The present invention applies broadly to cable television devices, and more specifically to cable television devices associated with receiving a cable television (CATV) signal, and distributing the same to a plurality of modem/gateway devices, one or more Multimedia over Coax Alliance (MoCA) devices, and legacy devices such as television sets.
Typical cable television (CATV) systems provide for sharing a common coaxial medium and permit various users in the system to communicate with the headend of the system, where the CATV signals originate, but not with each other (due to the directionality of signal flow imposed by the requirement that the various users be signal isolated from one another).
In recent years, Multimedia over Coax Alliance (MoCA) systems have been developed that operate in a different frequency spectrum or band than CATV systems. MoCA systems are designed to communicate bilaterally with each other, meaning that any port of a MoCA system device serves both an input and output port. MoCA devices are typically located within a home or building for permitting users therein to communicate with a single or dedicated MoCA networking device that provides functionality for each user to selectively record a television program for later viewing. It is important in such MoCA systems to keep the CATV input signals wholly isolated from the MoCA signals within the system. More specifically, one portion of such systems permit typical CATV signals to be connected to individual devices such as television sets, cable boxes, and so forth, in a standard manner, whereby all standard CATV signal ports are isolated from all MoCA ports in the system, as previously mentioned.
Cable gateway devices have the capability to communicate with the CATV headend in the CATV signal band, which is typically 5 to 1002 MHz (megahertz), and to communicate with MoCA devices in the MoCA frequency band, which is typically 1125 to 1675 MHz. Accordingly, such cable gateway devices permit information that is transmitted through a public CATV system to be shared amongst MoCA device users joined in a private network within a commercial or residential building. Such cable gateway devices permit CATV signals to be rebroadcast within a different frequency band via connections controlled through typically digital logic means, completely avoiding the use of physical switching or movement of cables between certain ports.
U.S. Pat. Nos. 8,752,114 and 9,356,976 describe a CATV/MoCA signal distribution system that provides the functionality described above. However, in order to electrically connect to more than one gateway or modem port, that CATV/MoCA signal distribution system requires multiple diplex filters that have many discrete parts that take up a lot of space on a circuit board, including many inductors that require tuning to establish the desired filter cutoff and transmission characteristics.
There is a need in the art for simplified and cost effective cable gateway splitters that isolate the CATV and MoCA bands, insuring that MoCA band signals cannot become involved with the CATV signals.
U.S. patent application Ser. No. 15/478,362 discloses a passive gateway device that avoids a direct signal path between a CATV signal input port and MoCA client or user input/output ports, permitting users in a building to connect a CATV signal to various TV sets, modems, and so forth, while at the same time permitting bidirectional communication between a plurality of users of individual in-home media devices within a building (e.g., multi-room digital video recording devices, gateway recording devices, multi-layer gaming devices, high speed data devices), each connected through a coaxial cable network terminated at the output ports of the invention and utilizing the RF spectrum allocated to Multimedia over Coax Alliance (MoCA). Notably, the MoCA gateway splitters disclosed in U.S. patent application Ser. No. 15/478,362 simplify the circuitry of the previous MoCA gateway splitters by utilizing only one diplex filter to integrate a plurality of modem/gateway devices. The single diplex filter may be a solid-state ceramic filter to further reduce the production labor required to tune the splitter consistently and efficiently.
While passive splitters like those disclosed in U.S. patent application Ser. No. 15/478,362 have their advantages, in some instances the CATV system may not provide a sufficient RF level to satisfy the needs of the modem/gateway devices. Accordingly, there is a need for additional improvements to the MoCA gateway splitters described in U.S. patent application Ser. No. 15/478,362.
In order to overcome the disadvantages of the prior art and the parent application, there is provided an active MoCA (Multimedia over Coax Alliance) gateway splitter device that includes a CATV input port for receiving a CATV input signal, an amplifier for amplifying the CATV signal, at least one MoCA port (connectable to a MoCA device), a plurality of modem/gateway ports (each connectable to a modem or gateway device); and a diplex filter that includes a low-pass filter section and a high-pass filter section. The CATV input port is electrically connected to the modem/gateway ports via the low-pass filter section and the MoCA port is electrically connected to the modem/gateway ports via the high-pass filter section. Accordingly, the MoCA device can communicate bidirectionally with the modem/gateway devices over a higher frequency band, the modem/gateway devices can communicate bidirectionally with the CATV input port over a lower frequency band, and the MoCA device is electrically isolated from the CATV input port.
By amplifying the CATV input signal, the active MoCA gateway splitter enables reliable communication with a media service provider (e.g., a CATV headend) even when signal levels at the installation location are not sufficient (for example, due to the topology of the distribution network).
Various embodiments of the present invention are described with reference to the drawings, in which like items are identified by the same reference designation.
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As described above, previous generations of MoCA gateway splitters have included a diplex filter for each gateway or modem port. As shown in
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The MoCA gateway splitter illustrated in
In the 2-way hybrid splitters 4 and 6, two capacitors 46 may be used in parallel between the ferrite transformer windings 42 and 44 to obtain a more distributed ground connection (not shown). The capacitors 46 provide for canceling small amounts of stray inductance in the interconnection between the ferrite core transformers 42 and 44, for improving high frequency return loss, and for isolation there between. The resistors 47 of the 2-way hybrid splitters 4 and 6 preferably have resistance of 180 ohms, but can have a resistance range of 150 ohms to 220 ohms depending on the characteristics of the particular ferrite core transformers 42 and 44 at low frequencies (e.g., between 5 MHz and 50 MHz). The capacitors 90 improve isolation and return loss at low frequencies.
The DC blocking capacitors 89 may each have a capacitance of 2200 pF (picofarads) and a voltage rating of 1000 volts. In the 2-way hybrid splitter circuits 4 and 6, the tapoff 43 for the ferrite core transformer 42 may be between the second turn and the fifth turn of the seven turns thereof. In the ferrite core transformer 44, the tapoff 43 may be between the second turn from each end of the four turns included. The capacitors 90 may each have a capacitance of 1000 pF. The capacitors 46 may each have a capacitance of 1 pF.
The MoCA gateway splitter shown in
The MoCA gateway splitter illustrated in
Co-fired ceramic devices are monolithic, ceramic microelectronic devices where the entire ceramic support structure and any conductive, resistive, and dielectric materials are fired in a kiln at the same time. In contrast to conventional semiconductor devices, where layers are processed serially with each new layer being fabricated on top of previous layers, co-fired ceramic are made by processing a number of layers independently and assembling them into a device as a final step. The diplex filter 914 may be, for example, a HMD024A-T filter made by Soshin.
When compared to a conventional discrete-element diplex filters (such as the diplex filter 14 shown in
The MoCA gateway splitter illustrated in
Additionally, the output of the low-pass filter 15 at inductor 68 is electrically connected to the resistive splitter 125 via conductive path 38 and the input of the high-pass filter 16 at capacitor 80 is connected to a separate ports of the resistive splitter 1025 via the conductive path 35. This allows more freedom in the layout and less interaction of component values in the cross-over frequency region between 1002 MHz and 1125 MHz. Note that modem and gateway devices are equivalent in that they both communicate bidirectionally with the CATV system in the lower portion of the spectrum, and they communicate bidirectionally with the MoCA devices in the upper portion of the spectrum.
In the embodiment shown in
In the low-pass filter section 15, the inductors 61, 62, 63, and 64 may each have a 0.3 mm (millimeter) wire diameter, a 1.5 mm coil diameter, and 2.5 turns. The capacitors 74, 76, and 78 may each have a capacitance of 0.75 pF. The inductors 65, 66, and 67 may each have a 0.3 mm wire diameter, 1.7 mm coil diameter, and 2.5 turns, respectively. The capacitors 73 and 75 may each have a capacitance of 1.8 pF. The capacitors 77 and 79 may each have a capacitance of 1.8 pF. The inductor 68 may have a 0.3 mm wire diameter, a 2.0 mm coil diameter, and 2.5 turns.
In the high-pass filter section 16, the capacitor 80 may have a capacitance of 1.2 pF. The capacitors 82, 86, and 87 may each have a capacitance of 1.8 pF, respectively. The capacitor 81 may have a capacitance of 2.2 pF. The capacitor 83 may have a capacitance of 2.0 pF. The capacitor 84 may have a capacitance of 1.5 pF. The capacitor 85 may have a capacitance of 6.8 pF. The capacitor 88 may have a capacitance of 2.5 pF. The inductor 69 may have a 0.3 mm wire diameter, a 1.5 mm coil diameter, and 2.5 turns. The inductors 70, 71 and 72 may each have a 0.3 mm wire diameter, a 1.7 mm coil diameter, and 2.5 turns.
In the 5-way resistive splitter 24, each of the resistors 53 through 57 may have a resistance of 51 ohms. In the 5-way splitter 1025, each of the resistors 91 through 95 may each have a resistance of 47 ohms since four of the ports are terminated through the low-pass filter 15, and four of the ports are terminated through high-pass filter 16. This choice of resistor values, being different than the case of resistive splitter 24, insures that the modem/gateway ports will have a characteristic impedance of 75 ohms in the low-pass and the high-pass spectra.
As shown in
The active MoCA gateway splitter 1200 includes many of the features described above, including a diplex filter 14 (or solid state diplex filter 914) with a low pass section 15 that is electrically connected to a CATV input 1 via a conductive path 34, a high-pass section 16 connected to a MoCA port 25 via a conductive signal path 39 (or multiple MoCA ports 25-28 connected, e.g., via a resistive splitter 24 and signal paths 3, 5, 7, and 9), and a connection between the low-pass 15 and high-pass 16 sections that is electrically connected to gateway/modem port 8 via conductive signal path 35 (or multiple modem/gateway ports 8 and 22 connected via hybrid splitter(s) 6 and signal paths 35, 36, 37, etc.).
Additionally, the active MoCA gateway splitter 1200 includes an amplifier 120 to communicate more reliably with the media service provider (e.g., the CATV headend) when signal levels at the installation location are not sufficient (for example, due to the topology of the distribution network). As shown in
The forward path (from the CATV port 1 to the diplex filter 14/914) is typically from 54, 85, or 102 MHz to 1002 or 1218 MHz. The amplifier 120 may amplify the forward path signal so that the net loss from the CATV port 1 to the modem/gateway ports 8, 22, etc. is about 0 dB (decibels). The signal level compensation provided by the amplifier 120 guarantees that the gateway devices will work in any installation situation, regardless of the input signal levels. In embodiments where the amplifier 120 is a bidirectional amplifier and includes diplex filters 1220 and 1240, the amplification of the forward path is performed by the amplifier 1232 between the high-pass sections 1222 and 1242, which have a cutoff frequency below the frequency band of the forward path.
The reverse path (from the diplex filter 14/914 to the CATV port 1) is typically from 5 MHZ to 42, 65, or 85 MHz. Amplification of the forward path signal adds loss to the return path. Accordingly, the amplifier 120 may be a bidirectional amplifier. In those embodiments, the low-pass sections 1222 and 1242 have a cutoff frequency above the frequency band of the forward path and the amplifier 1236 may amplify the reverse path so that the net loss from the gateway ports 8, 22, etc. to the input port 1 is about 0 dB. The signal level compensation provided by the amplifier 1236 enables modem/gateway communication between the modem or gateway device(s) and the CATV system.
The active MoCA gateway splitter 1200 may also include a passive VoIP (Voice over Internet Protocol) port 407 to ensure a reliable VoIP connection that is immune to power failure. As shown in
The hybrid splitter 4 is described above with reference to
The amplifier 120 includes an input diplex filter 1220 (with a high-pass section 1222 and a low-pass section 1226), output diplex filter 1240 (with a high-pass section 1242 and a low-pass section 1246), an amplifier 1232 (with resistors 1333, 1334, and 1335) for the forward CATV band connected between the high-pass sections 1222 and 1242 of the diplex filters 1220 and 1240, and an amplifier 1236 (with resistors 1337, 1338, and 1339) for the reverse band connected between the low-pass sections 1226 and 1246 of the diplex filters 1220 and 1240. The resistance of the resistors 1333-1335 may such that the net loss from the CATV port 1 to the gateway ports 1321-1324 is about 0 dB. The resistance of the resistors 1337-1339 may be such that the net loss from the gateway ports 1321-1324 to the CATV port 1 is about 0 dB. The input diplex filter 1220 and the output diplex filter 1240 may be similar to the diplex filter 14 described above with reference to
Each of the splitters 4, 6, 24, and 1406 illustrated in
Hybrid splitters 6 are used to connect the modem/gateway ports 8, 22, and/or 1321-1324 to the common port of the diplex filter 14 or 914 because hybrid splitters 6 have lower insertion loss than a resistive splitter and the loss from the input to the modem/gateway devices needs to be minimized, since input signal levels from the service provider are a variable. By minimizing the insertion loss, using hybrid splitters 6 to connect the modem/gateway ports 8, 22, and/or 1321-1324 to the common port of the diplex filter 14 or 914 insures that a greater number of installation cases will have enough signal to function reliably. Additionally, hybrid splitters 6 have a higher port-to-port isolation than resistive splitters which, in the reverse path, is beneficial for adjacent gateway devices that have high transmit levels. Devices like modems, media gateways, and settop boxes that transmit signals upstream from the home to the cable office may transmit at high levels to overcome the splitter and tap losses in the outside distribution plant. Cable operators have found that if these devices are not sufficiently isolated from each other, distortion can occur that obscures the content of the signals. Since the hybrid splitter 6 can be optimized for high isolation (e.g., >35 dB) in the upstream band, it is the best choice to combine several of these loud talkers connected to the gateway splitter. Using hybrid splitters 6 to connect the modem/gateway ports 8, 22, and/or 1321-1324 to the common port of the diplex filter 14 or 914 also reduces losses in the path from the modem/gateway devices to the MoCA client devices, allowing the MoCA gateway splitter to accommodate additional MoCA client devices.
Resistive splitters 24, meanwhile, have lower port-to-port losses, allowing the MoCA gateway splitter to accommodate more MoCA client devices. A resistive splitter 24 is also more cost effective, in part because it requires no tuning. Using a resistive splitter 24 is also far simpler than hybrid splitters 6 as the number of ports increase. Finally, the resistive splitters 24 have wider bandwidth limitations, which may be important if the upper boundary of the MoCA band shifts upward. (As the CATV spectrum expands from 1002 to 1218 MHz with the adoption of DOCSIS 3, for example, the lower boundary of the MoCA band above it is pushed from 1125 to 1275 MHz, pushing the upper boundary of the MoCA band from 1675 to 1825 MHz.) The resistive splitter 24 is more tolerant of this kind of bandwidth expansion than hybrid splitters 6 due to its circuit simplicity.
As one of ordinary skill in the art would recognize, all of the component values described above are meant to illustrating rather than limiting. Additionally, one of ordinary skill in the art would recognize that features described with reference to separate embodiments may be combined. For example, the MoCA gateway splitter illustrated in
The embodiments above have been described with reference to MoCA devices that communicate in the (higher) MoCA frequency spectrum, CATV signals in the (lower) CATV frequency spectrum, and gateway and modem devices that communicate in both the MoCA and CATV spectrum. However, the embodiments described above are not limited to MoCA and CATV devices. Instead, the embodiments described above are applicable to any system with devices that communicate in a high frequency spectrum, signals in a lower frequency spectrum, and devices that communicate over both the higher and lower frequency spectra.
The term “electrically connected” as used in the foregoing description and the following claims is not limited to a direct electrical connection but also includes indirect electrical connections through intermediate electrical components.
A “single diplex filter” as used in the foregoing description and the following claims means one low-pass filter and one high-pass filter with either a single port between the low-pass filter and the high-pass filter (as shown, for example, in
Although various embodiments of the invention have been shown and described, they are not meant to be limiting. Those of skill in the art may recognize certain modifications to these embodiments, which modifications are meant to be covered by the spirit and scope of the appended claims.
This application is a continuation-in-part of U.S. patent application Ser. No. 15/478,362, filed Apr. 4, 2017, which is related to U.S. patent application Ser. No. 13/868,261, now U.S. Pat. No. 8,752,114, filed on Apr. 23, 2013, and U.S. patent application Ser. No. 14/120,054, now U.S. Pat. No. 9,356,796, filed on Apr. 21, 2014, the entire contents of which are hereby incorporated by reference.
Number | Date | Country | |
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Parent | 15478362 | Apr 2017 | US |
Child | 15806411 | US |