Garmin GPS 48 User Manual

The Garmin GPS 48 is a rugged, waterproof handheld GPS receiver designed for marine, aviation, and outdoor navigation. It features a 12-parallel-channel GPS receiver for fast satellite acquisition, a high-contrast LCD display, NMEA 0183 interface for connecting to autopilots and chartplotters, built-in worldwide basemap, waypoint and route storage, track log recording, and a backlit keypad for low-light operation. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

1. Features at a Glance 2. Installation 3. First-Time Setup 4. Specifications 5. Controls and Settings 6. Connecting Devices 7. Navigation Functions 8. Advanced Features 9. Care & Cleaning 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: Waterproof housing (IPX7), 12-channel GPS receiver, LCD display with backlight, NMEA 0183 data port, external antenna connector, and ruggedized keypad.

Feature	Description
GPS Receiver	12 parallel channels for fast acquisition and tracking
Display	High-contrast LCD, 4-level adjustable backlight
Waterproof Rating	IPX7 (submersible to 1 meter for 30 minutes)
NMEA 0183 Interface	For connection to autopilots, chartplotters, and PCs
External Antenna Port	For optional external GPS antenna
Waypoint Storage	Up to 500 user-defined waypoints
Route Storage	Up to 20 reversible routes with 50 waypoints each
Track Log	Automatic track recording with 10 saved tracks
Power Source	4 AA batteries or external 10-40V DC input
Built-in Basemap	Worldwide cities, coastlines, and political boundaries

Installation

Unpack and inspect contents. Ensure all components are present.

Install Batteries: Open battery compartment, insert 4 AA batteries observing polarity.
Mounting: Use optional mounting bracket for permanent installation on boat or vehicle.
External Antenna: Connect optional external antenna to antenna port for improved reception.
External Power: Connect to 10-40V DC source using optional power/data cable.

WARNING! Ensure unit is powered off before connecting/disconnecting cables. Use proper marine-grade wiring for permanent installations.

First-Time Setup

Power on unit; follow initialization procedure.

Initial Satellite Acquisition: Place unit outdoors with clear sky view. Allow 2-15 minutes for first fix.
Set Language: Press MENU > Setup > System > Language to select preferred language.
Set Units: Press MENU > Setup > Units to select nautical, statute, or metric units.
Set Time: Press MENU > Setup > Time to set time format and time zone.
Calibrate Compass (if equipped): Follow on-screen prompts for electronic compass calibration.

CAUTION! Initial satellite acquisition requires clear view of sky. Avoid obstructions like buildings or heavy foliage.

Specifications

GPS Receiver: 12 parallel channels, WAAS capable.
Update Rate: 1 second continuous.
Accuracy: Position: <15 meters RMS, Velocity: 0.1 knot RMS.
Acquisition Time: Hot start: 15 seconds, Warm start: 45 seconds, Cold start: 2 minutes.
Display: 4.2 x 2.1 inch LCD, 100 x 160 pixels, FSTN with LED backlight.
Interface: NMEA 0183 version 2.0, RTCM 104 differential input.
Power: 4 AA batteries (alkaline or NiMH), 10-40V DC external input.
Battery Life: Up to 20 hours (alkaline, backlight off).
Waterproof: IPX7 standard (1 meter for 30 minutes).
Operating Temperature: -15°C to 70°C (5°F to 158°F).
Dimensions: 6.4" H x 2.7" W x 1.4" D (162 x 69 x 36 mm).
Weight: 9.5 oz (269 g) with batteries.

Controls and Settings

Access functions via front panel keys and menu system.

Front Panel Keys: POWER, PAGE (cycles display pages), ENTER/MARK (marks waypoints), GOTO (navigates to waypoint), MOB (Man Overboard function), IN/OUT (zooms display), UP/DOWN arrows (scrolls menus).

Menu Functions: Press MENU to access: Waypoint Manager, Route Planner, Track Log, Setup (System, Units, Time, Alarms, Interface), System Info.

Display Pages: Satellite Status, Position (Lat/Lon), Map, Highway (navigation), Pointer (compass rose).

Setup Options: Language, Units (nautical/statute/metric), Time (12/24 hr, time zone), Alarms (anchor drag, arrival, off-course), Interface (NMEA baud rate, data output).

Connecting Devices

NMEA 0183 Interface: Connect to autopilots, chartplotters, or PCs using optional data cable.

Power off all devices before making connections.
Connect data cable to GPS 48's data port.
Connect NMEA OUT wires to other device's NMEA IN.
Connect NMEA IN wires to other device's NMEA OUT (if needed).
Set correct baud rate in Interface setup menu (4800 baud typical).

Tip: Refer to your chartplotter or autopilot manual for specific NMEA wiring requirements.

Navigation Functions

Basic navigation operations for waypoints, routes, and tracks.

Mark Waypoint: Press ENTER/MARK at current location. Edit name/symbol if desired.
Go To Waypoint: Press GOTO, select waypoint from list or enter waypoint identifier.
Create Route: MENU > Route Planner > New Route. Add waypoints in sequence.
Follow Route: Select route from list, press NAVIGATE.
Track Log: MENU > Track Log to clear, save, or view track history.
Man Overboard: Press MOB to immediately mark current position and navigate back.
Sun/Moon Info: Access celestial data for fishing/hunting times.

WARNING! GPS is an aid to navigation. Always use traditional navigation methods as primary. GPS signals may be interrupted or inaccurate.

Advanced Features

Differential GPS (DGPS): Connect to external DGPS beacon receiver via NMEA interface for improved accuracy (2-5 meters). Interface Setup: Configure NMEA sentences output for specific chartplotter compatibility. Alarms: Set anchor drag, arrival, off-course, and clock alarms.

Care & Cleaning

Use mild soap and water with soft cloth to clean exterior. Rinse with fresh water after saltwater use. Do not use harsh chemicals or abrasives.

CAUTION! Ensure battery compartment seal is clean and properly seated before exposure to water. Do not open unit; no user-serviceable parts inside.

Regulatory Information

FCC Part 15: Class B digital device; complies with interference limits. This device complies with part 15 of the FCC Rules. Operation is subject to the condition that this device does not cause harmful interference. Copyright © Garmin Ltd. or its subsidiaries. Garmin and the Garmin logo are trademarks of Garmin Ltd. or its subsidiaries. For support, visit www.garmin.com or contact Garmin Product Support.

Troubleshooting

Symptom	Possible Cause	Corrective Action
No power	Dead batteries, poor connection	Replace batteries; check battery contacts; verify external power connection.
No satellite reception	Obstructed view, unit indoors	Move to open area with clear sky view; ensure external antenna connected properly.
Inaccurate position	Poor satellite geometry, multipath	Wait for better satellite geometry; move away from reflective surfaces.
No NMEA data output	Wrong baud rate, cable fault	Check Interface settings (4800 baud typical); verify cable connections.
Display difficult to read	Low contrast, backlight off	Adjust contrast in Setup menu; turn on backlight (POWER + IN).
Waypoint not saved	Memory full, user error	Delete unused waypoints; ensure ENTER pressed long enough to confirm.

Reset: Press and hold PAGE + POWER during power-on to reset to factory defaults (erases all user data).

Service: Contact Garmin Product Support or authorized service center. Do not attempt to repair unit yourself.