Automated Repair Service Bureau: Second-Generation Mechanized Loop TestingSystem - A Distributed Microprocessor Application

Second-Generation Mechanized Loop Testing System--A Distributed Microprocessor Application By H. RUBIN (Manuscript received December 2, 1980) The Mechanized Loop Testing (MLT) system is that part of the Automated Repair Service Bureau that provides automatic acquisition and analysis of electrical test data for customer telephone loops. The MLT-2 system is a second-generation MLT that has as its basic architectural features communication, loop access, and loop test distributed as closely as possible to the point of testing. Architectural components include a wire center-based Loop Testing System (LTS) and a centrally located Data Communication Network (DCN). Each LTS contains communication, access, and test capabilities, and is logically connected by the DCN to each controlling minicomputer (up to 12). The LTS and DCN are each composed of multiple microprocessor-based circuits. The architecture of MLT-2 is presented. Particular attention is given to the subjects of partitioning both hardware and software, to the development of change-tolerant software, and to intrasystem communication capabilities powerful enough to support a large number of distributed processors. In addition, special measurement techniques employed by MLT-2 that take advantage of analog and digital large-scale integration technology are discussed. Operational scenarios are included for an appreciation of how the MLT-2 system works. I. INTRODUCTION At Bell Telephone Laboratories, Mechanized Loop Testing (MLT) is a generic term used to describe that part of the Automated Repair 1257 Service Bureau (ARSB) that provides automatic acquisition and analysis of electrical test data for customer telephone loops.