How to Choose a GNSS Simulator
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There is significant variety in the quality, accuracy, and reliability of signals produced by GNSS simulation systems. Confusingly for many development and integration engineers, the lengthy specification lists supplied by manufacturers apply more to features and capability than to accuracy and performance. This means the focus falls on things like frequency dial breadth and number of channels, rather than a measure of result quality.
This presents an important issue in the development of a functional product, as poor test signal simulation could lead to:
• Poor choices in the selection and integration of receivers, chipsets, antennas, and protocols
• Long delays in new product introduction — redesigning devices for no reason
• Damaging quality control issues between manufacturers and tier one suppliers
• Functional devices being wasted after needlessly failing production line tests
For any test to be meaningful, it must be possible to clearly distinguish between errors in the device and inaccuracies introduced by the test setup. Accordingly, all test apparatus must always be an order of magnitude more accurate than the device under test. What this means is that if a device is expected to be accurate to within 10 m, the test equipment should be reliable to within 1 m. If the device’s acceptable margin of error is centimeters, the test resolution should be millimeters. Unfortunately, simulator accuracy is hard to quantify in a bite-sized, specification-sheet format. So, we ran several illustrative tests.