Verification of a computer simulator for digital transmission over twisted pairs.

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in EngineeringThis dissertation verifies a Computer Simulation Package for modeling pulse transmission over digital subscriber loops. Multigauge sections on subscriber cables can be studied. The model used for each section incorporates skin, proximity and eddy current effects. The model allows important quantities such as near end echo and overall transmission distortion of pulses to be.predicted. An experimental facility has been established in the laboratory for the purpose of validating the results produced by the simulator with results obtained over real cables. The experimental facility has as far as possible been automated by making use of computer controlled equipment for direct setup or the experiment, data transfer, and analysis. The results obtained from the pulse propagation program and that obtained from measurements are in close. agreement, rendering the Computer Simulation Package useful for analysing the performance of multi gauge digital subscriber loops.AC 201

1.25 Gbit/s ITU-T G.984.2 burst-mode transimpedance amplifier without reset pins

A

Customer premise service study for 30/20 GHz satellite system

Satellite systems in which the space segment operates in the 30/20 GHz frequency band are defined and compared as to their potential for providing various types of communications services to customer premises and the economic and technical feasibility of doing so. Technical tasks performed include: market postulation, definition of the ground segment, definition of the space segment, definition of the integrated satellite system, service costs for satellite systems, sensitivity analysis, and critical technology. Based on an analysis of market data, a sufficiently large market for services is projected so as to make the system economically viable. A large market, and hence a high capacity satellite system, is found to be necessary to minimize service costs, i.e., economy of scale is found to hold. The wide bandwidth expected to be available in the 30/20 GHz band, along with frequency reuse which further increases the effective system bandwidth, makes possible the high capacity system. Extensive ground networking is required in most systems to both connect users into the system and to interconnect Earth stations to provide spatial diversity. Earth station spatial diversity is found to be a cost effective means of compensating the large fading encountered in the 30/20 GHz operating band

Fast synchronization 3R burst-mode receivers for passive optical networks

This paper gives a tutorial overview on high speed burst-mode receiver (BM-RX) requirements, specific for time division multiplexing passive optical networks, and design issues of such BM-RXs as well as their advanced design techniques. It focuses on how to design BM-RXs with short burst overhead for fast synchronization. We present design principles and circuit architectures of various types of burst-mode transimpedance amplifiers, burst-mode limiting amplifiers and burst-mode clock and data recovery circuits. The recent development of 10 Gb/s BM-RXs is highlighted also including dual-rate operation for coexistence with deployed PONs and on-chip auto reset generation to eliminate external timing-critical control signals provided by a PON medium access control. Finally sub-system integration and state-of-the-art system performance for 10 Gb/s PONs are reviewed

Design of 10 Gb/s burst-mode receivers for high-split extended reach PONs

The continuous stream of new applications for the internet, increases the need for higher access speed in the currently deployed communication networks. Most networks in use today still consist of twisted copper wires, inherited from the telephone network. The disadvantages of reusing the existing telephone network are twofold. Firstly, the bandwidth of twisted copper wires is limited and secondly, a large number of switches and routers are needed throughout the network leading to an excessive power consumption. The hybrid fiber coax network that reuses the television distribution network is not free from these drawbacks. The bandwidth is also limited and power hungry amplifiers are needed to bridge the distance to and from the user. The future of broadband access lies in optical fiber networks. The optical fiber has a virtually unlimited bandwidth and the lower attenuation leads to less switches and amplifiers in the network, reducing the power consumption of the complete infrastructure. This dissertation describes the design of a 10 Gb/s burst-mode receiver for high-split extended reach passive optical networks (PONs). The designed receiver incorporates two very advanced features. Firstly, the burst-mode receiver locks its gain setting within 6 ns avoiding packet loss due to gain switching during data payload reception. Secondly, the burst-mode receiver detects both burst start and burst end, making it the first burst-mode receiver of its kind to operate without any time critical signal requirements from outside the burst-mode receiver. The presented work covers the chip-level architecture study and design of a 10 Gb/s burst-mode transimpedance amplifier and a 10 Gb/s post-amplifier, which are the two most critical components of a burst-mode receiver

Performance evaluation of currently available VLSI implementations satisfying U-interface requirements for an ISDN in South Africa.

A project report submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering.This project report examines the performance of three VLSI U-interface implementations satisfying the requirements of Basic Access on an ISDN. The systems evaluated are the Intel 89120,Siemens PEB2090 and STC DSP144, operating on 2BIQ, MMS4J and SU32 line codes respectively. Before evaluating the three abovementioned systems, a review of the underlying principles of U-interface technology is presented. Included in the review are aspects of transmission line theory, line coding, echo-cancellation, decision feedback equalisation, and pulse density modulation. The functional specifications of the three systems are then presented followed by a practical evaluation of each system. As an aid to testing the transmission systems, an evaluation board has been designed and built. The latter provides the necessary functionality to correctly activate each system, as well as the appropriate interfacing requirements for the error-rate tester. The U-interface transmission systems are evaluated on a number of test-loops, comprising sections of cable varying in length and gauge. Additionally, impairments are injected into data-carrying cables, in order to test the performance of each system in the presence of noise. The results of each test are recorded and analysed. Finally, a recommendation is made in favour of the 2BIQ U-interface. It is shown to offer superior transmission performance, at the expense of a slightly higher transmit-power level.Andrew Chakane 201