XDSL system having selectable hybrid circuitry
View Patent ↗An XDSL system comprising a hybrid circuit in operative communication with a transmission line and an XDSL modem associated with a subscriber premises. The hybrid circuit comprises a plurality of selectable impedance circuits having different impedance values. A controller selectively engages each of the impedance circuits in-line with the XDSL modem and the transmission line. The controller records the performance of the modem with each circuit engaged, and selects the desired impedance circuit as a function of the performance characteristics associated with each of the impedance circuits. The impedance circuit which provides the best performance characteristic is selected as the impedance circuit for normal modem operation.
1. An XDSL system comprising:
a hybrid circuit in operative communication with the remote end of a transmission line and also an XDSL modem associated with a subscriber premises, said hybrid circuit comprising a plurality of selectable Impedance circuits; and
a switch for connecting each of said plurality of selectable impedance circuits in-line with said XDSL modem and also said remote end of said transmission line in response to a control signal;
wherein one of said plurality of impedance circuits has an impedance value equal to a characteristic line impedance of said transmission line without a bridged tap; and
wherein another one of said plurality of impedance circuits has an impedance value equal to a characteristic line impedance with a bridged tap.
2. The XDSL system of claim 1 , wherein said XDSL system further comprises a controller for producing said control signal as a function of a performance characteristic associated with each of said impedance circuits.
3. The XDSL system of claim 1 , wherein the number of said plurality of selectable impedance circuits equals four.
4. The XDSL system of claim 2 wherein said performance characteristic is a data transmission rates and said control signal corresponds to the respective impedance circuit associated with the highest data transmission rate value.
5. A method of configuring an XDSL system, said method comprising the steps of:
providing a hybrid circuit in-line with the remote end of a transmission line and also an XDSL modem associated with a subscriber premises, said hybrid circuit comprising a plurality of selectable impedance circuits; and
engaging at least one of said plurality of selectable impedance circuits in-line with said remote end of said transmission line and also said XDSL modem in response to a control signa;
wherein the step of engaging includes the step of engaging seriatimly each of said plurality of impedance circuits in-line with said remote end of said transmission line and also said XDSL modem;
determining a performance characteristic of said XDSL system for each of said plurality of impedance circuits when engaged; and
outputting said control signal as a function of each said performance characteristic;
wherein each said performance characteristic is a data transmission rate, and said control signal corresponds to a first respective impedance circuit associated with a data rate greater than a selected rate.
6. The method of claim 5 , wherein said control signal alternatively corresponds to the respective impedance circuit associated with the highest data rate.
7. The method of claim 5 , wherein the step of outputting said control signal includes the step of comparing the performance characteristics respectively associated with said impedance circuits.
8. A method of configuring an XDSL system, said method comprising the steps of:
providing a hybrid circuit in-line with the remote end of a transmission line and also an XDSL modem associated with a subscriber premises, said hybrid circuit comprising a plurality of selectable impedance circuits; and
engaging at least one of said plurality of selectable impedance circuits in-line with said remote end of said transmission line and also said XDSL modem in response to a control signal;
wherein the step of engaging includes the step of engaging seriatimly each of said plurality of impedance circuits in-line with said remote end of said transmission line and also said XDSL modem;
determining a performance characteristic of said XDSL system for each of said plurality of impedance circuits when engaged; and
outputting said control signal as a function of each said performance characteristic;
wherein each said performance characteristic is a data transmission rate, and said control signal corresponds to a first respective impedance circuit associated with a data rate greater than a selected rate; and
wherein one of said plurality of impedance circuits has an impedance values value that is equal to a characteristic line impedance with a bridged tap.
9. An XDSL system comprising:
a hybrid circuit in operative communication with the remote end of a transmission line and also an XDSL modem associated with a subscriber premises, said hybrid circuit comprising a plurality of selectable impedance circuits;
a switch for connecting each of said plurality of selectable impedance circuits in-line with said XDSL modem and also said remote end of said transmission line in response to a control signal; and
a controller programmed to (i) determine a performance characteristic associated with each of said plurality of selectable impedance circuits when connected and also (ii) output said control signal as a function of each said performance characteristic associated with each of said impedance circuits;
wherein one of said plurality of impedance circuits comprises a 460 ohm resistor in parallel with a 1200 ohm resistor and 520 pF capacitor.
10. The XDSL system of claim 9 , wherein the number of said impedance circuits is equal to four.
11. The XDSL system of claim 9 , wherein said performance characteristic is a transmission data rate.
12. The XDSL system of claim 9 , wherein said performance characteristic is a transmission line attenuation.
13. The XDSL system of claim 9 , wherein said performance characteristic is a noise margin.