US3790723A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Test arrangement for a two-wire telephone channel
Assignee: Nokia of America Corp
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Filing: 1972-10-11
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Granted: 1974-02-05
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Expires: 1992-10-11
Abstract
Abstract There is disclosed an arrangement to test the transmission and signaling function of a two-wire carrier telephone channel. The arrangement includes a central office unit to which a test tone is applied for transmission to a subscriber unit. At the subscriber unit a test tone detector detects the test tone and actuates a switching arrangement to connect the tip conductor and ring conductor of a subscriber set together so as to cause a mistermination of a hybrid circuit in the subscriber unit thereby causing the test tone to be looped back to the central office unit where the magnitude of the test tone is measured. From the measurement of the test tone a faulty operation of the channel can be detected. The test tone detector includes a tuned circuit tuned to the frequency of the test tone, a precision halfwave rectifier circuit including a first solid state operational amplifier coupled to the tuned circuit and an output circuit including a second solid state operational amplifier coupled to the output of the rectifier circuit and to the tuned circuit to produce a full wave rectified output signal with voltage gain upon detection of the test tone to actuate the switching arrangement.
Inventors
- 👤 E Stewart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:27
CPC Classifications
H; H04; H04M; H04M3/00; H04M3/22; H04M3/26; H04M3/28; H04M3/30; H04M3/301; H04B; H04B3/00; H04B3/02; H04B3/46
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
289 words
A test arrangement for a two-wire telephone channel comprising: a central office unit including first transmit circuitry, first receive circuitry, and a first hybrid circuit appropriately connected to the input of said first transmit circuitry and the output of said first receive circuitry; a subscriber unit including second receive circuitry having its input coupled to the output of said first transmit circuitry by a first propagation medium, second transmit circuitry having its output coupled to the input of said first receive circuitry by a second propagation medium, a subscriber set having a tip conductor and a ring conductor, and a second hybrid circuit appropriately connected to the output of said second receive circuitry, the input of said second transmit circuitry and said tip and ring conductors; an oscillator to produce a test tone having a given frequency coupled to said first hybrid circuit which causes propagation of said test tone through said first transmit circuitry and said second receive circuitry; a test tone detector coupled to said second receive circuitry to detect said test tone and produce a control signal; a switching arrangement coupled to said detector and said tip and ring conductors, said switching arrangement being responsive to said control signal to interconnect said tip and ring conductors to cause a mismatch in a termination of said second hybrid circuit so that said test tone will be looped from the output of said second receive circuitry through said second hybrid circuit, said second transmit circuitry, said first receive circuitry and said first hybrid circuit; and a device coupled to said first hybrid circuit to measure the magnitude of said test tone at the output of said first receive circuitry to determine whether said telephone channel is functioning properly.
Claim 2
Dependent Claim
289 words
A test arrangement for a two-wire telephone channel comprising: a central office unit including first transmit circuitry, first receive circuitry, and a first hybrid circuit appropriately connected to the input of said first transmit circuitry and the output of said first receive circuitry; a subscriber unit including second receive circuitry having its input coupled to the output of said first transmit circuitry by a first propagation medium, second transmit circuitry having its output coupled to the input of said first receive circuitry by a second propagation medium, a subscriber set having a tip conductor and a ring conductor, and a second hybrid circuit appropriately connected to the output of said second receive circuitry, the input of said second transmit circuitry and said tip and ring conductors; an oscillator to produce a test tone having a given frequency coupled to said first hybrid circuit which causes propagation of said test tone through said first transmit circuitry and said second receive circuitry; a test tone detector coupled to said second receive circuitry to detect said test tone and produce a control signal; a switching arrangement coupled to said detector and said tip and ring conductors, said switching arrangement being responsive to said control signal to interconnect said tip and ring conductors to cause a mismatch in a termination of said second hybrid circuit so that said test tone will be looped from the output of said second receive circuitry through said second hybrid circuit, said second transmit circuitry, said first receive circuitry and said first hybrid circuit; and a device coupled to said first hybrid circuit to measure the magnitude of said test tone at the output of said first receive circuitry to determine whether said telephone channel is functioning properly.
Claim 3
Dependent Claim
39 words
An arrangement according to claim 1, further including a first resistor coupled to said switch arrangement to place a resistive ground on said tip and ring conductors when said test tone is detected and said control signal is produced.
Claim 4
Dependent Claim
67 words
An arrangement according to claim 1, wherein said detector includes a tuned circuit coupled to said second receive circuitry tuned to said given frequency, a precision halfwave rectifier circuit coupled to said tuned circuit, and an output circuit coupled to the output of said rectifier circuit and to said tuned circuit to produce a full wave rectified output signal with voltage gain upon detection of said tone.
Claim 5
Dependent Claim
167 words
An arrangement according to claim 3, wherein said tuned circuit includes ground potential, a first resistor having one terminal connected to said second receive circuitry, and a parallel coupled inductor-capacitor tuned circuit coupled between the other terminal of said first resistor and said ground potential; and said rectifier circuit includes a first solid state operational amplifier having an inverting input, a non-inverting input and an output, said non-inverting input being directly connected to said ground potential, a second resistor coupled between the junction of said first resistor and said parallel tuned circuit and said inverting input of said first amplifier, a first solid state diode being poled in a given direction connected between said output and said inverting input of said first amplifier, and a series circuit coupled between said output and said inverting input of said first amplifier in parallel with said first diode, said series circuit having a second solid state diode poled in a direction opposite to said givEn direction, and a third resistor.
Claim 6
Dependent Claim
125 words
An arrangement according to claim 4, wherein said output circuit includes a second solid state operational amplifier having an inverting input, a non-inverting input and an output, said non-inverting input being connected directly to said ground potential, a fourth resistor coupled between the junction of said second diode and said third resistor and said inverting input of said second amplifier, a fifth resistor coupled between the junction of said first resistor and said parallel tuned circuit and said inverting input of said second amplifier, a sixth resistor coupled between said output and said inverting input of said second amplifier, and a capacitor coupled in parallel to said sixth resistor, said output of said second amplifier providing said control signal when said test tone is detected.
Claim 7
Dependent Claim
98 words
An arrangement according to claim 3, wherein said output circuit includes ground potential, a solid state operational amplifier having an inverting input, a non-inverting input and an output, said non-inverting input being directly connected to said ground potential, a first resistor coupled between the output of said rectifying circuit and said inverting input, a second resistor coupled between said tuned circuit and said inverting input, a third resistor coupled between said output and said inverting input, and a capacitor coupled in parallel to said third resistor, said output providing said control signal when said test tone is detected.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-04 | 1977-08-06 | 1978-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-04 | 1981-08-06 | 1982-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-04 | 1985-08-06 | 1986-02-05 | $7700.00 | Window Closed / Lapsed |