Lowrance LMS-520C User manual

Pub. 988-0151-461
www.lowrance.com
LMS-520C & LMS-525C DF
Fish-finding Sonar & Mapping GPS
Installation and Operation
Instructions

Copyright © 2006 Lowrance Electronics, Inc.
All rights reserved.
No part of this manual may be copied, reproduced, republished, trans-
mitted or distributed for any purpose, without prior written consent of
Lowrance. Any unauthorized commercial distribution of this
manual is strictly prohibited.
Lowrance®is a registered trademark of Lowrance Electronics, Inc.
MapCreate™, FreedomMaps™and NauticPath™are trademarks of
LEI. Fishing Hot Spots®is a registered trademark of Fishing Hot Spots
Inc. LakeMaster®and Pro Maps are trademarks or registered trade-
marks of WayPoint Technologies, Inc. Navionics®is a registered
trademark of Navionics, Inc. DURACELL®is a registered trademark of
Duracell, Inc. RAYOVAC®is a registered trademark of Rayovac Corpo-
ration. Energizer®and e2®are registered trademarks of Energizer Hold-
ings, Inc.
Points of Interest Data in this unit are by infoUSA,
copyright ©2001-2006, All Rights Reserved. infoUSA is a
trademark of infoUSA, Inc.
Lowrance Electronics may find it necessary to change or end our poli-
cies, regulations and special offers at any time. We reserve the right to
do so without notice. All features and specifications subject to change
without notice. All screens in this manual are simulated. On the cover:
LMS-525CDF.
For free owner's manuals and the most current information on
this product, its operation and accessories,
visit our web site:
www.lowrance.com
Lowrance Electronics Inc.
12000 E. Skelly Dr.
Tulsa, OK USA 74128-2486
Printed in USA.

i
Table of Contents
Section 1: Read Me First! ......................................................... 1
Specifications: LMS-520c and LMS-525cDF.......................... 3
How to use this manual: typographical conventions ................ 10
Section 2: Installation............................................................. 13
Preparations ................................................................................ 13
Transducer Installation .............................................................. 13
Single-frequency transom installations ............................. 14
Dual-frequency transom installations ............................... 14
Single-frequency trolling motor installations ................... 14
Shoot-through hull installations ........................................ 14
Selecting a Transducer Location ............................................ 14
How low should you go? .......................................................... 16
Shoot-thru-hull vs. Transom Mounting ................................. 16
Transom Transducer Assembly And Mounting .................... 17
Trolling Motor Bracket Installation (single-frequency only) 23
Transducer Orientation and Fish Arches.............................. 23
Shoot-Thru-Hull Preparation ................................................. 24
Hulls with Flotation Materials........................................... 24
Testing Determines Best Location......................................... 25
Shoot-thru-hull Installation ................................................... 27
Speed/Temperature Sensors ................................................. 28
Optional Speed Sensor Installation ....................................... 28
Power Connections ...................................................................... 30
Powering Your Display Unit ...................................................... 31
Power Diagram A ........................................................................ 32
Power Diagram B ........................................................................ 33
Powering a NMEA 2000 Network Bus ...................................... 33
GPS Antenna/Receiver Module .................................................. 34
Connecting to a NMEA 2000 Network ...................................... 35
NMEA 0183 Wiring (Data cable) ........................................... 36
Mounting the Unit: Bracket, In-Dash or Portable.................... 39
MMC or SD Card Memory Card Installation............................ 42
Other Accessories ........................................................................ 44
Cleaning Towel ........................................................................ 44
Face Cover ................................................................................... 45
Section 3: Basic Sonar Operation ........................................ 47
Keyboard ...................................................................................... 47
Power/lights on and off ............................................................... 48
Main Menu................................................................................... 48
Pages ............................................................................................ 50
Satellite Status Page............................................................... 50
Navigation Page ...................................................................... 51

ii
Map Page ................................................................................. 51
Sonar Page ............................................................................... 52
Basic Sonar Quick Reference ............................................... 55
Sonar Operations ........................................................................ 56
Fish Symbols vs. Full Sonar Chart ........................................ 58
Section 4: Sonar Options........................................................ 61
ASP™(Advanced Signal Processing) ......................................... 61
Alarms.......................................................................................... 62
Depth Alarms .......................................................................... 62
Zone Alarm .............................................................................. 63
Fish Alarm ............................................................................... 64
GPS Alarms ............................................................................. 65
NMEA 2000 Alarms .................................................................... 66
Calibrate Speed ........................................................................... 67
Chart Speed ................................................................................. 68
Colorline™................................................................................... 69
Depth Cursor ............................................................................... 70
Depth Range - Automatic ........................................................... 71
Depth Range - Manual................................................................ 71
Depth Range - Upper and Lower Limits ................................... 72
FasTrack™................................................................................... 73
Fish I.D.™(Fish Symbols & Depths) ......................................... 74
FishTrack™.................................................................................. 76
Frequency (Change Transducer Frequency) ............................. 76
HyperScroll™............................................................................... 77
Log Sonar Chart Data................................................................. 78
Noise Rejection ............................................................................ 79
Overlay Data ............................................................................... 79
Ping Speed & HyperScroll™....................................................... 82
Reset Options............................................................................... 83
Reset Water Distance.................................................................. 84
Set Keel Offset............................................................................. 84
Sensitivity & Auto Sensitivity.................................................... 85
Automatic Sensitivity ............................................................. 86
Sonar Chart Mode ....................................................................... 87
Sonar Page & Sonar Chart Display Options ............................. 88
Full Sonar Chart ..................................................................... 88
Split Zoom Sonar Chart .......................................................... 89
Split Frequency Sonar Chart (LMS-525cDF only)................ 89
Digital Data/Chart .................................................................. 90
Customize Page Displays........................................................ 90
Flasher ..................................................................................... 92
Sonar with Custom Gauges ........................................................ 92

iii
Map with Sonar Split Screen.................................................. 94
Sonar Simulator .......................................................................... 95
Stop Chart.................................................................................... 97
Surface Clarity ............................................................................ 98
Transparency............................................................................... 99
Upper and Lower Limits........................................................... 100
Zoom & Zoom Bar...................................................................... 100
Zoom Pan ................................................................................... 100
Section 5: Sonar Troubleshooting ..................................... 101
Section 6: Basic GPS Operations ....................................... 105
Keyboard.................................................................................... 105
Power/lights on and off ............................................................. 106
Main Menu................................................................................. 106
Pages .......................................................................................... 108
Sonar Page ............................................................................. 108
Satellite Status Page............................................................. 108
Navigation Page .................................................................... 110
Map Page ............................................................................... 113
Map with Sonar ..................................................................... 117
Map with Custom Gauges..................................................... 118
Radar.......................................................................................... 119
Basic GPS Quick Reference ................................................ 121
Find Your Current Position...................................................... 122
Moving Around the Map: Zoom & Cursor Arrow Keys........... 122
Selecting Any Map Item with the Cursor................................ 123
Searching ................................................................................... 123
Set a Waypoint .......................................................................... 125
Navigate To a Waypoint ........................................................... 127
Set Man Overboard (MOB) Waypoint...................................... 127
Navigate Back to MOB Waypoint ............................................ 128
Navigate to Cursor Position on Map........................................ 128
Navigate to a Point of Interest ................................................. 130
Creating and Saving a Trail ..................................................... 130
Displaying a Saved Trail .......................................................... 132
Navigating Trails ...................................................................... 133
Visual Trailing....................................................................... 133
Navigate a Trail .................................................................... 133
Navigate a Back Trail (backtrack) ....................................... 135
Transfer Custom Maps and GPS Data Files ........................... 136
Cancel Navigation ..................................................................... 138
Section 7: Advanced GPS Operations.............................. 139
Find Distance from different Locations................................... 139
Find Distance from Point to Point ........................................... 139

iv
Icons ........................................................................................... 140
Create Icon on Map ............................................................... 140
Create Icon at Current Position ........................................... 140
Delete an Icon ........................................................................ 140
Navigate to an Icon ............................................................... 141
Routes ........................................................................................ 141
Create and Save a Route ...................................................... 142
Delete a Route ....................................................................... 144
Edit a Route Name ................................................................ 145
Edit Route Waypoints ........................................................... 145
Navigate a Route ................................................................... 146
Navigate a Route in Reverse ................................................ 146
Trails .......................................................................................... 147
Delete a Trail ......................................................................... 147
Edit a Trail Name ................................................................. 148
Edit a Trail Color .................................................................. 148
Edit a Trail Pattern............................................................... 148
Utilities ...................................................................................... 149
Alarm Clock ........................................................................... 149
Sun/Moon Rise & Set Calculator.......................................... 149
Trip Calculator ...................................................................... 149
Trip Down Timer ................................................................... 149
Trip Up Timer........................................................................ 149
Waypoints .................................................................................. 149
Edit a Waypoint..................................................................... 150
Selecting a Waypoint ............................................................ 150
Create Waypoint by Entering a Position ......................... 151
Set a Waypoint by Average Position.................................... 152
Set a Waypoint by Projecting a Position.............................. 152
Section 8: System & GPS Setup Options .......................... 153
Alarms........................................................................................ 153
Auto Satellite Search ................................................................ 154
Check MMC Files and Storage Space...................................... 155
Communications Port Configuration ....................................... 155
Configure NMEA....................................................................... 156
Coordinate System Selection.................................................... 156
Map Fix ...................................................................................... 158
Customize Page Displays.......................................................... 159
GPS Simulator........................................................................... 160
Hide GPS Feature ..................................................................... 162
Initialize GPS ............................................................................ 162
Map Auto Zoom ......................................................................... 163
Map Data ................................................................................... 163

v
Map Datum Selection................................................................ 165
Map Detail Category Selection................................................. 166
Map Orientation........................................................................ 166
NauticPath™USA Marine Charts........................................... 168
Nautical Chart Notes ............................................................ 168
Port Information.................................................................... 169
Tidal Current Information.................................................... 170
Tide Information ................................................................... 172
Navionics®Charts ..................................................................... 173
Overlay Data ............................................................................. 174
Pop-up Help ............................................................................... 178
Reset Options............................................................................. 179
Screen Contrast and Brightness .............................................. 180
Set Language ............................................................................. 181
Set Local Time ........................................................................... 181
Show WAAS Alarm ................................................................... 182
Software Version Information .................................................. 183
Sounds and Alarm Sound Styles .............................................. 184
Track Smoothing ....................................................................... 185
Trail Options.............................................................................. 185
Update Trail Option.............................................................. 186
Trail Visible/Invisible and Other Trail Options.................. 188
Transparency............................................................................. 188
Units of Measure ....................................................................... 189
Section 9: Searching.............................................................. 193
Find Streets ............................................................................... 194
Find Any Item Selected by Map Cursor .................................. 195
Find Interstate Highway Exits ................................................ 195
Find Map Places or Points of Interest (POI) ........................... 198
Find Streets or Intersections.................................................... 200
Find Waypoints ......................................................................... 203
Section 10: NMEA 2000 Device Configuration................ 207
NMEA 2000 Menu..................................................................... 207
Bus Setup................................................................................... 207
Engine & Tank Configuration.................................................. 208
Tank Select ........................................................................ 209
Tank Size ........................................................................... 209
Set Configuration button .................................................. 209
Device Configuration Menu.................................................. 210
Device Information and Device Data ................................... 210
Fuel Management Menu........................................................... 211
Tank Location .................................................................... 211
Fuel Added ......................................................................... 211

vi
Add Fuel............................................................................. 212
Fill Tank............................................................................. 212
Adding Fuel to Tank ............................................................. 212
Engine Operations................................................................. 212
Engine Select ..................................................................... 212
NMEA 2000 Alarms .................................................................. 213
Waypoint Sharing ..................................................................... 214
Backlight Synchronization ....................................................... 214
Configuring EP Sensors............................................................ 215
EP-35 Temperature Configuration ...................................... 215
Advanced Options menu ....................................................... 216
Instance.............................................................................. 216
Restore Defaults ................................................................ 216
EP-10 Fuel Flow Configuration............................................ 216
Advanced Options menu ....................................................... 217
Instance.............................................................................. 217
Restore Defaults ................................................................ 217
To restore default settings: ............................................... 218
EP-15 Fluid Level Configuration ......................................... 218
Advanced Options menu ....................................................... 220
Instance.............................................................................. 220
Restore Defaults ................................................................ 220
Suzuki Engine Interface Configuration............................... 221
Advanced Options menu ....................................................... 222
Instance.............................................................................. 222
Restore Defaults ................................................................ 222
Calibrating EP Sensors............................................................. 223
EP-10 Fuel Flow Calibration................................................ 223
EP-15 Fluid Level Calibration ............................................. 224
2-Point Calibration............................................................ 224
3-Point Calibration............................................................ 225
5-Point Calibration............................................................ 226
Fuel Flow Calibration in a Suzuki Engine Interface.......... 227
Engine Trim Calibration....................................................... 228
Reset Trim Calibration ......................................................... 229
Bennett Trim Tabs Calibration ............................................ 229
Section 11: Supplemental Material ................................... 231

vii
NOTICE!
The storage and operation temperature range for your unit is from -20
degrees to +167 degrees Fahrenheit (-28 degrees to +75 degrees Cel-
sius). Extended storage or operation in temperatures higher or lower
than specified will damage the liquid crystal display in your unit. This
type of damage is not covered by the warranty. For more information,
contact the factory's Customer Service Department; phone numbers are
listed on the last page of the manual.
WARNING!
A CAREFUL NAVIGATOR NEVER RELIES ON ONLY ONE METHOD
TO OBTAIN POSITION INFORMATION.
CAUTION
When showing navigation data to a position (waypoint), a GPS unit will show
the shortest, most direct path to the waypoint. It provides navigation data to the
waypoint regardless of obstructions. Therefore, the prudent navigator will not
only take advantage of all available navigation tools when traveling to a way-
point, but will also visually check to make sure a clear, safe path to the waypoint
is always available.
WARNING!
When a GPS unit is used in a vehicle, the vehicle operator is solely re-
sponsible for operating the vehicle in a safe manner. Vehicle operators
must maintain full surveillance of all pertinent driving, boating or flying
conditions at all times. An accident or collision resulting in damage to
property, personal injury or death could occur if the operator of a GPS-
equipped vehicle fails to pay full attention to travel conditions and vehi-
cle operation while the vehicle is in motion.

viii
Notes

1
Section 1: Read Me First!
How this manual can get you out on the road, fast!
Welcome to the exciting world of digital sonar and GPS! We know
you're anxious to begin navigating and finding fish, but we have a favor
to ask. Before you grab the unit and begin installing it, please give us a
moment or two to explain how our manual can help you get the best
performance from your compact, wide-screen, combination fish finder
and mapping GPS receiver.
First, we want to thank you for buying a Lowrance sonar/GPS unit.
Whether you're a first time user or a professional fisherman, you'll dis-
cover that your unit is easy to use, yet capable of handling demanding
navigation and sonar tasks. When you team your unit with our custom
mapping software MapCreate™, you have an incredible combination.
You won't find another combination GPS and sonar unit with this
much power and this many features for this price!
Our goal for this book is to get you on the water fast, with a minimum
of fuss. Like you, we'd rather spend more time boating or fishing and
less time reading the manual!
So, we designed our book so that you don't have to read the whole thing
from front to back for the information you want. At the start (or end) of
each segment, we'll tell you what content is coming up next. If it's a
concept you're already familiar with, we'll show you how and where to
skip ahead for the next important topic. We've also made it easy to look
up any tips you may need from time to time. Here's how:
The manual is organized into 10 sections. This first section is an intro-
duction to the LMS-520c and LMS-525cDF, sonar and GPS. It tells you
the basics you need to know before you can make the unit look around
and tell you where you are, or look below the surface to find some fish.
Section 2 will help you install your unit, the transducer and the GPS
antenna module. We'll show you how to get the MultiMedia Card
(MMC) correctly installed inside the unit. We'll also tell you about some
of the available accessories.
Section 3 covers Basic Sonar Operation. It will show you how easy it is
to run your sonar, right out of the box. This section features a one-page
Sonar Quick Reference. (If you've already jumped ahead and fig-
ured out how to install the unit yourself, and you just can't wait
any longer, turn to the Quick Reference on page 55 and head
for the water!)

2
After you've gained some experience with your sonar, you'll want to
check out Section 4, which discusses more advanced Sonar Options and
Other Features.
When you come to a sonar menu command on your unit’s screen, you can
look it up in the manual by skimming over the table of contents, just flip-
ping through Section 3 or scanning through the sonar options in Section 4.
If you're having difficulty with your sonar, you can find an answer to
the most common problems in Section 5, Sonar Troubleshooting.
The manual switches from sonar to navigation in Section 6, which in-
troduces you to Basic GPS Operations. This section features a one-
page GPS Quick Reference on page 121.
Section 6 contains short, easy-to-scan GPS lessons that follow one an-
other in chronological order. They're all you'll need to know to find your
way on the water quickly.
After you've learned the basics (or if you already have some GPS ex-
perience), you may want to try out some of the unit’s many advanced
navigation features. That brings us to Section 7, Advanced GPS Opera-
tions. This section contains the rest of your unit’s GPS command func-
tions, organized in alphabetical order.
When you come to a GPS menu command on the screen, you can look it
up in the manual by skimming over the table of contents, just flipping
through Section 6 or scanning through the command portion of Section
7.
Your unit is ready to use right out of the box, but you can fine tune and
customize it's operation with dozens of options. Since sonar is the unit's
key feature, we put the main sonar options in Section 4. Some options,
such as screen brightness settings, affect both sonar and GPS opera-
tions. We describe how to use those common options along with GPS
options in Section 8, System Setup and GPS Setup Options. Section 8 is
organized in alphabetical order.
In Section 9, we go into more detail on one of the unit’s most remarkable
GPS capabilities — Searching. We'll introduce a search example in the
Basic GPS Operation section, but there are so many map items you can
search for, we had to give this function it's own section in the manual! For
example, did you know your unit can look up business phone numbers,
functioning as a virtual Yellow Pages? We’ll show you how in Section 9.
Finally, in Section 10, we offer Supplemental Material, including a list
of the GPS datums used, warranties and customer service information.

3
Specifications: LMS-520c and LMS-525cDF
General
Display: ............................5.0" (12.7 cm) diagonal high contrast color
Film SuperTwist LCD; programmable to
viewing preference.
Resolution: ......................480 pixel x 480 pixel resolution; 230,400 to-
tal pixels.
Backlighting: ..................Incandescent backlit screen with multiple
lighting levels; backlit keypad.
Input power: ...................10 to 15 volts DC.
Case size: .........................5.4" H x 6.9" W x 3.4" D (13.8 x 17.6 x 8.6
cm); sealed and waterproof; suitable for salt-
water use.
MMC slots:.......................One with waterproof door (SD card compati-
ble).
Recording: ........................ GPS uses MMC & SD cards for recording trip
details and displaying charts or custom maps.
Sonar uses them to record and save sonar
chart logs.
Back-up memory:...........Built-in memory stores sonar records and
GPS data for decades. User settings are
stored when unit is turned off.
Languages: ......................10; menu languages selectable by user.
Sonar
Frequency: ......................LMS-525cDF: 50/200 kHz.
LMS-520c: 200 kHz.
Transducers: .....................A dual-frequency Skimmer®transducer with
built-in temperature sensor is packed with the
LMS-525cDF. It has 35°/12°cone angles. A
single-frequency Skimmer transducer with
built-in temperature sensor is packed with the
LMS-520c. It has a 20°cone angle. Transduc-
ers operate at speeds up to 70 mph (61 kts).
Transmitter:....................3,000 watts peak-to-peak/375 watts RMS.

4
Sonar sounding
depth capability:............LMS-525cDF: 2,500 feet/762 meters.
LMS-520c: 1,000 feet/305 meters.
(Actual capability depends on transducer
configuration and installation, bottom com-
position and water conditions. All sonar
units typically read deeper in fresh water
than in salt water.)
Depth display: ................Continuous display.
Graph recording: ...........Up to 1 GB on one MMC (or SD) card
Audible alarms:..............Deep/shallow/fish/zone.
Automatic ranging: .......Yes, with instant screen updates.
Auto bottom track: ........Yes
Zoom bottom track:.......Yes.
Split-screen zoom: .........Yes.
Surface water temp: .....Yes, built into transducer.
Speed/distance log: .......Yes, with optional speed sensor (sensor in-
cluded with LMS-525cDF.)
GPS
Receiver/antenna:............External; LGC-2000 12 parallel channel
NMEA 2000-ready GPS/WAAS re-
ceiver/antenna.
Background map: ..........Built-in custom, detailed Lowrance map.
Contains: enhanced detail of continental U.S.
and Hawaii. Includes more than 60,000 nav
aids and 10,000 wrecks/obstructions in
coastal and Great Lakes waters. Metro ar-
eas, selected major streets/highways and in-
terstate exit services details included.
Custom mapping:...........MapCreate™software optional; optional plug
and play LEI FreedomMaps™offer the same
high-detail without the computer work of
MapCreate. Other plug and play mapping
options include IMS™Fishing Hot Spots®,
LEI NauticPaths™charts and Navionics®
charts.

5
Mapping memory: ...........Up to 1 GB on one MMC (or SD) card.
Position updates:...........Every second.
Position points: ..............1,000 waypoints; 1,000 event marker icons.
Audible alarms:..............Arrival/off-course/anchor.
Graphic symbols for
waypoints or event
marker icons:..................63.
Routes: .............................100; up to 100 waypoints per route.
Plot Trails:.......................10 savable; up to 9,999 points per trail.
Zoom range: ....................39 ranges; 0.02 to 4,000 miles.
NOTE:
The above memory capacities refer only the unit’s on-board memory.
The amount of GPS or sonar data you can record and save for recall
later is only limited by the number of MMC cards you have.
How Lowrance Sonar Works
Sonar has been around since the 1940s, so if you already know how it
works, skip down to read about the relatively new technology of GPS.
But, if you've never owned a sonar fish finder, this segment will tell you
the under water basics.
Sonar is an abbreviation for SOund NAvigation and Ranging, a technol-
ogy developed during World War II for tracking enemy submarines.
(Lowrance developed the world's first transistorized sportfishing sonar in
1957.) A sonar consists of a transmitter, transducer, receiver and dis-
play. In simple terms, here's how it finds the bottom, or the fish:
The transmitter emits an electrical impulse, which the transducer con-
verts into a sound wave and sends into the water. (The sound frequency
can't be heard by humans or fish.) The sound wave strikes an object
(fish, structure, bottom) and bounces back to the transducer, which
converts the sound back into an electrical signal.
The receiver amplifies this return signal, or echo, and sends it to the
display, where an image of the object appears on the scrolling sonar
chart. The sonar's microprocessor calculates the time lapse between the
transmitted signal and echo return to determine the distance to the
object. The whole process repeats itself several times each second.
Your unit can record a log of the sonar signals that scroll across the
screen and save them to the MMC memory card. (These recordings are

6
also called sonar charts or sonar graphs.) You can replay this sonar log
in the unit using the Sonar Simulator function, or play it back on a per-
sonal computer using our free Sonar Viewer. The viewer is available for
download from the Lowrance web site, www.lowrance.com.
You can save several different sonar log files, erase 'em and record new
ones, over and over again. The size of your sonar recordings is only lim-
ited by the free space available on your MMC.
How Lowrance GPS Works
You'll navigate faster and easier if you understand how your unit scans
the sky to tell you where you are on the earth — and, where you're go-
ing. First, think of your unit as a small but powerful computer. (But
don't worry — we made the unit easy to use, so you don't need to be a
computer expert to find your way!) It includes a keypad and a screen
with menus so you can tell it what to do. The screen also lets the unit
show your location on a moving map, as well as point the way to your
destination.
This gimbal-mounted unit uses an external antenna/receiver module,
which makes the whole system work something like your car radio. But
instead of your favorite dance tunes, this receiver tunes in to a couple
of dozen GPS satellites circling the earth. (It will also listen in to the
WAAS satellites in orbit, but more about that in the upcoming segment
introducing you to GPS and WAAS.)
Your unit listens to signals from as many satellites as it can "see"
above the horizon, eliminates the weakest signals, then computes its
location in relation to those satellites. Once the unit figures its latitude
and longitude, it plots that position on the moving map shown on the
screen. The whole process takes place several times a second!
The performance doesn't stop there. Stored in the permanent memory
of each unit is a basic background map of the entire world. We lock it in
here at the factory — you can't change or erase this map.
The background map is suitable for many navigation chores, but for
maximum accuracy and much more detail, you need our optional map-
making software, MapCreate™. Some unit features — such as search-
ing for businesses and addresses — won't work without a custom Map-
Create map.
There is so much detail in our background map (and even more in
MapCreate) that we'll describe their contents and differences in Section
6, Basic GPS Operations, on page 105.
Another portion of the unit’s onboard memory is devoted to recording
GPS navigation information, which includes waypoints, event marker

7
icons, trails and routes. This lets you look back the way you came.
Think of this data storage like the hard drive memory in a computer or
a tape in a cassette tape recorder. You can save several different GPS
data files, erase 'em and record new ones, over and over again. These
GPS Data Files (file format *.usr) can be shared between, not only the
LMS-520c and LMS-525cDF, but other Lowrance GPS units and even
personal computers.
Your unit has one more thing in common with a personal computer.
Just as computers have a floppy disk drive for storing and exchanging
files, the unit has a slot for an MMC (MultiMedia Card) or SDC (Secure
Digital card) flash memory card. These solid-state memory devices are
about the size of a postage stamp, but can hold data ranging from 8 MB
to 1 GB. (Compare that to a floppy disk's 1.44 MB capacity!) Your unit
uses all that MMC space for two key GPS purposes. (The MMC is also
used to record sonar logs.)
First, you can backup your onboard GPS Data Files by copying them to
the MMC. Since the MMC is removable (like a floppy disk or a cassette
tape), you can store these GPS Data Files on a personal computer
equipped with an MMC card reader. (Or store them on a pocketful of
MMCs, if you don't have a computer.) Our MapCreate mapping software
can save, edit or create its own GPS Data Files, which can be copied to
the MMC and then loaded from the MMC into unit’s memory. (NOTE:
No matter where they come from, GPS Data Files must be loaded from
the MMC into memory before your unit can use them.)
The other key GPS use for MMCs is storage of special high-detail, cus-
tom maps, which you can produce on your computer with our MapCre-
ate software. These MapCreate custom maps contain much greater de-
tail than the basic background map. These Custom Map Files (file
format *.lcm) not only may be shared between the LMS-520c and
525cDF, but also with other Lowrance GPS and sonar/GPS units as
well as personal computers. (For example, the exact same MMC, cus-
tom map files and GPS data files can be used interchangeably between
your gimbal-mounted unit and the hand-held iFINDER™GPS re-
ceiver.)
Your unit automatically reads Custom Map Files directly from the
MMC or SDC. To use a custom map, all you need to do is slide an MMC
containing a map into the unit.
Introduction to GPS and WAAS
Well, now you know the basics of how your unit does its work. You
might be ready to jump ahead to Section 2, Installation & Accessories,

8
on page 13, so you can mount your unit and plug in the power. Or you
might want to see how our text formatting makes the manual tutorials
easy to skim. If that's the case, move on to "How to Use This Manual"
on page 10. But, if you want to understand the current state of satellite
navigation, look over this segment describing how GPS and its new
companion WAAS work together to get you where you're going.
The Global Positioning System (GPS) was launched July 17, 1995 by
the United States Department of Defense. It was designed as a 24-
hour-a-day, 365-days-a-year, all weather global navigation system for
the armed forces of the U.S. and its allies. Civilian use was also avail-
able at first, but it was less accurate because the military scrambled
the signal somewhat, using a process called Selective Availability (SA.)
GPS proved so useful for civilian navigation that the federal govern-
ment discontinued SA on May 2, 2000, after the military developed
other methods to deny GPS service to enemy forces. Reliable accuracy
for civilian users jumped from 100 meters (330 feet) under SA to the
present level of 10 to 20 meters (about 30 to 60 feet.)
Twenty-four satellites orbit 10,900 nautical miles above the Earth, pass-
ing overhead twice daily. A series of ground stations (with precisely sur-
veyed locations) controls the satellites and monitors their exact locations
in the sky. Each satellite broadcasts a low-power signal that identifies
the satellite and its position above the earth. Three of these satellites are
spares, unused until needed. The rest virtually guarantee that at least
four satellites are in view nearly anywhere on Earth at all times.
A minimum of three satellites are required to determine a 2D fix.
The system requires signal reception from three satellites in order to
determine a position. This is called a 2D fix. It takes four satellites to
determine both position and elevation (your height above sea level —
also called altitude.) This is called a 3D fix.

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Remember, the unit must have a clear view of the satellites in order to
receive their signals. Unlike radio or television signals, GPS works at
very high frequencies. These signals can be easily blocked by trees,
buildings, an automobile roof, even your body.
Like most GPS receivers, the unit doesn’t have a compass or any other
navigation aid built inside. It relies solely on the signals from the satel-
lites to calculate a position. Speed, direction of travel, and distance are
all calculated from position information. Therefore, in order it to de-
termine direction of travel, you must be moving and the faster, the bet-
ter. This is not to say that it won’t work at walking or trolling speeds —
it will. There will simply be more "wandering" of the data shown on the
display.
GPS alone is plenty accurate for route navigation, but the U.S. Federal
Aviation Administration has special aircraft navigation needs that go
beyond basic GPS. So, the FAA has developed a program to boost GPS
performance with its Wide Area Augmentation System, or WAAS. The
FAA commissioned the system on July 11, 2003.
WAAS is designed to increase GPS accuracy to within 7.6 meters vertically
and horizontally, but it consistently delivers accuracies within 1-2 meters
horizontal and 2-3 meters vertical, according to the FAA. It does this by
broadcasting correction signals on GPS frequencies. Your unit automati-
cally receives both GPS and WAAS signals.
However, there are some fringe areas of the U.S., including parts of
Alaska that do not yet receive robust WAAS coverage. Continued WAAS
development is planned to extend WAAS coverage in the years to come.
WAAS boosts the accuracy of land GPS navigation, but the system is
designed for aircraft. The satellites are in a fixed orbit around the
Equator, so they appear very low in the sky to someone on the ground
in North America. Aircraft and vessels on open water can get consis-
tently good WAAS reception, but terrain, foliage or even large man-made
structures can sometimes block the WAAS signal from ground receivers.
You'll find that using your GPS receiver is both easy and amazingly
accurate. It’s easily the most accurate method of electronic navigation
available to the general public today. Remember, however, that this
receiver is only a tool. Always have another method of navigation avail-
able, such as a map or chart and a compass.
Also remember that this unit will always show navigation information
in the shortest line from your present position to a waypoint, regardless

10
of terrain! It only calculates position, it can’t know what’s between you
and your destination, for example. It’s up to you to safely navigate
around obstacles, no matter how you’re using this product.
How to use this manual: typographical conventions
Many instructions are listed as numbered steps. The keypad and arrow
"keystrokes" appear as boldface type. So, if you're in a real hurry (or
just need a reminder), you can skim the instructions and pick out what
menu command to use by finding the boldface command text. The fol-
lowing paragraphs explain how to interpret the text formatting for
those commands and other instructions:
Arrow Keys
The arrow keys control the movement of dotted cross-hair lines on your
mapping screen called the cursor. The arrow keys also control a hori-
zontal line depth cursor on the sonar screen. The arrow keys help you
move around the menus so you can execute different commands. They
are represented by symbols like these, which denote the down arrow
key, the up arrow, the left arrow and the right arrow: ↓↑←→.