Garmin 695 Car Stereo System User Manual


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Garmin GPSMAP 695/696 Owner’s Manual
190-00919-00 Rev. F
128
Hazard Avoidance
OverviewGPS NavigationFlight PlanningHazard AvoidanceAdditional FeaturesAppendicesIndex
NEXRAD Abnormalities
There are possible abnormalities regarding displayed NEXRAD images. Some, but
not all, of those include:
•Groundclutter
•Strobesandspuriousradardata
•Sunstrobes,whentheradarantennapointsdirectlyatthesun
•Militaryaircraftdeploymetallicdust(chaff)whichcancausealterationsinradar
scans
•Interferencefrombuildingsormountains,whichmaycauseshadows
•PoorreceptionfromGroundBasedTransceivers(GBTs)cancauseportionsofthe
received radar imagery to not be displayed
NEXRAD Limitations
Certain limitations exist regarding the NEXRAD radar displays. Some, but not all, are
listed for the user’s awareness:
•NEXRAD base reectivitydoes not providesufcient information to determine
cloud layers or precipitation characteristics (hail vs. rain). For example, it is not
possible to distinguish between wet snow, wet hail, and rain.
•NEXRADbasereectivityissampledattheminimumantennaelevationangle.An
individual NEXRAD site cannot depict high altitude storms at close ranges, and
has no information about storms directly over the site.
neXrAd intensity
Colors are used to identify the different NEXRAD echo intensities (reflectivity)
measured in dBZ (decibels of Z). “Reflectivity” (designated by the letter Z) is the
amount of transmitted power returned to the radar receiver. The dBZ values increase
as returned signal strength increases. Precipitation intensity is displayed using colors
corresponding to the dBZ values.
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