Abstract: A monitoring system for a network having a plurality of segments including plurality of identical monitoring instruments respectively connected to the segments. Each monitoring instrument includes an interconnection circuit card for connecting to its segment, a microcomputer circuit card connected to the interconnection circuit card, an interface circuit card connected to the microcomputer circuit card, a plurality of status lamps respectively connected to the interface circuit card, a plurality of switches for providing self testing, resetting, alarm, instrument selecting, segment selecting, connected to the interface circuit card, and a plurality of switches for providing transmit/receiving or transmitting only, a monitor mode, a verify mode, and an auto fault mode, connected to the interface circuit card.

Abstract: A situation awareness display device for providing a graphical display of e relative position of remote units moving along with and in proximity to the local unit utilizing the device.

Abstract: HF and VHF radio channels which are subject to time-varying propagation aalies and to interference are arranged in groups according to frequency band. Within each group are several channels, each spaced sufficiently close so that they experience essentially the same propagation. The several channels in each group are continuously measured to find which channels have the least ambient energy levels, then one of those channels is selected in a random manner to transmit data.