Abstract: Relatively low cost asymmetric digital subscriber line (ADSL) service and auxiliary POTS service are delivered over extended distances (e.g., at least 20–25 kft), by a hybrid ADSL-SDSL architecture insertable between central office and remote sites of an ADSL system. Central office and remote site transceivers employ trellis coded pulse amplitude modulation and a data rate that conforms with the signal transport capability of an extended distance symmetric DSL (SDSL) loop, while providing a 64K POTS channel. The central office and remote site transceivers controllably insert idle asynchronous transfer mode (ATM) cells in upstream and downstream ADSL channels to compensate for timing differences with ADSL equipment.

Abstract: A power management circuit for a remote access platform extracts power from a wireline for powering a ring generator that generates a ringing voltage signal that is distributed to a plurality of subscriber circuits. A power-limited voltage converter steps up the wireline voltage to a higher ‘isolating’ voltage, charging a capacitor coupled to the ring generator. A monitor circuit reduces the power that the power-limited voltage converter can draw, if the wireline voltage drops too low. This prevents the wireline voltage from collapsing should the remote terminal be deployed at a distance from wireline voltage source (the central office) greater than its specified capability.

Abstract: An upstream transceiver, coupled to an upstream end of a long haul, single digital subscriber loop of an extended range asymmetrical digital subscriber line communication system, ‘spoofs’ a (co-located) digital subscriber line access multiplexer to reduce its downstream data rate over a short haul loop to the upstream transceiver. The reduced downstream data rate is compatible with the data rate that can be supported by the long haul loop and also accommodates an auxiliary (64K) POTS channel thereover. The reduced data rate may be derived by preliminary signal quality measurements upon the long communication loop conducted between the upstream transceiver and a downstream transceiver coupled to a remote end of the long haul loop.

Abstract: A ‘lifeline’ POTS back-up mechanism is operative to provide emergency plain old telephone service connectivity over a span-powered two-wire metallic digital subscriber loop pair, in response to a customer's phone going off-hook, during a lack of normal operating condition of the digital circuit path. A ground fault interruption signal is generated in a remote terminal and used to activate respective POTS by-pass paths in the remote terminal and a central office terminal.

Abstract: A ringing voltage power management circuit is configured to extract an isolated high-value intermediate voltage from a central office powered digital subscriber line through a current limiting circuit, and to charge a storage capacitor that serves as an energy reservoir for the ring generator of a subscriber line circuit. The storage capacitor and the current limiting circuit isolate the peak power drawn by the ringing load from the telephone line and translate the ringing signal's (20 Hz) ripple to the sub-Hz oscillations of the ringing cadence.

Abstract: A power management circuit for a remote access platform extracts power from a wireline for powering a ring generator that generates a ringing voltage signal that is distributed to a plurality of subscriber circuits. A power-limited voltage converter steps up the wireline voltage to a higher ‘isolating’ voltage, charging a capacitor coupled to the ring generator. A monitor circuit reduces the power that the power-limited voltage converter can draw, if the wireline voltage drops too low. This prevents the wireline voltage from collapsing should the remote terminal be deployed at a distance from wireline voltage source (the central office) greater than its specified capability.

Abstract: An autobaud mechanism is executed by transceivers coupled to opposite ends of a communication loop, such as an extended range SDSL loop, to resolve the maximum data rate that can be supported by the loop, using signal power and quality measurements to first estimate the length of the SDSL loop and thereafter iteratively adjust baud rate and/or number of bits/per baud, as necessary, to realize an SDSL baud rate that will ensure error-free transmission over the loop.

Abstract: Relatively low cost asymmetric digital subscriber line (ADSL) service and auxiliary POTS service are delivered over extended distances (e.g., at least 20-25 kft), by a hybrid ADSL-SDSL architecture insertable between central office and remote sites of an ADSL system. Central office and remote site transceivers employ trellis coded pulse amplitude modulation and a data rate that conforms with the signal transport capability of an extended distance symmetric DSL (SDSL) loop, while providing a 64K POTS channel. The central office and remote site transceivers controllably insert idle asynchronous transfer mode (ATM) cells in upstream and downstream ADSL channels to compensate for timing differences with ADSL equipment.

Abstract: An autobaud mechanism is executed by transceivers coupled to opposite ends of a communication loop, such as an extended range SDSL loop, to resolve the maximum data rate that can be supported by the loop, using signal power and quality measurements to first estimate the length of the SDSL loop and thereafter iteratively adjust baud rate and/or number of bits/per baud, as necessary, to realize an SDSL baud rate that will ensure error-free transmission over the loop.

Abstract: An upstream transceiver, coupled to an upstream end of a long haul, single digital subscriber loop of an extended range asymmetrical digital subscriber line communication system, ‘spoofs’ a (co-located) digital subscriber line access multiplexer to reduce its downstream data rate over a short haul loop to the upstream transceiver. The reduced downstream data rate is compatible with the data rate that can be supported by the long haul loop and also accommodates an auxiliary (64K) POTS channel thereover. The reduced data rate may be derived by preliminary signal quality measurements upon the long communication loop conducted between the upstream transceiver and a downstream transceiver coupled to a remote end of the long haul loop.

Abstract: The life of the hydrogenation catalyst in reducing a mixture of glycolate ester to ethylene glycol can be extended by lowering the polyglycolide ester content of the mixture by transesterification, that is, heating in the presence of alcohol, after which the resulting mixture is hydrogenated.

Abstract: A catalyst composition having an intrinsic surface area above about 60 square meters per gram as measured by the BET nitrogen adsorption method, said catalyst comprising from about 1 to 30 weight percent of a finely divided silica component, and from about 1 to 99 weight percent of a hydrogenating component comprising copper in either elemental or compound form and zinc oxide.

Abstract: In the reaction of 3-methyl-3-buten-1-ol with aqueous formaldehyde forming isomeric alkene-1,5-diols, particularly 3-methylene-1,5-pentanediol and 3-methyl-2-pentene-1,5-diol, it has been found that yields of the diols surprisingly are substantially increased if the reaction is effected in the presence of added isobutene and the mol ratio of 3-methyl-3-buten-1-ol to formaldehyde is at least 1:1.

Abstract: A catalyst composition having an intrinsic surface area above about 60 square meters per gram as measured by the BET nitrogen adsorption method, said catalyst comprising from about 1 to 30 weight percent of a finely divided silica component, and from about 1 to 99 weight percent of a hydrogenating component comprising copper in either elemental or compound form and zinc oxide.

Abstract: An alkenediol is produced from an alkenol by contacting the alkenol with formaldehyde at a pH maintained between about 4 and 7. Preferably this pH range is maintained by adding a buffering agent composed of a weak acid and the salt of a weak acid. Particularly advantageous buffering agents are the lower organic polycarboxylic acids with disodium or dipotassium hydrogen phosphate and sodium or potassium dihydrogen phosphate with disodium or dipotassium hydrogen phosphate.

Abstract: At a temperature in the range 100.degree. C to 225.degree. C the destructive dissociation of cobalt carbonyl compounds to cobalt metal and residue is inhibited by the action of one or more azoxy-dentated chelation ligands.

Abstract: Straight chain aldehydes are prepared from straight chain olefins of about 3 to 20 carbon atoms by catalytic hydroformylation with carbon monoxide and hydrogen in the presence of cobalt catalyst and in the presence of soluble primary, secondary or tertiary aliphatic, or cycloaliphatic amine modifier of 1 to 12 carbon atoms.

Abstract: At a temperature in the range 100.degree. C. to 225.degree. C. the destructive dissociation of cobalt carbonyl compounds to cobalt metal and residue is inhibited by the action of one or more azoxy-dentated chelation ligands.

Abstract: In a process for the conversion of normal butane to maleic anhydride at a pressure between about 15 and 100 psig and a temperature above 675.degree. F, by contacting the normal butane with an oxygen-containing gas and an oxidation catalyst disposed in a fixed catalyst bed or set of tubes in a reactor vessel, and withdrawing an effluent comprising unreacted normal butane, oxygen, Co, Co.sub.2, N.sub.2 and maleic anhydride from the catalyst bed or tubes, improvements in yield, product quality and plant operability are obtained by rapidly cooling the effluent gas to a temperature below 675.degree. F. One method of accomplishing this is by contacting the effluent gas with cooling coils contained within the reactor but below the catalyst bed.

Abstract: A process for the preparation of citric acid which comprises contacting an unsaturated compound selected from 3-methylene-1,5-pentanediol and its esters with a nitric acid solution in an amount of 2 to 50 mols of nitric acid feed per mol of unsaturated compound feed, and at least 0.005 mol percent nitrogen dioxide based on nitric acid, at a temperature between -10.degree. and 120.degree. C., to thereby oxidize said unsaturated compound to citric acid. Preferably the contacting of the unsaturated compound so as to synthesize citric acid is carried out in the absence of any substantial amount of vanadium as the presence of vanadium catalysts has been found to effectively prevent the recovery of good yields of citric acid from the process.The citric acid synthesis preferably is carried out by an overall process wherein isobutene is reacted with two mols of formaldehyde to produce 3-methylene-1,5-pentanediol, which is then converted to citric acid by reaction with nitrogen dioxide/nitric acid.