Garmin GMX 200 Pilot's Manual & Reference

Also see for GMX 200: Pilot's guide Reference guide Installation Pilot's Guide & Reference Specification

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87Detailed OperationRadarGarmin GWX 68 Radar DescriptionThe Garmin GWX 68 Airborne Color WeatherRadar is a four color digital pulsed radar with 6.5kilowatts of power. It combines excellent range andadjustable scanning profiles with a high-definitiontarget display. The pulse width is four microsecondson all ranges except the 2.5 nm range. The GWX 68uses a one microsecond pulse width at this range toreduce the smearing of targets on the display. Thisallows better target definition at close range.To focus radar scanning on specific areas, SectorScanning offers pilot-adjustable horizontal scan angleof 10 degrees. A vertical scanning function helps toanalyze storm tops, gradients and cell buildup activityat various altitudes.Principles of Pulsed Airborne Weather RadarThe term RADAR is an acronym for RAdio Detect-ing and Ranging. Pulsed radar locates targets by trans-mitting a microwave pulse beam that, upon encounter-ing a target, is then reflected back to the radar receiveras a return “echo.” The microwave pulses are focusedand radiated by the antenna, with the most intenseenergy in the center of the beam and decreasing inten-sity near the edge. The same antenna is used for bothtransmitting and receiving. The returned signal is thenprocessed and displayed on the GMX 200 MFD.Radar detection is a two-way process that requires12.36 micro-seconds for the transmitted microwavepulses to travel out and back for each nautical mileof target range. It takes 123.6 micro-seconds for atransmitted pulse to make the round trip if a target is10 nautical miles away.The GWX 68 weather radar should be used toavoid severe weather, not for penetrating severeweather. The decision to fly into an area of radartargets depends on target intensity, spacing betweenthe targets, aircraft capabilities and pilot experience.Pulse type weather radar detects only precipitation,not clouds or turbulence. The display may indicateclear areas between intense returns, but this does notnecessarily mean it is safe to fly between them. OnlyDoppler radar can detect turbulence.Airborne weather radar has other capabilitiesbeyond weather detection. It also has the ability todetect and provide distance to objects on the ground,such as, cities, mountains, coastlines, rivers, lakes, andoceans.Radar Beam from 12 inch Antenna