In GNSS surveying, the direct _____ has to be with the satellites and not with the stations in the project ______ network.

In GNSS (Global Navigation Satellite System) surveying, establishing a direct line of sight is crucial for optimal performance. This means that the satellite signals need to travel unobstructed from the satellites to the GNSS receiver. A clear line of sight ensures that the signals received are strong and accurate, which is vital for precise positioning and measurements.

The context of this question involves understanding GNSS infrastructure and its operational principles. The term "control" refers to the network of reference stations or control points that provide data for corrections and enhance the precision of positioning. However, the direct interaction in terms of signals must fundamentally occur between the satellites and the receivers. If there are obstructions (like buildings or trees) impacting this line of sight, it can lead to signal degradation or loss, resulting in inaccurate positioning.

The word "planning" in the context of a "planning network" would pertain more to the operational setup of a GNSS network rather than the immediate need for a clear signal path. Thus, the correct pairing highlights the importance of maintaining an unobstructed line of sight with satellites to ensure effective GNSS surveying, while the control network serves a supportive role rather than being the direct medium of communication for signal acquisition.