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Trajectories

Note: This feature is not available in GSG-51/52/53.

In the context of GNSS testing, a trajectory is the predefined path a receiver is traveling during the execution of a scenario. GSG-5/6 can be used to simulate virtually any user trajectory. You can:

  • Use predefined (built-in) trajectories
  • Modify predefined trajectories (using the GSG unit, or the GSG StudioView software)
  • Create trajectory files in StudioView, and upload them.

Note: If the RSG Option (OPT-RSG) is installed on your unit, you can also control movement in real-time.

At the start of the scenario the nose of the user is pointing north. The orientation of the vehicle body changes with movement so that its nose is aligned with the vehicle’s course. In cases with changing altitude the nose will still point in a horizontal direction, not changing the body attitude. This default behavior can be changed by using SCPI commands which change pitch, roll, and yaw of the simulated vehicle.

Predefined Trajectories

GSG units come with several built-in trajectories. The exact list of these predefined trajectories varies from GSG model to model. The following is a selection:

  • Static: The user is not moving, but the latitude, longitude and altitude defined in the Scenario configuration are used as user position throughout the scenario replay.
  • 3GPP: The user is moving on a rectangular trajectory as defined in the Technical Specification 3GPP TS 25.171 V7.1.0, Section 5.5, Table 11 and Figure 1:

    The specification describes the trajectory as follows:

    “The UE [User Equipment, (Spectracom)] moves on a rectangular trajectory of 940 m by 1440 m with rounded corner defined in figure 1. The initial reference is first defined followed by acceleration to final speed of 100 km/h in 250 m. The UE then maintains the speed for 400 m. This is followed by deceleration to final speed of 25 km/h in 250 m. The UE then turn 90 degrees with turning radius of 20 m at 25 km/h. This is followed by acceleration to final speed of 100 km/h in 250 m. The sequence is repeated to complete the rectangle.”

    The complete specification can be found under http://www.3gpp.org/DynaReport/25-series.htm.
  • Circle: The user is moving in a circle throughout the scenario replay. When Circle is selected, a dialog is shown asking the parameters describing this trajectory. These parameters include diameter [meter], speed [m/s] and direction [clockwise/anticlockwise].


The start position of the trajectories is the position specified in the Configuration View 1/3, under Latitude, Longitude and Altitude.

User-Created Trajectories

GSG supports the simulation of custom-made trajectories. The trajectories are typically created with the GSG StudioView software (see also: Creating a Trajectory in StudioView).

Two trajectory file types are supported: