GB2613600A - Cable network device - Google Patents
Cable network device Download PDFInfo
- Publication number
- GB2613600A GB2613600A GB2117722.5A GB202117722A GB2613600A GB 2613600 A GB2613600 A GB 2613600A GB 202117722 A GB202117722 A GB 202117722A GB 2613600 A GB2613600 A GB 2613600A
- Authority
- GB
- United Kingdom
- Prior art keywords
- series
- directional
- network device
- cable network
- upstream
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B3/00—Line transmission systems
- H04B3/54—Systems for transmission via power distribution lines
- H04B3/56—Circuits for coupling, blocking, or by-passing of signals
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P5/00—Coupling devices of the waveguide type
- H01P5/12—Coupling devices having more than two ports
- H01P5/16—Conjugate devices, i.e. devices having at least one port decoupled from one other port
- H01P5/18—Conjugate devices, i.e. devices having at least one port decoupled from one other port consisting of two coupled guides, e.g. directional couplers
- H01P5/184—Conjugate devices, i.e. devices having at least one port decoupled from one other port consisting of two coupled guides, e.g. directional couplers the guides being strip lines or microstrips
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/48—Networks for connecting several sources or loads, working on the same frequency or frequency band, to a common load or source
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/10—Adaptations for transmission by electrical cable
- H04N7/102—Circuits therefor, e.g. noise reducers, equalisers, amplifiers
- H04N7/104—Switchers or splitters
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/10—Adaptations for transmission by electrical cable
- H04N7/106—Adaptations for transmission by electrical cable for domestic distribution
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/005—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
Abstract
There is provided a cable network device, 50, such as a multitap device, comprising a first series of interconnected directional couplers, 56, connected to a downstream signal input, 52, with each directional coupler in the first series connected to a separate tap port, 60, and a second series of interconnected directional couplers, 62, connected to an upstream signal output, 54, wherein the downstream signal input, 52, and the upstream signal output, 54, are separate and pairs of directional couplers created from one directional coupler from each of the first series and second series are connected together to enable an upstream signal path routed through the tap port, 60, and directional coupler, 56, in the first series to reach the upstream signal output, 54. The directional couplers of the first series maybe microstrip couplers and the directional couplers of the second series maybe ferrite directional couplers.
Description
Title: Cable network device
Field of the invention
This invention relates to a cable network device for use in cable television and broadband networks and in particular to a multitap device.
Background of the invention
In a broadband network, amplifiers are used to amplify electric signals from a central network head end down to an individual user (downstream) or from the individual in user back to the head end (upstream). Upstream and downstream frequencies are separated in range, the upstream signals using a lower frequency range and the downstream signals using a higher frequency range. Multitaps are situated within the network to provide a plurality of ports for connection to user homes, each port typically connected to a single home.
To provide homes with an ever faster, more wideband, upstream signal network frequency ranges require altering and to accommodate this amplifier devices using directional couplers instead of diplex filters are often used as amplifier devices without diplex filters will accommodate changes in frequency ranges and do not require upgrading every time the frequency ranges alter, unlike amplifiers using diplex filters. However such amplifiers can cause degradation of downstream signal due to signal reflection.
Summary of the invention
In accordance with the invention, there is provided a cable network device comprising a first series of interconnected directional couplers connected to a downstream signal input with each directional coupler in the first series connected to a separate tap port, and a second series of interconnected directional couplers connected to an upstream signal output, wherein the downstream signal input and upstream signal output are separate and pairs of directional couplers created from one directional coupler from each of the first series and second series are connected together to enable an upstream signal path routed through the tap port and directional coupler in the first series to reach the upstream signal output.
Preferably each directional coupler connects to an adjacent coupler in the same series and also connects to a single directional coupler in the other series The directional couplers of the first series are preferably microstrip couplers with desirably a coupled port of the microstrip directional coupler connected to the tap port.
An isolated port of the microstrip coupler is preferably connected to the other in directional coupler in the pair of directional couplers.
Preferably the directional couplers of the second series are ferrite directional couplers.
The cable network device is preferably configured to have an isolation from the downstream signal input to an upstream signal output of greater than 40 dB, and more preferably greater than 60 dB The cable network device may be a multitap device.
Such a cable network device may be used in combination with an amplifier comprising a directional coupler to create separate upstream and downstream paths.
The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a schematic diagram of a prior art amplifier and multitap arrangement; Figure 2 is a schematic diagram of a multitap in accordance with the invention; Figure 3 is a schematic diagram of an amplifier for use with the multitap of Figure 2; and Figure 4 is a graph showing isolation with frequency for the multitap of Figure 2.
Description
A diagram of a prior art amplifier 10 used in a broadband, data and/or telecommunications network is shown in Figure 1, amplifier 10 using directional couplers 12, 14 instead of diplex filters to separate upstream and downstream signals for amplification. Input connector 16 receives downstream signal 20 and splits this into separate downstream and upstream paths using directional couplers 12, 14. Amplifier elements 22, 24 amplify signals conveyed along the uni-directional signal paths between directional couplers 12, 14. At output 26, amplified downstream signal 30 passes to splitter 32 which is connected to two 12-way multitaps 34, 34', each tap providing twelve tap ports for connecting users to the network.
Splitter 32 has a finite return loss and as such some of amplified signal 30 is reflected in back to amplifier 10. The reflected signal 40 travels upstream and is amplified by upstream amplifier element 24. At input 16 this amplified reflection signal 41 will again be partly reflected due to the finite return loss associated with input 16. The secondary reflected and amplified signal 42 travels back downstream, in the same direction as the original signal 20. Depending on the gain of amplifier elements 22, 24, signal levels, return loss, modulation and timing of the signals, these signal reflections can lead to degradation of original signal 20 In order to address these disadvantages, the present invention provides a 12-way multitap 50 as shown in Figure 2 which provides twelve tap ports as with prior art multitaps shown in Figure 1. Multitap 50 comprises a separate downstream input 52 and upstream output 54, with an interconnected series or cascade of twelve directional couplers 56 in the downstream path providing a connection to each tap port 60, 60', 60", 60-and an interconnected series or cascade of twelve directional couplers 62 in an upstream path returning upstream signals to separate upstream output 54. Each cascade is terminated by a resistor 55, 55', typically having a value of 75 Ohms. For multitaps with fewer ports, for example a 4-way tap, each cascade will consist of the same number of directional couplers a there are tap ports.
Directional couplers 56 are microstrip couplers, also known as tilted taps, with the output 57 of each microstrip coupler 56 connected to the input 58 of the next microstrip coupler 56 so as to allow the downstream signal received at input 52 to reach all tap ports. Each tap port 60 is connected to a coupled port 64 of microstrip coupler 56 with a proportion of the downstream signal from input 52 drawn off to supply each tap port which is in turn connected to a coaxial cable routed to a connected home.
The isolated port 66 of each microstrip coupler 56 is connected to a single directional coupler 62 in the interconnected cascade of directional couplers 62 in the upstream return path leading to upstream output 54. Each directional coupler in the first cascade associated with downstream input 52 is paired with a single directional coupler in the second cascade associated with upstream output 54. Thus an interconnected pair of directional couplers is provided for each tap port. Directional couplers 62 are of preference ferrite transformer-type directional couplers.
If desired an optional high pass filter 70, with a pass frequency above the lowest expected downstream frequency, typically in the range of 100 or 200MHz, is disposed between input 52 and a first directional coupler 56. An optional low pass filter 72, with a pass frequency below the highest expected upstream frequency usually in the range of 400-700MHz, is disposed between output 54 and directional coupler 62 closest to output 54.
In use, a downstream signal present at downstream input 52 travels along the first cascade formed from microstrip couplers 56 and a small, defined, portion of the signal energy is coupled to each tap port 60. The downstream signal does not appear on isolated port 66 due to the nature of the directional coupler.
An upstream signal generated in a connected home travels from tap port 60 to isolated port 66 of microstrip coupler 56 with little insertion loss, and thence to directional coupler 62 connected to isolated port 66. The upstream signal is not present at output port 57 of microstrip directional coupler 56 due to the nature of the directional coupler ensuring tap to tap isolation.
The upstream signals from the respective tap ports 60 travel along the upstream path connecting the second cascade of directional couplers 62 and route through the optional low pass filter 72 to upstream output port 54.
This configuration results in a multitap with separate and RF isolated downstream input and upstream output ports connectable to an amplifier 80 with a separate downstream output 82 and upstream input 84, see Figure 3. Any reflected downstream signal does not reach upstream amplifier element 86 as there is isolation between the separate upstream and the downstream connectors of multitap 50 and is therefore not amplified and cannot reach input connector 88 of amplifier 80. Therefore, there is no reflection signal travelling in the same direction as the original downstream signal. The reflected signal cannot travel in the opposite direction through the downstream amplifier element 90.
For a 12-way tap with a highpass filter at 200MHz and a lowpass filter set to 400MHz, the isolation between the downstream input port 52 and upstream output port 54 is shown in Figure 4 on a scale from 12 to 1900MHz and 0 to -100dB and is well over 60dB.
The high isolation avoids reflection problems and also prevents issues with amplifier oscillation. For a typical amplifier, an upstream to downstream isolation in the multitap of >40dB would be sufficient to avoid reflection problems.
Claims (10)
- Claims 1. A cable network device comprising a first series of interconnected directional couplers connected to a downstream signal input with each directional coupler in the first series connected to a separate tap port, and a second series of interconnected directional couplers connected to an upstream signal output, wherein the downstream signal input and upstream signal output are separate and pairs of directional couplers created from one directional coupler from each of the first series and second series are connected together to enable an upstream signal path routed through the tap port and directional coupler in the first series to reach the upstream signal output.
- 2. A cable network device according to claim 1, wherein each directional coupler connects to an adjacent coupler in the same series and also connects to a single directional coupler in the other series.
- 3. A cable network device according to claim 1 or claim 2, wherein the directional couplers of the first series are microstrip couplers
- 4. A cable network device according to any of the preceding claims, wherein a coupled port of the microstrip directional coupler is connected to the tap port.
- 5. A cable network device according to any of the preceding claims, wherein an isolated port of the microstrip coupler is connected to the other directional coupler in the pair of directional couplers.
- 6. A cable network device according to any of the preceding claims, wherein the directional couplers of the second series are ferrite directional couplers.
- 7. A cable network device according to any of the preceding claims configured to have an isolation from the downstream signal input to an upstream signal output of greater than 40 dB.
- 8. A cable network device according to any of the preceding claims configured to have an isolation from the downstream signal input to an upstream signal output of greater than 60 dB
- 9. A cable network device according to any of the preceding claims being a multitap device.
- 10. A cable network device according to any of the preceding claims when used in combination with an amplifier comprising a directional coupler to create separate in upstream input and downstream output.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2117722.5A GB2613600A (en) | 2021-12-08 | 2021-12-08 | Cable network device |
NL2033235A NL2033235B1 (en) | 2021-12-08 | 2022-10-05 | Cable network device |
ATA50934/2022A AT525682B1 (en) | 2021-12-08 | 2022-12-07 | Cable Network Device |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2117722.5A GB2613600A (en) | 2021-12-08 | 2021-12-08 | Cable network device |
Publications (2)
Publication Number | Publication Date |
---|---|
GB202117722D0 GB202117722D0 (en) | 2022-01-19 |
GB2613600A true GB2613600A (en) | 2023-06-14 |
Family
ID=80080956
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB2117722.5A Pending GB2613600A (en) | 2021-12-08 | 2021-12-08 | Cable network device |
Country Status (3)
Country | Link |
---|---|
AT (1) | AT525682B1 (en) |
GB (1) | GB2613600A (en) |
NL (1) | NL2033235B1 (en) |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2549375A (en) * | 2016-03-09 | 2017-10-18 | Technetix Bv | Cable network device |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4327117C2 (en) * | 1993-08-16 | 1995-04-13 | Spaun Electronic Gmbh | Device for an antenna system for distributing a satellite reception signal |
US20090113510A1 (en) * | 2005-10-12 | 2009-04-30 | Paul Gothard Knutson | Band Switchable Taps and Amplifier for Use in a Cable System |
CN201048432Y (en) * | 2007-05-14 | 2008-04-16 | 杨子文 | Frequency-division section type broadband branching device |
GB201007457D0 (en) * | 2010-05-05 | 2010-06-16 | Technetix Group Ltd | Cable network device |
GB2528278B (en) * | 2014-07-16 | 2020-12-16 | Technetix Bv | Cable tap |
GB201520975D0 (en) * | 2015-11-27 | 2016-01-13 | Technetix Bv | Cable tap |
GB2568275B (en) * | 2017-11-10 | 2021-12-01 | Technetix Bv | Cable tap |
-
2021
- 2021-12-08 GB GB2117722.5A patent/GB2613600A/en active Pending
-
2022
- 2022-10-05 NL NL2033235A patent/NL2033235B1/en active
- 2022-12-07 AT ATA50934/2022A patent/AT525682B1/en active
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2549375A (en) * | 2016-03-09 | 2017-10-18 | Technetix Bv | Cable network device |
Also Published As
Publication number | Publication date |
---|---|
NL2033235A (en) | 2023-06-22 |
AT525682A1 (en) | 2023-06-15 |
AT525682B1 (en) | 2023-07-15 |
NL2033235B1 (en) | 2023-10-20 |
GB202117722D0 (en) | 2022-01-19 |
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