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Positioning Application, GNSS Receivers: Why doesn't my receiver find a PVT solution when connected to a Spirent simulator?

  • Spirent GNSS Simulator
  • PosApp (all versions)
  • GNSS receiver
There are numerous reasons why a GNSS receiver may fail to track simulated satellites or to produce a PVT (Position, Velocity and Time) solution. If you are seeing this problem, try the following steps:
  • ​Reset the receiver. The simulated navigation data might conflict with saved PVT/satellite information and be rejected by the receiver.
  • Check that the atmosphere settings are the same for PosApp and the receiver. If the receiver is compensating for atmospheric effects that PosApp isn't applying, it may fail to produce a valid PVT solution.
  • Is the scenario start time realistic? A receiver manufactured in 2010 may not believe it is 1980!
  • Check the settings in the signal sources file.
    • Ensure that each signal you are trying to track has the RF carrier, PRN code and navigation message enabled.
    • Check that these settings are applied to all satellites.
  • Check the path losses in your test setup. Each simulator has a high-level RF output at the rear which can be used to provide a stronger signal if the losses are too high. Please contact Spirent Global Services if you have any questions about how to use or calibrate your test setup when using the high-level port.
  • Consider the front-end noise of the receiver. Receivers using an active antenna will have a noise figure dominated by the antenna. When connected to a simulator, the noise figure will be dominated by the first stage after the input, which is insignificant when an active antenna is used. As a result, the simulated power may need to be increased to produce the same signal-to-noise ratio at the receiver.

SOL10185 provides more in-depth information about receiver operation and how this might affect your testing with a Spirent simulator.

Product : Positioning,SimREPLAYplus,SimREPLAY,SimGEN,PosApp,Receiver,SimTEST