Network data filtering

Details Network data filtering Network data filtering

1998-12-14

2001-10-02

Chin, Wellington (Department: 2664)

Multiplex communications

Generalized orthogonal or special mathematical techniques

Fourier transform

C370S243000, C370S246000

Reexamination Certificate

active

06298037

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to networks using existing telephone wiring, and, in particular, to filtering high frequency components from electrical signals transmitted along the network and passing low frequency components of the electrical signals to devices using POTS technology (Plain Old Telephone System).
For example, asymmetric digital subscriber line (ADSL) networks transmit electrical signals representing information along existing telephone wiring. The information is, for example, both high frequency digital signals, such as video from a service provider transmitting a pay-per-view movie to a customer or Internet data, and low frequency analog voice signals, such as the voices of a telephone call carried along the lines of the service provider. Both types of information, high frequency signals and low frequency signals, are combined as components of a single electrical signal.
ADSL networks transmit high frequency digital data asymmetrically. ADSL networks transmit data upstream from a subscriber node (e.g., a home or an office) to a provider node (e.g., a telephone company or an Internet service provider) at a slower rate than the networks transmit data downstream to the subscriber node. In addition, ADSL networks transmit analog voice signals at an even lower frequency than either the upstream or downstream data. In addition, both the upstream and downstream frequency ranges can contain several sub-bands or sub-channels that allow several sets of data to be transmitted in the same direction at the same time by using different frequencies within the respective ranges.
When electrical signals arrive at the subscriber node, the high and low frequency signal components are separated into separate electrical signals for use by an appropriate device such as a television, a personal computer, or a telephone set. To separate the signal into the various frequency components, hardware is installed at the subscriber node. For example, home wiring is broken and a POTS splitter is connected to the home wiring between the break. The POTS splitter separates the low frequency electrical signal components from the electrical signal and sends the low frequency component to the low frequency devices, such as a telephone set, along one wiring path while sending the high frequency component along another path. The POTS splitter sends the high frequency signal component to an ADSL modem and the low frequency signal component to the low frequency devices.
Current methods of adapting subscriber nodes, such as homes, to ADSL technology require changing existing hardware, e.g., inserting the POTS splitter requires changing the existing home wiring and providing additional wiring for the high frequency signal. However, one of the primary advantages of ADSL technology is that it utilizes the existing twisted pair wiring that already exists in most homes. Thus, methods of adapting subscriber nodes to ADSL technology, which require alterations to existing wiring at the subscriber node, reduce the advantages of providing services over an ADSL network.
As another example, future home phone network applications (home PNA) may also use existing telephone wiring within a home to create a local area network (LAN) within the home. While an ADSL network transmits high frequency components on the order of approximately 20 kHz to 1 MHz, residential LANs could transmit even high frequency components on the order of approximately 4 MHz to 10 MHz. As with ADSL technology, methods of adapting existing wiring for use in a residential LANs that require extensive modifications would decrease the advantages of utilizing existing wiring.
SUMMARY OF THE INVENTION
One aspect of the invention is an electronic filter which can be used in conjunction with the existing twisted pair wiring that exists in most homes without requiring modifications to the wiring. The electronic filter receives electrical signals that are transmitted along an asymmetric digital subscriber line of a network. The filter passes low frequency components of the electronic signals to a data receiving device utilizing POTS technology, such as a telephone set.
The electronic filter contains electronic components arranged along a signal processing path. The filter also includes input and output connectors that have corresponding input and output voltage nodes. The voltage node of the input connector provides electrical inputs to the electronic filter, and input connector is electrically connectable to the asymmetric digital subscriber line. The output connector provides electrical outputs from the electronic filter to the data receiving device when the output connector is in electrical communication with the device.
The electronic filter is adapted to selectively pass frequency components of the electrical signals. The filter passes frequency components below a predetermined corner frequency from the input connector to the output connector; the filter does not pass frequency components above the predetermined corner frequency from the input to the output connector.
Preferred embodiments of this aspect of the invention include one or more of the following features.
The input and output connectors can be RJ-11 or RJ-45 connectors and additionally can be jacks or plugs. The connector is modularly formed as a stand alone unit or can be formed as part of an outlet containing a jack connected as a fixture in at a subscriber node. The filter can have an input impedance that matches the output impedance of the local loop and can, for example, be a passive elliptic filter. The filter can be designed with a corner frequency of eight kilohertz.
Each embodiment within the scope of the claims may have one or more of the following advantages. The electronic filter allows existing wiring at a subscriber node, such as a home, to be utilized without requiring modifications to the existing wiring. When installed, the electronic filter filters low frequency electrical signal components from electronic signals, and, thus, eliminates the adverse effects that the high frequency electrical signal components have on data receiving devices, such as telephone sets, for example, signal noise.
The electronic filter is easily installed between the ADSL network and a data receiving device. The electronic filter incorporates the structure of existing jacks and plugs, such as an RJ-11 connector or an RJ-45 connector which, for example, are normally used in homes and offices for voice and data connectivity respectively. Passive embodiments of the electronic filter do not require an additional power source. The electronic filter can be a stand-alone device or can be formed integrally with a jack that can be installed as a replacement outlet in the wall, or other location of the home. Stand-alone embodiments of the electronic filter can be easily installed, removed, and moved to other locations.


REFERENCES:
patent: 5832057 (1998-11-01), Furman
patent: 5848150 (1998-12-01), Bingel
patent: 6136388 (2000-10-01), Raoux et al.

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