What Is A GPS Simulator?

As GPS receivers are built into more mission-critical devices for difficult application environments, and designed with the emerging capabilities of a multitude of GNSS constellations and augmentation systems, developers and manufacturers need better ways to guarantee performance. That’s where a GPS simulator comes in.

While the test engineer has a variety of choices for testing GPS-based position, navigation and timing functions of their integrated GPS receivers, simulation offers the most flexibility, compared to testing with over-the-air signals (“live sky”), or record and replay solutions. Having complete control over the generation of GPS signals is the only way to have confidence in your hardware and software’s ability to perform – under any condition.

To understand a GPS simulator, it is helpful to understand some of the details of GPS transmissions. The GPS constellation consists of at least 24 satellites, orbiting every 12 hours, broadcasting navigation data on different frequencies. GPS is just one of several global navigation satellite systems (GNSS) in operation, or soon to be in operation. Most navigation applications today use the GPS L1 frequency at the radio frequency 1575.42 MHz. Onto this carrier frequency, satellites transmit identification information and a navigation message that contains synchronized time, the satellite’s orbital data (ephemeris), and data on the expected positions of all the satellites in the constellation (almanac). It is from this data that receivers can accurately calculate its distance from several satellite signals at the same time to achieve its navigation solution through trilateration.