Patent Application
20060262478
This invention relates to an AC power line communication system. More particularly, the invention relates to a surge protected broadband AC power line communication system which is able to distribute broadband digital signals over the AC power lines in a home while protecting the system from overvoltage conditions on the AC power lines.
Power line communication systems are known in the art. These communication systems are used, for example, to facilitate telephonic communications in locations where little or no availability exists for dedicated telephone wires. At least one such system is known which incorporates limited overvoltage protection for AC outlets.
U.S. Pat. No. 6,055,435 provides a power line communication system for transmitting telephone signals over the AC power lines in a home. While the system provides surge protected AC outlets, the system does not provide surge protection for the base or extension units which incorporate the sensitive electronics for transmitting and receiving the telephone signals over the AC power lines. The surge suppressor shown in FIG. 4 of U.S. Pat. No. 6,055,435 employs high capacitance MOVs which would attenuate the RF signals on the AC power lines. As a result, the surge suppressor must be isolated from the base and extension units and AC power lines and cannot provide surge protection for the base and extension units. See FIG. 1 and column 3, lines 20-25.
Wireless broadband communication systems are also known. These systems are commonly referred to as “Wi-Fi.” They employ a wireless router connected to a cable modem and allow persons within the operating range of the router to access the internet from their computers. A problem exists with Wi-Fi in that criminals are now gaining access to unsecured Wi-Fi networks. This problem was the subject of a front page article in the Mar. 19, 2005 issue of The New York Times entitled “Growth of Wireless Internet Opens New Path for Thieves.” See pages A1 and A10.
A need exists for a system which is capable of transmitting and receiving broadband digital information securely on AC power lines while, at the same time, providing overvoltage protection for the sensitive electronic components of that system.
It is an object of the present invention to provide a surge protected broadband power line communication system which does not suffer from the security defects of Wi-Fi.
It is also an object of the invention to provide a broadband power line communication system which provides overvoltage protection for the sensitive electronics in the base and extension units.
It is a further object of the invention to provide a broadband surge suppressor which is capable of providing overvoltage protection for the sensitive electronics in the base and extension units without significantly attenuating the RF signals being transmitted and received by those units through the broadband surge suppressor and over the AC power lines.
It is a still further object of the invention to provide a broadband power line communication system with surge protected AC outlets which are isolated from the RF signals on the AC power lines while, at the same time, providing overvoltage protection for the sensitive electronics in the base and extension units.
The present invention overcomes the above-mentioned problems and other limitations of the background and prior art and achieves the above-mentioned objectives by providing a surge protected broadband power line communication system that comprises a local module with a base unit and a remote module with an extension unit. Both modules include broadband surge suppressors adapted to be connected to an AC power line. The base and extension units are connected to the surge suppressors and transmit and receive broadband digital signals through the surge suppressors and over the AC power line. The local and remote modules also have RF isolator filters connected to the surge suppressors and surge protected AC outlets connected to the outputs of the isolator filters.
It will be appreciated by those skilled in the art that the foregoing brief description and the following detailed description are exemplary and explanatory of this invention, but are not intended to be restrictive thereof or limiting of the advantages which can be achieved by this invention. Thus, the accompanying drawings, referred to herein and constituting a part hereof, illustrate preferred embodiments of this invention, and, together with the detailed description, serve to explain the principles of this invention.
Additional aspects, features, and advantages of the invention, both as to its structure and operation, will be understood and will become more readily apparent when the invention is considered in the light of the following description made in conjunction with the accompanying drawings, wherein:
The surge protected broadband power line communication system of the present invention is shown in block diagram form in
The base unit may be connected (e.g. by an RJ 45 jack) to a source of broadband digital signals such as a cable modem, or a satellite TV antenna or voice over intent protocol (VoIP) signals. The extension unit may be connected (e.g. by an RJ 45 jack) to devices which utilize broadband digital signals such as a computer or a TV set top box. The system of the present invention effectively provides an internal ethernet connection over AC power line 18. It is significant that, in the system shown in
Surge protection is provided by a three electrode gas discharge tube 68 in combination with metal oxide varistors (MOVs) 64, 66, 70 and 72. The gas discharge tube (GDT) presents a very high impedance to RF signals on the AC power lines because the GDT has very low capacitance. This is in contrast to MOVs, which have significantly higher capacitance and would, in the absence of the GDT, attenuate the RF signals on the AC power lines. The surge protection circuit shown in
In the preferred embodiment of the invention, EEPROMs 108 are three-wire serial devices made by Atmel Corporation, 2325 Orchard Parkway, San Jose, Calif. 95131. In particular, preferred EEPROMs are Atmel AT93C46 devices. The Atmel website is www.atmel.com. In the preferred embodiment, the ethernet physical layer interface is made by Micrel Semiconductor, 2180 Fortune Drive, San Jose, Calif. 95131. In particular, the preferred Micrel ethernet physical layer interface is Micrel KS8721SL. The Micrel website is www.micrel.com. In the preferred embodiment, the preferred processor is made by Intellon Corporation, 5100 West Silver Springs Blvd., Ocala, Fla. 34482. In particular, the preferred processor is the Intellon INT5200 Single Chip PowerPacket™ Transceiver. The Intellon website is www.intellon.com.
Each local module 10 and each remote module 12 has a unique “MAC” number assigned to it. The same is true of each cable modem and each computer network interface card. MAC is sometimes (incorrectly) referred to as Media Access Control but the correct term is Medium Access Control. See Newton's Telecom Dictionary, 16 Edition, for a full explanation of MAC. Digital signals arriving at RJ45 112 are in packet form and contain the MAC address of the local or remote module. Ethernet physical layer interface 110 supports an MII (Media Independent Interface) which facilitates communication with processor 106. As explained in Newton's Telecom Dictionary, the MII is part of the Fast Ethernet specification and is used to connect the MAC layer to the physical layer. The processor in base unit 20 changes the MAC address in the incoming digital signals to that of extension unit 30 and converts the incoming digital signals to RF signals which are then placed on the AC power line. If extension unit 30 is connected to the network interface card in a computer and the computer user desires to send an e-mail over the internet, the extension unit receives the packets of digital information from the computer containing the MAC number of the extension unit, the extension unit changes the MAC number to that of the base unit and converts the digital signals from the computer to RF signals which are then placed on the AC power line which, as noted earlier, forms a local area network (LAN).
Accordingly, although the above description of illustrative embodiments of the present invention, as well as various illustrative modifications and features thereof, provides many specificities, these enabling details should not be construed as limiting the scope of the invention, and it will be readily understood by those persons skilled in the art that the present invention is susceptible to many modifications, adaptations, variations, and equivalent implementations without departing from this scope and without diminishing its attendant advantages. It is further noted that the terms and expressions have been used as terms of description and not terms of limitation. There is no intention to use the terms or expressions to exclude any equivalents of features shown and described or portions thereof. It is therefore intended that the present invention is not limited to the disclosed embodiments but should be defined in accordance with the claims that follow.
