摘要:
An optical fiber coated with a single ultraviolet cured resin wherein the attenuation losses are less than 0.5 decibels/kilometer. The resin has a tensile modulus of about 7,800 psi. This cable is particularly useful in loosely wrapped cable structures such as open channel or loose tube cables.
摘要:
High-speed digital transmission can be achieved with existing phone lines and HDSL chipsets while retaining plain old telephone service (POTS) with full failsafe capability. Two original ISDN signals [4,5] at a rate of 160 kbps and one POTS channel [10] digitized at 64 kbps are multiplexed by a MIPCS card [6] of a signal provider [1]. The resulting digital signal is transported over a twisted cable pair [2] which has an approximate maximum length of 16 kft based on the current technology. At a receiving end, the signal is demultiplexed and regenerated by a subscriber's MIPCS card [7]. The subscriber's MIPCS card is line-powered via the cable [2] to avoid dependence upon local power. The regenerated signals are transmitted over one POTS line [42] and two ISDN cables [8,9] to remote premises. Both MIPCS cards have bypass relays for the POTS lines to ensure the subscriber's POTS access in the event of a local power outage or electronic failure.
摘要:
The stress-induced birefringent single mode optical fiber includes an optical core having a high refractive index and a high thermal expansion coefficient. An arrangement formed from an optical material having a low refractive index and a low thermal expansion coefficient is disposed to engage the outer surface of the core tangentially at opposite ends of a diameter of the core to establish a stress therein. Air encompasses the remainder of the outer surface of the core to provide a light guiding cladding for the core and, hence, the fiber itself. The arrangement to establish the stress may include a pair of flat plates engaging the outer surface of the core tangentially which are entrapped in a circular tube which is concentric with the core such that air is entrapped between the plates and the circular tube to provide the light guiding cladding. Alternatively, an elliptical tube is provided to engage the outer surface of the core at the minor axis of the elliptical tube to provide the desired stress in the fiber. In this case air is enclosed in the elliptical tube to provide the light guiding cladding.
摘要:
An arrangement for collapsing tubular formations into optical preforms includes a control arrangement which controls the ratio of hydrogen to oxygen in an oxyhydrogen burner flame during the collapsing operation toward overabundance of hydrogen when it is desired to increase the degree of evaporation of glass from the outer surface of a tubular proportion being collapsed. This arrangement is used for bringing the ratio of the cross-sectional area of the core region to that of the cladding region in an optical preform resulting from the collapse into or close to a predetermined range, regardless of the initial value of this ratio in the original tubular formation, by evaporating more or less of the glass from the outside of the tubular formation during the collapse.
摘要:
Method and apparatus for providing a long loop broadband service which allows data from different ADSL users to be shared and transported across a group (possibly a group of one) of line-powered, repeatered copper pairs utilizing a symmetric transmission approach is disclosed. Multiple ADSL users are able to share the bandwidth on pair(s) between the Remote Terminal Unit and Central Termination Unit by converting the ADSL data into ATM cells that are properly addressed and sent over the pair(s). Straight-Through Repeaters can be used in between the Central Termination Unit and the Remote Termination Unit on each of the pairs to extend the reach of the system. In this manner, the reach of ADSL (or other) internet access can be increased from its present 15 to 18 kft limitation to over 40,000 feet using 26 gauge wire, effectively reaching over 99% of subscribers.
摘要:
High-speed digital transmission can be achieved with existing phone lines and HDSL chipsets while retaining plain old telephone service (POTS) with full failsafe capability. One original digital data signal �4! at a rate of at least 352 kbps and typical 384 kbps and one POTS channel �10! digitized at 64 kbps are multiplexed by a HPCS card �6! of a signal provider �1!. The resulting digital signal is transported over a twisted based on the current technology. At a receiving end, the signal is demultiplexed and regenerated by a subscriber's HPCS card �7!. The subscriber's HPCS card is line-powered via the cable �2! to avoid dependence upon local power. The regenerated signals are transmitted over one POTS line �42! and one data line �8! to or within a remote premise. Both HPCS cards have bypass relays for the POTS line to ensure the subscriber's POTS access in the event of a local power outage or electronic failure.
摘要:
An arrangement for collapsing tubular formations into optical preforms includes a control arrangement which controls the pressure build-up at the downstream end of the tubular formation during all of but the last one of the collapsing increments to control the flow of a gaseous medium through the interior of the tubular formation from an upstream end to and beyond the downstream end of the tubular formation. The magnitude of the back-up pressure is controlled by a set point controller in dependence on the actual value of the back-up pressure, the set point controller being operative for counteracting any deviation from the desired pressure. The set point controller controls the flow-through cross-section of a control valve that admits a pressurized inert gas to a region situated downstream of the downstream end of the tubular formation and also downstream of the point at which the pressure build-up is being measured.
摘要:
A method and related apparatus for concurrent transmission and reception of at least one analog voice telephone signal and at least one ISDN service signal between a first location and a second location over a single twisted pair using a digitally encoded signal that is selected from the group consisting of 2B1Q and 4B3T signals. The method further includes the steps of sending line power over the single twisted pair, transferring the digitally encoded signal to the second location over the single twisted pair, and detecting non-operation of the digitally encoded signal between the first location and the second location to thereby impose a bypass lifeline and provide the analog telephone signal at the second location over the single twisted pair. The method also includes the step of providing the ISDN signal and the analog telephone signal at the second location over the single twisted pair when the non-operation is not detected. The present method and apparatus can provide at least a 2-to-1 pair gain by multiplexing signals representing the analog voice telephone signal and ISDN service signal, in a specific embodiment.
摘要:
High-speed digital transmission can be achieved with existing phone lines and HDSL chipsets. Two original ISDN signals [4,5] at a rate of 160 kbps are multiplexed by a MICS card [6] of a signal provider [1]. The resulting digital signal is transported over a twisted cable pair [2] which has an approximate maximum length of 16 kft. At a receiving end, the signal is demultiplexed and regenerated by a subscriber's MICS card [7]. The subscriber's MICS card is line-powered via the cable [2] to avoid dependence upon local power. The regenerated signals are transmitted over two ISDN cables to remote premises which can be as far as 18 kft away.
摘要:
A method for fabricating a fiber with optical cores of diameters between 2 to 20 microns is depicted. A first step includes the fabrication of a step-index preform of predetermined dimensions. The preform is drawn into a conventional fiber by conventional techniques resulting in a fiber having an outer diameter of about 120 microns or larger. The fiber is then emplaced in a glass tube. The tube is collapsed on the fiber by heating the same resulting in a second preform. This preform is again drawn into a fiber by conventional techniques to obtain a final fiber having core dimensions indicative of single mode operation with compatible outer diameters.