US3742154A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Continuous inband testing of trunks with automatic trunk substitution upon detecting a defective trunk
Assignee: AT&T Inc
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Filing: 1971-12-30
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Granted: 1973-06-26
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Expires: 1991-12-30
Abstract
Abstract The integrity of a dedicated trunk is checked by providing equipment for periodically transmitting inband test signals in both directions over the trunk. Each of the test signals is a 2,400 Hz signal periodically transmitted over the trunk from the near end. Equipment at the far end responds by returning a 2,600 Hz acknowledgment pulse over the trunk. Filters at both ends of the trunk prevent interference of the test signals with the voice frequency communications thereon. A counter at the near end of the trunk is initialized for each test signal transmitted to the far end and is blocked from counting by each acknowledgment signal returned over the trunk. Upon transmitting two successive test signals to the far end and not receiving acknowledgment signals, the counter is incremented to the count of two and controls an automatic transfer of the voice frequency communications on the dedicated trunk to a spare trunk the integrity of which is similarly checked.
Inventors
- 👤 R Bidlack
- 👤 Kelvey W Mc
- 👤 J Rezelman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 19:28
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/74
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
138 words
An arrangement for maintaining the integrity of a communications path between two terminal locations through a trunk means comprising a spare trunk, means operable for substituting said spare trunk for said trunk means, meanS at a first one of said locations for transmitting a series of first timed pulse signals over said trunk means to said second location, means at said second one of said locations responsive to a receipt of each of said first signals for sending a second timed pulse signal over said trunk means to said first location, integrity check means at said first location and including means checking the receipt of each of said second signals, and means controlled by said check means in the absence of a predetermined plurality of said second signals sent over said trunk means for operating said substituting means.
Claim 2
Dependent Claim
138 words
An arrangement for maintaining the integrity of a communications path between two terminal locations through a trunk means comprising a spare trunk, means operable for substituting said spare trunk for said trunk means, meanS at a first one of said locations for transmitting a series of first timed pulse signals over said trunk means to said second location, means at said second one of said locations responsive to a receipt of each of said first signals for sending a second timed pulse signal over said trunk means to said first location, integrity check means at said first location and including means checking the receipt of each of said second signals, and means controlled by said check means in the absence of a predetermined plurality of said second signals sent over said trunk means for operating said substituting means.
Claim 3
Dependent Claim
40 words
the invention in accordance with claim 1 wherein said checking means includes means for counting to a predetermined plural count under control of said transmitting means and in response to the absence of received second signals at said first location.
Claim 4
Dependent Claim
112 words
The invention in accordance with claim 2 wherein said substituting means comprises individual switch means at each of said locations, said counting means controlling the energization of said switch means at said first location to effect the substitution of said spare trunk for said trunk means thereat upon said counting means counting to said predetermined plural count, means concurrently controlled by said counting means for effecting the transmission of a transfer signal over said spare trunk to said second location, and means responsive to the receipt of said transfer signal for operating said switch means at said second location to effect the substitution of said spare trunk for said trunk means thereat.
Claim 5
Dependent Claim
87 words
The invention in accordance with claim 3 wherein each of said first timed pulse signals comprises a first prescribed tone signal of a first prescribed frequency and each of said second timed pulse signals comprises a second prescribed tone signal of another prescribed frequency for distinguishing between said first and second signals on said trunk means, and further comprising means cooperating with said transmitting means for incrementing said counting means to effect said counting, and means responsive to said second tone signal to recycle said counting means.
Claim 6
Dependent Claim
90 words
The invention in accordance with claim 3 further comprising means for transmitting a transfer acknowledgment signal over said spare trunk to said first location responsive to the operation of said switch means at said second location, and alarm means primed by said acknowledgment signal transmitting means to be operated to indicate a failure to substitute said spare trunk for said trunk means a predetermined time after the transmission of said transfer signal over said spare trunk, and said alarm means operation being canceled by the receipt of said acknowledgment signal.
Claim 7
Dependent Claim
38 words
The invention in accordance with claim 5 further comprising means operated after a defect in said trunk means is cleared for automatically releasing said substituting means to effect the substitution of said trunk means for said spare trunk.
Claim 8
Dependent Claim
128 words
Equipment for checking a plurality of communication paths comprising means applying a series of first signals to one end of each of said paths, means for returning a second signal over each of said paths in response to a receipt of each of said first signals, means individual to each one of said paths at said one end thereof for indicating a trouble condition in the absence of a receipt of a predetermined number of said second signals at said one end of said paths, and switch means at said one end of said paths responsive to a trouble indication from said indicating means associated with a first one of said paths for transferring communication signals carried on said first path to a second one of said paths.
Claim 9
Dependent Claim
128 words
Equipment for checking a plurality of communication paths comprising means applying a series of first signals to one end of each of said paths, means for returning a second signal over each of said paths in response to a receipt of each of said first signals, means individual to each one of said paths at said one end thereof for indicating a trouble condition in the absence of a receipt of a predetermined number of said second signals at said one end of said paths, and switch means at said one end of said paths responsive to a trouble indication from said indicating means associated with a first one of said paths for transferring communication signals carried on said first path to a second one of said paths.
Claim 10
Dependent Claim
84 words
The invention in accordance with claim 7 wherein said transferring means further comprises switch means at said other end of said first and second paths for transferring communication signals carried on said first path to said second Path at said other end, means applying a transfer signal to said second path in response to said indicating means indicating a trouble condition, and means for operating said switch means responsive to the receipt of said transfer signal at said other end of said second path.
References Cited (Backward Citations)
US2666099A
Cited
US2680162A
Cited
US3155772A
Cited
US3364468A
Cited
US3364467A
Cited
US3423539A
Cited
US3409877A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-25 | 1976-12-25 | 1977-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-25 | 1980-12-25 | 1981-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-25 | 1984-12-25 | 1985-06-26 | $7700.00 | Window Closed / Lapsed |