2.3 Non-synchronic Loop Constructio 3. Pla f GPS Surve 3.1 General Remarks L. Designing a GPS network will have to consider 3. The optimum planning of a GPS survey has to 1. Project objectives 3. Observation technique, and Site or satellite configurations 2. GPS surveying differs essentially from classical one 3. Type of receivers 4. Economic aspects 5. Data processing considerations(software allows for 2. No need for intervisibility between the sites single baseline vectors or for multipoint solutions) 3. Different planning 4. Execution 5. Processing techniques 3.2 Pre-survey Planning 4. Contrary to the design of triangulation o L Point Selection: trilateration networks. the followings are not so critic for GPS networks Small-scale maps(1: 25000 to 1: 100000)for point selection. All desired survey points are plotted on the map along Line length. with the known control points Three basic considerations in choosing a point: 1. No obstructions above 20 elevation to avoid satellite signal blockage For large projects with many sites and many 2. No reflecting surfaces(e.g, metal structures, fences receivers, planning a GPS survey could be aided by the water surfaces) in the vicinity of the antenna to avoid use of computer programs to save time and resources. 3. No nearby electrical installations(e. g, transmitters)to avoid signal disturbances5 2.3 Non-synchronic Loop Construction 3. Planning of GPS Survey 3.1 General Remarks 1. Designing a GPS network will have to consider 1. Project objectives 2. Equipment, 3. Observation technique, and 4. Organization. 2. GPS surveying differs essentially from classical one because 1. Weather independent 2. No need for intervisibility between the sites 3. Different planning 4. Execution 5. Processing techniques 3. The optimum planning of a GPS survey has to consider 1. Site or satellite configurations, 2. Number of receivers 3. Type of receivers 4. Economic aspects 5. Data processing considerations (software allows for single baseline vectors or for multipoint solutions) 6. Whether 4. Contrary to the design of triangulation or trilateration networks, the followings are not so critical for GPS networks • Geometric strength, • Line length. For large projects with many sites and many receivers, planning a GPS survey could be aided by the use of computer programs to save time and resources. 3.2 Pre-survey Planning 1. Point Selection: • Small-scale maps (1:25000 to 1:100000) for point selection. • All desired survey points are plotted on the map along with the known control points Three basic considerations in choosing a point: 1. No obstructions above 20° elevation to avoid satellite signal blockage. 2. No reflecting surfaces (e.g., metal structures, fences, water surfaces) in the vicinity of the antenna to avoid multipath. 3. No nearby electrical installations (e.g., transmitters) to avoid signal disturbances