Digital elliptic filter design

A program written in FORTRAN and implemented on a Digital Equipment Corporation VAX 11/780 is presented for the systematic design of digital elliptic filters through user-defined frequency response specifications. An introduction to digital filters is presented first; it is followed by a chapter that compares FIR and IIR digital filters. Applications of digital elliptic filters are then discussed in order to suggest applications where elliptic filters can be used. A chapter on the theory of elliptic filters presents the mathematical equations required to implement the design program. The algorithms and derivations used to compute the elliptic functions and theoretical design equations are presented in the chapter on algorithmic implementation. A flowchart of the program is provided to trace the program's logic. The chapters on using the program and its capabilities are provided near the end of this document along with some design examples. Portability issues are also addressed. An appendix at the end of this report contains a copy of the FORTRAN source code.