In a GNSS network, what does the baseline represent?

• A. The length from the receiver to the satellite.
• B. The time difference between receiver clocks.
• C. The difference in clock biases between satellites.
• D. The vector between two GNSS receivers forming a part of the network.

Answer: (D)

In a GNSS network, the baseline is the vector from one receiver to another within the same network, describing their relative position in three dimensions. This vector, with components dx, dy, and dz, is what the network adjustment solves for, tying all network points to a common reference frame while canceling much of the common errors like satellite and receiver clock biases. It’s not the distance to a satellite (that would be a range measurement) nor the clock differences between receivers or satellites; those are separate quantities used in the observation model.