Multipath

In case of a receiver operating in a real-world environment, satellite signals are likely to be affected by obstructing and reflecting objects, the later ones inducing multipath signals. Multipath signals of reflected or diffracted satellite signals are always time-delayed compared to direct LOS signals and experience changes within its signal amplitude. Thus, several signals of a single satellite arrive at the receiver, decreasing the accuracy of the pseudorange measurement.

The Multipath tab is divided into two different sections:

1. Receiver Selection

Select the receiver for which multipath should be applied and if the multipath simulation should be enabled.

2. Multipath Signals & Obstruction Mask

• Multipath Signals: Determines the number of signals additionally superimposed on the simulated base signal for all echoes in the Obstruction Mask.

• Environment: The environment determines model's distribution parameters which are a function of the satellite's elevation. The satellite's signal power and a statistical delay are computed based on the direct-path and echo parameters and the satellite's orientation relative to the receiver (see Multipath). Possible environments are:

  • Open
  • Rural
  • Suburban
  • Urban
  • Highway
    

• Obstruction Mask Timeline: Each row represents an obstruction mask, that is applied to the receiver at the given time offset [s]. The time offset is defined relative to the beginning of the scenario. By clicking on the button within the obstruction mask table, a separate dialog allows for editing the currently selected obstruction mask.

Note

All obstruction masks with the same name share one instance, e.g. if one changes the "Tunnel" obstruction mask, all obstruction masks with the name "Tunnel" will be changed in the same way.

Each grid point in the displayed azimuth-elevation grid needs to be set to a specific category. Four different types of categories can be selected:

• LOS only: only the LOS signal is received.
• LOS + Echoes: a LOS signal as well as several reflected signal paths are received.
• Echoes only: several echo paths are received, but not LOS signal.
• Obstruction: the satellite is obstructed and no signals are received.

By clicking on the button a separate dialog allows for adding a new obstruction mask. Here, a predefined obstruction mask (e.g. "Tunnel") can be inserted or a completely new one can be created for a certain time offset.