Garmin G500 Pilots Guide - Page 191

4.8 GWX Weather Radar (Optional) Foreword Sec 1 System Sec 2 PFD Sec 3 MFD Sec 4 Hazard Avoidance Features Sec 5 Additional 4.8.1 Garmin GWX 68 Radar Description The Garmin GWX 68 Airborne Color Weather Radar is a four color digital pulsed radar with 6.5 kilowatts of power. It combines excellent range and adjustable scanning profiles with a high-definition target display. The pulse width is four microseconds on all ranges except the 2.5 NM range. The GWX 68 uses a one microsecond pulse width at this range to reduce the smearing of targets on the display. This allows better target definition at close range. To focus radar scanning on specific areas, Sector Scanning offers pilotadjustable horizontal scan angles of 20º, 40º, 60º, or 90º. A vertical scanning function helps to analyze storm tops, gradients, and cell buildup activity at various altitudes. Other features include: • Extended Sensitivity Time Control (STC) logic that automatically correlates distance of the return echo with intensity, so cells do not suddenly appear to get larger as they get closer. • WATCH™ (Weather Attenuated Color Highlight) which helps identify possible "shadowing" effects of short-range cell activity - identifying areas where radar return signals are weakened, or attenuated, by intense precipitation (or large areas of lesser precipitation) and may not fully reflect the "storm behind the storm." • Weather Alert that looks ahead for intense cell activity in the 80-320 NM range, even if these ranges are not being monitored. 4.8.1.1 Principles of Pulsed Airborne Weather Radar The term RADAR is an acronym for RAdio Detecting and Ranging. Pulsed radar locates targets by transmitting a microwave pulse beam that, upon encountering a target, is then reflected back to the radar receiver as a return "echo." The microwave pulses are focused and radiated by the antenna, with the most intense energy in the center of the beam and decreasing intensity near the edge. The same antenna is used for both transmitting and receiving. The returned signal is then processed and displayed on the G500 MFD. Radar detection is a two-way process that requires 12.36 micro-seconds for the transmitted microwave pulses to travel out and back for each nautical mile 190-01102-02 Rev. B Garmin G500 Pilot's Guide 4-63 Sec 6 Annun. & Alerts Sec 7 Symbols Sec 8 Glossary Appendix A Appendix B Index