GB2415571A - Signal splitter - Google Patents
Signal splitter Download PDFInfo
- Publication number
- GB2415571A GB2415571A GB0413977A GB0413977A GB2415571A GB 2415571 A GB2415571 A GB 2415571A GB 0413977 A GB0413977 A GB 0413977A GB 0413977 A GB0413977 A GB 0413977A GB 2415571 A GB2415571 A GB 2415571A
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- GB
- United Kingdom
- Prior art keywords
- coupled
- nodes
- pair
- output nodes
- filter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000006855 networking Effects 0.000 claims abstract description 5
- 239000003990 capacitor Substances 0.000 claims description 21
- 235000014676 Phragmites communis Nutrition 0.000 claims description 15
- 230000001939 inductive effect Effects 0.000 claims description 12
- 238000001914 filtration Methods 0.000 claims description 10
- 238000004804 winding Methods 0.000 claims description 7
- 230000000694 effects Effects 0.000 description 5
- 101150012579 ADSL gene Proteins 0.000 description 2
- 102100020775 Adenylosuccinate lyase Human genes 0.000 description 2
- 108700040193 Adenylosuccinate lyases Proteins 0.000 description 2
- 230000000875 corresponding effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000004913 activation Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000002079 cooperative effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M11/00—Telephonic communication systems specially adapted for combination with other electrical systems
- H04M11/06—Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors
- H04M11/062—Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors using different frequency bands for speech and other data
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/46—Networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/46—Networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source
- H03H7/463—Duplexers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/738—Interface circuits for coupling substations to external telephone lines
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Telephonic Communication Services (AREA)
- Filters And Equalizers (AREA)
Abstract
A signal splitter 10 has a common mode choke circuit 20 including a choke coil T1 having a pair of first input nodes (a) coupled to an incoming telephone line, and a pair of first output nodes (b) coupled to a networking interface unit such as an asymmetric digital subscriber line (ADSL) modem. A low-pass filter circuit 40 has a pair of second input nodes (c) coupled respectively to the first output nodes (b) of the choke coil T1, and a pair of second output nodes (d). A noise filter module 60 has a pair of third input nodes (e) coupled respectively to the second output nodes (d) of the low-pass filter circuit 40, and a pair of third output nodes (f) coupled to a telephony instrument.
Description
SIGNAL SPLITTER
The invention relates to a signal splitter, more particularly to a signal splitter that is capable of providing animproved filtering effect when a telephony instrument coupled thereto is in an on-hook mode.
ReferringtoFigurel,aconventionalsignalsplitter 10' is shown to include a low-pass filter circuit 40' and a noise filter module 60'.
The low-pass filter circuit 40' has a pair of first input nodes (A) coupled to an incoming telephone line and a networking interface unit, such as an ADSL modem, andapairoffirstoutputnodes(B). Thelow-pass filter circuit 40' is capable of suppressing a high-frequency component of the incoming signal in the incoming telephonelineandpermittingalowfrequencycomponent of the incoming signal in the incoming telephone line to pass therethrough, and adjusts impedance matching characteristics, thereby resulting in low interface loss and low echo loss. The low-pass filter circuit includes first and second filter inductors (L2, L1) coupled respectively to the first input nodes (A), a third filter inductor (L5) coupled to the first input and output nodes (A, B), a first resistor-capacitor circuit 41' coupled to the first filter inductor (L2) and one of the first output nodes (B), a second resistor-capacitor circuit 42' coupled to the second filterinductor (L1) end the other one of the first output node (B), and a filter capacitor (C9) coupled across the first output nodes (B).
Thenoisefiltermodule 60' has a pair ofsecondinput nodes (C) coupled respectively to the first output nodes (B) of the low-pass filter circuit 40', and a pair of second output nodes (D) coupledtoatelephonyinstrument, such as a telephone set or a facsimile machine. The noise filtermodule 60' is capable of filtering a signal passing through the low-pass filter circuit 40' and to be supplied to the telephony instrument. The noise filter module 60' includes: first and second capacitor-inductor circuits 61, 62, each of which is coupled to a respective one of the second input nodes (C), and a respective one of the second output nodes (D); a reed switch (K2), a resistor (R5) and a capacitor (C4) coupled in series across the second input nodes (C); and a capacitor (C5), a resistor (R6) and a reed switch (K1) coupled in series across the second output nodes (D). Each reed switch (K1, K2) has a Zener diode (D1, D2) connected in parallel thereto.
In actual operation, when the telephony instrument is in an on-hook mode, the reed switches (K1, K2) are in an OFF-state. When the telephone instrument is switched from the on-hook mode to an off-hook mode, the reed switches (K1, K2) are excised end are switched from the OFF-state to an ON-state as a result of an inductive magnetic geld attributed toflowofanincreased amount of electric current through thelow-pass filter circuit 40'.
The following are some of the drawbacks of the conventional signal splitter 10': 1. Since the conventional signal splitter 10' lacks a choke element, common mode noise from an incoming signal in the incoming telephone line cannot be effectively suppressed.
2. Since filtering when the telephony instrument is in the on-hook mode is conducted using only the filter capacitor (C9) of the low-pass filter circuit 40', the filtering effect is unsatisfactory when applied to telephony services operated in the on-hook mode, such as facsimile reception and caller ID display.
3. Due to the presence of the two reed switches (K1,
K2), the inductive magnetic field cannot ensure
simultaneous and accurate excitation of the two reed switches (K1, K2) during transition of the telephony instrument from the on-hook mode to the off-hook mode, thereby affecting adversely the filtering effect.
Therefore, the object of the present invention is to provide a signal splitter that can eliminate the
aforesaid drawbacks of the prior art.
Accordingtothepresentinvention,asignalsplitter comprises: a common mode choke circuit including a choke coil having a pair of first input nodes adapted Lo tee coupled toanincomingtelephoneline, end a pair of first output nodes adapted to be coupled to a networking interface unit, thechokecoilbeingoapableofsuppressingcommon mode noise from an incoming signal in the incoming telephone line; a low-pass filter circuit having a pair of second input nodes coupled respectively to the first output nodes of the choke coil, and a pair of second output nodes, the low-pass filter circuit being capable of suppressing a high-frequency component of the incoming signal in the incoming telephone line and permitting a lowfrequency component oftheincoming signal in the incoming telephone line to pass therethrough; and a noise filter module having a pair of third input nodes coupled respectively to the second output nodes ofthelowpassfiltercircuit,andapairofthirdoutput nodes adapted to be coupled to a telephony instrument, the noise filter module being capable of filtering a signal passing through the low-pass filter circuit and to be supplied to the telephony instrument.
Other features and advantages of the present inventionwillbecomeapparentinthefollowingdetailed description of the preferred embodiment with reference to the accompanying drawings, of which: Figure 1 is a schematic electrical circuit diagram illustrating a conventional signal splitter; Figure 2 is a schematic electrical circuit diagram illustrating the preferred embodiment according to the present invention; Figures 3a and 3b are voltage and current charts of the preferred embodiment when a telephony instrument is switched from an offhook mode to an on-hook mode; and Figures 4a and 4b are voltage and current charts of the preferred embodiment when the telephonyinstrument is switched from the on-hook mode to the off-hook mode.
Before the presentinventionisdescribedin greater detail, itshouldbenotedthatlikeelementsaredenoted by the same reference numerals throughout the
disclosure.
Referring to Figure 2, the preferred embodiment of a signal splitter lo according to the present invention is shown to include a common mode choke circuit 20, a low-pass filter circuit 40, and a noise filter module 60.
The common mode choke circuit 20 includes a choke coil 21 having a pair of first input nodes (a) adapted to be coupled to an incoming telephone line, and a pair of first output nodes (b) adapted to be coupled to a networking interface unit, such as an ADSL modem. The chokecoil21iscapableofeuppressingcommonmodenoise from anincoming signal in the incoming telephone line.
In this embodiment, the choke coil 21 includes a common core (not shown), and two mutually inductive windings (T1-1, T1-2) wound on the common core.
The low-pass filter circuit 40 has a pair of second input nodes (c) coupled respectively to the first output nodes (b) of the choke coil 21, and a pair of second output nodes (d). The low-pass filter circuit 40 is capable of suppressing a high-frequency component of the incoming signal in the incoming telephone line and permitting a low-frequency component of the incoming signal in the incoming telephone line to pass therethrough. In this embodiment, thelow-pass filter circuit 40 includes first and second filter inductors 41, 42, first and second resistor-capacitor circuits 43, 44, and a first filter capacitor (C5). The first filter inductor 41 has the second input nodes (c) and a pair of fourth nodes (g), and includes a common core, and two mutually inductive windings (L1-1, L1-2) wound on the common core. The second filter inductor 42 is coupled across the fourth nodes (g)andthesecondoutput nodes (d), and includes a common core, and two mutually inductivewindings(L2-l,L2-2)woundonthecommoncore.
The first resistor-capacitor circuit 43 is coupled to one of the fourth nodes (g) and a corresponding one of the second output nodes (d). The second resistor-capacitor circuit 44 is coupled to the other one of the fourth nodes (g) and the other one of the second output nodes (d). The first filter capacitor (C5) is coupled across the second output nodes (d).
The noise filter module 60 has a pair of third input nodes(e) coupledrespectivelytothesecondoutputnodes (d) of the low-pass filter circuit 40, and a pair of third output nodes (f) adapted to be coupled to a telephony instrument, such as a telephone set or a facsimile machine. The noise filter module 60 is capable of filtering a signal passing through the low-pass filter circuit 40 and to be supplied to the telephony instrument. In this embodiment, the noise filter module 60 includes a current-limiting resistor (R3), a second filter capacitor (C6) and a reed switch (K1) coupledin series across the thirdinput nodes (e), a third filter inductor 61, a pair of third filter capacitors (C3,C4), andafourthfiltercapacitor (C7).
Is The third filter inductor 61 has the third input and output nodes (e, f), and includes a common core, and two mutually inductive windings (L3-1, L3-2) wound on the common core. Each of the third filter capacitors (C3, C4) is coupled between a respective one of the third input nodes (e) and a corresponding one of the third output nodes (f). The fourth filter capacitor (C7) is coupled across the third output nodes (f). The noise filter module 60 further include a Zener diode (Z1) coupled in parallel to the reed switch (K1).
In actual operation, when the telephony instrument is switched from an off-hook mode to an on-hook mode at tl, the incoming telephone line is provided with an increasedvoltage,asshowninFigure3a,andadecreased current flows through the low-pass filter circuit 40, as shown in Figure 3b. The reed switch (K1) is in an OFF-state. At this time, the signal splitter 10 of the this invention provides an improved filtering effect es a result of cooperative action of the first end fourth filter capacitors (C5, C7) when compared to the abovementioned conventional signal splitter 10'. The signal splitter 10 can thus provide better filtering effect when applied to telephony services operated in theon-hookmode, suchaefacsimilereceptionandcaller ID display. When the telephony instrument is switched from the on-hook mode to the off-hook mode at t2, the incoming telephone line is provided with a decreased voltage, asshowninFigure4a, end anincreased current flows through the low-pass filter circuit 40, as shown in Figure 4b. The reed switch (K1) is thus excited as a result of an inductive magnetic field attributed to flow of an increased amount of electric current through the low-pass filter circuit 40 so as to switch from the OFF-state to the ON-state.
It is noted that, due to the presence of the choke coil21, the signal splitterl0 of the presentinvention can effectively suppress common mode noise from the incoming signal in the incoming telephone line.
Furthermore, due to the configuration (two mutually inductive windings wounded a common core) of each of thechokecoil21, andthefirsttothirdfilterinductors 41, 42, 61, magnetic flux leakage can be minimized such that mix- activation of the reed switch (K1) can be avoided. s 1 0
Claims (6)
- CLAIMS: l. A signal splitter comprising: a common mode choke circuitincluding a choke coil having a pair of first input nodes adapted to tee coupled toanincomingtelephoneline, end a pair of first output nodes adapted to be coupled to a networking interface unit, saidchokecoilbeingcapableofsuppressingcommon mode noise from an incoming signal in the incoming telephone line; a low-pass filter circuit having a pair of second input nodes coupled respectively to said first output nodes of said choke coil, and a pair of second output nodes, said low- pass filter circuit being capable of suppressing a high-frequency component of the incoming signal in the incoming telephone line and permitting along-frequency component of the incoming signal in the incoming telephone line to pass therethrough; and a noise filter module having a pair of third input nodes coupled respectively to said second output nodes of said low-pass filter circuit, and a pair of third output nodes adapted to be coupled to a telephony instrument, said noise filter module being capable of filtering asignalpassing through saidlow-pass filter circuit and to be supplied Lo the telephonyinstrument.
- 2. The signal splitter as claimed in Claim l, wherein said choke coil includes acommoncore, end two mutually inductive windings wound on said common core. 1 1
- 3. The signal splitter as claimed in Claim 1 or Claim 2, wherein said low-pass filter circuit includes: afirstfilterinductorhavingsaidsecondinputnodes and a pair of fourth nodes, said first filter inductor including a common core, and two mutually inductive a second filter inductor coupled across said fourth nodes and said second output nodes, said second filter inductor including a common core, and two mutually inductive windings wound on said common core; a first resistor-capacitor circuit coupled to one of said fourth nodes and a corresponding one of said second output nodes; a second resistorcapacitor circuit coupled to the other one of said fourth nodes and the other one of said second output nodes; and a first filter capacitor coupled across said second output nodes.
- 4. The signal splitter as claimed in Claim 1, Claim 2 or Claim 3, wherein said noise filter module includes: a current-limiting resistor, a second filter capacitor and a reed switch coupled in series across said third input nodes; a third filter inductor having said third input and output nodes, said third filter inductor including a common core, and two mutually inductive windings wound on said common core; a pair of third filter capacitors, each of which is coupled between a respective one of said third input nodes end a corresponding one of said third output nodes; and a fourth filter capacitor coupled across said third output nodes; said reed switch being excited as a result of aninductive magnetic field attributed to flow of anincreased amount of electric current through said low-pass filter circuit so as to switch fromanOFF-state to en ON-state when the telephonyinstrumentis switched from an on-hook mode to an off-hook mode.
- 5. The signal splitter as claimed in Claim 4, wherein said noise filter module furtherincludes a Zener diode coupled in parallel to said reed switch.
- 6. The signal splitter substantially as hereinbefore described with reference to end asillustratedin Figure 2 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0413977A GB2415571B (en) | 2004-06-22 | 2004-06-22 | Signal splitter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0413977A GB2415571B (en) | 2004-06-22 | 2004-06-22 | Signal splitter |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB0413977D0 GB0413977D0 (en) | 2004-07-28 |
| GB2415571A true GB2415571A (en) | 2005-12-28 |
| GB2415571B GB2415571B (en) | 2006-11-15 |
Family
ID=32799965
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0413977A Expired - Fee Related GB2415571B (en) | 2004-06-22 | 2004-06-22 | Signal splitter |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2415571B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1890474A1 (en) * | 2006-08-17 | 2008-02-20 | Stefano Marcetti | Automatic noise suppression system for telephone line interfaces |
| EP1901540A1 (en) * | 2006-09-13 | 2008-03-19 | Ycl Electronics Co., Ltd. | ADSL splitter |
| EP1901538A1 (en) * | 2006-09-13 | 2008-03-19 | Ycl Electronics Co., Ltd. | Signal splitter |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6137880A (en) * | 1999-08-27 | 2000-10-24 | Westell Technologies, Inc. | Passive splitter filter for digital subscriber line voice communication for complex impedance terminations |
| JP2003152894A (en) * | 2001-11-19 | 2003-05-23 | Hitachi Ferrite Electronics Ltd | Splitter circuit |
| WO2003045043A1 (en) * | 2001-11-14 | 2003-05-30 | Excelsus Technologies, Inc. | High performance micro-filter and splitter apparatus |
-
2004
- 2004-06-22 GB GB0413977A patent/GB2415571B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6137880A (en) * | 1999-08-27 | 2000-10-24 | Westell Technologies, Inc. | Passive splitter filter for digital subscriber line voice communication for complex impedance terminations |
| WO2003045043A1 (en) * | 2001-11-14 | 2003-05-30 | Excelsus Technologies, Inc. | High performance micro-filter and splitter apparatus |
| JP2003152894A (en) * | 2001-11-19 | 2003-05-23 | Hitachi Ferrite Electronics Ltd | Splitter circuit |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1890474A1 (en) * | 2006-08-17 | 2008-02-20 | Stefano Marcetti | Automatic noise suppression system for telephone line interfaces |
| EP1901540A1 (en) * | 2006-09-13 | 2008-03-19 | Ycl Electronics Co., Ltd. | ADSL splitter |
| EP1901538A1 (en) * | 2006-09-13 | 2008-03-19 | Ycl Electronics Co., Ltd. | Signal splitter |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0413977D0 (en) | 2004-07-28 |
| GB2415571B (en) | 2006-11-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20100622 |