Line of sight, LOS

Robotized Total Stations (RTS) are modem theodolites coupled with precise laser distance meters that can measure automatically the position of artificial targets (usually optical prisms), by measuring three parameters a vertical angle (Vz), a horizontal angle (Hz) and a distance (d). The targets are installed so that the optical Line-Of-Sight (LOS) towards the RTS can be maintained over time. 

A frequency shift A vwith respect to the outgoing laser frequancy v results from the relative movement of the scatter elements along the line-of-sight (LOS) of the instrument. This movement relates to the mean wind velocity in the observed volume (Flesia and Korb, 1999, and references cited there) [4]. 

The electromagnetic propagation model defined in the simulation seenario is a simple but widely used model for wireless networks. The visibility between nodes ean be with or without line of sight. In the first ease, when there is no obstacle that interferes with communication between two nodes, we employ amedium communication type Line Of Sight (LOS). On the other hand, if there is an obstacle that causes attenuation between the two communicating nodes, aNon-Line-Of-Sight (NLOS) medium communication was used. This experiment considered both mediums. 

Fig.6.83. Spectrum of the supernova 1987 A in the Large Magellanic Cloud, recorded 7 days after the explosion. The prominent lines are due to the hydrogen Balmer series, Doppler-shifted and broadened due to very high expansion velocities (lO.OOOkm/s). The line is partly seen also in emission. An insert shows narrow Na absorption lines due to cold gas clouds moving with different velocities along the line of sight [6.159]...

If the target is in motion and has a line-of-sight component of velocity toward the radar of vlos. the target will see a frequency that, to first order in ulos/c, equals /tx + (i los/c)/tx, where /tx is the transmitter frequency. The target reradiates the Doppler-shifted... 

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