US3562439A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telephone inband signalling system
Assignee: Raytheon Co
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Filing: 1968-06-24
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Granted: 1971-02-09
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Expires: 1988-06-24
Abstract
Abstract A telephone inband signalling system converts first and second DC signal levels by detecting a change in either direction between the signals to produce a voltage of predetermined time duration which exceeds the time between dial pulses. This latter voltage is employed to simultaneously (a) short the voice path, thereby preventing feedback to the calling party, and (b) enhance the tone of a 2600 hz. oscillator. The oscillator is then onoffed in response to the dial pulses coming over the input. At the end of the conversation, a muted 2600 hz. tone is continuously transmitted indicating an idle line.
Inventors
- 👤 Leo K Lugten
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:38
CPC Classifications
H; H04; H04Q; H04Q1/00; H04Q1/18; H04Q1/30; H04Q1/50
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
130 words
A telephone signalling system for converting first and second DC signal voltage levels into inband AC signals between remote stations comprising: a. means for detecting a change between said DC voltage levels and issuing a signal of predetermined duration; b. a voice frequency path; c. an AC signal source normally coupled to said path; d. a switch, coupled to said detector means and responsive to the signal issuing therefrom for interrupting said voice frequency path at the input for the duration of said detector means signal; and e. means coupled between said signal source and said path and responsive to said detector means signal and one of said DC signal level voltages for enhancing said AC signal level over said path during the occurrence of said one DC signal level.
Claim 2
Dependent Claim
130 words
A telephone signalling system for converting first and second DC signal voltage levels into inband AC signals between remote stations comprising: a. means for detecting a change between said DC voltage levels and issuing a signal of predetermined duration; b. a voice frequency path; c. an AC signal source normally coupled to said path; d. a switch, coupled to said detector means and responsive to the signal issuing therefrom for interrupting said voice frequency path at the input for the duration of said detector means signal; and e. means coupled between said signal source and said path and responsive to said detector means signal and one of said DC signal level voltages for enhancing said AC signal level over said path during the occurrence of said one DC signal level.
Claim 3
Dependent Claim
46 words
The telephone signalling system claimed in claim 2 wherein said enhancing means comprises an attenuator normally coupled between said AC signal source and said path, said enhancing means including means for effectively removing said attenuator means for the duration of said signal from said detector means.
Claim 4
Dependent Claim
21 words
The telephone signalling system claimed in claim 3 wherein said detector means signal time duration exceeds the time between dial pulses.
Claim 5
Dependent Claim
55 words
The telephone signalling system claimed in claim 4 wherein the attenuator means comprises a pair of diodes connected in push-pull and coupled across AC signal source and said switch including a transistor coupled the input to said path, said transistor and the center point of said diodes being coupled in common to said detector means.
References Cited (Backward Citations)
US2765371A
Cited
US3306984A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-02-08 | 1974-08-10 | 1975-02-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-08 | 1978-08-10 | 1979-02-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-08 | 1982-08-10 | 1983-02-09 | $7700.00 | Window Closed / Lapsed |