The traditional celestial navigation system(CNS) is used the moon, stars, and planets as celestial guides. Then the star tracker(i.e. track one star or planet or angle between it) and star sensor(i.e. sense many star simultaneous) be used to determine the attitude of the spacecraft. Pulsar navigation also be introduced to CNS. Maser is another interested celestial in radio astronomy which has s...

Over the past decade, wireless sensor networks have advanced in terms of hardware design, communication protocols, and resource efficiency. Recently, there has been growing interest in mobility, and several small-profile sensing devices that control their own movement have been developed. Unfortunately, resource constraints inhibit the use of traditional navigation methods because these typical...

The objective of this research was to develop an unmanned surface vehicle (USV) platform for autonomous navigation in the paddy field. The surface vehicle used in this research was a radio controlled air propeller vessel that had been modified into an unmanned surface vehicle platform. A GPS compass system was attached to the top of the USV platform as the navigation system to provide the posit...

GPS has revolutionized outdoor navigation and tracking, providing highly accurate positioning anywhere in the world. However, as it uses high frequency radio waves, it suffers heavily from multipath and attenuation effects that are caused by buildings, thick vegetation and is completely unusable underground. There is a strong need to be able to position people, equipment and assets in undergrou...

The radio holography methodology may be applied in the scientific programs for future small satellite that will use radio signals emitted by radio navigation, radio communication satellites for precise measuring effects of radio waves propagation at low elevation angles and for global monitoring of radio communication channels passed through the atmosphere and ionosphere. Another task consists ...

COSMIC GPS Radio occultation systems are developed for investigating global ionospheric and tropospheric features of atmosphere ionospheric effects are a major critical concern in radio communications and navigation systems. The predominant ionospheric effect is scintillation, which causes small scale fading in GNSS received signals. Hence, there is a necessity to understand the ionospheric mor...

Radio frequency (RF) indoors localization is adopted by automated guided vehicles (AGVs) positioning due to availability of communications framework sub-system (e.g. ZigBee wireless network) in the entire working system. AGV (i.e. a type of wheeled mobile robot) communications sub-system can therefore support RF localization hardware without additional cost. Mobile communications for indoors en...

Precision ranging radios are a critical aid to integrated locating, tracking, navigation, and guidance systems, especially when GPS service is degraded or unavailable [5]. In this work, a high-precision, software-defined, round-trip time-of-flight, direct sequence spread spectrum (DSSS) ranging radio operating in the 2.4 GHz ISM band is presented. This system builds upon our previous brassboard...

Observations of extended radio emission in some GPS sources suggest that they may not be a young version of the classical doubles. The compact source would be confined by the presence of a dense medium in the center of the galaxy. The existence of such a dense environment is supported by the observation of disturbed optical morphologies indicating galaxygalaxy interaction or mergers. A simple m...