Garmin GPS- Manuals

Page 2 - CONTENTS

09/25/02 GPS_field_guide 8:19 A9/P9 2 CONTENTS CHAPTER 1: INTRODUCTION TO GPS 1.1 What is GPS ?…………………………………………………………...21.2 How does GPS work ?…………………………………………………..3 1.3 Source of GPS signal errors……………………………………………...7 CHAPTER 2: WHY USING GPS IN THE CONTEXT OF THE WHO WHS ? CHAPTER 3: PRESENTATION...

Page 3 - CHAPTER 1: INTRODUCTION TO GPS; Space segment; Figure 1

09/25/02 GPS_field_guide 8:19 A9/P9 3 CHAPTER 1: INTRODUCTION TO GPS 1.1 What is GPS? The Global Positioning System (GPS) is a system allowing to precisely identify locationson the earth's surface. The GPS system has 3 parts (Figure 1): · The Space segment : a network of 24 satellites placed into or...

Page 4 - The satellite signal:

09/25/02 GPS_field_guide 8:19 A9/P9 4 1.2 How does GPS work? GPS satellites circle the Earth twice a day in a very precise orbit at an altitude of around19 000 Kilometres (Figure 2). This constellation allows any user to access between five and eight satellites from any point on the Earth . Figure 2...

Page 5 - satellite signal

09/25/02 GPS_field_guide 8:19 A9/P9 5 The receiver: 1. Calculates the distance to the first satellite he is able to catch. Let's suppose that thereceiver calculates a distance of 17'000 km between this first satellite and the receiver.This will mean that the receiver is located somewhere on a sphere...

Page 6 - Figure 5

09/25/02 GPS_field_guide 8:19 A9/P9 6 3. Repeats the operation mentioned under point 2 with a third satellite. In our examplethe receiver finds out that it is 20,000 km from the third satellite which narrows itsposition down even further, to the two points (Figure 5 point b) where the 20,000 kmspher...

Page 7 - Sources of GPS signal errors; Figure 6; and bad visibility (b) of satellites due to obstacles; will not work indoors, underwater or underground.

09/25/02 GPS_field_guide 8:19 A9/P9 7 1.3 Sources of GPS signal errors Even if today's GPS receivers are extremely accurate, certain atmospheric factors andother sources of error can affect the accuracy of GPS receivers. If most of the sources of error are unavoidable, it is important for the user t...

Page 8 - Figure 6 Examples of signal multipath; Figure 8

09/25/02 GPS_field_guide 8:19 A9/P9 8 There may also be sources of signal multipath (i.e on Figure 8) occurring when the GPSsignal is reflected off these objects before reaching the receiver. This increases the traveltime of the signal and creates errors of distance estimation between the satellite ...

Page 9 - CHAPTER 2: WHY USING GPS IN THE CONTEXT OF; zones or ethnic regions.

09/25/02 GPS_field_guide 8:19 A9/P9 9 CHAPTER 2: WHY USING GPS IN THE CONTEXT OF THE WHO WHS ? The first reason for using GPS in the WHS context is the added value it gives to thesurvey by allowing the geographical dimension to be taken into account withoutrequiring important investment (many GPS re...

Page 10 - CHAPTER 3: THE GARMIN ETREX UNIT; Overview of the unit; Figure 9; - Front view of the Garmin eTrex device

09/25/02 GPS_field_guide 8:19 A9/P9 10 CHAPTER 3: THE GARMIN ETREX UNIT The Garmin eTrex GPS receiver has been chosen for the WHO WHS because it is easy touse and inexpensive. Its utilisation in the context of different surveys operated in the field has proven itssuitability for this kind of work. T...

Page 13 - Utilisation of the eTrex unit; Important Battery Installation Information:; POWER; Button firmly to turn on the unit.

09/25/02 GPS_field_guide 8:19 A9/P9 13 3.2 Utilisation of the eTrex unit This section presents the major elements that will be used in the context of the WHO WHS. It introduces you to the basic features of the eTrex as well as some basic definitions ofterms in a more detailed way than presented on t...

Page 20 - UP; or; DOWN; button again in order to save the; ENTER; button

09/25/02 GPS_field_guide 8:19 A9/P9 20 The 'UNITS' setup page This page (Figure 21) allows the user to setup the units of the different parameters. It isimportant to make sure that this page contains the setting specific to the WHS asindicated in the Figure 21 a) and in the Quick Reference Guide. Fi...

Page 21 - CHAPTER 4: TROUBLESHOOTING; and use

09/25/02 GPS_field_guide 8:19 A9/P9 21 CHAPTER 4: TROUBLESHOOTING 4. 1 eTrex does not turn on: 1. Check to see if the batteries are installed correctly and if the battery terminals areclean. 2. If the eTrex does not turn on after point 1: place a fresh set of AA batteries in theunit (refer to Quick ...

Page 23 - eTrex does not display the local time in the 'SETUP' page; Make sure the eTrex is configured as indicated in point; Quick Reference; and redo the reading correctly.

09/25/02 GPS_field_guide 8:19 A9/P9 23 4.6 eTrex does not display the local time in the 'SETUP' page The eTrex operates on universal time (or GMT, Greenwich Mean Time ).It is not necessary to have your local time displayed. Do not worry about a wrongdisplayed time. 4.7. The geographic coordinates I ...

Page 24 - GLOSSARY; Coordinates

09/25/02 GPS_field_guide 8:19 A9/P9 24 GLOSSARY Accuracy : How close to the real value a measurement is. Backlight: Selectable on/off illumination that lights the display for enhanced screen at night and in low light. Contrast: The difference between the lightest and darkest areas on a display scree...