Garmin GTX 330 Manual

A SERVICE OF

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15

Part Two: Section 2

XM Weather

NEXRAD Intensity

ColorsareusedtoidentifythedifferentNEXRAD

echo intensities (reﬂectivity)measuredindBZ(deci-

belsofZ).“Reectivity”istheamountoftransmitted

power returned to the radarreceiver.Reectivity

(designatedbytheletterZ)coversawiderangeof

signals(fromveryweaktoverystrong).So,amore

convenient number for calculations and comparison, a

decibel(orlogarithmic)scale(dBZ),isused.ThedBZ

values increase as the strength of the signal returned

to the radar increases. There are seven gradations for

rain,twogradationsformixedrainandsnow,andtwo

gradations for snow.

To display the NEXRAD Intensity Legend:

1. While viewing the XM Weather page, press the

MENU key to display the Page Menu.

2. Turn the large or small knob to select “Display

legend?”

3. Press ENT to display the NEXRAD Intensity

Legend.

4. Turn the large or small knob to scroll through

the full table. Press CLR to return to the normal

view.

NEXRAD Abnormalities

There are possible abnormalities regarding dis-

playedNEXRADimages.Some,butnotall,causesof

abnormal displayed information include:

 •GroundClutter

 •Strobesandspuriousradardata

 •Sunstrobes,whentheradarantenna points

directly at the sun

 •Militaryaircraftdeploymetallicdustwhichcan

cause alterations in radar scans

 •Interferencefrombuildingsormountains,

which may cause shadows

 •Scheduledmaintenancemayputaradaroff-line

190-00356-30 Rev F