Fundamentals of Surveying (FS) Practice Exam

In GPS survey procedure, which of the following is the most important measurement?

1. Barometric pressure

2. Relative humidity

3. Antenna height

4. Distance from nearest control point

The correct answer is: Antenna height

In GPS survey procedures, measuring the antenna height is crucial for achieving accurate positioning results. This measurement directly impacts the calculation of the position of the surveying instrument in relation to the earth's surface. The height of the antenna above the ground level must be known to compute the correct three-dimensional coordinates of the survey point. Accurate antenna height measurements help in correcting for any errors that may arise from the differences in elevation between the GPS antenna and the reference point. This is particularly important because GPS systems provide positional data based on satellite signals relative to the Earth's center, and without knowing the exact height of the antenna, the derived coordinates can be significantly inaccurate. Thus, it is essential to ensure that this measurement is precise to maintain the integrity of the survey results. Other factors such as barometric pressure and relative humidity, while they can affect GPS signal propagation and overall atmospheric conditions, do not directly relate to the spatial accuracy at the survey point in the same way that antenna height does. Additionally, although knowing the distance from the nearest control point is relevant for referencing and correction purposes, it does not hold the same crucial significance as the immediate need to ensure the correct measurement of the antenna's height for precise data acquisition.