Engineers at ECAC have pioneered in applying numerical mapping techniques to the solution of electromagnetic compatibility problems. Data processing procedures for making digitized topographic data useful as a problem solving tool have been developed, (Ref. 1) and an economical means for acquiring digitized topographic data has been developed by Army Map Service personnel. (Ref. 2,3,4) As of February 1, 1967, the topographic data base contained data representing approximately 25% of the United States. A collection plan has been established with the Army Map Service to supply additional data on a routine basis.