Simulation equals simplification
One of the most important benefits of testing a GNSS receiver using an RF simulator rather than using either live or recorded signals from real-world satellites is the ability to simplify the test in order to observe a specific response from the receiver.
The formula for calculating the estimated position error of a GNSS receiver is a complex one that takes into account many outside factors. When using a simulator, the majority of these outside variables can be eliminated from the equation. Clearly this cannot be done when testing a receiver using real-world satellite signals, and so the simulator offers the only practical means of observing the performance of the receiver in response to simple stimuli.
Of course, this is not to say that an RF simulator is limited to simple testing. A fully equipped RF constellation simulator can be used to create complex test scenarios combining signals from multiple satellite navigation systems, together with simulated motion and outside factors ranging from ionospheric disturbances to multipath phenomena and radio frequency interference.
However, it is the ability to simulate each of these phenomena individually as well as combining them that offers the GNSS receiver designer, developer and manufacturer with the flexibility to fully exercise receiver designs against all key performance criteria. And because each test–whether simple or complex–is fully repeatable, the effects of design changes can be clearly seen, enabling performance optimisation against specific and general benchmarks.
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