Cyclic interrogation system for telephone line condition - compares successive line condition signals to reduce data flowing between sampler and central evaluator

摘要

The cyclic interrogation system, for telephone line conditions, is designed to reduce the amount of information flowing between sampler and central evaluator without losing certainty of detecting line condition changes in any line in a group. Line condition signals are passed to an input memory. A comparator compares the output of a follow-up memory and the previous condition of any line obtained during a previous sample. The comparator controls a coder that enters the direction of condition change and the address of the line concerned into a central unit.