US3601538A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Carrier and voice-frequency telephone system
Assignee: Stromberg Carlson Corp
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Filing: 1969-02-24
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Granted: 1971-08-24
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Expires: 1989-02-24
Abstract
Abstract This system serves the purpose of providing private line service over an existing telephone line and includes a central office terminal at one end of the line and a subscriber terminal at the other end of the line. Physical phones may be connected to the existing line and a line circuit at the central office is coupled to the line for connecting the central office equipment to the phones. Both the subscriber and the central office terminals have transmitting channels in which a carrier oscillator signal may be modulated and applied to the line. The control functions in the system are operated in response to the absence or presence of carrier oscillations on the line. Circuits are provided at the central office terminal which are responsive to a reception of a carrier signal transmitted from the subscriber terminal, or in off-hook condition of one of the physical phones for turning on the central office terminal carrier oscillator. The subscriber terminal has a battery which is connected to the line to receive charging current therefrom in the absence of central office terminal carrier signals and is disconnected from the line in response to the presence of central office carrier signals. Ringing current for the telephone which is connected to the subscriber carrier terminal is generated by modulating the central office carrier. The modulated carrier operates the ringer circuitry at the subscriber carrier terminal. Both the subscriber carrier terminal and the central office terminal therefore cooperate with each other to produce the requisite control functions.
Inventors
- 👤 Peter J May
- 👤 Uno Randmere
- 👤 Frederick C Sabernick
- 👤 Morris A Suntop
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 02:33
CPC Classifications
H; H04; H04Q; H04Q11/00; H04Q11/02
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
300 words
A telephone system for providing a carrier channel over an existing voice frequency telephone line which is adapted to have a plurality of physical telephone sets connected thereto, said system comprising a. a central office terminal at one end of said existing line, b. a subscriber terminal at the opposite end of said existing line, c. said central office terminal having a first carrier frequency oscillator, d. said subscriber terminal having a second carrier frequency oscillator, e. said terminals each having a transmit channel including a different one of said first and second oscillators and a receive channel coupled at one end thereof to said line, the opposite end of said central office channel being connected to a telephone circuit which provides voice frequency signals for transmission to said transmit channel and receives voice frequency signals from said receive channel, the opposite end of said subscriber terminal channels being coupled to a telephone set, f. means for connecting a voice frequency telephone line circuit to said line for direct voice frequency communications with said physical telephone sets, g. means for applying direct current potential to said existing line, h. a battery in said subscriber terminal, i. means for charging said battery from said existing line direct current, j. control means for said first oscillator connected to said central office terminal receive channel and to said line for rendering said first oscillator operative to apply a carrier signal to said line when either any of said physical telephone sets goes off hook or when a carrier signal is received by said receive channel from said subscriber terminal, and k. control means for said charging means connected to said subscriber terminal receive channel for disconnecting said battery from said line when a carrier signal is received by said subscriber terminal receive channel.
Claim 2
Dependent Claim
300 words
A telephone system for providing a carrier channel over an existing voice frequency telephone line which is adapted to have a plurality of physical telephone sets connected thereto, said system comprising a. a central office terminal at one end of said existing line, b. a subscriber terminal at the opposite end of said existing line, c. said central office terminal having a first carrier frequency oscillator, d. said subscriber terminal having a second carrier frequency oscillator, e. said terminals each having a transmit channel including a different one of said first and second oscillators and a receive channel coupled at one end thereof to said line, the opposite end of said central office channel being connected to a telephone circuit which provides voice frequency signals for transmission to said transmit channel and receives voice frequency signals from said receive channel, the opposite end of said subscriber terminal channels being coupled to a telephone set, f. means for connecting a voice frequency telephone line circuit to said line for direct voice frequency communications with said physical telephone sets, g. means for applying direct current potential to said existing line, h. a battery in said subscriber terminal, i. means for charging said battery from said existing line direct current, j. control means for said first oscillator connected to said central office terminal receive channel and to said line for rendering said first oscillator operative to apply a carrier signal to said line when either any of said physical telephone sets goes off hook or when a carrier signal is received by said receive channel from said subscriber terminal, and k. control means for said charging means connected to said subscriber terminal receive channel for disconnecting said battery from said line when a carrier signal is received by said subscriber terminal receive channel.
Claim 3
Dependent Claim
39 words
The invention as set forth in claim 1 including means responsive to an off-hook condition of the telephone set connected to said subscriber terminal for rendering said second oscillator operative to apply a carrier signal to said existing line.
Claim 4
Dependent Claim
70 words
The invention as set forth in Claim 2 wherein said off-hook condition responsive means includes a coupling circuit for connecting the transmitter of said subscriber telephone set to said subscriber terminal channels including a current path between said battery and said transmitter, and a gate circuit connected to said second oscillator and to said coupling circuit for inhibiting said second oscillator in response to current flow in said coupling circuit.
Claim 5
Dependent Claim
52 words
The invention as set forth in claim 1 including a ringing amplifier connected to said subscriber terminal receive channel and to said subscriber terminal telephone set for applying said carrier, which is modulated by ringing frequency current from said telephone circuit in said central office terminal transmit channel, to said last-named set.
Claim 6
Dependent Claim
62 words
The invention as set forth in Claim 4 wherein said subscriber terminal receive channel includes a demodulator for translating said modulated carrier into voice frequency signals, said ringing amplifier being coupled to said subscriber terminal receive channel between said demodulator and the existing line connected end of said subscriber terminal receive channel whereby said modulated carrier is coupled to said ringing amplifier.
Claim 7
Dependent Claim
29 words
The invention as seT forth in claim 5 including means responsive to an off-hook condition of the telephone set connected to said subscriber terminal for inhibiting said ringing amplifier.
Claim 8
Dependent Claim
55 words
The invention as set forth in claim 1 wherein said first oscillator control means includes control circuits for said first oscillator, and means included in said means for connecting said voice frequency telephone line circuit to said line for operating said control circuits in response to said off-hook condition of said existing physical telephone sets.
Claim 9
Dependent Claim
21 words
The invention as set forth in claim 7 wherein said means included in said line circuit connecting means is a relay.
Claim 10
Dependent Claim
30 words
The invention as set forth in claim 8 wherein said line circuit connecting means comprises a low-pass filter, the coil of said relay comprising an inductive element of said filter.
Claim 11
Dependent Claim
176 words
In a telecommunication system including an exchange having a transmitter for applying carrier and voice frequency signals to a telephone line and a receiver receiving carrier and voice frequency signals from the telephone line, a telephone set connected to the line, and a carrier terminal including a transmitter for applying carrier signals to the telephone line and a receiver for receiving carrier signals from the telephone line, a power system for energizing said telephone and carrier terminal comprising: means in said exchange for applying a unidirectional energizing potential to said line; battery means for providing a source of energizing potential for said terminal; charging circuit means for charging said battery means from the unidirectional energizing potential applied to said line; detection circuit means for detecting when the telephone is off hook and causing said exchange transmitter to apply a carrier signal to the line while the telephone is off hook, and circuit means responsive to a carrier signal on said line for inhibiting said charging circuit means while the carrier signals are present on said line.
Claim 12
Dependent Claim
176 words
In a telecommunication system including an exchange having a transmitter for applying carrier and voice frequency signals to a telephone line and a receiver receiving carrier and voice frequency signals from the telephone line, a telephone set connected to the line, and a carrier terminal including a transmitter for applying carrier signals to the telephone line and a receiver for receiving carrier signals from the telephone line, a power system for energizing said telephone and carrier terminal comprising: means in said exchange for applying a unidirectional energizing potential to said line; battery means for providing a source of energizing potential for said terminal; charging circuit means for charging said battery means from the unidirectional energizing potential applied to said line; detection circuit means for detecting when the telephone is off hook and causing said exchange transmitter to apply a carrier signal to the line while the telephone is off hook, and circuit means responsive to a carrier signal on said line for inhibiting said charging circuit means while the carrier signals are present on said line.
Claim 13
Dependent Claim
29 words
The power system defined in claim 10 wherein said detection means detects the presence of direct current flow through the line due to the off-hook condition of the telephone.
Claim 14
Dependent Claim
56 words
A power system as defined in claim 11 wherein said detection means comprises at least one relay coil connected in series with the telephone line so that said relay is actuated when the telephone goes off hook, and contacts of said relay when activated actuate the exchange transmitter to apply a carrier signal to the line.
Claim 15
Dependent Claim
135 words
A telephone communication system comprising: a telephone line; a telephone exchange connected to said line including carrier transmitter and receiver sections, means for applying battery potential to said line, and means for applying voice signals to said line and receiving voice signals from said line; at least one telephone set connected to said line; a subscriber carrier terminal connected to said line including carrier transmitter and receiver sections, a battery, and means for charging said battery from the potential applied to the line by said exchange; means in said exchange for detecting when a telephone set has gone off hook and enabling the terminal transmitter section to apply a carrier signal to the line, and means in said terminal for detecting the presence of a carrier signal on said line for inhibiting said charging means.
Claim 16
Dependent Claim
135 words
A telephone communication system comprising: a telephone line; a telephone exchange connected to said line including carrier transmitter and receiver sections, means for applying battery potential to said line, and means for applying voice signals to said line and receiving voice signals from said line; at least one telephone set connected to said line; a subscriber carrier terminal connected to said line including carrier transmitter and receiver sections, a battery, and means for charging said battery from the potential applied to the line by said exchange; means in said exchange for detecting when a telephone set has gone off hook and enabling the terminal transmitter section to apply a carrier signal to the line, and means in said terminal for detecting the presence of a carrier signal on said line for inhibiting said charging means.
Claim 17
Dependent Claim
30 words
The power system as defined in claim 13 wherein said detection means detects the presence of direct current flow through the line due to the off-hook condition of the telephone.
Claim 18
Dependent Claim
56 words
A power system as defined in claim 14 wherein said detection means comprises at least one relay coil connected in series with the telephone line so that said relay is actuated when the telephone goes off hook, and contacts of said relay when activated actuate the exchange transmitter to apply a carrier signal to the line.
References Cited (Backward Citations)
US3510584A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-23 | 1975-02-22 | 1975-08-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-23 | 1979-02-22 | 1979-08-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-23 | 1983-02-22 | 1983-08-24 | $7700.00 | Window Closed / Lapsed |