Patent Application
20180288491
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.
There is a need in the art for a simplified and cost effective cable gateway splitter that isolates the CATV and MoCA bands, insuring that MoCA band signals cannot become involved with the CATV signals.
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. As shown, for example, in
Accordingly, there is a need in the art for an even more simplified and cost effective cable gateway splitter that isolates the CATV and MoCA bands.
The present invention is a passive gateway device that avoids a direct signal path between a CATV signal input port and MoCA client or user input/output ports, a function not known to be provided in conventional extended bandwidth splitters. The present inventive device permits 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, 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), for example. The dedicated devices for users can be Media Center client devices enabling Multi-room Digital Video Recording (MR-DVR), multi-player gaming, or high speed data communications. The recording device can be a gateway recording device, for example.
The simplest embodiment of the invention is a three-port diplex filter that divides an RF spectrum of communication frequencies into a lower frequency band and an upper frequency band. The lower and the upper bands are isolated from each other, but the common port between the low-pass and the high-pass sections has access to both.
In a first practical embodiment of the present invention, a CATV input signal is connected directly to the low-pass filter section of a diplex filter. A common output from the diplex filter is connected to a modem/gateway port, and the high-pass filter section is connected to a resistive splitter for permitting a network of bidirectional communication devices to communicate with each other through a plurality of ports of the resistive splitter and with the modem/gateway devices through the high-pass section of the diplex filter.
In a second practical embodiment of the present invention, a CATV input signal is connected directly to the low-pass filter section of a hybrid filter. More specifically, the second embodiment of the invention includes a port for receiving a CATV input signal, connected to the low-pass section of a diplex filter. The diplex filter provides for a common connection to a splitter means connected to a plurality of modem and/or gateway ports, and another output from a high-pass section thereof to a resistive splitter. The resistive splitter provides connection to a plurality of MoCA ports.
In a third practical embodiment of the invention, a two-way hybrid splitter means receptive of CATV input signals connects these signals to a diplex filter, and to an RF output port for connection of CATV signals to legacy devices (e.g., cable boxes, television sets, etc.). The diplex filter includes a low-pass filter section that cuts off near the high end of the CATV signal band (for example, at about 1002 MHz), and a high-pass filter section for passing MoCA band signals. The high-pass filter section of the diplex filter provides a MoCA signal connection to a resistive splitter connected to a plurality of MoCA ports. The diplex filter provides a common signal connection to a splitter connected to a plurality of modem/gateway output ports for feeding both CATV signals and MoCA band signals from both the low-pass and high-pass filter sections.
Previous generations of MoCA gateway splitters have provided an effective means to enable both conventional RF receivers for the consumption of media directly (and interactively from a central media service like a CATV system for program content) and bidirectional interne data communication. In addition, the MoCA Gateway splitters have enabled a new generation of in-home devices that broker media content and data between an external media service and a network of client terminal devices in the home that communicate in the MoCA frequency band. However, previous generations of MoCA gateway splitters have included a diplex filter for each gateway or modem port. The MoCA gateway splitters disclosed here accomplish the same objectives, but simplify the circuitry of the previous generation by utilizing only one diplex filter to integrate a plurality of modem/gateway devices.
Additionally, because further advancements in media service deployment are trending toward the use of modem/gateway devices exclusively, some embodiments may eliminate the RF port access for legacy equipment like televisions and set top converters to accommodate an additional port for an additional gateway device. This represents a further simplification in circuitry which enables significant production economy improvements.
Finally, the MoCA gateway splitters disclosed here may utilize solid-state ceramic filters that further reduce the production labor required to tune the splitter consistently and efficiently.
Various embodiments of the present invention are described with reference to the drawings, in which like items are identified by the same reference designation, wherein:
As shown in
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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 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
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 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.
