Apparatus for coupling signals to or from a two-wire line
First Claim
1. Apparatus comprising:
- a transformer having at least one first winding and at least one second winding;
a filter having a predetermined pass band for coupling signals in the pass band to or from a two-wire line, the filter including a shunt capacitor coupled in series with the at least one second winding across the two-wire line; and
means, coupled in parallel with the at least one first winding, having a relatively low impedance at frequencies in the pass band and a relatively high impedance at frequencies outside the pass band of the filter;
whereby signals at said frequencies outside the pass band of the filter can be coupled to or from the two-wire line via the transformer.
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Accused Products
Abstract
Voice-band signals are coupled to and from a telephone subscriber line via a low-pass filter which has a shunt capacitor coupled across the line. In order to simultaneously couple above voice-band signals to and from the line, this capacitor is coupled to the line via windings of a transformer. The above voice-band signals are coupled via the transformer to and from the line, for example via series inductors which are series resonant with the filter capacitor, as reflected through the transformer, at above voice-band signal frequencies. A parallel resonant circuit, which has a low impedance in the voice-band, is connected in parallel with a winding of the transformer to prevent degradation of the filter characteristics in the voice-band.
95 Citations
8 Claims
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1. Apparatus comprising:
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a transformer having at least one first winding and at least one second winding; a filter having a predetermined pass band for coupling signals in the pass band to or from a two-wire line, the filter including a shunt capacitor coupled in series with the at least one second winding across the two-wire line; and means, coupled in parallel with the at least one first winding, having a relatively low impedance at frequencies in the pass band and a relatively high impedance at frequencies outside the pass band of the filter; whereby signals at said frequencies outside the pass band of the filter can be coupled to or from the two-wire line via the transformer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification
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- Resources
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Current AssigneeNortel Networks Limited (Nortel Networks Corporation)
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Original AssigneeNorthern Telecom Limited (Nortel Networks Corporation)
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InventorsBunner, Charles B. D., Nakhla, Michael S., Carsten, Ralph T.
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Primary Examiner(s)Olms, Douglas W.
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Assistant Examiner(s)Rokoff, Kenneth I.
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Application NumberUS06/333,666Time in Patent Office916 DaysField of Search179/2 DP, 179/170 D, 370/30, 370/76, 370/69.1, 370/123, 333/119, 333/131, 333/100, 333/4, 333/5US Class Current370/488CPC Class CodesH04M 11/062 using different frequency b...
