports combined into one common path prior to the optical return path transmitter With the use of segmenting boards or a modified diplex filter, dual return RF amplifiers and second/dual return path optical transmitter, the return path ports of a node/amplifier can be segmented All of the design examples described in this paper have been reduced to practice, and it is the belief of the inventors that these concepts and designs will work in/on other the vendors' nodes/amplifiers

The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification However, both the organization and method of operation of embodiments, together with further advantages and objects thereof, may best be understood by reference to the following descnption taken with the accompanying drawings wherein like reference characters refer to like elements

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of embodiments, and to show how the same may be earned into effect, reference will now be made, by way of example, to the accompanying drawings in which

FIGS 1-5 illustrate implementation of a first embodiment of the present invention

FIGS 6-11 illustrate implementation of a second embodiment of the present invention

FIGS 12-15 illustrate implementation of a third embodiment of the present invention

FIGS 16-23 illustrate implementation of a fourth embodiment of the present invention

FIGS 24-27 illustrate various heat sinks as applied to embodiments of the present invention

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Embodiments of the present invention allow return path segmentation of existing nodes thereby avoiding a need to replace the existing node/amplifier housing For example, by removing and/or modifying existing return path plug-in circuitry and adding an additional return amplifier and return optical transmitter, the return path of a node/amplifier can be segmented into l x 3, 2 x 2 or a l x 2 port configuration, depending on the node/amplifier used for segmentation Embodiments of the present invention thereby provide a field configurable CATV return path node port combiner/splitter network using a dual CATV retum amplifier with, in come cases, a common heat sink

For the following examples, it is assumed that a field engineer or technician will understand and know how to assemble and disassemble a node/amplifier to perform the following installation of new parts as well as the removal of old parts It is further assumed that the field engineer or technician will know how to rebalance the RF paths/ports of all of the examples below EXAMPLE A' FIG 1 (Prior Art) is a typical block diagram of an Augat/Scientific Atlanta 6940 node/amplifier FIG 2 is an example of the electrical segmentation circuit according to an embodiment of the present invention for the Augat/Scientific Atlanta 6940 optoelectronic node/amplifier of FIG 1 FIG 3 is a photograph of the electrical segmentation circuit of FIG 2 as mounted in the Augat/Scientific Atlanta 6940 optoelectronic node/amplifier of FIG 1 FIG 4 is the node/plug-m layout for 2 x 2 segmentation combinations for the Augat/Scientific Atlanta 6940 optoelectronic node/amplifier of FIG 1 as provided by the electrical segmentation circuit of FIG 2 FIG 5 is the node/plug-in layout for 1 \ 3 segmentation combinations for the Augat/Scientific Atlanta 6940 optoelectronic node/amplifier of FIG 1 as provided by the electrical segmentation circuit of FIG 2

With reference to FIGS 1-5, the Augat Scientific Atlanta 6940 optoelectronic node currently combines all of the return paths into one path via the plug-in RF combiner board PDD2 and then all of the signals are returned on one return path optical transmitter (see FIG 1 for a block diagram and parts location) In order to segment the 6940 optoelectronic node/amplifier, first the field engineer or technician brings to the site a new return path combiner board (FIGS 2 and 3) and configures the new retum path combiner board for a 1 x 3 (FIG 5) or a 2 x 2 (FIG 4) port combination FIGS 2, 3, 4 and 5 illustrate such configurations and port combinations Second, the field engineer or technician removes the original plug-in RF combiner board PDD2 and places the RF adapter board of FIG 2 in the plug-m location of the original RF combiner board PDD2

Third, the field engineer or technician then will plug in place the new RF segmenting board on top of the new RF adapter board in accordance to what ports are to be routed FIGS 4-5 illustrate port configuration arrangements Forth, the field engineer or technician will then place in the new segmented high gam return path optical transmitter and route its input RF cable over to the new RF adapter board and plug it into Jl (see Fig 3 ) Lastly, the field engineer or technician will connect up the fiber optic pigtail of the high gain return path optical transmitter to a dark fiber optic in the fiber optic cable going back to the headend At the headend, an additional new return path receiver will receive the new return path for said node/amplifier Installation and return path segmentation complete In this return path example there was no need to use a dual return amplifier with a common heat sink, because the hybrid that is used in the existing version of the return path optical transmitter was replaced out with a higher gain hybrid In addition to replacing out the hybrid, the input lead was terminated with a 75 ohm resistor and the input DC blocking capacitor on the RF path was removed, so that a new RF cable could be connected to provide the RF from the new RF segmented board (Jl, TX B) (see Fig 3 ) The purpose of the 75 ohm resistor is to provide an RF termination for the unused leg of the splitter that provided RF to primary and secondary transmitters when they were both used in the old configuration

EXAMPLE ^CB' FIG 6 (Prior Art) is a typical block diagram of a General Instruments/Motorola

Starlme Broadband Telecommunications Node (BTN 2) FIG 7 (Prior Art) is an example of the electncal schematic for the combiner circuit for the General Instruments/Motorola Starlme Broadband Telecommumcations Node (BTN 2) of FIG 1 FIG 8 is an electrical schematic for a segmentation circuit according to an embodiment of the presentation for a General Instruments/Motorola Starlme Broadband Telecommunications Node (BTN 2) FIG 9 is a photograph of the electrical segmentation circuit of FIG 8 as mounted in the General Instruments/Motorola Starlme Broadband Telecommumcations Node (BTN 2) of FIG 1 FIG 10 is a photograph of the electrical segmentation circuit of FIGS 8 and 9 with a dual hybrid common heat sink for the General Instruments/Motorola Starlme Broadband Telecommunications Node (BTN 2) of FIG 1 FIG 11 is a photograph of the electrical segmentation circuit with the dual hybπd with common heat sink for a General Instruments/Motorola Starlme Broadband Telecommunications Node (BTN 2) In FIG 11, pad port selectors are shown The General Instruments Motorola Starlme Broadband Telecommunications Node (BTN

2) also employs a plug-in RF combiner board that is used to combme all of the return RF ports together (see FIG 6 for a block diagram and parts location) In order to segment the BTN 2 node/amplifier, first the field engineer or technician removes the old RF combiner plug-in board and existing return path hybrid (see FIG 7, for a schematic example) Second, the field engineer or technician and plugs in the new RF combmer board and the dual retum path amplifier with common heat sink (see FIG 8, 9, 10, & 11, for a schematic example and for part locations and views) Third, the field engineer or technician screws down the dual return path amplifier with common heat sink and places (and screws down) the RF cable assembly on top of the dual return path amplifier with common heat sink

Forth, one end of the RF cable assembly will then be connected to the new RF combiner board via Jl (see FIG 10 ) The other end of the RF cable assembly is then routed over to the second return path optical transmitter (modified) and connected Lastly the RF combiner pads are then aligned to the desired return path port configuration needed for the BTN 2, using the arrow designation on top of the RF combiner pad to select RF path 'A' or 'B' (see FIG 11 ) EXAMPLE C FIG 12 (Prior Art) is a typical block diagram of a Scientific Atlanta 6920 optoelectronic node/amplifier FIG 13 is an example of a schematic diagram for an electrical segmentation circuit embodiment of the present invention for a Scientific Atlanta 6920 optoelectronic node/amplifier FIG 14 is a photograph of the electrical segmentation circuit of FIG 13 as mounted in the Scientific Atlanta 6920 optoelectromc node/amplifier of FIG 12 FIG 15 is a photograph of the modified Return Optical Transmitter for a Scientific Atlanta 6920 optoelectronic node/amplifier

The Scientific Atlanta 6920 optoelectronic node currently combines all of the return paths into one path via the plug-in retum path RF combiner board, and then all of the signals are returned on one return path optical transmitter (see FIG 12 for a block diagram and parts location) In order to segment the 6920 optoelectronic node, first the field engineer or technician must remove the old plug-in return path RF combmer board and return path amplifier Second, the field engineer or technician will place the new combination dual return path RF amplifier and combiner board in the old place of the retum RF amplifier and combiner boards, as well as install the second new optical return path transmitter (see FIGs 13, 14, & 15 for schematic and photos for the Dual RF Amplifier with Common Heat Sink and for the optical transmitters ) Third, the field engineer or technician will route the RF path 'B' over to second optical retum path transmitter and connect it up (see FIG 15 )

Since there is a some RF combining done on the main RF board, the return RF ports can only be segmented into two paths with RF port 'Main' going onto transmitter 'A' and port(s) 'Aux 1 ' and/or ' Aux 2" going onto transmitter 'B' The modified retum path optical transmitter will utilize an RF connector such as an 'F' or MCX connector mounted to the end to receive the RF path ^*B' from the new dual return path RF amplifier with common heat

EXAMPLE D' FIG 16 (Pπor Art) is a typical block diagram of a General Instruments/Motorola Starlme Mini-Bπdger node/amplifier FIG 17 (Pπor Art) is a block diagram for an electπcal segmentation circuit for a General Instruments/Motorola Starlme Mini-Bπdger node/amplifier FIG 18 is a photograph of an electπcal segmentation circuit embodiment of the present invention for General Instruments Starlme Mini-Bπdger node/amplifier of FIG 16 FIG 19 is a photograph of a Dual Return Optical Transmitter embodiment of the present invention for the General Instruments Starlme Mini-Bπdger node/amplifier of FIG 16 FIG 20 is an electrical assembly view (top) for a diplexer segmentation circuit embodiment of the present invention for the General Instruments Starlme Mini-Bπdger node/amplifier of FIG 16 FIG 21 is an electπcal assembly view (side) of the diplexer segmentation circuit of FIG 20 FIG 22 is an electrical cable assembly view for the diplexer segmentation circuit of FIGS 20-21 FIG 23 is a top side and bottom side drawing of the printed circuit board used to connect the RF inputs and outputs for the RF path 'B' on the dual return path amplifier with common heat sink of FIG

The General Instruments/Motorola Starlme Mini-Bπdger node/amplifier currently combines all of the retum paths into one path via the return path RF combiner network on the main RF board, and then all of the signals are amplified and returned on one return path optical transmitter (see FIG 16 for a block diagram and parts location) Since there are three RF returns (ports) and no plug-in return RF combmer board, the mini-Bridger nod/amplifier can only be segmented into two paths with port 2 feeding the original return path optical transmitter (see FIG 1 for the new block diagram and new parts locations) The second path (ports 3 & 4, the ports are combined on the main RF board pπor to the diplex filter) is normally feed through a plug-in diplex filter board, but instead of being routed through to the existing combiner network on the main RF board, the RF trace on the new diplexer filter board to pin 2 is cut and a coaxial cable is attached to reroute the RF path 'B' to a second return path RF amplifier on the a dual return path amplifier with common heat sink type # 1 (see FIG 18, for photo of the modified Diplexer Filter Board and Dual RF Amplifier with Common Heat Sink Type #1) In order to maintain an RF balance in the combiner network on the main RF board, the pin 3 is terminated with a 75 ohm resistor (805 surface mount package) to chassis ground (see FIGs 20, 21, 22, & 23 for part placements and assembly views for the Modified Diplexer Filter Board and the cable stripping guide)

In order to segment the Mini-Bπdger node/amplifier into two paths, first the field engineer or technician must remove the old existing plug-in diplexer filter board and return path RF amplifier Second, the field engineer or technician will place the new dual return path RF amplifier with common heat sink and diplexer plug-in board in the old places of the return RF amplifier and diplexer filter plug-in board (see FIG 18, for photo of the Diplexer and Dual RF Amplifier with common Heat Sink Type # 1 ) Third, the field engineer or technician will screw down the new dual return path RF amplifier with common heat sink Forth, the field engineer or technician will route the RF path 'B' from the new diplex filter over to second new dual return path RF amplifier with common heat sink and electrically connect/mount (screw down) the cable assembly to the new dual return path RF amplifier with common heat sink Fifth, the field engineer or technician will install the new dual optical return path transmitter, in place of the old optical return path transmitter (see FIG 19, for photo of the Dual Optical Transmitter) Lastly, the field engineer or technician will route the RF path 'B' from the new dual retum path RF amplifier with common heat sink over to the new dual return optical return path transmitter and connect up RF path 'A' as well to the new dual transmitter

A new dual return optical transmitter was designed to fit into a single older transmitter housing, since there us no additional room in the node housing to install a second optical return path transmitter This new return path optical transmitter will utilize an RF connector such as an 'F' or MCX connector to receive the RF path 'B' from the new dual return path RF amplifier with common heat sink, therefore, the existing optical retum path transmitter must be removed (see FIG 19, for photo of the Dual Optical Transmitter) Since there is a some RF combining done on the mam RF board, the return RF ports can only be segmented into two paths with RF port 2 combined onto transmitter 'A' portion of the dual transmitter housing (RF cable with an 'F' connector) and ports 3 & 4 combined onto transmitter 'B' portion of the dual transmitter housing (see FIG 19, for photo of the Dual Optical Transmitter)

HEAT SINKS FOR THE DUAL RF AMPLIFIERS For the Dual RF amplifier with a Common Heat Sink that was used in the SA 6920 node/amplifier, a peace of flat stock brass (copper and tin plated brass can also be used was well to dissipated heat into the node/amplifier housing) was bent up at a πght angle and screwed to the underside of the printed circuit board (see FIG 14 ), using self threading screws through the top of the PCB The Dual RF amplifier with a Common Heat Sink used on the General

Instruments/Motorola Starlme Mini-Bπdger node/amplifier was milled out of aluminum stock and has the following key features 1 a hole and notch for a 24 gauge wire to be routed through the block to provide power from the amplifier A' to amplifier 'B\ 2 the two mounting holes to secure the block to the node/ amplifier housing and recessed to allow clearance for the PCB used to provide mput and output connections for the RF path 'B' (see FIGs 24 & 55)

The Dual RF amplifier with a Common Heat Sink used on the General Instruments/Motorola Starlme Broadband Telecommumcations Node (BTN 2) node/amplifier was also milled out of aluminum stock and has the additional key feature a notch was cut out for the return path 'A' printed circuit board to be inserted during assembly into the node/amplifier, this notch provides a mounting location similar to the old mounting procedure for the old RF return cable assembly (see FIGs 26 & 27 ) Thus, embodiments of the present invention allow existing CATV/Telecom providers using existing node/amplifier to segment their return path ports to provide greater return bandwidth from a given node Electrical segmentation circuits according to embodiments of the present invention allow for the return path ports of a CATV broadband node/amplifiers to be segmented Electπcal segmentation circuits according to embodiments of the present invention are field configurable using modified pads and/or circuits or diplex filters Embodiments of the present invention make use of two electrical amplifier circuits placed on a common heat sink thereby allowing for compactness and thermal management of amplifier circuits

It will be appreciated that the present invention is not restricted to the particular embodiments that have been described and illustrated, and that variations may be made therein without departing from the scope of the invention as found in the appended claims and equivalents thereof

Claims

CLAIMS What is claimed is 1 A method of segmenting a network node return path, the method comprising identifying an installed node having non-segmented return path, removing from said node a first return path circuitry, said first return path circuitry being non-segmented, inserting into said node a second return path circuitry, and configuring said node at said second return path circuitry to originate a segmented return path

2 The method of Claim 1, wherein said first return path circuitry comprises plug-in circuitry demountable from a plug-in site of said node

3 The method of Claim 2, wherein said inserting step comprises inserting said second return path circuitry at said plug-in site of said node

4 The method of Claim 2, wherein said first return path circuitry comprises a plug-in RF combiner board 5 The method of Claim 4, wherein said second return path circuitry compπses a plug-in board

6 The method of Claim 1 , wherein said second return path circuitry compπses circuitry formed for insertion into said node in place of said first return path circuitry

7 The method of Claim 6, wherein said first and said second return path circuitry each compnse a plug-in circuit relative to said node

8 The method of Claim 1 , wherein said network compπses a CATV network

9 The method of Claim 1 , wherein said second retum path circuitry is field configurable 10 The method of Claim 9, wherein said second retum path circuitry is field configurable by at least one of modified pads, modifiable circuits, and diplex filters

1 1 The method of Claim 9, wherein said second return path circuitry is port configurable

12 The method of Claim 1 1, wherein node ports are selected for dedication to return path transmission 13 The method of Claim 9, wherein node ports are selected for configuration including at least one of a 2 by 2 port configuration and a 1 by 3 port configuration

14 The method of Claim 1 , wherein said second retum path circuitry compπses a retum amplifier coupled to a return optical transmitter

15 The method of Claim 1 , further compπsing couplmg said second return path circuitry to an unused optical fiber to optically inject therein to at least a portion of said segmented return path signal 16 In a CATV network including a plurality of existing nodes receiving forward optical signals and distributing said forward optical signals as RF signals to a plurality of RF ports and receiving at said RF ports a plurality of remm RF signals combined together within said node as a common RF signal and returned in common as a common return signal, an improvement comprising the steps modifying at least one of said existing nodes to maintain separate said plurality of return RF signals as a first subset of said plurality of return RF signals and as a second subset of said plurality of return RF signals, combining said first subset as a first segment return signal and applying said first segment retum signal to a first optical transmitter, and combining said second subset as a second segment return signal and applying said second segment retum signal to a second optical transmitter 17 The improvement of Claim 16, wherein said first optical transmitter previously earned said common return signal and said second optical transmitter couples to a previously unused optic fiber 18 The improvement of Claim 16, wherein said combining said first subset comprises combining and amplifying said first subset of said plurality of RF signals, and applying the combined first subset RF signal to said first optical transmitter 19 The improvement of Claim 18, wherein said first optical transmitter compπses a portion of said existing node

20 The improvement of Claim 16, wherein said combining said second subset compnses combining and amplifying said second subset of said plurality of RF signals, and applying the combined second subset of said RF signals to said second optical transmitter

21 The improvement of Claim 20, wherein said second optical transmitter is incorporated into said existing node in said modifying step

22 The improvement of Claim 16, wherein said modifying step mcludes removing an existing RF combiner circuit from said existing node and inserting therefor a modified RF combiner circuit to divide said plurality of RF retum signals into said first subset and said second subset

23 The improvement of Claim 22, wherein said existing RF combiner circuit compπses a plug-in circuit imtially coupled to said existing node at a mounting site and said modified RF combiner circuit couples to said node at said mounting site

24 The improvement of Claim 23, wherein said modified RF combiner circuit applies said first plurality of RF signals to said mounting site for transmission as said first segment return signal 25 The improvement of Claim 23, wherein said modified RF combiner circuit applies said second plurality of RF signals along an independent RF independent of said mounting site

26 The improvement of Claim 16, wherein said modifying step includes cutting a circuit trace of said existing node to route said RF return signal

27 The improvement of Claim 26, wherein said modifying step comprises routing said captured combined RF signal into said second subset and RF isolation termination of the first subset

28 The improvement of Claim 16, wherein said first optical transmitter couples to an optic fiber previously used to carry said common retum signal

29 The improvement of Claim 16, wherein said second optical transmitter couples to a previously unused optic fiber

30 The improvement of Claim 16, wherein a dual RF amplifier with common heat sink dπves said first and second optical transmitters

31 The improvement of Claim 16, wherein said method compπses selected routing of node ports along selected return paths by field configuration 32 The improvement of Claim 16, wherein said field configuration compnses modified RF combiner board orientation at a mounting site of said node

33 The network of Claim 16, wherein said modified RF combiner board includes port configuration pads and said field configuration comprises insertion path selectors at said configuration pad