Note on Calculation of Ladder Coefficients for Symmetrical and Inverse Impedance Filters on a Digital Computer

The authors have been engaged for the last two years on a wide project of tabulation of ladder coefficients and subsidiary data for an important class of filters, designed on the basis of insertion loss theory and having Tchebycheff behavior in both the pass and the suppression bands. All calculations were done on the English Electric Digital Computer DEUCE (Digital Electronic Universal Computing Engine) by A. K. Rhodes, who was responsible for programming, computation, and tabulation of the results. The tables have now been ready for some time and publication of a volume "Tables of Ladder Coefficients and Related Data for Symmetrical and Inverse Impedance Filters," embodying these as well as a detailed instruction for their use is expected to take place early in 1959. The aim of this article is to describe generally the contents of these tables and also to relate certain interesting features of the programs used, as well as difficulties encountered during computation.