Showing papers on "High-bit-rate digital subscriber line published in 1981"

A Tutorial on Two-Wire Digital Transmission in the Loop Plant

Abstract: This paper explores the constraints on the design of twowire repeaterless digital subscriber loop (DSL) systems. Broadly categorized, the design depends on the technical feasibility of the approach used to achieve two-wire transmission, constraints related to compatibility with other systems sharing the same cable, and immunity to central office noise. Each of these varies With the choice of system parameters including the transmission rate, transmit power, choice of line codes, etc. Technical feasibility is evaluated by computer simulation studies. Compatibility with other systems is explored by crosstalk calculations. Noise immunity considerations, as they translate into digital line power levels, are also explored.

Digital signal subscriber loop and interface circuit

Abstract: A TDM PCM telephone system and a telephone user terminal are interconnected by a digital subscriber loop circuit which provides at least a single channel communication path for digital signals of data or encoded voice origin. The digital subscriber loop circuit includes transmit and receive paths and a line interface circuit. The line interface circuit converts a selected channel of binary signals appearing at a subscriber line port of the telephone system into a corresponding bipolar return to zero (BPRZ) signals for transmission on the receive signal path. The line interface circuit also converts BPRZ signals from the transmit signal path to corresponding binary signals. These binary signals are accumulated and stored. At a time coincident with the selected channel occurrence, the line interface circuit transmits the stored signals to the subscriber line port for acceptance by the telephone system. In one arrangement, the digital subscriber loop is interfaced at opposite ends by a universal line interface circuit (ULIC) which provides for compatible use with two TDM signal formats and with any one of a plurality of commercially available single channel codecs in the associated telephone user terminal.

Time-Shared Two-Wire Digital Subscriber Transmission System and Its Application to the Digital Telephone Set

Abstract: Adopting digital techniques in the local network area will enhance the possibility of extending digital operation capability to the subscriber's equipment. The problem is to convey digital signals at a bit rate of at least 64 kbits/s in both directions over existing two-wire subscriber loops. This paper describes a time-shared two-wire digital subscriber transmission system in which the directional separation of two signals (GO and RETURN) is accomplished by the time division bidirectional transmission method in burst-mode, and also reports results of investigations on the feasibility of an all digital telephone subscriber loop system.

Subscriber Line Testing for Digital Switching Offices

Abstract: This paper presents an overview of subscriber line testing as provided in Northern Telecom's Digital World®family of host and remote digital switching systems. Capabilities provided in Digital World satisfy the major telco needs related to subscriber line testing. The various products incorporate interfaces to external test systems as well as internal line test facilities. A new subscriber line measurement technique is identified. It offers further advantages in speed and accuracy and has many potential applications in the analog and digital switching environments.

Basic Principles of Digital Subscriber Sets

Abstract: The introduction of digital exchanges into the local telephone network in the future will lead to the application of digital subscriber sets, where all speech and signal coding is carried out in the proximity of the telephone. In order to use the two-wire network the problems of digital transmission must be considered together with those of synchronization, signaling, speech conversion, and powering. This paper deals with the basic solutions and shows the concept for a first model of a digital subscriber set.