CA2169670C - Telephone line coupler - Google Patents
Telephone line couplerInfo
- Publication number
- CA2169670C CA2169670C CA002169670A CA2169670A CA2169670C CA 2169670 C CA2169670 C CA 2169670C CA 002169670 A CA002169670 A CA 002169670A CA 2169670 A CA2169670 A CA 2169670A CA 2169670 C CA2169670 C CA 2169670C
- Authority
- CA
- Canada
- Prior art keywords
- signal
- ring
- tip
- outputs
- output
- 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.)
- Expired - Fee Related
Links
Classifications
-
- 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
- H04M1/74—Interface circuits for coupling substations to external telephone lines with means for reducing interference; with means for reducing effects due to line faults
- H04M1/745—Protection devices or circuits for voltages surges on the line
Abstract
The telephone line coupler circuit has a single transmit opto-coupler whose output includes a DC bias component connected to a gate of a line seize switch for connecting a DC line seize load across the ring and tip contacts of the telephone line. The line seize switch is saturated by the transmit opto-coupler bias output and the AC component of the transmit opto-coupler output is sent over the telephone lines. The receive opto-coupler is used both for receiving communications signal and for detecting the ring signal. The band pass filter connected to the output of the receive opto-coupler may be switched to pass a ring signal frequency band or a communications frequency band. The circuit operates using two opto-coupler devices while conventional circuits require for opto-coupler devices.
Description
21 f~9670 TELEPHONE LINE COUPLER
Field of the Invention The present invention relates to a telephone line coupler circuit for connecting telephone subscriber equipment to a telephone line, as well as to a method for isolating and connecting subscriber equipment to a telephone line.
Background of the Invention A telephone line coupler circuit is found in most every type of electronic equipment connected to a telephone line such as modems and fax machines. In order to protect the electronic equipment from surges on the telephone line and side to prevent different ground voltages from causing erroneous operation in the subscriber equipment, transformers or opto couplers are used in the coupler circuit to connect the subscriber electronic equipment for the telephone line.
Coupler circuits which use opto-couplers are known in the art. In U.S. Patent 4,727,535 to Brandt, a coupler circuit is described in which a single opto-coupler is used for relaying the analog AC transmit signal and another opto-coupler device is used for relaying the received AC signal. The telephone line connect and disconnect circuit (e.g. a line relay) is not disclosed. In U.S. Patent 4,203,006 to Mascia, one opto-coupler is used for relaying a ringing signal to a modem, a second opto-coupler is used in relaying a line seize signal from the modem to the telephone line access coupler and a transformer is used in place of a pair of opto-couplers for relaying the received and transmitted AC signals from the coupler to the modem.
In the known prior art coupler circuits using opto-couplers, the basic functions of relaying A
2169fi70 the AC transmit signal all require separate opto-coupler devices. In the case that a transformer used, the bi-directional nature of the transformer allows for single device to be used for relaying the received and the transmitted communication signal. In a standard telephone line coupler circuit, the cost of the opto-coupler devices is a substantial portion of the component cost for the circuit.
Summary of the Invention It is accordingly an object of the present invention to provide a telephone line coupler circuit for coupling a telephone line to a subscriber electronic device with isolation between the telephone line and the subscriber device in which the number of opto-couplers is reduced.
In accordance with the first aspect of the present invention, there is provided a telephone line coupler circuit for connecting telephone subscriber equipment to a telephone line, the circuit comprising:
ring and tip connector means for connecting to telephone line ring and tip contacts and providing ring and tip signal outputs; a high impedance DC load and a gated line switch connected in series between the ring and tip signal outputs for controllably conducting an "off-hook" current between the ring and tip signal outputs; a transmit opto-coupler means having a transmit signal input and output; means connecting the output terminal to the tip output and to a gate input of the gated line switch; means for controllably providing a low level DC bias signal to the transmit signal input and generating sufficient current on the output to substantially saturate the gated line switch and seize the line; means for providing an outgoing AC signal to the transmit signal input; and AC signal receive means connected to the 21~9G70 ring and tip outputs for detecting an incoming AC
signal and producing an incoming AC signal output.
The invention also provides a telephone line coupler circuit for connecting telephone subscriber equipment to a telephone line, the circuit comprising:
ring and tip connector means for connecting to telephone line ring and tip contacts and providing ring and tip signal outputs; a high impedance DC load and a line switch connected in series between the ring and tip signal outputs for controllably conducting an "off-hook" current between the ring and tip signal outputs; signal transmit means having a transmit signal input and being connected to the ring and tip outputs for transmitting AC signal; AC communications signal receive means connected to the ring and tip outputs for detecting an incoming AC communications signal and producing an incoming AC communications signal output; and AC ring signal detect means connected to the ring and tip outputs for detecting a telephone ring signal on the telephone line and generating a ringing output signal; wherein: the AC
communications signal receive means and the AC ring signal detect means share a common receive opto-coupler device.
Preferably, the AC communication signal receive means and the AC ring signal detect means comprise a single band pass amplifier circuit which is switchable between two frequency bands, that is a first frequency band for the telephone ring signal and a second frequency band for received communication signals. Also preferably, the band pass filter amplifier is switched between the ring frequency band to the communications frequency band by the line seize signal connected to the means for controllably providing a load level DC bias signal to the transmit signal input of the transmit opto-coupler means.
Field of the Invention The present invention relates to a telephone line coupler circuit for connecting telephone subscriber equipment to a telephone line, as well as to a method for isolating and connecting subscriber equipment to a telephone line.
Background of the Invention A telephone line coupler circuit is found in most every type of electronic equipment connected to a telephone line such as modems and fax machines. In order to protect the electronic equipment from surges on the telephone line and side to prevent different ground voltages from causing erroneous operation in the subscriber equipment, transformers or opto couplers are used in the coupler circuit to connect the subscriber electronic equipment for the telephone line.
Coupler circuits which use opto-couplers are known in the art. In U.S. Patent 4,727,535 to Brandt, a coupler circuit is described in which a single opto-coupler is used for relaying the analog AC transmit signal and another opto-coupler device is used for relaying the received AC signal. The telephone line connect and disconnect circuit (e.g. a line relay) is not disclosed. In U.S. Patent 4,203,006 to Mascia, one opto-coupler is used for relaying a ringing signal to a modem, a second opto-coupler is used in relaying a line seize signal from the modem to the telephone line access coupler and a transformer is used in place of a pair of opto-couplers for relaying the received and transmitted AC signals from the coupler to the modem.
In the known prior art coupler circuits using opto-couplers, the basic functions of relaying A
2169fi70 the AC transmit signal all require separate opto-coupler devices. In the case that a transformer used, the bi-directional nature of the transformer allows for single device to be used for relaying the received and the transmitted communication signal. In a standard telephone line coupler circuit, the cost of the opto-coupler devices is a substantial portion of the component cost for the circuit.
Summary of the Invention It is accordingly an object of the present invention to provide a telephone line coupler circuit for coupling a telephone line to a subscriber electronic device with isolation between the telephone line and the subscriber device in which the number of opto-couplers is reduced.
In accordance with the first aspect of the present invention, there is provided a telephone line coupler circuit for connecting telephone subscriber equipment to a telephone line, the circuit comprising:
ring and tip connector means for connecting to telephone line ring and tip contacts and providing ring and tip signal outputs; a high impedance DC load and a gated line switch connected in series between the ring and tip signal outputs for controllably conducting an "off-hook" current between the ring and tip signal outputs; a transmit opto-coupler means having a transmit signal input and output; means connecting the output terminal to the tip output and to a gate input of the gated line switch; means for controllably providing a low level DC bias signal to the transmit signal input and generating sufficient current on the output to substantially saturate the gated line switch and seize the line; means for providing an outgoing AC signal to the transmit signal input; and AC signal receive means connected to the 21~9G70 ring and tip outputs for detecting an incoming AC
signal and producing an incoming AC signal output.
The invention also provides a telephone line coupler circuit for connecting telephone subscriber equipment to a telephone line, the circuit comprising:
ring and tip connector means for connecting to telephone line ring and tip contacts and providing ring and tip signal outputs; a high impedance DC load and a line switch connected in series between the ring and tip signal outputs for controllably conducting an "off-hook" current between the ring and tip signal outputs; signal transmit means having a transmit signal input and being connected to the ring and tip outputs for transmitting AC signal; AC communications signal receive means connected to the ring and tip outputs for detecting an incoming AC communications signal and producing an incoming AC communications signal output; and AC ring signal detect means connected to the ring and tip outputs for detecting a telephone ring signal on the telephone line and generating a ringing output signal; wherein: the AC
communications signal receive means and the AC ring signal detect means share a common receive opto-coupler device.
Preferably, the AC communication signal receive means and the AC ring signal detect means comprise a single band pass amplifier circuit which is switchable between two frequency bands, that is a first frequency band for the telephone ring signal and a second frequency band for received communication signals. Also preferably, the band pass filter amplifier is switched between the ring frequency band to the communications frequency band by the line seize signal connected to the means for controllably providing a load level DC bias signal to the transmit signal input of the transmit opto-coupler means.
Accordingly, the invention also provides a telephone line coupler circuit for connecting telephone subscriber equipment to a telephone line, the circuit comprising: ring and tip connector means for connecting to telephone line ring and tip contacts and providing ring and tip signal outputs; a high impedance DC load and a gated line switch connected in series between the ring and tip signal outputs for controllably conducting an "off-hook" current between the ring and tip signal outputs; a transmit opto-coupler means having a transmit signal input and output; means connecting the output terminal to the tip output and to a gate input of the gated line switch; means for controllably providing a low level DC bias signal to the transmit signal input and generating sufficient current on the output to substantially saturate the gated line switch and seize the line; means for providing an outgoing AC signal to the transmit signal input; AC communications signal receive means connected to the ring and tip outputs for detecting an incoming AC communications signal and producing an incoming AC communications signal output;
and AC ring signal detect means connected to the ring and tip outputs for detecting a telephone ring signal on the telephone line and generating a ringing output signal; wherein: the AC communications signal receive means and the AC ring signal detect means share a common receive opto-coupler device.
The invention also provides methods for isolating and connecting subscriber equipment to a telephone line. According to a first aspect, the invention provides a method of isolating and connecting a transmit signal generated by subscriber electronic equipment to a telephone line. The method comprises providing a transmit opto-couple, adding a DC bias to the electronic equipment transmit signal coming from the electronic equipment to obtain a combined signal A
and feeding the combined signal to the transmit opto-coupler, the DC bias being sufficient to generate a low level DC output on a line side of the transmit opto-coupler, using the low level DC output to trigger a line seize circuit connected to the telephone line to draw a minimum current required by a central office to seize the telephone line, and transmitting an isolated copy of the transmit signal output from the transmit opto-coupler on the telephone line.
According to a second aspect, the invention provides a method of isolating and connecting a ring signal and a communications receive signal on a telephone line to subscriber electronic equipment.
The method comprises providing a receive opto-coupler, connecting the receive opto-coupler using first circuit elements to the telephone line to detect and isolate an incoming AC communications signal, connecting the receive opto-coupler using second circuit elements to the telephone line to detect and isolate a ring signal, detecting the ring signal at an output of the receive opto-coupler in the subscriber electronic equipment when the subscriber electronic equipment is in an on-hook state, and detecting the incoming AC communications signal at the output of the receive opto-coupler in the subscriber electronic equipment when the subscriber electronic equipment is in an off-hook state.
Brief Description of the Drawing The invention will be better understood by way of the following detailed description of a preferred embodiment with reference to the appended drawing in which:
FIGURE 1 is a block diagram of the telephone line coupler circuit according to the preferred embodiment.
- 4a -A
Detailed Description of the Preferred Embodiment In the preferred embodiment as illustrated in Figure 1, the telephone line coupler circuit according to the invention comprises a telephone line ring/tip connector providing ring and tip outputs 10 and 11 respectively. In the case that the polarity may be reversed by the telephone company, a diode bridge 12 is provided for providing the correct polarity to the rest of the circuit. A receive opto-coupler 16 is connected to the positive ring output of the diode bridge 12 through a capacitor and line seize switch 15 to the negative tip output of bridge 12. A
DC line seize load 14 and a line seize switch 15 are connected in series between the ring and tip outputs of bridge 12. In order to seize the telephone line, a small DC current must pass through the coupler circuit in order for the telephone company central office equipment to consider the line to be in use.
A transmit opto-coupler 20 has an input consisting of a DC bias signal from a DC bias source 22 and an AC signal component coming from transmit amplifier 24. A comparator circuit is used to block the AC signal in the absence of the DC bias signal and to allow the DC bias signal to pass through in the absence of the AC signal. When the line seize signal 23 is energized, the DC bias voltage from 22 causes the transmit opto-coupler to output a base DC level which saturates the line seize switch 15 to provide the minimum required DC current through load 14 to seize the line. The DC bias level is chosen to provide a sufficient output to saturate line seize switch even when the AC component from transmit amplifier 24 is superimposed. The AC output from opto-coupler 20 is also fed through a resistance directly to the tip output of bridge 12. For pulse M.. 216 fi7 ~
dialling, a separate pulse dialling input is provided which is ORed with line seize signal 23.
When the circuit is in the "on-hook" state, line seize signal 23 is low and the band pass filter amplifier 18 is set to amplify AC signals in a frequency range of the telephone ring signal. Current from outputs 10 and 11 corresponding to a ring signal pass through ring signal filter 13 across the receive opto-coupler 16. Return current passes through diode 17. The received communication/ring signal output from amplifier 18 produces an AC output corresponding to the ring signal appearing on outputs 10 and 11.
The subscriber device connected to the output of amplifier 18 detects the presence of the ring signal and upon deciding to answer, places an output on line seize signal line 23 resulting in amplifier 18 switching to filtering and amplifying frequencies in the communication band and resulting in DC bias source 22 providing a DC bias signal to transmit opto-coupler 20 which causes the line seize switch 15 to be saturated and the line to be seized by passing the required DC current through load 14. Since the receive opto-coupler 16 is connected to the transmit opto-coupler 20, a minimum draw of current to place the light-emitting diode of receive opto-coupler 16 in an operational range is achieved. As an AC signal comes into receive opto-coupler 16, a faithful isolated AC output is generated.
As can be appreciated, the line coupler circuit according to the invention requires only two opto-coupler devices for the purposes of relaying ring signal, communication signal, transmission and seizing the telephone line. While in the preferred embodiment, the band pass filter amplifier 18 is shown as a single block circuit having a single output, it is of course possible to provide two separate filter/amplifier circuits connected to the output of .. 2~6g~~~
opto-coupler 16 without requiring a connection to line seize signal line 23 to switch between the two filters .
and AC ring signal detect means connected to the ring and tip outputs for detecting a telephone ring signal on the telephone line and generating a ringing output signal; wherein: the AC communications signal receive means and the AC ring signal detect means share a common receive opto-coupler device.
The invention also provides methods for isolating and connecting subscriber equipment to a telephone line. According to a first aspect, the invention provides a method of isolating and connecting a transmit signal generated by subscriber electronic equipment to a telephone line. The method comprises providing a transmit opto-couple, adding a DC bias to the electronic equipment transmit signal coming from the electronic equipment to obtain a combined signal A
and feeding the combined signal to the transmit opto-coupler, the DC bias being sufficient to generate a low level DC output on a line side of the transmit opto-coupler, using the low level DC output to trigger a line seize circuit connected to the telephone line to draw a minimum current required by a central office to seize the telephone line, and transmitting an isolated copy of the transmit signal output from the transmit opto-coupler on the telephone line.
According to a second aspect, the invention provides a method of isolating and connecting a ring signal and a communications receive signal on a telephone line to subscriber electronic equipment.
The method comprises providing a receive opto-coupler, connecting the receive opto-coupler using first circuit elements to the telephone line to detect and isolate an incoming AC communications signal, connecting the receive opto-coupler using second circuit elements to the telephone line to detect and isolate a ring signal, detecting the ring signal at an output of the receive opto-coupler in the subscriber electronic equipment when the subscriber electronic equipment is in an on-hook state, and detecting the incoming AC communications signal at the output of the receive opto-coupler in the subscriber electronic equipment when the subscriber electronic equipment is in an off-hook state.
Brief Description of the Drawing The invention will be better understood by way of the following detailed description of a preferred embodiment with reference to the appended drawing in which:
FIGURE 1 is a block diagram of the telephone line coupler circuit according to the preferred embodiment.
- 4a -A
Detailed Description of the Preferred Embodiment In the preferred embodiment as illustrated in Figure 1, the telephone line coupler circuit according to the invention comprises a telephone line ring/tip connector providing ring and tip outputs 10 and 11 respectively. In the case that the polarity may be reversed by the telephone company, a diode bridge 12 is provided for providing the correct polarity to the rest of the circuit. A receive opto-coupler 16 is connected to the positive ring output of the diode bridge 12 through a capacitor and line seize switch 15 to the negative tip output of bridge 12. A
DC line seize load 14 and a line seize switch 15 are connected in series between the ring and tip outputs of bridge 12. In order to seize the telephone line, a small DC current must pass through the coupler circuit in order for the telephone company central office equipment to consider the line to be in use.
A transmit opto-coupler 20 has an input consisting of a DC bias signal from a DC bias source 22 and an AC signal component coming from transmit amplifier 24. A comparator circuit is used to block the AC signal in the absence of the DC bias signal and to allow the DC bias signal to pass through in the absence of the AC signal. When the line seize signal 23 is energized, the DC bias voltage from 22 causes the transmit opto-coupler to output a base DC level which saturates the line seize switch 15 to provide the minimum required DC current through load 14 to seize the line. The DC bias level is chosen to provide a sufficient output to saturate line seize switch even when the AC component from transmit amplifier 24 is superimposed. The AC output from opto-coupler 20 is also fed through a resistance directly to the tip output of bridge 12. For pulse M.. 216 fi7 ~
dialling, a separate pulse dialling input is provided which is ORed with line seize signal 23.
When the circuit is in the "on-hook" state, line seize signal 23 is low and the band pass filter amplifier 18 is set to amplify AC signals in a frequency range of the telephone ring signal. Current from outputs 10 and 11 corresponding to a ring signal pass through ring signal filter 13 across the receive opto-coupler 16. Return current passes through diode 17. The received communication/ring signal output from amplifier 18 produces an AC output corresponding to the ring signal appearing on outputs 10 and 11.
The subscriber device connected to the output of amplifier 18 detects the presence of the ring signal and upon deciding to answer, places an output on line seize signal line 23 resulting in amplifier 18 switching to filtering and amplifying frequencies in the communication band and resulting in DC bias source 22 providing a DC bias signal to transmit opto-coupler 20 which causes the line seize switch 15 to be saturated and the line to be seized by passing the required DC current through load 14. Since the receive opto-coupler 16 is connected to the transmit opto-coupler 20, a minimum draw of current to place the light-emitting diode of receive opto-coupler 16 in an operational range is achieved. As an AC signal comes into receive opto-coupler 16, a faithful isolated AC output is generated.
As can be appreciated, the line coupler circuit according to the invention requires only two opto-coupler devices for the purposes of relaying ring signal, communication signal, transmission and seizing the telephone line. While in the preferred embodiment, the band pass filter amplifier 18 is shown as a single block circuit having a single output, it is of course possible to provide two separate filter/amplifier circuits connected to the output of .. 2~6g~~~
opto-coupler 16 without requiring a connection to line seize signal line 23 to switch between the two filters .
Claims (6)
1. A telephone line coupler circuit for connecting telephone subscriber equipment to a telephone line, the circuit comprising:
ring and tip connector means for connecting to telephone line ring and tip contacts and providing ring and tip signal outputs;
a high impedance DC load and a gated line switch connected in series between said ring and tip signal outputs for controllably conducting an "off-hook" current between said ring and tip signal outputs;
a transmit opto-coupler means having a transmit signal input and output;
means for connecting said transmit signal output to said tip output and to a gate input of said gated line switch;
means for controllably providing a low level DC bias signal to said transmit signal input and generating sufficient current on said transmit signal output to substantially saturate said gated line switch and seize said telephone line;
means for providing an outgoing AC signal to said transmit signal input; and AC signal receive means connected to said ring and tip outputs for detecting an incoming AC signal and producing an incoming AC signal output.
ring and tip connector means for connecting to telephone line ring and tip contacts and providing ring and tip signal outputs;
a high impedance DC load and a gated line switch connected in series between said ring and tip signal outputs for controllably conducting an "off-hook" current between said ring and tip signal outputs;
a transmit opto-coupler means having a transmit signal input and output;
means for connecting said transmit signal output to said tip output and to a gate input of said gated line switch;
means for controllably providing a low level DC bias signal to said transmit signal input and generating sufficient current on said transmit signal output to substantially saturate said gated line switch and seize said telephone line;
means for providing an outgoing AC signal to said transmit signal input; and AC signal receive means connected to said ring and tip outputs for detecting an incoming AC signal and producing an incoming AC signal output.
2. A telephone line coupler circuit for connecting telephone subscriber equipment to a telephone line, the circuit comprising:
ring and tip connector means for connecting to telephone line ring and tip contacts and providing ring and tip signal outputs;
a high impedance DC load and a gated line switch connected in series between said ring and tip signal outputs for controllably conducting an "off-hook" current between said ring and tip signal outputs;
a transmit opto-coupler means having a transmit signal input and output;
means for connecting said transmit signal output to said tip output and to a gate input of said gated line switch;
means for controllably providing a low level DC bias signal to said transmit signal input and generating sufficient current on said transmit signal output to substantially saturate said gated line switch and seize said telephone line;
means for providing an outgoing AC signal to said transmit signal input;
AC communications signal receive means connected to said ring and tip outputs for detecting an incoming AC
communications signal and producing an incoming AC
communications signal output; and AC ring signal detect means connected to said ring and tip outputs for detecting a telephone ring signal on said telephone line and generating a ringing output signal; wherein:
said AC communications signal receive means and said AC ring signal detect means share a common receive opto-coupler device.
ring and tip connector means for connecting to telephone line ring and tip contacts and providing ring and tip signal outputs;
a high impedance DC load and a gated line switch connected in series between said ring and tip signal outputs for controllably conducting an "off-hook" current between said ring and tip signal outputs;
a transmit opto-coupler means having a transmit signal input and output;
means for connecting said transmit signal output to said tip output and to a gate input of said gated line switch;
means for controllably providing a low level DC bias signal to said transmit signal input and generating sufficient current on said transmit signal output to substantially saturate said gated line switch and seize said telephone line;
means for providing an outgoing AC signal to said transmit signal input;
AC communications signal receive means connected to said ring and tip outputs for detecting an incoming AC
communications signal and producing an incoming AC
communications signal output; and AC ring signal detect means connected to said ring and tip outputs for detecting a telephone ring signal on said telephone line and generating a ringing output signal; wherein:
said AC communications signal receive means and said AC ring signal detect means share a common receive opto-coupler device.
3. A telephone line coupler circuit for connecting telephone subscriber equipment to a telephone line, the circuit comprising:
ring and tip connector means for connecting to telephone line ring and tip contacts and providing ring and tip signal outputs;
a high impedance DC load and a line switch connected in series between said ring and tip signal outputs for controllably conducting an "off-hook" current between said ring and tip signal outputs;
signal transmit means having a transmit signal input and being connected to said ring and tip outputs for transmitting AC signal;
AC communications signal receive means connected to said ring and tip outputs for detecting an incoming AC
communications signal and producing an incoming AC
communications signal output; and AC ring signal detect means connected to said ring and tip outputs for detecting a telephone ring signal on said telephone line and generating a ringing output signal;
wherein said AC communication signal receive means and said AC ring signal detect means share a common receive opto-coupler device and a common band pass filter circuit switchable between a frequency band of said ring signal and a frequency band of communications signal received over said telephone line, a switching of said filter circuit being in response to a control signal for said line switch.
ring and tip connector means for connecting to telephone line ring and tip contacts and providing ring and tip signal outputs;
a high impedance DC load and a line switch connected in series between said ring and tip signal outputs for controllably conducting an "off-hook" current between said ring and tip signal outputs;
signal transmit means having a transmit signal input and being connected to said ring and tip outputs for transmitting AC signal;
AC communications signal receive means connected to said ring and tip outputs for detecting an incoming AC
communications signal and producing an incoming AC
communications signal output; and AC ring signal detect means connected to said ring and tip outputs for detecting a telephone ring signal on said telephone line and generating a ringing output signal;
wherein said AC communication signal receive means and said AC ring signal detect means share a common receive opto-coupler device and a common band pass filter circuit switchable between a frequency band of said ring signal and a frequency band of communications signal received over said telephone line, a switching of said filter circuit being in response to a control signal for said line switch.
4. A telephone line coupler circuit for connecting telephone subscriber equipment to a telephone line, the circuit comprising:
ring and tip connector means for connecting to telephone line ring and tip contacts and providing ring and ti-p signal outputs;
a high impedance DC load and a gated line switch connected in series between said ring and tip signal outputs for controllably conducting an "off-hook" current between said ring and tip signal outputs;
a transmit opto-coupler means having a transmit signal input and output;
means connecting said transmit signal output to said tip output and to a gate input of said gated line switch;
means for controllably providing a low level DC bias signal to said transmit signal input and generating sufficient current on said transmit signal output to substantially saturate said gated line switch and seize said line;
means for providing an outgoing AC signal to said transmit signal input;
AC communications signal receive means connected to said ring and tip outputs for detecting an incoming AC
communications signal and producing an incoming AC
communications signal output; and AC ring signal detect means connected to said ring and tip outputs for detecting a telephone ring signal on said telephone line and generating a ringing output signal;
wherein said AC communications signal receive means and said AC ring signal detect means share a common receive opto-coupler device and include a shared band pass filter circuit switchable between a ring signal frequency band and a communication signal frequency band, said filter circuit being switched by a line seize signal fed to said low level DC bias signal providing means.
ring and tip connector means for connecting to telephone line ring and tip contacts and providing ring and ti-p signal outputs;
a high impedance DC load and a gated line switch connected in series between said ring and tip signal outputs for controllably conducting an "off-hook" current between said ring and tip signal outputs;
a transmit opto-coupler means having a transmit signal input and output;
means connecting said transmit signal output to said tip output and to a gate input of said gated line switch;
means for controllably providing a low level DC bias signal to said transmit signal input and generating sufficient current on said transmit signal output to substantially saturate said gated line switch and seize said line;
means for providing an outgoing AC signal to said transmit signal input;
AC communications signal receive means connected to said ring and tip outputs for detecting an incoming AC
communications signal and producing an incoming AC
communications signal output; and AC ring signal detect means connected to said ring and tip outputs for detecting a telephone ring signal on said telephone line and generating a ringing output signal;
wherein said AC communications signal receive means and said AC ring signal detect means share a common receive opto-coupler device and include a shared band pass filter circuit switchable between a ring signal frequency band and a communication signal frequency band, said filter circuit being switched by a line seize signal fed to said low level DC bias signal providing means.
5. The circuit as claimed in claim 1, wherein said ring and tip connector means comprise a diode bridge.
6. The circuit as claimed in claim 2, 3 or 4, wherein said ring and tip connector means comprise a diode bridge, said AC ring signal detect means being connected to said ring and tip signal outputs before said diode bridge.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002273148A CA2273148C (en) | 1995-11-08 | 1996-02-16 | Telephone line coupler |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/555,042 | 1995-11-08 | ||
| US08/555,042 US5751803A (en) | 1995-11-08 | 1995-11-08 | Telephone line coupler |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002273148A Division CA2273148C (en) | 1995-11-08 | 1996-02-16 | Telephone line coupler |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2169670A1 CA2169670A1 (en) | 1997-05-09 |
| CA2169670C true CA2169670C (en) | 1999-10-05 |
Family
ID=24215746
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002169670A Expired - Fee Related CA2169670C (en) | 1995-11-08 | 1996-02-16 | Telephone line coupler |
| CA002273148A Expired - Fee Related CA2273148C (en) | 1995-11-08 | 1996-02-16 | Telephone line coupler |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002273148A Expired - Fee Related CA2273148C (en) | 1995-11-08 | 1996-02-16 | Telephone line coupler |
Country Status (2)
| Country | Link |
|---|---|
| US (3) | US5751803A (en) |
| CA (2) | CA2169670C (en) |
Families Citing this family (37)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5751803A (en) | 1995-11-08 | 1998-05-12 | Shmuel Hershkovit | Telephone line coupler |
| KR0175447B1 (en) * | 1995-12-26 | 1999-04-01 | 김광호 | Ring Detection Circuit and Method for Wired / Wireless Combined Telephone |
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-
1995
- 1995-11-08 US US08/555,042 patent/US5751803A/en not_active Ceased
-
1996
- 1996-02-16 CA CA002169670A patent/CA2169670C/en not_active Expired - Fee Related
- 1996-02-16 CA CA002273148A patent/CA2273148C/en not_active Expired - Fee Related
-
2000
- 2000-05-12 US US09/570,415 patent/USRE39406E1/en not_active Expired - Lifetime
-
2006
- 2006-07-10 US US11/483,104 patent/USRE42590E1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2273148C (en) | 2002-06-25 |
| USRE42590E1 (en) | 2011-08-02 |
| CA2273148A1 (en) | 1997-05-09 |
| USRE39406E1 (en) | 2006-11-21 |
| US5751803A (en) | 1998-05-12 |
| CA2169670A1 (en) | 1997-05-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20140218 |