PLANNING OF OBSERVATIONS IN POSITIONNING BY SATELLITES
تخطيط عملية الرصد لتحديد المواقع بالأقمار الصنعية
The relative accuracy of positioning by satellites depends on observation duration (period) and geometry of visible satellites distribution as well as the base line length. The relation between relative accuracy and observation period means job cost. Also, the relation between satellites geometry and observation period means job cost. Till now, there are no clear criteria for these relations. The aim of this paper is to study these relations and to suggest recommendations for observation operation. In this study, it was considered that, observation period, length of base line and geometry of satellites, are independent features in relation with relative accuracy. The experiments were applied on base lines: 0.5 , 1 , 2 , 10 and 15 km respectively, and the equipments used were Lieca 530. The result of this study reached to the following findings. Observations can be done in area containing obstructions, if the number of visible satellites is enough above masking the angle; very low altitude satellites reduce the relative accuracy; the effect of the observation period on relative accuracy dimishes as the time of observation become longer. Generally speaking, it can be considered that, for base lines up to /15/ km, observation period for more than one hour would not increase the accuracy, because the relative accuracy becomes stable after that time limit.
The relative accuracy of positioning by satellites depends on observation duration (period) and geometry of visible satellites distribution as well as the base line length…