The statistical characteristics of the angular power distribution of the wireless channel in mine tunnels are the concern of this paper. Firstly, we develop a ray-based channel model which provides the angular power spectrum (APS) in tunnels. We discuss the allowed rays existing in a tunnel based on the modal theory. The number of the allowed rays is limited. The directions of the rays are disc...

In the pre-era of Global Navigation Satellite System (GNSS), Astronomy was only technique available for determination position or Azimuth. Still, to understand space-based technique, a good knowledge is necessary; concept Celestial Sphere, Coordinates Bodies, and various categories Time. The celestial coordinate systems are based on fixed point in space, Vernal Equinox First Point Aries(γ). Thi...

Obstacle recognition is one of the key technologies for Unmanned Undersea Vehicle (UUV). In this paper, the design of obstacle recognition based on multi-beam forward looking sonar is presented. First of all, Gaussian mixed model operator is adopted in adaptive threshold segmentation to segment the sonar image into regions of interest and background. Secondly, we use morphological operation to ...

This paper presents a motion compensation algorithm which is capable of dealing with large motion errors for highly squinted spotlight SAR. The approach consists of a phase error compensation, a shift to correct the delay time error and an interpolation/resampling in azimuth. For pulsed SAR with a 30° squint angle, the proposed algorithm compensates motion errors that are 10 times greater than ...

The bob of a spherical pendulum (or particle on a smooth sphere under gravity) oscillates between two levels, and the change of azimuth in passing from the lower to the higher level, or vice versa, is the same for all such passages during a single motion. Using the language of orbit theory, we shall refer to this change of azimuth as the apsidal angle. It is a function of the two constants of t...