EP0062442A2
Expired / Lapsed
EP
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Apparatus for coupling signals to or from a two-wire line
Assignee: Nortel Networks Ltd
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Filing: 1982-03-23
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Granted: —
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Expires: 2002-03-23
Abstract
Abstract Voice-band signals are coupled to and from a telephone subscriber line (12) via a low-pass filter (15 or 16) which has a shunt capacitor (22) 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 (25) of a transformer (23). The above voice-band signals are coupled via at least one series inductor (26) and the transformer (23) to the line, the inductor (26) and the transformer (23) to the line, the inductor being series resonant with the filter capacitor (22), as reflected through the transformer (23), at the above voice-band signal frequency. Two such series inductors (26, 27) provide for efficient coupling of signals to and from the line (12) at two different frequencies, facilitating simultaneous transmission and reception of above voice-band signals, for example FSK data signals, via the line. Parallel resonant circuits (28, 29 and 26, 30) are also provided to prevent degradation of the filter characteristics in the voice-band and to prevent coupling of receive frequency components from the transmit signal to the receive signal line (33).
Inventors
- 👤 Ralph Thomas Carsten
- 👤 Michael Sobhy Nakhla
- 👤 Charles Brian David Bunner
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 01:04
CPC Classifications
H; H04; H04M; H04M11/00; H04M11/06; H04M11/062; H04L; H04L27/00; H04L27/0002
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
137 words
Apparatus comprising a transformer having at least one first winding and at least one second winding, characterized by further comprising: a filter (15 or 16) having a predetermined pass band for coupling signals in the pass band to or from a two-wire line (12), the filter (15 or 16) including a shunt capacitor (22) coupled to the two-wire line (12) via the at least one second winding (25); and an inductor (26 or 27) coupled in series with the at least one first winding (24) and forming with the capacitor (22), as reflected through the transformer (23), a series resonant circuit having a predetermined resonance frequency outside the pass band, whereby signals substantially at the predetermined resonance frequency are coupled to or from the two-wire line (12) via the inductor (26 or 27) and the transformer (23).
Claim 2
Dependent Claim
137 words
Apparatus comprising a transformer having at least one first winding and at least one second winding, characterized by further comprising: a filter (15 or 16) having a predetermined pass band for coupling signals in the pass band to or from a two-wire line (12), the filter (15 or 16) including a shunt capacitor (22) coupled to the two-wire line (12) via the at least one second winding (25); and an inductor (26 or 27) coupled in series with the at least one first winding (24) and forming with the capacitor (22), as reflected through the transformer (23), a series resonant circuit having a predetermined resonance frequency outside the pass band, whereby signals substantially at the predetermined resonance frequency are coupled to or from the two-wire line (12) via the inductor (26 or 27) and the transformer (23).
Claim 3
Dependent Claim
34 words
Apparatus as claimed in claim 1, characterized in that the transformer (23) comprises two second windings (25) connected in series with the capacitor (22), one on each side thereof, across the two-wire line (12).
Claim 4
Dependent Claim
51 words
Apparatus as claimed in claim 1, characterized in that the transformer (23) comprises two second windings (25) each connected in series with a respective wire of the two-wire line (12), the capacitor (22) being connected between the two second windings (25) on the side thereof remote from the two-wire line (12).
Claim 5
Dependent Claim
51 words
Apparatus as claimed in claim 1, 2, or 3, characterized by including a parallel resonant circuit (28, 29), resonant at substantially the predetermined resonance frequency and having a relatively low impedance in the pass band of the filter, coupled across the at least one first winding (24) of the transformer (23).
Claim 6
Dependent Claim
54 words
Apparatus as claimed in any of the preceding claims, characterized by including a capacitor (30) coupled in parallel with the inductor (26) to form a parallel resonant circuit having a second predetermined resonance frequency outside the pass band, whereby signals substantially at the second predetermined resonance frequency are not coupled via the inductor (26).
Claim 7
Dependent Claim
81 words
Apparatus as claimed in any of the preceding claims, characterized by including a second inductor (27) coupled in series with the at least one first winding (24) and forming with the capacitor (22), as reflected through the transformer (23), a second series resonant circuit having a second predetermined resonance frequency outside the pass band, whereby signals substantially at the second predetermined resonance frequency are coupled to or from the two-wire line (12) via the second inductor (27) and the transformer (23).
Claim 8
Dependent Claim
31 words
Apparatus as claimed in any of the preceding claims, characterized in that the filter (15 or 16) is a low-pass filter and the two-wire line (12) comprises a telephone subscriber line.
Claim 9
Dependent Claim
84 words
Apparatus as claimed in any of the preceding claims, wherein the filter comprises reactive components, including the shunt capacitor, which define the predetermined pass band, the filter having an input port of input inpedance Zin for termination with a source impedance Zl, and having an output port of output impedance Zout for termination with a load impedance Z2, characterized in that the impedances of said reactive components (17 to 22) are selected to substantially minimize the quantities |Zin-Z2| and |Zout-Z1| in said pass band..
Claim 10
Dependent Claim
31 words
Apparatus as claimed in claim 8 characterized in that the impedances of said reactive components (17 to 22) are selected to minimize the sum |Zin-Z2| + |Zout-Z1| in said pass band.
References Cited (Backward Citations)
No citation records indexed.
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