A voice-band transmission-measuring set using swept-band techniques
Worthington C. Lent · Transactions of the American Institute of Electrical Engineers Part I Communication and Electronics · 1960
The nationwide telephone service which the country enjoys today is largely the result of careful systems engineering of which one objective is the establishment and application of uniform transmission standards. Transmission measurements constitute the essential means by which circuit design can be verified and the performance characteristics dictated by it maintained during operation.