To characterize the transmission performance of the public switched network, the Bell System conducted an intensive field measurement study of endoffice-to-end-office connections from October 1982 to January 1983. A special multistage sampling plan and ASPEN, a flexible, automatic data acquisition system based on the UNIX™ operating system, were developed to evaluate the more than 10,000 transmission paths included in the study. This paper describes both the ASPEN measurement system and the sampling plan. A
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