An Automated 20-20,000-cps Transmission Measuring Set for Laboratory Use

Automatic measurement techniques have been widely and successfully applied in situations where many repetitive measurements of a similar type are required. In many cases the measuring instruments are programmed for a specific measurement or sequence of measurements, and versatility is of minor importance. This paper describes an automatic transmission measuring set that was developed for laboratory use in the 20- to 20,000-cps frequency range to measure two-port networks having a wide variety of characteristics. 2501 2502 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1903 The first section of the paper specifies the quantities that are measured and the range and accuracy of the measurements, and lists the functions that the skilled operator of a manual measuring set must perform when making laboratory measurements. In Section II some of the factors involved in data taking are discussed, and the chosen method of automatic data selection is described. Section III describes, in broad terms, the measuring and control circuits used. Operation of the automated set in the manual, semiautomatic, and automatic modes is described in Section IV. A more detailed description of the measuring and control circuits, along with a description of some of the more important subsystems, is given in Section V. In Section VI some of the most important systems considerations which influenced the measuring set design are discussed. Section VII gives the results of tests made to confirm the measuring set accuracy and to evaluate, using selected networks, the operation of the automatic control and data selection functions of the measuring set.