2. Observation Window: I. Satellite Visibility(P. 150) 1. The optimum window of satellite availability is the period when num of satellites can be observed Observation Window: To optimum daily observati riod and to decide how it should be subdivided into 2. The difference between sidereal time and Universal time sessions UT) is 4 minutes 3. The length of the window is a function of the location 2. Geometrie D 1. The tracked satellites should be geometrically well distributed with(ideally) one in each of the four quadrants 3. ionospheric Refraction: 1. Observations during night hours may be ate because the ionospheric effect is usually quiet 2. Daylight hours are preferred for organizational 3. Sessions Session length vs. baseline length for Sessions: The specific time period chosen for an conventional static surveying and single observation frequency receivers Observation Time: The following factors to determine the length of a particular observation 1. Length of the baseline Session min 2. Number of visible satellites(affects geometry) tive geometry of the satellites and the change in 35-60 4. SNR of the received satellite signal 55-90 Summary What have we learnt? Which parts are important?6 2. Observation Window: Observation Window: To optimum daily observation period and to decide how it should be subdivided into sessions. 1. The optimum window of satellite availability is the period when a maximum of satellites can be observed simultaneously. 2. The difference between sidereal time and Universal Time (UT) is 4 minutes. 3. The length of the window is a function of the location. 1. Satellite Visibility (P. 150): 1. The tracked satellites should be geometrically well distributed with (ideally) one in each of the four quadrants. 2. Geometric Distribution of Satellites: 1. Observations during night hours may be appropriate because the ionospheric effect is usually quieter. 2. Daylight hours are preferred for organizational reasons. 3. Ionospheric Refraction: 3. Sessions: Sessions: The specific time period chosen for an observation. Observation Time: The following factors to determine the length of a particular observation: 1. Length of the baseline 2. Number of visible satellites (affects geometry) 3. Relative geometry of the satellites and the change in geometry 4. SNR of the received satellite signal. 20 55-90 10 35-60 5 25-45 1 20-35 Baseline [km] Session [min] Session length vs. baseline length for conventional static surveying and single frequency receivers Summary What have we learnt? Which parts are important?