Integrated Refraction Effects Prediction System (Ireps)

Microwave radio propagation in a marine environment frequently exhibits unexpected behavior. These propagation anomalies are usually caused by non‐standard distributions in vertical refractivity. Even though the potentially serious effect of propagation anomalies on tactical warfare is generally acknowledged, very little is presently being done in the operational Fleet to solve the problem. One of the reasons responsible for the lack of effort in this area is that the acquisition, conversion, and interpretation of refractivity data usually involves cumbersome computations and some background in atmospheric physics. This problem can be overcome by the proper use of automatic data processing techniques. Following similar efforts in underwater acoustic propagation, an “Integrated Refractive Effects Prediction System” (IREPS) is being developed at the Naval Electronics Laboratory Center (NELC). The purpose of IREPS is to provide an “onboard” capability to assess the effect of atmospheric refractive anomalies on sensor performance. The effort involves the development of models which express the effects of refractive anomalies in terms of equipment performance, the verification of these models, the software development of the models for shipboard implementation, and the inclusion of meteorological statistical data to estimate the probability of encountering refractive anomalies as a function of geographic area and season. A preliminary shipboard demonstration is planned for spring 1976. The hardware used for this demonstration consists of a mini‐computer with an interactive graphic display terminal on which the operator is queried by the program for required inputs and on which results are presented in easy‐to‐understand graphic displays.