GPS sky

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By: ahmedsalim (114 month(s) ago)

thank u

By: unleash.thunder (117 month(s) ago)

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Presentation Transcript

GPS SKY : 

GPS SKY What is the Sky Doing Today?

Objective : 

Objective

Slide 3: 

Summary of Topics - Importance of Planning - Review how GPS Calculates Positions - Check Out The Sky - Planning Ahead

Slide 4: 

Planning the GPS Day Recreational GPS is very forgiving It’s for fun! Not for worrying about PDOP,SNR,Mask Angle,blah blah… Designed to Work inside your Pocket! Still important - as will be demonstrated

Slide 5: 

Tracking a GPS Satellite Vehicle (SV) One of 29 12,000 miles up 6000 mph JTRACK http://liftoff.msfc.nasa.gov /RealTime/JTrack/3D/JTrack3D.html

How to Calculate a Position : 

How to Calculate a Position Measure the Distance to the Satellites Review

How to Calculate Distance : 

How to Calculate Distance Speed of Light x Travel Time Distance Time signal left satellite Current time Review

Minimum # of Satellites Required : 

Minimum # of Satellites Required 4 Unknowns Require 4 Satellites time ...……………… (1) satellite latitude ……………. (1) satellite longitude .…………. (1) satellite elevation …..…….… (1) satellite 4 Satellites = 3D Good 3 Satellites = 2D BAD A Garmin will allow 2D positioning! Watch Out!

PDOPPosition Dilution of Precision : 

- Want tetrahedron as large as possible - Want index as low as possible PDOPPosition Dilution of Precision

Garmins View of Mapping : 

Garmins View of Mapping Typical Mapping Grade GPS Settings - PDOP = 99 - SNR = 2 - Mask Angle = 5 º PDOP = 6 SNR = 6 Mask Angle = 15º Garmin Says... GO FOR IT!

PDOP / DOPPosition Dilution of Precision : 

Rules of Thumb PDOP of 6 or Less - Good DOP of 3 or Less - Good PDOP / DOPPosition Dilution of Precision Garmin only Shows DOP That’s 1/2 of PDOP Garmin III Plus Screen

Slide 12: 

Tools for Predicting - See PDF on How To: CD</software/TrimblePlanSoftware Almanac File: Software: From CD </software/TrimblePlanSoftware or http://www.trimble.com/planningsoftware_ts.asp

PDOP and Visibility Graphs : 

PDOP and Visibility Graphs Instructor Runs Trimble Planning Software for Today

PDOP and Visibility Graphs : 

PDOP and Visibility Graphs

It’s Your Decision : 

It’s Your Decision Plenty of satellites In a hurry to go Limited control Must collect now Reasons to plan Reasons not to plan More efficient More economical Forewarned

Plan Ahead : 

Plan Ahead External Antenna Wait till Good Sky Returns Offsets Map Using other Means? Steps You Can Take

Break : 

17 Coming Up GPS Sky Garmin Setup Get Outside! Break

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