Garmin MX20 Installation Manual - page 12
Introduction
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MX20 Installation Manual
Figure 1-1. Example of a MX20 System Block Diagram
The MX20 display is also available with an internal GPS. The internal GPS position source permits a
Navigation Uncertainty Category (NUC) value to be calculated and transmitted for ADS-B broadcast via
the legacy UAT. The MX20 internal GPS data is ignored by the GDL 90 UAT since the GDL 90 UAT
has an internal GPS receiver to generate the same data. Legacy UATs are those installed in original
Capstone-equipped aircraft. The GDL 90 UAT is the next generation UAT data link radio. MX20
software version V5.6 provides an installation configuration parameter to enable or disable the GDL 90
UAT control functions. The MX20 I/O model is not available with the optional GPS engine.