This paper discusses a minicomputer-based communication system monitor used by the U.S. Department of Defense to improve the service availability and reduce the operating costs of the new multichannel digital transmission systems. A brief history of the development of the monitor and a general description of the present-generation hardware and software are included.

This paper discusses measurement of signals received over a 160-km (100-mi) line-of-sight microwave radio link operating at 8.4 GHz. Signals were recorded at both ends of the path at various times over a period of about 18 months. The effects of macroscale meteorological conditions are mentioned, particularly those which are peculiar to the central European location of the path. The data obtained from this measurement effort are presented both in terms of radio link availability, which includes the effects of diversity improvement, and in terms of long-term propagation performance, which considers only single receiver signal level variability. The data were also analyzed to obtain distributions of fade duration for single receivers and for both receivers in a diversity configuration. The study supports the idea that it is possible to achieve reliable propagation at 8 GHz on a link as long as 160 km, and with less than normal or conventional vertical diversity spacing.