Garmin 125 Sounder User Manual

GPS 125

ZOOM

Sounder

Marine

Navigator

Owner’s Manual

&

Reference

Software Version 2.0 or above
© 1997 GARMIN Corporation

1200 E. 151st Street, Olathe, KS USA 66062
Tel: [phone] or 800-800-1020
Fax: [phone]
Web Site Address: www.garmin.com

GARMIN (Europe) Ltd.
Unit 5, The Quadrangle, Abbey Park, Romsey, SO51 9AQ, U.K.
Tel: [phone]
Fax: [phone]

GARMIN (Taiwan) Corp.
4th Fl., No. 1., Lane 45,
Pao-Hsing Road,
Hsin Tien, Taiwan R.O.C.
Phone: [phone]
Fax: [phone]

All rights reserved. No part of this manual may be reproduced or transmitted in any
form or by any means, electronic or manual, including photocopying and recording, for
any purpose without the express written permission of GARMIN.

Information in this document is subject to change without notice. GARMIN reserves
the right to change or improve its products and to make changes in the content without
obligation to notify any person or organization of such changes or improvements.

GARMIN, AutoLocate, and TracBack are all trademarks of GARMIN Corporation
and may not be used without the expressed permission of GARMIN.

July 1997 Part #190-00111-00 Rev. B Printed in Taiwan.

GPS 125

INTRODUCTION

SOUNDER

Overview

Operator’s

Manual

Welcome to the easiest-to-use combination GPS/Depth Sounder on the
water! The GPS 125 Sounder represents GARMIN’s continuing commitment to
provide mariners with quality navigation and fishfinding information in a versa­tile, accurate, and user-friendly design which will be useful for years to come. It
is important that you take the time to read through the operator’s manual to
understand the operating features of the GPS 125 Sounder. The manual is orga­nized into four sections for your convenience:

Introduction gives a quick overview of the manual and contains the table
of contents and glossary of navigation terms.

Getting Started takes you through step-by-step instructions to initialize the
receiver for first-time use and introduces you to the basic features of the unit
with a quick-start orientation to the GPS 125 Sounder. This section has been
designed to acquaint you with the unit and provide a basic working knowledge
necessary to use the unit in typical conditions.

Reference provides detailed explanations of the advanced features and oper­ations of the GPS 125 Sounder in a topical format. This allows you to concen­trate on a specific topic quickly, without reading through entire sections of text
that you may not need.

The Appendix section contains installation instructions and items with mul­tiple listings, such as: map datums, time offsets, and the index.

See your GARMIN dealer for accessories including our PC kit and standard
or temperature reading in-hull and transom-mount transducers.

Thanks for choosing the GARMIN GPS 125 Sounder. We hope it will help
you meet all of your navigation and fishfinding needs.

i

INTRODUCTION

Caution

The GPS system is operated by the government of the United States,
which is solely responsible for its accuracy and maintenance. The system is
subject to changes which could affect the accuracy and performance of all
GPS equipment. Although the GPS 125 Sounder is a precision electronic
NAVigation AID (NAVAID), any NAVAID can be misused or misinterpreted
and, therefore, become unsafe.

Use the GPS 125 Sounder at your own risk. To reduce the risk of
unsafe operation, carefully review and understand all aspects of this
Operator’s Manual and thoroughly practice operation using the simulator
mode prior to actual use. When in actual use, carefully compare indications
from the GPS 125 Sounder to all available navigation sources including the
information from other NAVAIDs, visual sightings, maps, etc. For safety,
always resolve any discrepancies before continuing navigation.

NOTE: This device meets requirements for Part 15 of the FCC limits for
Class B digital devices for home or office use. It has been tested for compli­ance with all necessary FCC standards. This equipment generates, uses, and
can radiate radio frequency energy and, if not installed and used in accor­dance with the instructions, may cause harmful interference to radio commu­nications. However, there is no guarantee that interference will not occur in a
particular installation. If this equipment does cause harmful interference to
other equipment, which can be determined by turning the equipment off and
on, the user is encouraged to try and correct the interference by relocating the
equipment or connecting the equipment to a different circuit than the affected
equipment. Consult an authorized dealer or other qualified service technician
for additional help if these remedies do not correct the problem. Operation is
subject to the following conditions: (1) This device cannot cause harmful
interference, and (2) this device must accept any interference received,
including interference that may cause undesired operation. The GPS 125
Sounder does not contain any user-serviceable parts. Repairs should only be
made by an authorized service center. Unauthorized repairs or modifications
could void your warranty and your authority to operate this device under Part
15 regulations.

ii

INTRODUCTION

Table of

Contents

SECTION ONE Introduction

Glossary/Navigation Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4

SECTION TWO Getting Started

Turning On and Initializing the Receiver . . . . . . . . . . . . . . . . . . . . . .5-7

Primary Page Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-9

Marking a Waypoint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Position Page and Map Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-12

Going to A Waypoint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Using the Highway Page and Cancelling a GOTO . . . . . . . . . . . . .13-14

Using The Sounder Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14-17

Clearing a Map and Turning Off . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

SECTION THREE Reference

Satellite Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17-19

Position Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Marking, Saving, and Using Waypoints . . . . . . . . . . . . . . . . . . . . .21-28

TracBack Navigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29-30

Creating and Using Routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31-36

Sounder Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37-40

Map Plotting, Zooming, and Cursor Movement . . . . . . . . . . . . . . .41-43

Using the Compass and Highway Navigation Pages . . . . . . . . . . . .44-46

Menu Page and Distance/Sun Calculation . . . . . . . . . . . . . . . . . . . . . .47

Track Log Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47-48

Interface Setup and DGPS Interface . . . . . . . . . . . . . . . . . . . . . . . .49-51

System Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51-52

Navigation Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53-55

Map Page Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55-56

Alarms Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

Sounder Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58-61

Navigation Simulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62-63

Appendix A––Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64-69

Appendix B—Wiring and Specifications . . . . . . . . . . . . . . . . . . . .70-71

Appendix C—Messages and Time Offsets . . . . . . . . . . . . . . . . . . .72-73

Appendix D—Map Datums . . . . . . . . . . . . . . . . . . . . . . . . . . . . .74-76

Appendix E––Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77-78

1

INTRODUCTION

Glossary

The GPS 125 Sounder is a powerful navigation tool that can guide you any­where in the world. To better understand its operation and capabilities, it may be
helpful to review the basic terms and concepts briefly explained below.

Other navigation and GPS definitions used in the manual are defined in the
appropriate reference sections of the manual.

Almanac Data

Satellite constellation information (including location and health of satellites) that is
transmitted to your receiver from every GPS satellite. Almanac data must be acquired
before GPS navigation can begin.

Bearing (BRG)

The compass direction from your position to a destination.

Course Made Good (CMG)

The bearing from the “active from” position (your starting point) to your present
position.

Crosstrack Error (XTE)

The distance you are off a desired course in either direction.

Desired Track (DTK)

The compass course between the “from” and “to” waypoints.

Differential GPS (DGPS)

An extension of the GPS system that uses land-based radio beacons to transmit position
corrections to GPS receivers.

Estimated Time of Arrival (ETA)

The time of day of your arrival at a destination.

Estimated Time Enroute (ETE)

The time left to your destination at your present speed.

Ground Speed (SOG)

The velocity you are traveling relative to a ground position.

2

INTRODUCTION

Glossary

Latitude

The north/south measurement of position perpendicular to the earth’s polar axis.

Longitude

An east/west measurement of position in relation to the Prime Meridian, an imagi-

nary circle that passes through the north and south poles.

Position

An exact, unique location based on a geographic coordinate system.

Sensitivity

A measure of how sensitive the sounder is to sonar echoes.

Speed Over Water (SOW)

The speed you are traveling over the surface of the water.

Thermocline

A layer of water separating warmer water above from cooler water below.

Track (TRK)

The direction of movement relative to a ground position.

Universal Transverse Mercator (UTM)

A grid coordinate system that projects global sections onto a flat surface to measure

position in specific zones.

Velocity Made Good (VMG)

The speed you are traveling in the direction of your destination.

Waypoint

A specific location saved in the receiver’s memory.

Whiteline

A term applied to the checkered portion of the sonar display which shows the area

of strongest sonar return (typically the bottom).

3

INTRODUCTION

NORTH

“ACTIVE FROM”

WAYPOINT

NORTH

DTK

CROSSTRACK ERROR

BRG

TRK

GROUND SPEED

DISTANCE

“ACTIVE TO”

WAYPOINT

“ACTIVE LEG”

Navigation

Basics

navigation information using degrees, a measurement mea­sured in a clockwise direction from a north reference. North
is described as 000º, east as 090º, south as 180º, and west as
270º. The diagram and compass rose below provide a graphic
illustration of the navigation terms used by the GPS 125
Sounder. More information on basic navigation and GPS are
available at your local library or bookstore.

The GPS 125 Sounder provides steering guidance and

4

Getting Started with Your GPS

Welcome to the exciting world of GARMIN GPS!
The GPS 125 Sounder represents GARMIN’s continuing
commitment to provide marine users with quality navi­gation information in a versatile, user-friendly design
they will enjoy for years to come. To get the most out
of your GPS receiver, be sure to read through the ini­tialization and Getting Started sections of this manual,
and refer to the reference section for complete details
on the GPS 125 Sounder’s advanced features.

Initializing Your GPS for First-Time Use

The first time you power up your new GPS 125
Sounder is an important step in getting the best possi­ble future GPS performance.

Because a GPS receiver can only receive signals
from satellites above the horizon, it needs to know
what satellites to look for at any given time. By using
an almanac (a timetable of satellite numbers and their
orbits) stored in the receiver’s memory, the GPS 125
Sounder can determine the distance and position of
any GPS satellite and then use this information to
determine your position.

To obtain this almanac data, your GPS receiver
needs to be initialized or given the opportunity to “find
itself”, the very first time it is turned on. Once you
have initialized the unit, the GPS 125 Sounder will
compute future fixes more rapidly, usually in a few
minutes.

Remember, that initializing the unit is only neces­sary under the following conditions:

• First-time use from the factory

• If the receiver has been moved over 500 miles
from the last calculated position with power
off

• If the receiver’s memory has been cleared and
all stored data has been lost

GETTING

STARTED

Initialization

Welcome Page

The welcome page will
appear as soon as the GPS
125 Sounder is turned on
and remain on while the
unit conducts a brief
self-test.

5

GETTING

STARTED

Initialization

The EZinit prompt will
automatically appear if the
receiver needs to be initial­ized. The prompt may also
appear during normal use if
the antenna is shaded.

Initializing the Receiver

The receiver is shipped from the factory in
AutoLocate™ mode, which enables the GPS 125
Sounder to determine its location anywhere in the
world. To speed up the initialization process, we recom­mend using EZinit described below, which will usually

provide a fix in a few minutes.

Before you initialize, make sure your GPS 125
Sounder unit, antenna, and transducer have been cor­rectly installed on your boat according to the instruc­tions in Appendix A.

To turn the GPS 125 Sounder on:

1. Press and hold Puntil the receiver turns on.

The welcome page will be displayed while the unit
conducts a self test.

Once testing is complete, the welcome page will be
replaced by the status page, with the EZinit prompt
ready for you to select one of two initialization
methods:

•Select Country––allows you to initialize the
receiver by selecting your present position from a
list of countries in the GPS 125 Sounder’s internal
database. This usually provides a position fix in a
few minutes.

TM

•AutoLocate

––allows the GPS 125 Sounder to
initialize itself and calculate a position fix without
knowing your present position. This usually pro­vides a position fix in 7.5-15 minutes.

If the EZinit prompt has not automatically
appeared on the Satellite Page:

Use the arrow keypad to
highlight the country,
region, or state of your pre­sent position from the list
and press ENTER. If the
country is not listed, select
the closest country instead.

6

1. Press the Fkey.

Note: If the EZinit prompt appears at any time after
you have initialized the receiver (because satellite sig­nals are being obstructed by trees, etc.), highlight ‘No
Re-Init’ with the arrow keypad and press ENTER.

To initialize the receiver:

1. If the ‘country’ option is not highlighted, press the
key repeatedly to move the field highlight to the ‘coun­try’ option and press the

F

key.

D

2. Use theDkey to scroll through the list options until
the country of your present position appears.

3. Use

U

to highlight the country/state/region you’re in.
If the country you’re in is not listed, select another
country within 500 miles of your present position.

GETTING

STARTED

Initialization

4. Press

F

to finish.

The GPS 125 Sounder will now begin searching for
the appropriate satellites for your location and should
acquire a position within a few minutes. You can verify
that you have acquired a position by watching the
Satellite Page transition to the Position Page (provided
you haven’t pressed any other buttons) or by looking for
a ‘2D NAV’ or ‘3D NAV’ status at the top left corner of
the Satellite Page.

Initialization Troubleshooting

If you have trouble initializing the receiver or
acquiring a position, check the following:

• Does the antenna have a clear view of the sky?

If there are nearby buildings, heavy tree cover, a

covered boat slip, etc., the unit may not be receiving

enough satellite signals to calculate a position.

• Have you selected the right country/state/region
from the EZinit list?

Check for the correct approximate lat/long on the
Position Page or reselect the appropriate country
from the list to restart the initialization.

• Have you moved more than 500 miles from the
last calculated position with the receiver off?

Reinitialize the receiver, selecting the country/state/
region of your new location from the EZinit list.

Your unit should now be initialized. If you want to
complete the Getting Started Tour at another time, you
may now turn the GPS 125 Sounder off (see below) or
you may continue.

To turn the GPS 125 Sounder off:

The GPS 125 Sounder’s
Satellite Page will help you
determine which satellites
are in view and whether or
not any satellites are being
“shaded” or blocked from
the receiver’s antenna.

By monitoring the signal
strength bars at the bottom
of the page and the sky view,
you’ll be able to see how
moving to another area with
a clearer view of the sky will
improve satellite reception
and speed up signal
acquisition.

1. Press and hold Pfor approximately three seconds
until the receiver turns off.

7

GETTING

STARTED

Primary Pages

Satellite Page

The Satellite Page will
allow you to monitor
satellite signal reception
and strength.

Primary Pages

The GPS 125 Sounder uses six primary “pages” to
give you information. The pages are arranged in a con­tinual loop and can be easily viewed in forward or
reverse order by pressing either the Jor
Before we start the tour, let’s briefly look at these pages.

Q

key.

J

Q

Satellite Page

The Satellite Page shows satellite positions and
signal strength. Satellite positions are shown using a
“birds-eye-view” display. Signal strength bars are shown
for each satellite in use. Satellite status and estimated
position error (EPE) are shown in the upper corners.

Position Page

The Position Page shows you where you are, what
direction you’re heading and how fast you’re going. The
top of the page contains a compass tape which is a
graphic representation of your heading. Your track and
speed are indicated immediately below, with the digital
depth displayed at the bottom of the page.

Sounder Page

8

The graphic compass tape reflects your head-

!

#

ing only while you are moving.

The rest of the page shows your current position in
three dimensions: latitude, longitude and altitude. A
trip odometer and 12/24-hour clock are also provided.

Sounder Page

The Sounder Page gives a view of the water
beneath your boat while displaying sonar contacts and
bottom contour.

Map Page

The Map Page acts as a window that allows you to
view your position, the “path” you have traveled over,
and nearby waypoints. A diamond icon in the center of
the screen represents your present position. As you
move, you will see a thin line, called a track log, appear
along the path you have just covered. Names of stored
waypoints can also be shown on the map.

The bottom corners of the page will always display
your current track and speed, with the digital depth
shown in the center. If you are navigating to a way­point, highlighting an on-screen waypoint, or panning
the cursor, the corresponding distance and bearing will
be shown at the top corners.

Navigation Page

A navigation page gives you directional guidance
when going to a waypoint. The GPS 125 Sounder has
two navigation page choices: the Highway Page or the
Compass Page. The Highway Page is the default and
will be briefly explained here. The Compass Page is
covered on pg. 46.

The Highway Page uses a graphic highway to
show your movement in relation to your desired
course. The upper section shows bearing and distance
to the waypoint and your current track and speed. The
middle portion contains the actual highway. The bot­tom of the page contains the estimated time enroute
(ETE) and your velocity made good (VMG).

GETTING

STARTED

Primary Pages

& Backlighting

Map Page

The Map Page shows your
progress on a moving map
plotter and gives a bird’s­eye-view of surrounding
waypoints.

Menu Page

The last primary page is the Menu Page. The
Menu Page gives you access to the GPS 125 Sounder’s
waypoint management, route, track log, and setup fea­tures through a list of submenus.

Screen Backlighting

The GPS 125 Sounder features three levels of back­lighting. Activate the backlight by pressing the POWER
key briefly. Each press of the button advances the back­lighting to the next level and then turns it off.
Backlighting will remain on until turned off.

Highway Page

With the Highway Page,
you will get graphic steer­ing guidance in navigating
a route or to a single way­point.

9

GETTING

STARTED

Marking A

Waypoint

To save a waypoint with the
default three-digit name,
simply press the MARK key
followed by the ENTER key.
The GPS 125 Sounder will
then return to the page pre­viously displayed.

Getting Started Tour

Now that your GPS receiver has been initialized and
you are familiar with the primary pages, it’s time to take
a tour. This is a live tour and is to be conducted with
your unit installed and with the boat in the water. The
tour will take you through the receiver’s basic features
and functions as you move about on the water and
assumes that the GPS 125 Sounder is turned on, initial­ized, and that you have not changed any of the factory
settings (units of measure, selectable fields, etc.). If
these settings have been changed, the pictures and
descriptions in this manual may not match what you
see on your screen.

Navigation Simulator

If you are not able to take the Getting Started tour
with your boat in the water, you may use the built-in
navigation simulator to practice using the GPS 125
Sounder. To use the simulator, see pg. 60.

Marking a Waypoint

To begin the live tour, let’s take the position you
have acquired (either by just initializing the unit or by
having turning the unit on) and mark it as a waypoint.

1. Press the Mkey to capture and hold your position.

Press the UP arrow to move
forward through the alpha­bet or numbers and DOWN
to move backward.

10

To mark a position, you must have a 2D or 3D

!

#

fix, or have the receiver in simulator mode. If
you try to mark a position without a position fix,
a ‘No GPS Position’ message will be displayed.

The mark position page will appear, showing the
captured position and a default 3-digit waypoint name.
Let’s change the name something more meaningful, like
‘DOCK’.

1. Press theDkey once to move the field highlight
from the ‘SAVE?’ field to the name field.

2. Press

3. Press and hold the
bet until the letter ‘D’ appears.

to clear the default name.

F

U

key to scroll through the alpha-

4. Press the Rkey once to move the character highlight
to the next character space.

5. Repeat steps 3 and 4 until the word ‘DOCK’ is shown.

6. Press

7. Press the
to the ‘SAVE?’ field.

to complete entry of the name.

F

key twice to return the field highlight

D

GETTING

STARTED

Marking

Waypoint &

Map Page

8. Press the
the position as a waypoint named ‘DOCK’.

key to confirm that you want to save

F

The mark position page will now be replaced by
the Position Page (or whatever page was displayed
prior to pressing the

key). The ‘DOCK’ waypoint

M

is now stored in the GPS 125 Sounder’s memory, and
will remain there until you manually remove it or clear
the receiver’s memory. For more on waypoint manage­ment, see pg. 21-28.

Using the Position and Map Pages

Now that you’ve marked a position, let’s see how
the Position and Map Pages can be used to monitor
your progress as we head out into the open water.

As always, ensure your primary focus is on

!

#

boating traffic and monitor the GPS 125
Sounder briefly when operating your boat.

Graphic

Track Over

Ground

Tr i p

Odometer

Position
Display

Compass Tape

Current Speed

Altitude

12/24 Hour

Time

Digital Depth

The direction you are moving (track) and your
speed are shown on the top of the Position Page, below
the graphic compass tape. The latitude, longitude, and
approximate altitude of your position--with a resettable
trip odometer--are displayed in the middle of the page,
with the time of day and digital depth shown below.

The arrow keypad is used
for all data entry. Use the
UP and DOWN keys to
select letters, numbers, or
menu options, and use the
LEFT and RIGHT keys to
move the cursor forward or
backward along the line.

The Map Page displays
your present position as a
diamond icon and provides
a real-time graphic “bread­crumb” display of your
track right on the screen.

11

GETTING

STARTED

Position/Map

Pages and

GOTO

The moving map’s default
screen orientation is track
up orientation. “Track up”
means that your current
direction of travel is always
up (or towards the top of)
the screen. It can also be set
for north up, or desired
track orientation through
the map setup page.

Using the Position and Map Pages (continued)

Now let’s change the display to the Map Page and

watch the track log of our tour:

1. Press Jto change from the Position Page to the
Map Page.

Your current position is shown as the diamond in
the middle of the screen. The dark circle below the dia­mond represents the position you created, with the line
between the two showing your track.

1. Once you have reached an area that allows for gener­al changes in direction without interfering in the pas­sage of other boats, mark your current position again
and name this waypoint “CHANNL”. (See ‘Marking a
Waypoint’ on pg. 10-11).

2. Next, make a moderate turn in any direction safe for
navigation and proceed for another 3 minutes.

Going To a Waypoint

Once you’ve stored the ‘CHANNL’ waypoint in
memory, you can use the GPS 125 Sounder to guide
you to it by performing a simple GOTO. A GOTO is
simply the receiver drawing a straight-line course from
your present position to the destination you’ve selected.

Use caution when navigating. A “straight-line”

!

#

course reflects the shortest distance to a way­point, and does not navigate around obstruc­tions, such as land or buoys, etc.

The GOTO waypoint page
allows you to select a desti­nation from a list of all
available waypoints in the
GPS 125 Sounder’s
memory.

12

Now that you have moved away from ‘CHANNL’ for
three minutes, let’s try navigating back to it.

To select a GOTO destination:

1. Press the Gkey. The GOTO waypoint page will
appear, displaying all the waypoints in memory in
alphabetical order.

2. Use

U

or Dto highlight the ‘CHANNL’ waypoint.

3. Press the

gate to the displayed waypoint. The Highway Page
(default) will appear.

key to confirm that you want to navi-

F

Using the Highway Page

GETTING

STARTED

Bearing to
Waypoint

Current Track

Destination

Waypoint

“Finish Line”

Position Diamond

Estimated

Time Enroute

Pointer to Waypoint

Digital Depth

Distance to

Waypoint

Current Speed

Destination Waypoint

CDI Scale

Velocity Made

Good

The GPS 125 Sounder’s Highway Page provides
graphic steering guidance to a destination, with an
emphasis on a straight-line course to the desired way­point and the distance and direction you are off course.
The bearing and distance to a waypoint, along with
your current track and speed are displayed at the top of
the screen, with your estimated time enroute (ETE) and
velocity made good (VMG), or the speed you are
approaching your destination, shown at the bottom.

As you head toward your destination, the middle
section of the screen provides visual guidance to your
waypoint on a moving graphic “highway”.

Your present position is represented by the dia­mond in the center of the course deviation scale. The
line down the middle of the highway represents your
desired track.

As you navigate toward a waypoint, the highway
will actually move, indicating the direction you’re off
course, relative to the position diamond on the CDI
scale. When the highway is pointing straight up the
screen, the waypoint is directly ahead. If the destina­tion waypoint is to the left, the top of the highway will
lead toward the left, and vice versa. To stay on course
simply steer in the direction the highway leads (left or
right) until the highway leads straight up the page.

Using the

Highway Page

A waypoint is directly
ahead when the highway is
pointing straight up. In the
above example, the way­point is to the right (111º) of
our present course (100º).
Turn right until the highway
points straight up the
screen.

Once you are one minute
from the destination (based
on your present speed and
course), an arrival message
will appear on the message
page.

13

GETTING

STARTED

Highway/

Sounder Page &

Cancelling GOTO

The 125 Sounder will also
provide steering guidance
with a graphic Compass
Page.

To change the display from
the Highway Page, press
ENTER twice.

Using the Highway Page (continued)

While navigating, you may use the Compass Page

(see picture below left) instead of the Highway Page.

To select the Compass Page:

1. While viewing the Highway Page press Ftwice.

The Compass Page will now become the displayed
navigation page. This page provides a directional point­er to your destination by using a compass display to
show direction of travel. This provides better steering
guidance at slower speeds for travel with many direc­tional changes.

To return to the Highway Page, press ENTER twice.

Cancelling a GOTO

If you decide to stop navigating to the active way­point waypoint, all you have to do is cancel the GOTO.

To cancel an active GOTO:

1. Press the Gkey.

2. Use the arrow keypad to move the field highlight to the
‘CANCEL GOTO?’ prompt at the bottom of the page and
press

F

.

Once a GOTO is activated,
the GPS 125 Sounder pro­vides steering guidance
until the GOTO is canceled.
To cancel a GOTO, high­light the cancel prompt at
the bottom of the page and
press ENTER.

14

Using the Sounder Page

Now that you have learned the basics of GPS
Navigation, let’s briefly look at how the GPS 125
Sounder works for you as a fishfinder. The fishfinding
features are covered in detail on pg. 37-40.

The top of the Sounder Page shows the range mode
being used, the water temperature (if using a tempera­ture-sensitive transducer), and the digital depth, while
the middle of the page contains a right-to-left moving
sonar image of the water beneath your boat. (Note:
items appear as they pass under your transducer. Those
objects appearing on the right side of the screen are
closer to you than those objects on the left.) Fish are
displayed as a darkened arch or a fish icon in three dif­ferent sizes. Thermoclines (layers of water separating
warmer water above and cooler water below) appear as
dotted patterns just above the bottom.

Using the Sounder Page (continued)

The area of strongest sonar return (whiteline) is
displayed as light and dark checkering. Typically, the
bottom will be the primary source of the whiteline. A
thin whiteline indicates a softer bottom while a thicker
whiteline shows a harder bottom. A black line is used
to show the point where water meets the whiteline.
This black line will follow the bottom contour, along
with any significant objects lying on the bottom. Along
the left side of the screen (typically) is an adjustable

scale which shows the current display’s range of depth.

Range Modes

The GPS 125 Sounder uses two range modes: auto
and manual. ‘Auto’ displays the most information pos­sible while continuously displaying the bottom.
‘Manual’ lets you select the displayed range. You may
switch between auto and manual modes by using the
arrow keypad or by using the sounder setup menu.

To switch from auto to manual mode:

1. Press the Uor Dkeys until the desired depth
range is displayed on the depth scale at the left side
of the page.

2. Press

F

to confirm the selected range.

To switch from manual to auto mode:

GETTING

STARTED

Sounder Page,

Range Modes, &

Sounder Zoom

GARMIN’s exclusive See­Thru technology will allow
you to distinguish sonar tar­gets from bottom clutter and
thermoclines.

1. Press the arrow keypad up or down until a repeated
beep sounds. ‘Auto’ will be shown in the range field at
the top left corner of the screen, and press

F

.

Underwater waypoints

The underwater waypoint feature marks a way­point’s position and its depth. This makes it easier to
find and use an object such as a stump for a future
fishing location. For instructions on marking an under­water waypoint, see pg. 38.

Sounder Zoom

The sounder zoom function allows you to see the
current display picture at 2 times (2X) or 4 times (4X)
magnification. 2X means that the screen displayed will
now cover 1/2 the range you were originally viewing in
twice the detail, and 4X shows 1/4 the original range at
four times the detail. Because less area is being shown
(in a zoom screen) objects can be seen in greater detail.

Use the target cursor to
mark the desired underwa­ter location.

Note: The bearing and
range shown are to the cur­sor’s location from your pre­sent position.

15

GETTING

STARTED

Sounder Zoom

& Zoom
Window

The zoom function is accessed by using the IN and

OUT key when viewing the Sounder Page.

Once activated, the zoomed picture becomes the
Sounder Page display. Note: The zoom function can
only be deactivated by pressing the OUT key until the
original zoom scale appears.

The zoom function operates in either Auto range or
Manual range. Zooming while in Auto will continue to
follow the bottom contour, while zooming in Manual
will show the selected depth.

To access the sounder zoom function:

1. While viewing the Sounder Page, press Ionce.
The 2X screen will appear. Note: the current zoom scale
will be displayed in the upper left corner of the screen.

2. Press

I

once more to advance to the 4X screen.

Pressing the IN key once
while on the Sounder Page
activates the 2X Zoom.

The zoom window may be
moved at any time by using
the arrow keypad.

16

3. To deactivate the sounder zoom function, press
once. You may also press and hold Huntil the original
scale picture appears and a triple beep sounds.

I

Moving the Zoom Window

You may move the displayed range on a zoomed
screen at any time, just as you would a non-zoom
screen, by pressing the arrow keypad up or down. This
will move the zoom “window”.

If you prefer to keep the window in its new posi­tion, you will need to save the change. Note: Saving the
new window position requires different steps if you are
in Auto range when you move the window versus being
in Manual when the window is moved.

To save a zoom window range in Auto:

1. Press the Rkeypad up to view a shallower range or
down to view a deeper range. The range scale on the
left side of the zoomed picture will be highlighted.

2. When the window reaches the desired range, press

F

to accept. A ‘Change To Manual Range?’ window

will appear. Highlight ‘Yes” and press

3. If you do not want to save the range, highlight ‘No’ and
press

F

zoom window.

4. Press
display.

. You may then resume manually moving the

Q

at any time to return to an auto range mode

F

.

Moving the Zoom Window (continued)

To save a zoom window range in Manual:

1. Press the Rkeypad up to view a shallower range or
down to view a deeper range. The range scale on the
left side of the zoomed picture will be highlighted.

2. When the window reaches the desired range, press

F

to accept.

GETTING

STARTED

Clearing the

Map Page &

Power OFF

3. If you do not want to save the range, press
return to the previous window range.

Q

to

Clearing a Cluttered Map Page Display

After you’ve used the GPS 125 Sounder for a few
trips, you may find that your map display has become
a bit messy from keeping track of your every move. For
practice, let’s clean up the screen by clearing the track
log (the plot points left on the Map Page) we’ve just
created during the Getting Started Tour.

1. Press Jor Quntil the Menu Page appears.

2. Use the

D

‘TRACK LOG’ option.

3. Press

4. Press the
option. The clear log confirmation page will appear.

5. Use the

6. Press

key to move the field highlight to the

to access the track log page.

F

U

key twice to highlight the ‘CLEAR LOG?’

L

key to highlight the ‘Yes?’ prompt.

to finish.

F

Turning the Receiver Off

You’ve now gone through the basic operation of
your new GPS receiver and probably know a little more
than you think about how it works. We encourage you
to experiment with the GPS 125 Sounder until it
becomes an extension of your own navigation skills. If
you encounter any problems using the unit or want to
take advantage of the GPS 125 Sounder’s more
advanced features, refer to the reference section.

To turn the GPS 125 Sounder off:

1. Press and hold the Pkey for 3 seconds.

Highlight the ‘CLEAR
LOG?’ prompt and press
ENTER to clear the track
log.

Note: Once all 768 points
are used during normal
operation, the oldest point
will be continuously deleted
to make room for the latest
track log point to be stored.

Holding the POWER key
for three seconds ensures
against unwanted shut-off
by accidentally pressing the
key.

17

REFERENCE

Satellite Page

Satellite Page

Overview

When backlighting is on, a
bulb icon will appear on the
Satellite Page.

Use the icon to determine if
backlighting is turned on
during daylight hours.

Satellites being tracked but
blocked from use (03,17)
will be displayed in reverse
video, with the correspond­ing signal strength bar
hollow.

Status

Satellite

Numbers

Estimated

Position Error

Satellite

Sky View

The Satellite Page displays the status of various
receiver functions. The status information will help you
understand what the GPS 125 Sounder is doing at any
given time, and tell you whether or not the receiver has
calculated a position fix.

Sky View and Signal Strength Bars

The sky view and signal strength bars give you an
indication of what satellites are visible to the receiver,
whether or not they are being used to calculate a posi­tion fix, and the signal quality. The sky view in the cen­ter of the page shows a bird’s-eye view of the position of
each satellite relative to the receiver’s last known posi­tion. The outer circle represents the horizon (north up);
the inner circle is 45º above the horizon; and the center
point is a position directly overhead.

When the receiver is looking for a particular satel­lite, the corresponding signal strength bar will be blank
and the sky view indicator will remain highlighted in
reverse video. Once the receiver has found the satellite,
a hollow signal strength bar will appear, indicating that
the satellite has been found and the receiver is collect­ing data from it. The satellite number in the sky view
will also change from reverse video to normal presenta­tion. As soon as the GPS 125 Sounder has collected the
necessary data to use the satellite for positioning, the
hollow bar will become solid.

18

Receiver Status and EPE

Receiver status is indicated at the top left of the
screen, with the current horizontal accuracy (estimated
position error, in feet or meters) at the top right. The
status will show one of the following conditions:

Searching— the GPS 125 Sounder is looking for

any available satellites in view.

TM

AutoLocate

— the GPS 125 Sounder is initializ-

ing and collecting new almanac data. This process

can take 7.5 to 15 minutes.

Acquiring— the receiver is collecting data from

available satellites, but has not collected enough

data to calculate a 2D fix.

2D Nav (2D Navigation)–– at least three satellites

with good geometry have been locked onto and a

2-dimensional position fix (latitude and longitude)

is being calculated. ‘2D Diff’ will appear when you

are receiving DGPS corrections in 2D mode.

3D Nav (3D Navigation)— at least four satellites

with good geometry have been locked onto, and

your position is now being calculated in latitude,

longitude and altitude. ‘3D Diff’ will appear when

you are receiving DGPS corrections in 3D mode.

Poor Cvrg (Poor GPS Coverage)— the receiver is

no longer tracking enough satellites for a 2D or 3D

fix.

Not Usable— the receiver is unusable, possibly

due to incorrect initialization or abnormal satellite

conditions. Turn the unit off and back on to reset.

SIM (Simulating Navigation)— the receiver is in

simulator mode.

REFERENCE

Receiver Status

& EZinit

A ‘POOR CVRG’ status
will appear on the Satellite
Page if the receiver has lost
the satellites required to
compute a fix. Make sure
the external antenna is not
covered and is connected to
the GPS 125 Sounder.

EZinit Option Prompt

The Satellite Page also provides access to the EZinit
prompt whenever a position fix has not been calculated
(the unit must be in searching, AutoLocate, acquiring,
simulator or poor coverage status). This allows you to
manually reinitialize the unit (see pg. 6-7 for instruc­tions), and is useful if you have traveled over 500 miles
with the receiver off and you know it must be initial­ized to your new position (the GPS 125 Sounder will
automatically offer the EZinit prompt after 10 minutes
of unsuccessful satellite acquisition).

If you travel more than 500
miles with the receiver off,
reinitialize the unit to your
new position by using the
EZinit feature. To access
EZinit, press ENTER from
the Satellite Page before any
satellites are acquired.

19

REFERENCE

Backlighting &

Position Page

The speed and track dis­played on the Position Page
may fluxuate at slow speeds
(or when you’re standing
still) because of position
errors caused by Selective
Availability.

Screen Backlighting

The GPS 125 Sounder features three levels of back­lighting. Activate the backlight by pressing the POWER
key briefly. Each press of the button advances the back­lighting to the next level and then turns it off.
Backlighting will remain on until turned off.

Position Page

The GPS 125 Sounder’s Position Page shows you
where you are, the direction you are heading, and your
speed (up to 99.9 mph), and is most useful when you
are traveling without an active destination waypoint. A
compass tape at the top of the page displays your cardi­nal heading (while moving), with current track and
speed over the ground indicated below. The rest of the
page shows your present position in three dimensions
(latitude, longitude and altitude). The units of measure
for speed, distance, position and altitude are user-selec­table through the navigation setup menu (see pg. 53).
The 12/24-hour clock and time offset options are avail­able from the system setup menu (see pg. 52).

Trip Odometer

The Position Page also features a resettable trip
odometer to measure your total distance traveled.

To reset the trip odometer:

To reset the trip odometer,
highlight the trip field and
press ENTER. Use the
LEFT arrow key to clear the
distance field, and press
ENTER to confirm.

20

1. Press the Dkey until the trip field is highlighted.

2. Press

3. Press

F

F

,

followed by L.

to finish.

Altitude Display

When the GPS 125 Sounder is acquiring satellites or
navigating in the 2D mode, the last known altitude will
be used to compute your position. If the altitude shown
is off by several hundred feet, you can manually enter
your altitude for greater accuracy. Note that GPS alti­tudes can fluxuate due to errors.

To enter an altitude:

1. Press the Dkey until the altitude field is highlighted
and press

2. Use the arrow keypad to enter the altitude and press

.

F

F

.

Marking and Saving Waypoints

Knowing your present position is only part of any
navigation equation. You also need to keep track of
where you’ve been and where you are going.
Waypoints serve as electronic markers that let you keep
track of starting points, destinations, navaids and any
other important position.

The GPS 125 Sounder allows you to mark, store
and use up to 250 waypoints. A waypoint position can
be entered by taking an instant electronic fix, by manu­ally entering coordinates, or by entering range and
bearing in reference to an existing waypoint. If you try
to mark a waypoint without having a position fix,
you’ll be notified with a ‘No GPS Position’ message.

To mark your present position:

1. Press the Mkey to capture your position.

The mark position page will appear, showing the
captured position and a default 3-digit waypoint name.

To change the default position name:

1. Press the Dkey once to move the field highlight
from the ‘SAVE?’ field to the name field.

2. Press
of the name.

3. Use the arrow keypad to enter the name.

to clear any existing data and begin entry

F

REFERENCE

Marking &

Saving

Waypoints

The GPS 125 Sounder will
automatically name new
waypoints with a default
three-digit name, with the
current digital depth as the
default comment. You may
then highlight either field,
press ENTER, and enter
your own name or
comment.

4. Press
highlight will move to the “comment” field.

If you’d like to add this waypoint to a route:

1. Press Donce to highlight the route field and press
the

2. Use the
and press

3. Press the

If you do not want to add this waypoint to a

route:

1. Highlight the ‘SAVE?’ field and press the Fkey.

to confirm the waypoint name. The field

F

key.

F

or Dkeys to enter a route number

U

.

F

key again to save the waypoint.

F

To add a waypoint to a
route as you are marking its
position, enter the desired
route number, highlight
‘SAVE?’ and press ENTER.

21

REFERENCE

Nearest

Waypoints Page

Waypoint Submenus

The GPS 125 Sounder has three waypoint submenu
pages that let you manage a large number of waypoints
quickly and efficiently. The nearest waypoints, waypoint
list and waypoint definition pages are accessed through
the Menu Page.

To select a waypoint submenu page:

1. Press Jor Quntil the Menu Page appears.

To select a waypoint sub­menu, highlight the desired
option and press ENTER.

The compass heading
(BRG) and distance (DST)
to the nine nearest way­points are updated continu­ously.

2. Use the
submenu page you want to use.

3. Press

4. To return to the Menu Page, press the

and Dkeys to highlight the waypoint

U

to display the submenu page.

F

J

key.

Nearest Waypoints Page

The nearest waypoints page shows the nine nearest
waypoints that are within 100 miles of your present
position, with the bearing and range noted for each
waypoint. During an emergency, the nearest waypoints
page can give you the closest points of safety in your
area at a glance.

The nearest waypoints page will also let you retrieve
a waypoint definition page or go to a selected waypoint
right from the list.

To review the waypoint definition page of a high­lighted waypoint from the list:

1. Press the Fkey.

To return to the nearest waypoint page (when the
‘DONE?’ field is highlighted):

1. Press the Fkey.

To go to a highlighted list waypoint:

1. Use the Uand Dkeys to highlight a listed way­point.

22

2. To select a highlighted nearest waypoint as a destina­tion, press the

3. Once the GOTO waypoint page appears, press the

key to confirm the selected waypoint as your

F

destination.

G

key.