Patent US3545459A successfully refreshed from Google Patents.
US4536618A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telephone line interface
Assignee: PRACTICAL PERIPHERALS Inc A CORP OF
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Filing: 1983-10-14
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Granted: 1985-08-20
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Expires: 2003-10-14
Abstract
Abstract A telephone line interface for direct connect telephone line connections characterized by low cost and minimal package size requirements. The telephone line interface utilizes a small signal transformer with a primary winding couplable to the line by actuation of a relay. A secondary winding of the transformer is coupled to an integrated circuit which performs the functions of ring detect and dial tone detect, and separation of the received signal and the transmit signal when transmitting and receiving simultaneously. Ring signal detection on the secondary side of the coupling transformer substantially reduces the size and cost of the ring detect circuitry, as the secondary of the transformer may be provided with over-voltage protection, whereas the line side of the transformer must survive particularly high surge voltages, thereby requiring high voltage isolation not obtainable by way of conventional integrated circuits. Other aspects and features of the invention are disclosed.
Inventors
- 👤 Arthur L. Serrano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 10:30
CPC Classifications
H; H04; H04M; H04M3/00; H04M3/005
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
229 words
Apparatus for detecting the ring signal on first and second telephone lines comprising; a coupling transformer having a primary winding and a secondary winding, each having at least two leads thereon, a switch means for controllably changing between open and closed conditions to provide electrical conduction between first and second switch contact means when in said closed condition, said first switch contact means being a means for connection to the first telephone line, said second switch contact means being coupled to said first primary lead for said coupling transformer, said second primary lead of said coupling transformer including means for coupling to the second telephone line, open line load means coupled between said first and second switch contact means for providing a predetermined linear load on the phone lines when said switch means is open, and ring signal sensing means coupled to said first and second secondary leads of said coupling transformer for sensing the presence of a ring signal on the telephone lines when said switch means is open, said ring signal sensing means including filter means for attenuating signals not within the predetermined frequency range of the ring signal, and sensing means coupled to said filter means for sensing the presence of an output of said filter means within the predetermined frequency range of the ring signal and providing a ring detect output signal in response thereto.
Claim 2
Dependent Claim
229 words
Apparatus for detecting the ring signal on first and second telephone lines comprising; a coupling transformer having a primary winding and a secondary winding, each having at least two leads thereon, a switch means for controllably changing between open and closed conditions to provide electrical conduction between first and second switch contact means when in said closed condition, said first switch contact means being a means for connection to the first telephone line, said second switch contact means being coupled to said first primary lead for said coupling transformer, said second primary lead of said coupling transformer including means for coupling to the second telephone line, open line load means coupled between said first and second switch contact means for providing a predetermined linear load on the phone lines when said switch means is open, and ring signal sensing means coupled to said first and second secondary leads of said coupling transformer for sensing the presence of a ring signal on the telephone lines when said switch means is open, said ring signal sensing means including filter means for attenuating signals not within the predetermined frequency range of the ring signal, and sensing means coupled to said filter means for sensing the presence of an output of said filter means within the predetermined frequency range of the ring signal and providing a ring detect output signal in response thereto.
Claim 3
Dependent Claim
58 words
The apparatus of claim 1 wherein said sensing means includes a threshold means whereby said sensing means will sense the presence of an output of said filter means within the predetermined frequency range of the ring signal and provide a ring detect output signal in response thereto when the output of said filter means exceeds a predetermined threshold.
Claim 4
Dependent Claim
34 words
The apparatus of claim 1 wherein said filter means includes means to compensate for the variation of the output of said coupling transformer with frequency within the expected frequency range of typical ring signals.
Claim 5
Dependent Claim
210 words
Apparatus for detecting the ring signal on first and second telephone lines comprising; a coupling transformer having a primary winding and a secondary winding, each having at least two leads thereon, a switch means for controllably changing between open and closed conditions to provide electrical conduction between first and second switch contact means when in said closed condition, said first switch contact means being a means for connection to the first telephone line, said second switch contact means being coupled to said first primary lead of said coupling transformer, said second primary lead of said coupling transformer including means for coupling to the second telephone line, open line load means coupled between said first and second switch contact means for providing a predetermined linear load on the phone lines when said switch means is open, and ring signal sensing means coupled to said first and second secondary leads of said coupling transformer for sensing the presence of a ring signal on the telephone lines when said switch means is open and providing a ring detect output signal in response thereto, said ring signal sensing means being frequency and threshold selective to respond primarily to signals within the predetermined frequency range of ring signals and of at least a predetermined amplitude.
Claim 6
Dependent Claim
210 words
Apparatus for detecting the ring signal on first and second telephone lines comprising; a coupling transformer having a primary winding and a secondary winding, each having at least two leads thereon, a switch means for controllably changing between open and closed conditions to provide electrical conduction between first and second switch contact means when in said closed condition, said first switch contact means being a means for connection to the first telephone line, said second switch contact means being coupled to said first primary lead of said coupling transformer, said second primary lead of said coupling transformer including means for coupling to the second telephone line, open line load means coupled between said first and second switch contact means for providing a predetermined linear load on the phone lines when said switch means is open, and ring signal sensing means coupled to said first and second secondary leads of said coupling transformer for sensing the presence of a ring signal on the telephone lines when said switch means is open and providing a ring detect output signal in response thereto, said ring signal sensing means being frequency and threshold selective to respond primarily to signals within the predetermined frequency range of ring signals and of at least a predetermined amplitude.
Claim 7
Dependent Claim
29 words
The apparatus of claim 4 wherein said ring signal sensing means includes frequency selective means for substantially compensating for the frequency dependence of the output of said coupling transformer
Claim 8
Dependent Claim
252 words
Apparatus for detecting the ring signal on first and second telephone lines comprising; a coupling transformer having a primary winding and a secondary winding, each having at least two leads thereon, a switch means for controllably changing between open and closed conditions to provide electrical conduction between first and second switch contact means when in said closed condition, said first switch contact means being a means for connection to the first telephone line, said second switch contact means being coupled to said first primary lead for said coupling transformer, said second primary lead of said coupling transformer including means for coupling to the second telephone line, open line load means coupled between said first and second switch contact means for providing a predetermined linear load on the phone lines when said switch means is open, filter means coupled to said first and second secondary leads of said coupling transformer, said filter means being a means for providing a filter means output primarily responsive to signals within the predetermined frequency range of ring signals received from said coupling transformer, threshold means coupled to said filter means for imposing a predetermined threshold level on the output of said filter means, zero crossing detector means coupled to said threshold means for detecting zero crossings in the signal received therefrom and for providing a square wave output in response thereto, and output means coupled to said zero crossing detector means for detecting the square wave output and providing a ring signal detection signal in response thereto.
Claim 9
Dependent Claim
252 words
Apparatus for detecting the ring signal on first and second telephone lines comprising; a coupling transformer having a primary winding and a secondary winding, each having at least two leads thereon, a switch means for controllably changing between open and closed conditions to provide electrical conduction between first and second switch contact means when in said closed condition, said first switch contact means being a means for connection to the first telephone line, said second switch contact means being coupled to said first primary lead for said coupling transformer, said second primary lead of said coupling transformer including means for coupling to the second telephone line, open line load means coupled between said first and second switch contact means for providing a predetermined linear load on the phone lines when said switch means is open, filter means coupled to said first and second secondary leads of said coupling transformer, said filter means being a means for providing a filter means output primarily responsive to signals within the predetermined frequency range of ring signals received from said coupling transformer, threshold means coupled to said filter means for imposing a predetermined threshold level on the output of said filter means, zero crossing detector means coupled to said threshold means for detecting zero crossings in the signal received therefrom and for providing a square wave output in response thereto, and output means coupled to said zero crossing detector means for detecting the square wave output and providing a ring signal detection signal in response thereto.
Claim 10
Dependent Claim
22 words
The apparatus of claim 6 wherein said output means is a frequency sensitive means for detecting a square wave of particular frequencies.
Claim 11
Dependent Claim
35 words
The apparatus of claim 6 wherein said filter means includes a means to compensate for the variation of the output of said coupling transformer with frequency within the expected frequency range of typical ring signals.
References Cited (Backward Citations)
US3603740A
Cited
US4390752A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-08-19 | 1989-02-18 | 1989-08-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-08-19 | 1993-02-18 | 1993-08-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-08-19 | 1997-02-18 | 1997-08-20 | $7700.00 | Window Closed / Lapsed |