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| Number | Title | Issue Date |
| 4845735 | Non-interfering method for measuring propagation delay of telecommunications network and apparatus for accomplishing same Methods and apparatus for measuring propagation delay over a line without interfering with data communications over the line are disclosed. A known signal is sent and looped back over a secondary channel, and the loop time is measured. Because the known s... | 07/04/1989 |
| 4766594 | Digital network system having arrangement for testing digital subscriber line A digital network system having an arrangement for testing a digital subscriber line includes a switching device, an exchange terminal device as a subscriber circuit connected with the switching device, a subscriber line connected with the exchange termin... | 08/23/1988 |
| 4764949 | Subscriber/craftsperson ringback apparatus A telephone ringback apparatus includes a microprocessor-controlled communications device which is connectable with telephone equipment contained in a central office, such as a toll trunk facility, having the capability of identifying the number of a call... | 08/16/1988 |
| 4688208 | Time division exchange for carrying out a loop-back test A time division exchange interchanges predetermined time slots of a time division multiplexed signal and returns it to a network during a loop-back test. A buffer memory in a time division multiplexed trunk is used to interchange the predetermined time sl... | 08/18/1987 |
| 4688209 | Method and apparatus for looping around a digital transmission line at a channel unit Method and apparatus for looping around a digital transmission line (150) at a predetermined channel unit (172) to test the line from either end of the line. Each channel unit in the line is responsive to a first and a second received control code to perf... | 08/18/1987 |
| 4675862 | Loop around data channel unit A channel unit (172) for looping around a digital transmission line (150) in response to first and second received control codes. When the first and second received control codes are both first predetermined control codes from one end of the line, the dat... | 06/23/1987 |
| 4660194 | Method and apparatus for testing a subscriber's line circuit in a packet switched multiplexed data/voice communication system In a packet switched multiplexed data/voice communication system, timed loopbacks along a subscriber line are effected by purposely extinguishing or killing the DATA carrier sewing the line.... | 04/21/1987 |
| 4630268 | Communication circuit loopback test apparatus To perform a loopback condition for testing purposes, the present apparatus supplies a null signal from an end terminal on a communication link through a set of repeater stations to reinitialize the repeater stations. It then sends N+1 pulses of a frequen... | 12/16/1986 |
| 4622438 | Subscriber line radio concentration system with automatic response for a loop back test In a subscriber line radio concentration system for concentrating a plurality of subscriber terminal stations through radio channels to a master station, at least one of the subscriber terminal stations comprises an automatic response equipment. The autom... | 11/11/1986 |
| 4582964 | Remote loop-around carrier test system A testing system for testing a selected telephone carrier channel wherein that channel is selectively interrupted at a selected repeater station along its route and bi-directionally looped back for testing. Selection and the looping back process is contro... | 04/15/1986 |
| 4582965 | Coin trunk test set A test set which tests coin trunk circuits for both normal and abnormal operations. A pair of light-emitting diodes monitor battery feed and reverse current. A first set of switch contacts simulate coin deposit while a second set of switch contacts connec... | 04/15/1986 |
| 4577072 | Telephone equipment tester A tester for telephones and telephone answering systems features a dialing test capability for high speed dialing systems by providing the dialed digits in a single display element serially in time at a delayed rate set by strobing the digits from a memor... | 03/18/1986 |
| 4564933 | Supervision of digital transmission systems A supervisory method for a digital optical submerged transmission system in which a multi-bit test signal is detected by a repeater while receiving a loop-back signal for causing loop-back condition, and the mix of the bits of the test signal is changed t... | 01/14/1986 |
| 4560842 | Telecommunication system loop-back unit A loop-back unit for connection at the subscriber's end of a line (15) to provide a loop-back line testing facility, the unit comprising a transformer (1) with a first winding (3) and second winding (5) of relatively high inductance, connected in series a... | 12/24/1985 |
| 4538033 | Data bridge with gating and/or testing A communication bridge joining a primary communication channel to a plurality of secondary communication channels has electrically operated switches in series with the respective ports to the secondary communication channels. Control signals applied to th... | 08/27/1985 |
| 4529979 | Remote return loop control in a data transmission system In a return loop control system in a data transmission system having data transmission units such as modems connected at opposite ends of a transmission line, a return loop being formed at one of the data transmission units by a command signal from the ot... | 07/16/1985 |
| 4467148 | Telephone line analyzer A telephone line analyzer provides automatic attenuation measurement of tie trunk lines and other telephone lines through measurement of the electrical level of a tone responder. The analyzer is primarily directed to testing telephone lines interconnected... | 08/21/1984 |
| 4446340 | Customer premises loop test unit powered from the normal central office power source A loopback circuit for use in testing a telephone line between the central office and a subscriber's equipment. The loopback circuit is located at the subscriber's end of the line and is powered solely by the normal central office power source.... | 05/01/1984 |
| 4258236 | Remote telephone line switching and testing Apparatus for remote switching and testing of a four-wire telephone line system is disclosed. The telephone line provides four-wire service between a first location and one or more second remote locations. The switching and testing apparatus provides the ... | 03/24/1981 |
| 4196321 | Loopback test system A subscriber loop carrier system is disclosed for frequency multiplexing a plurality of subscriber channels on a single twisted metallic pair using frequency division techniques. Supervisory signaling is accomplished from the central office to a remote lo... | 04/01/1980 |
| 4168402 | Electronic trunk selector Modular electronic trunk selectors are known which have a number of incoming trunk modules and a common control module. Incoming trunks are connected to outgoing trunks by the common control module. The invention disclosed is a trunk selector of this type... | 09/18/1979 |
| 4129756 | Telephone exchange signalling unit A telephone exchange signalling unit is provided having looping means for feeding back and comparing transmitted data multiplets directly with its input data. This test is ordered by the control unit of the telephone exchange without the necessity of usin... | 12/12/1978 |
| 4086448 | Loop-around test circuit for telecommunications lines A control unit circuit for loop-around testing of telecommunication lines improves over its predecessor by circuitry that accepts a tone from either of the incoming lines without directly connecting the lines, thus to prevent fraudulent use of telephone l... | 04/25/1978 |
| 4045624 | Continuous monitoring in carrier telephone systems A continuous monitoring arrangement for a carrier telephone system utilizes the subscriber carrier at a reduced level when the subscriber set is on-hook. Proper reception of the reduced carrier level at the central office circuit during on-hook condition ... | 08/30/1977 |
| 4029913 | Remote accessing system for telephone lines A system for electronically selecting and establishing test loop circuits between a remote test position and any of a large number of communication lines at an access location. Extensive logic circuits at the access end and the test end exchange informati... | 06/14/1977 |
| 4007339 | Arrangement serving operator assistance calls requiring routing back to originating offices An additional concentrator is provided in a Traffic Service Position System (TSPS) similar to that disclosed in A. E. Joel, Jr. Pat. No. 3,731,000, issued May 1, 1973, to facilitate the handling of operator assistance telephone calls requiring routing bac... | 02/08/1977 |
| 3943305 | Telephone line control system Telephone line testing equipment in which a series of alternating current tone pulses are transmitted from the central office along the lines to a sensing means placed at a remote point in the circuit. The sensing means receives the coded tone pulse seque... | 03/09/1976 |
