Estimated Time Enroute (ETE) The time left to your destination at your present speed. Grid Coordinate system that projects the earth on a flat surface, using square zones for position measurements. UTM/UPS and Maidenhead formats are grid systems. Ground Speed (SPD) The velocity you are traveling relative to a ground position. Latitude The north/south measurement of position perpendicular to the earths polar axis. Longitude An east/west measurement of position in relation to the Prime Meridian, an imaginary circle that passes through the north and south poles. Navigation The process of traveling from one place to another and knowing where you are in relation to your desired course. Position An exact, unique location based on a geographic coordinate system. 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 the destination. Waypoint A specific location saved in the receivers memory.

Navigation Basics

The GPS 48 provides steering guidance and navigation information using degrees, a measurement measured in a clockwise direction from a north reference. North is described as 000, east as 090, south as 180, and west as 270. The diagram and compass rose below provide a graphic illustration of the navigation terms used by the GPS 48. More information on basic navigation and GPS are available at your local library or bookstore.

ACTIVE TO WAYPOINT

SP EE D

RA CK ER

ACTIVE FROM WAYPOINT

ND CR OS ST RO R

Page 5
Keypad Usage & Data Entry

B P M G E Q U D L R

Turns the unit on and off and activates screen backlighting. Scrolls through the main data pages in sequence and returns display from a submenu page to a primary page. Captures a position and displays the mark position page. Displays GOTO page with the waypoint highlighted for GOTO operation. Pressing GOTO twice activates MOB. Confirms data entry and activates highlighted fields to allow data entry. Returns display to a previous page, or restores a data fields previous value. Selects alphanumerical characters and menu choices and moves the field highlight from field to field. Moves the selected character field and moves the field highlight from field to field.

Initialization Troubleshooting If you have trouble initializing the receiver or acquiring a position, check the following:
Does the unit have a clear view of the sky?
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 or the unit is indoors.
If there are large buildings or mountains nearby, or if there is heavy tree cover, the receiver 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/lon 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.
Use the arrow keypad to highlight the country and region or state (if necessary) of your present position from the list and press ENTER. If the country is not listed, select the closest country instead.

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Primary Pages
Primary Pages Before we start the tour, lets briefly look at the five primary information pages used for the GPS 48. Switch between pages by pressing either the Q or J keys.
Satellite Page The Satellite Page shows satellite positions and signal strength. Satellite positions are displayed using two circles and a center point. The outer circle shows satellites on level with the horizon; the inner circle is 45 above the horizon; and the center point represents satellites directly overhead. Knowing satellite positions will show you the direction of any blocked signals. The bottom of the page contains a row of signal strength bars corresponding to each satellite being used. Position Page The Position Page shows you where you are, what direction youre heading and how fast youre 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.
Satellite Page The Satellite Page will allow you to monitor satellite signal reception and strength.
The graphic compass tape reflects your heading only while you are moving.

Position Page

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.

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Map Page
The Map Page acts as a window. It allows you to view your position, the path you have traveled over, and nearby navaids, cities and waypoints. A diamond icon in the center of the screen represents your current position. As you move, you will see a thin line - called a track log - appear along the path you have just covered. The GPS 48 contains a builtin marine database that displays city locations and nautical navaids on the moving map. The database is covered on pages 21-22. The bottom corners of the map will always display your current track and speed. When going to a waypoint, highlighting an on-screen waypoint, or using the panning target crosshair, the corresponding distance and bearing are shown at the top corners of the map. The top of the screen contains the zoom, pan, and configuration fields.

Each waypoint may also be assigned a custom waypoint symbol for easy waypoint recognition on the map.
To change the waypoint symbol:
1. Highlight the waypoint symbol field, and press E. 2. Select the house symbol, and press E. 3. Move the cursor to the DONE? prompt, and press E.

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Using the Position Page Walk at a brisk pace for 3-4 minutes and watch the Position Page. The direction you are moving (track), your speed, trip distance, and altitude are shown on the upper half of the screen. The latitude and longitude of your position are displayed in the middle of the page, with the time of day shown below.
Lets continue by moving to the next page:

1. Press P.

Map Page & Going to a Waypoint
Map Page The next page is the Map Page. To ensure we can see our entire trip on the map, lets change the map scale from.2nm (default) to 1.2nm.
1. Use the arrow keys to highlight the ZM field at the top left of the Map Page and press E. 2. Press the U arrow until 1nm is shown and press E. 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.
The Map Page shows your present position as a diamond icon in the center of the map. The house symbol labeled HOME is the waypoint you created and the line connecting the two is your track log.
1. Now turn approximately 90 to your right and continue walking for another 2-3 minutes. Notice how the display changes, always keeping the direction you are moving at the top of the map.
Going to a Waypoint Once youve stored a waypoint in memory, you may return to it by performing a GOTO. A GOTO is a straight-line course from your present position to the destination youve selected. Lets navigate back to our starting position, the HOME waypoint.
To select a GOTO destination:
1. Press G. 2. Highlight the HOME waypoint, and press E. The GOTO waypoint page allows you to select a destination from a list of all available waypoints in the GPS 48s memory.
Youll notice that youll automatically return to the Map Page, and a straight line will connect your current position to the position of the GOTO waypoint.

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Highway Page
Bearing to Waypoint Track Over Ground Destination Waypoint Graphic Highway Distance to Waypoint Speed Over Ground CDI Scale User Selectable Field

Clearing the Map, Contrast, & Power Off
Adjusting Screen Contrast You can access the GPS 48s contrast feature from the Satellite Page.
To adjust the screen contrast:
1. Press P or Q until the Satellite Page appears. 2. Press Lor Rto adjust the level of contrast, and press E.
Highlight the CLEAR LOG? prompt and press ENTER to clear the track log.
Screen Backlighting Three levels of screen backlighting are available for nighttime use. Activate backlighting by pressing the B key briefly. To change the level of backlighting, press the B key repeatatly until the desired level is of backlight is selected. Backlighting will remain on for the time specified on the system setup page (See page 48) or until turned off. Turning the Receiver Off Youve 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 48 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 48s more advanced features, turn to the reference section.

To turn the GPS 48 off:

1. Press and hold the B key for 3 seconds. Pressing the LEFT or RIGHT arrows from the Satellite Page will automatically activate the screen contrast bar.

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REFERENCE

Satellite Page

Status Field Battery Indicator Estimated Position Error Skyview Display Signal Strength Indicators
The GPS 48 Satellite Page will help you determine which satellites are in view, and whether or not any satellites are being shaded or blocked from receiving satellite signals (See satellite 02 above). By periodically monitoring the signal strength bars at the bottom of the page and the north up sky view, you will 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.
The GPS 48s Satellite Page displays the status of various receiver functions. The status information will help you understand what the GPS 48 is doing at any given time, and will 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 satellite sky view shows a birds-eye-view of the position of each available satellite relative to the units last known position. The outer circle represents the horizon (north up); the inner circle is 45 above the horizon; and the center point is directly overhead. You can use the sky view to help determine if any satellites are being blocked, and whether you have a current position fix (indicated by a 2D NAV or 3D NAV in the status field). You can also set the sky view to a track up configuration by changing the orientation option on the Map Page. (See pg. 24 for setup instructions.) While the receiver is looking for satellites the satellite number will be highlighted in the sky view. When the receiver locates and begins satellite reception, the satellite number will no longer be highlighted and a hollow strength indicator will be displayed at the bottom of the page. After the receiver has gathered the satellite information and can use the satellite for navigation the strength indicator bar will become solid. As soon as the GPS 48 has gathered enough satellites to calculate a position the status field will indicate a 2D or 3D fix.

The battery level indicator is calibrated for alkaline batteries. Voltage differences will display Ni-Cad and lithium batteries differently. No other receiver functions are affected.
The GPS 48 features an internal lithium battery that will maintain the units memory when the receiver is not running off batteries or external power.
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.
Backlighting Bulb Icon The GPS 48 features full-screen backlighting with three selectable levels of brightness. To activate the backlight, press the B key briefly. To increase the brightness, repeatedly press the B key. The backlight will remain on until cycled off or the backlight timeout setting has been reached (see page 48). Note: A bulb icon will appear on the Satellite Page when backlighting is turned on. Emergency Erase Function You may erase the GPS 48s memory in four quick steps. This will cause all stored data to be deleted, including: routes, waypoints, and the track log.
To erase all stored data:
1. Ensure that the GPS 48 is turned off. 2. While holding down the Mkey, hold down the B key to turn the unit on. A warning message will appear with Yes? highlighted, and ask you to confirm your selection. 3. If you do not wish to erase all stored data, select No? by pressing R and E to cancel the emergency erase. 4. If you do wish to complete the emergency erase, press E to confirm.
Upon activating the Emergency Erase Function, you will be asked to confirm your decision.

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Position Page The second page in the GPS 48s primary page sequence is the Position Page. This page shows you where you are, what direction youre heading, and how fast youre going, and its most useful when you are traveling without an active destination waypoint. The graphic heading display at the top of the page indicates the direction youre heading (while youre moving). Directly below this display are the track, speed, and trip odometer and altitude fields (default). Track is the compass direction representing your course over the ground, and speed is how fast youre moving. The center of the page shows your current latitude and longitude in degrees and minutes. The GPS 48 uses this basic information to mark exact positions as waypoints, which help guide you from one place to another. The lower center of the page is a 12- or 24-hour clock. Both the trip odometer and the altitude fields are user selectable. Both fields offer a trip odometer, trip timer, and elapsed time. The left field offers additional selections for average speed and maximum speed, the right field for altitude. The following user-selectable options are available on the Position Page: Trip Odometer (TRIP) total distance traveled since last reset. Trip Timer (TTIME) total (cumulative) time in which a ground speed has been maintained since last reset. Elapsed Time (ELPSD) hours and minutes since last reset. Average Speed (AVSPD) average speed traveled. Maximum Speed (MXSPD) maximum speed traveled since last reset. Altitude (ALT) vertical distance above sea level.

Note: A map scale represents the distance shown from the bottom to the top of the Map Page. For example, when viewing the 10 mile scale, the distance represented between the top of the screen and bottom is 10 miles.
The four corners of the Map Page are used to show your course, speed, and distance to either a cursor or to a destination waypoint.

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Marine Database
Marine Database The GPS 48 contains an updateable, marine database that displays city locations and nautical navaids on the moving map. Check the Garmin website for possible nautical navaid updates. City locations are depicted by a small square icon, cities are displayed at the zoom scale specified on the city setup menu (see page 26). The nautical navaids contained in the GPS 48 marine database include racons, radio beacons, fog horns, daybeacons (red triangles, green squares and white diamonds), lit and unlit navaids. Each navaid is represented by a symbol on the map that will help quickly identify the type of navaid. There are 10 symbols representing the different types of navaids Foghorn Racon Radio Beacon Daybeacon (red triangle) Daybeacon (green square) Daybeacon (white diamond) Lit Navaid (color indicated in symbol)
Navaid labels contain abbreviated descriptions of the navaids. To view the label, highlight the navaid or zoom in until the navaid label is visible.
City locations are displayed on the map. To configure the city locations, highlight OPT, press ENTER and select CITY SETUP.
Lit Navaid (multicolor) Unlit Navaid (color indicated in symbol) Unlit Navaid (multicolor)

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Marine Database (cont) Lit and unlit navaids are designated by the primary color. The navaid symbol will have the first letter in the primary color displayed in the symbol. Information about the navaid is contained in the navaid label. The navaid label can be activated two ways, either by reaching the label zoom scale set in navaid setup (see page 27) or by panning the map cursor to the navaid (see page 22). The navaid label contains an abbreviated description of the navaid. Lit Navaids have a description string with two required parts, type of light(s), color of light(s) and an optional third, period of light(s). There are many different light types; fixed, flashing, occulating and directional are just a few of these many types. There are 7 primary light colors portrayed in the unit; White, Red, Green, Orange, Yellow or Amber, Violet and Blue. Unlit Navaids can either have a normal worded description such as TR ON PILE, or a special designation code for the shape and color within the description string. Fog Signal labels include type of sound, whistle, bell, horn, siren or diaphone and the sound characteristic, normally blasts per time. There may be an optional field showing the duration of the blast. Radio Beacons act as short range electronic navaids. The label includes their operating frequency and possibly the Morse Code characteristics assigned to that radio beacon by the Coast Guard. Racon is an acronym for RAdar beaCON. The label identifies the racon station by a series of dashes and dots. When triggered by a radar signal the racon transmits this coded reply which will appear on the radar display.

The turn option will show you the number of degrees you need to turn to head directly to your destination.

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Using the Compass Page
Bearing to Waypoint Destination Waypoint
Pointer to Waypoint Speed Over Ground
In this example, the Compass Page indicates that you are traveling in a south westerly (210 degrees) direction and the destination waypoint is north east (69 degrees) of your current direction of travel.
In this example, the Compass Page indicates that you are traveling in an easterly (91 degrees) direction and the destination waypoint is south (177 degrees) of your current direction of travel.
The Compass Page provides better steering guidance than the Highway Page for travel at slower speeds (ex. walking) and for travel with many directional changes. The bearing (BRG) and distance (DST) to the waypoint are displayed at the top of the page, below the destination waypoint name. The distance displayed is the straight-line distance from your present position to the destination waypoint. The bearing indicates the exact compass heading from you to the destination. The middle of the page features a rotating compass ring that shows your course over ground while you are moving (track up orientation), with a pointer arrow to the destination displayed in the center. The arrow shows the direction of your destination from the direction you are moving. For instance, if the arrow points up, you are going directly to the waypoint. If the arrow points any direction (left, right, down, etc.), turn toward the arrow until it points up. Then continue in that direction. The bottom of the page shows your track (TRK), speed (SPD), and a user-selectable field for ETE, ETA, CTS, XTK, VMG, or TRN. When you are one minute away from your destination (based on your current speed and track over ground), the GPS 48 will alert you with a flashing onscreen message box.

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Using the Highway Page
Bearing to Waypoint Track Over Ground Destination Waypoint Graphic Highway Distance to Waypoint Speed Over Ground CDI Scale

User Selectable Field

The GPS 48s Highway Page provides graphic steering guidance to a destination waypoint, with a greater emphasis on the straight-line desired course 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. As you head toward your destination, the middle 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 moveindicating the direction youre off courserelative 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 to 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. If you do get off the desired course by more than 1/5th of the selected CDI range, the exact distance you are off course will be displayed where the CDI scale setting normally appears. If you get too far off course (the highway has disappeared), a message box will appear to indicate what course to steer to get back on course. (For information on how to set this scale, see pg. 44.) As you approach a waypoint, a horizontal finish line will move toward the bottom of the highway. When the finish line reaches the CDI scale, youve arrived at your destination.

To enter a proximity waypoint from the Menu Page:
1. Highlight PROXIMITY WPTS and press E. 2. Highlight the first empty waypoint field and press E. 3. Use the U or D key to scroll through stored waypoints until the desired waypoint appears. 4. Press E. The distance (DST) field will be automatically highlighted. Enter the desired distance. 5. Press the E key.
Quickly edit proximity waypoints by highlighting the waypoint name and pressing ENTER.
To review or remove a proximity waypoint:
1. Use U and D to select a proximity waypoint and press E. 2. Highlight REVIEW? or REMOVE? and press E.
If REVIEW? is chosen, the waypoint page will appear, and you may make any changes to the selected waypoint. If REMOVE? is chosen, the proximity waypoint page will reappear with the waypoint removed. Press Q or P to return to the Menu Page.

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Waypoint Definition Page
Waypoint Name Position Coordinates
Reference Waypoint Bearing from Reference Waypoint Function Prompts

Waypoint Comment

Distance from Reference Waypoint
The waypoint definition page lets you create new waypoints manually or review and edit an existing waypoints coordinates, symbols, and comments. It is also used to delete an individual waypoint from memory (see pg. 37). To create a new waypoint manually, youll need to know its position coordinates or its approximate distance and bearing from an existing waypoint.
To create a waypoint by entering coordinates:
1. From the waypoint definition page, highlight NEW?, and press E. 2. Enter a waypoint name, and press E. 3. Press E to select a waypoint symbol, make your selection, and press E. 4. Highlight the DONE? prompt, and press E to return to the waypoint page. 5. Highlight the position field, enter your position, and press E. 6. Press E to confirm the DONE? prompt.
The GPS 48s advanced waypoint planning features allow you to create new waypoints and practice navigation without ever setting foot outside. If you create a new waypoint by entering coordinates from a map, you may want to re-mark the waypoints exact position once you get there. To re-define an existing waypoints position coordinates from the waypoint definition page, simply highlight the DST field and press ENTER. Use the LEFT arrow key to set the distance to 0.00, and press ENTER to confirm. The old coordinates will be replaced by the coordinates of your present position (you must have a valid 2D or 3D position fix).

Use the on-screen menu to select the desired editing function.
On-Route GOTOs At the beginning of this section, we mentioned that the GPS 48 will automatically select the route leg closest to your position as the active leg. This will give you steering guidance to the desired track of the active leg. Note that the first waypoint selected as the destination waypoint will be the route leg closest to your present position. This may mean youre not navigating to the first waypoint in the active routeyou may be navigating to the last. If you prefer to navigate a route out of sequence, you can perform an on-route GOTO from the active route page.
To perform an on-route GOTO from the active route page:
1. Highlight the desired route waypoint, and press G. 2. Once the GOTO waypoint page appears with the waypoint highlighted, press E. To edit or review a route waypoint from the active route page, highlight the desired waypoint and press ENTER.
Note that after you reach the on-route GOTO waypoint, the GPS 48 will automatically resume navigating the rest of the route in sequence using the page you were on before performing a GOTO.

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Menu Page & System Setup
Menu Page The GPS 48s Menu Page provides access to additional pages (submenus) that are used to select and customize operation and navigation setup. These eight pages are divided into categories by function. Weve already gone over the waypoint and route management pages in their respective sections. Lets review the rest of these pages in the order they appear on the Menu Page.
To select a submenu page from the Menu Page:
1. Highlight the page, and press E. 2. To return to the Menu Page, press Q.
The Menu Page allows the user quick access to the units setup pages.
Distance and Sun Calculations The distance and sun calculation page will give you the distance and bearing between any two waypoints or between your present position and a waypoint. It will also calculate the sunrise and sunset (in local time) for a particular date at either your present position or any stored waypoint.
To perform a distance and sun calculation:
1. Highlight the FROM field, enter the desired waypoint, and press E. 2. Highlight the TO field, enter the destination waypoint, and press E. 3. The DATE field will become highlighted. Enter the date youll arrive at your destination, and press E.
If you havent marked your present position as a waypoint or you leave the TO field blank, the sunrise and sunset at your present position will be shown.
Setup Menu The setup menu allows the user to access the units system, navigation, interface and alarms setup pages.
The GPS 48 will calculate the sunrise and sunset times of any stored waypoint or your present position. To calculate, enter the date and year and press ENTER.

Note: You must enter a speed for all fields in the GPS 48 to function.
The GPS 48 does not track satellites in simulator mode. Although you can create and save waypoints and routes while using the simulator mode, never attempt to use the simulator mode for actual navigation.

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Appendix A
Never attempt any repairs yourself. To protect your GPS 48, keep it in its carrying case when not in use, and never allow gasoline or other solvents to come into contact with the case. Clean the case and lens with a soft cloth and a household window cleaner. PHYSICAL Case: Size: Weight: Temperature Range: PERFORMANCE Receiver: Acquisition Time: 12 parallel channel, differential-ready Approx. 15 seconds (warm start) Approx. 45 seconds (cold start) Approx. 5 minutes (AutoLocateTM) Update Rate: Position Accuracy: Velocity Accuracy: Dynamics: POWER Input: Battery Life: Internal Backup: Four 1.5 volt AA batteries or 10-32 vDC Up to 24 hours (with 4 AA batteries) lithium battery Power Consumption: 1 watt 1/second, continuous 1-5 meters (3-17 ft.) with DGPS corrections* 15 meters (49 ft.) RMS** 0.1 knot RMS steady state 6g Water proof rated to IEC 529 IPX4 standards. 6.15H x 2W x 1.23 D (15.6 x 5.1 x 1.23 cm) Approx 9.5 ounces (269g) w/ batteries 5 to 158F (-15 to 70C)
Specifications & Wiring
NOTE: Alkaline batteries lose a significant amount of their capacity as temperature decreases. If youre using the GPS 48 in below freezing temperatures, use lithium batteries for longer battery life. Extensive use of screen backlighting will significantly reduce battery life. Specifications subject to change without notice. *With optional DGPS Input. ** Subject to accuracy degradation to 100m 2DRMS under the US DOD-imposed Selective Availability Program.

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APPENDIX A

unit view

DATA IN (WHITE)

GROUND (BLACK)

POWER (RED)

DATA OUT (BROWN)

Three optional cables are available to connect the GPS 48 to an external power source or interface with another unit or PC: Cigarette Lighter Adapter Allows connection to a 12-volt DC cigarette lighter plug. Part No. 010-10085-00. Data Transfer Cable Allows data transfer between GARMIN GPS units. The GPS 48 is compatible with the following units: GPS 12/12XL/ 38/40/45/45XL, GPS II/II plus and the GPS III. Information that can be transferred includes the almanac, waypoints, routes, and tracklog. However, waypoint symbols are only transferrable from or to units that support waypoint symbols. PC Kit Interface Cable PC interface cable with 9-pin D serial data connector. Part No. 010-10141-00. The following interface formats are supported by the GPS 48 for driving three NMEA devices: NMEA 0180 NMEA 0182 NMEA 0183 version 1.5 Approved sentences: GPRMB, GPRMC, GPWPL Proprietary sentences: PGRMM (map datum), PGRMZ (altitude) PSLIB (beacon rec. control) NMEA 0183 version 2.0 Approved sentences: GPGGA, GPGSA, GPGSV, GPRMB, GPRMC, GPRTE, GPWPL Proprietary sentences: PGRME (estimated error), PGRMM (map datum), PSLIB (beacon receiver control) DGPS corrections are accepted on RTCM-104 v. 2.1 format.

To change the Setup TD settings: 1. Highlight the Position Frmt field on the navigation setup menu, and press E. Select LORAN TD, and press E. 2. Select the field to change, and press E. 3. Highlight the new setting, and press E.

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The GPS 48 uses a flashing on-screen message indicator to alert you to important information. Whenever the message indicator appears, press PAGE to view the message page. There are two types of messages: temporary alerts and condition alerts. Temporary alerts are cleared from the message page after viewing, while condition alerts remain until the condition has been resolved. Pay careful attention to all messages for your own safety.

APPENDIX B

Messages & Time Offsets
Active WPT Cant be DeletedYou have attempted to change the active to or active from waypoint. Clear the active route or GOTO before making your changes. Accuracy has been DegradedThe accuracy of the GPS 48 has been degraded beyond 500 meters due to poor satellite geometry or data quality. You should check other navigational sources to verify the position indicated. Already ExistsThe name you are entering already exists in the GPS 48s memory. ApproachingYou are one minute away from reaching a destination waypoint. Battery Power is LowThe batteries are low and should be replaced. No DGPS PositionNot enough data is available to compute a DGPS position. No RTCM InputBeacon receiver is improperly connected or baud rates do not match. Poor GPS CoverageThe GPS 48 cannot acquire the necessary number of satellites to compute a position. Try another location with a clearer view of the sky. Power Down and Re-initThe GPS 48 is not able to calculate a position due to abnormal satellite conditions. Turn the unit off and verify the last position shown by other means. Try the unit again later, possibly in a different location. PROX AlarmYou have entered the alarm circle for a specific proximity waypoint. Proximity OverlappedThe alarm circles of two proximity waypoints overlap which could cause difficulty in monitoring distances to each waypoint. Proximity Wpt cant be DeletedThe waypoint you are trying to delete is listed as a proximity waypoint and must be removed from the list before it can be deleted. Read Only Mem has FailedThe permanent memory has failed and the unit is not operable. Received an Invalid WPTA waypoint was received during upload transfer that has an invalid identifier. Receiver has FailedA failure in receiver hardware has been detected. If this message persists, do not use the unit and take it to an authorized dealer for repair. Route is FullYou have attempted to add more than 30 waypoints to a route. Route is not EmptyYou have attempted to copy into a route already in use. Route Waypoint Cant be DeletedThe waypoint you are trying to delete is part of a route. Delete the waypoint from the route before removing it from memory. Route Waypoint was DeletedA route waypoint entered does not exist in the database and has been deleted from the route

Prov S Chln 63 Puerto Rico Qatar National Qornoq Reunion Rome 1940 RT 90 Santo (Dos) Sao Braz Sapper Hill 43 Schwarzeck Sth Amrcn 69
South Asia SE Base SW Base
Timbalai 1948 Tokyo Tristan Ast 68 Viti Levu 1916 Wake-Eniwetok WGS 72 WGS 84 Zanderij
Old Hawaiian- Mean Value Oman- Oman Old Survey Grt BritnEngland, Isle of Man, Scotland, Shetland Isl., Wales Canary Islands Potsdam-Germany Pitcairn Astro 67- Pitcairn Is Prov So Amricn 56- Bolivia, Chile,Colombia, Ecuador, Guyana, Peru, Venezuela Prov So Chilean 63- S. Chile Puerto Rico & Virgin Islands Qatar National- Qatar Qornoq- South Greenland Reunion- Mascarene Island Rome 1940- Sardinia Island Sweden Santo (Dos)- Espirito Santo Island Sao Braz- Sao Miguel, Santa Maria Islands (Azores) Sapper Hill 1943- East Falkland Island Schwarzeck- Namibia South American 69Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Guyana, Paraguay, Peru, Venezuela, Trinidad and Tobago South Asia- Singapore Southeast Base- Porto Santo and Madiera Islands Southwest Base- Faial, Graciosa, Pico, Sao Jorge and Terceira Islands (Azores) Timbalai 1948- Brunei and E. Malaysia (Sarawak and Sabah) Tokyo- Japan, Korea, Okinawa Tristan Astro 1968- Tristan da Cunha Viti Levu 1916- Viti Levu/ Fiji Islands Wake-Eniwetok- Marshall Isl. World Geodetic System 1972 World Geodetic System 1984 Zanderij- Surinam

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APPENDIX D The following list shows the abbreviations for lit and unlit navaid labels followed by a brief description of the abbreviation.
Lit Navaid Abbreviations F FL FL(2) FFL Q VQ OC ISO MO(A) AL DIR Fixed continuous and steady light Single Flashing flash repeated on given time period, not to exceed 30 per minute Group Flashing group of regularly repeating flashes Fixed and Flashing fixed light combined with a flashing light of higher intensity Quick Flashing light flashes at a rate of 60 flashes per minute Very Quick light flashes at a rate greater than 60 flashes per minute Occulating alternating light and dark with duration of light longer than dark Isophase alternating light and dark with duration of light and dark equal. Morse Code different flash durations used to represent morse code characters Alternating different colors flashing alternately Directional prefix indicates the light is directional

Navaid Abbreviations

FL(2+1) Composite Group Flashing a complex light

Lit Navaid Primary Colors W = White Or = Orange R = Red Bu = Blue G = Green Y = Yellow Vi = Violet Am = Amber
Unlit Navaid Abbreviations S = Square M = Safe Water J = Junction C = Crossing T = Triangle N = Special Purpose K = Range
Unlit Navaid Key Colors G = Green R = Red W = White Y = Yellow B = Black

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APPENDIX E
Acquisition Time.57 Activating a Route.43 Active Route Page.44 Acquiring a position.6 Alarm Setup.54 Alkaline batteries.57 Altitude (ALT).18 AutoLocate.6 Average Speed (AVSPD).17
DGPS Interface.52 Date and Time.47 Deleting Waypoints.37 Distance/Sun Calculations 46
EZinit.7, 15 Editing Routes.45 Elapsed Time (ELPSD).17 Emergency Erase.16 Est. Time Enroute (ETE).17 Est. Time of Arrival (ETA) 17 F Find City.26, 55
Backlighting Timer.48 Battery Level.16 Battery Life.58 Battery Installation.59
CDI.12, 31, 50 Cancelling a GOTO.12 Cautions.ii Cigarette Lighter Adapter.58 City Setup.26 Clearing Routes.44 Clearing the Track Log 13, 26 Compass Page.9, 12, 28, 30 Configuring the Map Page 22 Copying Routes.44 Course deviation indicator 50 Course to Steer (CTS).29 Creating Routes.43 Creating Waypoints.35 Crosstrack Error (XTK).GOTO.38 Getting Started Tour.6 Glossary.2 Going To a Waypoint.11 Graphic steering.28

Highway Page.28, 31

I/O format.52 Initializing.6 Interface Setup.52 Inverting a Route.43

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Language Setup.55 Loran TD Positiion Format 60
PC Kit.i, 58 Panning.22 Position Accuracy.57 Position Averaging.32 Position Formats.49 Position Page.8, 17 Power and Data Cables.57 Primary Pages.8 Proximity Waypoints.34
Mag. Heading Reference.50 Man Overboard Function.38 Map Cursor.23 Map Datums.49, 63 Map Orientation.24 Map Page.11, 18 Map Setup.24 Marine Database.21 Marking a Position.32 Maximum Speed.18 Maximum Speed (MXSPD) 17 Menu Page.9, 46 Messages.61
Receiver Status.15 Reference Waypoints.35 Renaming Waypoints.37 Repairs.57, 69 Routes Clearing.44 Copying.44 Creating.43 Editing.45 Inverting.43 Navigating Routes.41 On-Route GOTOs.45 Route Definition Page.42 User-defined route.42
NMEA Formats. 58 Navaid Setup.27 Navigating Routes.41 Navigation Page.9, 28 Navigation Setup.49 Nearest Waypoints.33

DealFinder: A Collaborative, Location-Aware Mobile Shopping Application*
Wesley Chan MIT Media Laboratory Personal Information Architecture Group 20 Ames St., E15-468G Cambridge, MA 02139 USA +wesleyc@media.mit.edu

ABSTRACT

We present DealFinder, a position-aware shopping application for mobile devices that illustrates how collaboration can help consumers make more informed purchasing decisions. DealFinder enables users to share product reviews, pricing information, and shopping experience, allowing them to filter any information they find based on their position. Keywords: Mobile applications, collaboration, wireless and hand-held devices, location-based services, context aware computing.

INTRODUCTION

The emergence of high-bandwidth wireless networks and the wide proliferation of always-connected mobile devices will enable new and compelling collaborative applications. Collaborative mobile applications, coupled with locationbased services, will empower users to share information based on similar interests and context when and where they need that information. Only a few of these applications exist today. As the wireless data infrastructure improves, however, many more collaborative applications will emerge. We created DealFinder (figure 1a), a position-aware shopping application for mobile devices, to illustrate how consumers can collaborate and use the context of location to make more -informed decisions about their purchases. DealFinder currently enables users to asynchronously share information about product prices and availability. For instance, a person comparison-shopping for television sets at different local electronic stores can use DealFinder to upload prices to our public database. Other shoppers who will are looking for a similar television set will be able to find prices on TV sets , based on their location (e.g. find prices for TV sets at stores within 10 miles of my current position), using a series of simple forms (figure 1b). In a similar manner, shoppers will also be able to share information about deals or seasonal sales by uploading *Submitted to the CHI 2001 Conference on Dec. 8, 2000.
Figure 1a, 1b: Hardware Implementation of DealFinder; Form for user to input parameters to find location-specific deals.
them to the database, so that other bargain hunters can later search for them based on position. We are in the process of implementing several other collaborative shopping features for DealFinder. We are adding a feature that allows customers to share their experience about shopping at particular stores or about purchasing particular products. For example, a customer will be able to let other shoppers know that they thought a specific store had excellent customer service, or why they ended up purchasing a particular television set after looking at six other ones. Other shoppers will be able retrieve this information based on their preferences and filter the results using their current position. For instance, a shopper casually browsing for DVD movies at a local video store will be able to access reviews, written by other users, for only those movies in stock at that particular store and for a particular genre. With DealFinder, shoppers will be able to make more informed buying decision by examining the previous buying history of other users they explicitly trustfor example, personal friends or other users that have contributed outstanding product reviews.

BACKGROUND

DealFinder is part of Project Voyager, an endeavor at the MIT Media Laboratory that aims to build a platform that simplifies the prototyping of collaborative and context aware mobile applications [3]. Using the Voyager platform, which is still under development, we previously built a
position-aware mobile tour guide for the MIT campus that delivers multimedia content to visitors at specific points of interests. We were also greatly influenced by the work on several location-aware and collaborative mobile applications. Much of this work has focused on creating mobile tour guides, including the CyberGuide project [1] and Cheversts context -aware electronic tour guide [2]. Furthermore, other location-aware applications at the Media Lab, including Impulse [4], provided guidance in our design of DealFinder. However, these applications ignore how collaboration can improve their user scenarios or enable new ones. Thus, the proliferation of nume rous virtual communities, product review web sites, Internet chat applications, and online discussion boards illustrates the importance of developing collaborative applications. Along these lines, both DealFinder and Project Voyager seek to explore and enable prototype implementations of collaborative and context -aware applications for mobile devices.

IMPLEMENTATION

and video) to take advantage of future high-bandwidth wireless networks such as GPRS or 3G-CDMA. Currently, shopping data is cached on the local device as a text file and new data is periodically uploaded and downloaded to a web server at the Lab. However, this solution is neither scalable nor elegant. Thus, we are in the process of upgrading our infrastructure to use Wherehoo [6], a system which allows you to store and retrieve location-indexed data by position. With these improvements, we will be able to deploy a more robust and scalable version of DealFinder. This will allow shoppers to search for and share additional information including product reviews and personal buying history. These enhancements will enable us to properly evaluate how collaborative mobile applications can enhance a users shopping experience.

CONCLUSION

DealFinder uses much of the infrastructure provided by Project Voyager, including a platform for tracking location using a Global Positioning System (GPS) receiver, storing position-indexed data remotely on the Media Labs Wherehoo servers [5], displaying maps and location information, and delivering multimedia content (audio, photographs, text). Project Voyager currently supports only one mobile device platformMicrosofts PocketPC standard. Thus, we chose to use Compaqs iPaq H3650 PocketPC device to host our DealFinder application. To detect location, we use a Garmin GPS 48 receiver and transmit location information to the application via the PocketPCs serial port. To upload and retrieve data, we use a Sierra Wireless AirCard 300 CDPD modem attached to the devices PC Card slot. Our prototype additionally allows users to search for and contribute pricing information and deals stored on a remote database server. This is done via a series of pre-generated forms that the user can access from the applications builtin menus. The user simply fills in several fields and retrieves a list of deals or uploads his/her contribution to the database.

FUTURE WORK

We described our effort to prototype a collaborative, location-based mobile shopping application using commercially available hardware, existing wireless data infrastructure, and a prototyping toolkit that is still under development at the MIT Media Lab. While there are still numerous features we have yet to implement, DealFinder is a compelling demonstration of how collaborative mobile applications can help users improve their shopping experience by empowering them to access relevant information when and where they want it. Collaborative mobile applications, such as DealFinder, will empower us to share and access information without having to be tethered to a desktop computer, providing a powerful new interface to information that can potentially enhance many of the tasks we undertake today.

ACKNOWLEDGMENTS

We thank Dr. Mike Hawley, Dr. Brian Smith, Jon Brunsman, Dr. Ted Selker, and Dr. Henry Liberman for their advice and assistance on this project. We also thank the TTT consortium and Microsoft Research for their financial support.

REFERENCES

1. G.D. Abowd, C.G. Atkeson, J. Hong, S. Long., R. Kooper, M. Pinkerton. Cyberguide: A mobile context aware tour guide. ACM Wireless Networks. 3 (1997) 421-433. 2. K. Cheverst, N. Davies, K. Mitchell, A. Friday, C. Efstratiou. Developing a Context -aware Electronic Tourist Guide, in CHI Letters, vol. 2, no1. Apr. 2000. 3. Project Voyager Web Site. Available at: http://www.media.mit.edu/pia/voyager/ 4. J. Youll, J. Morris, R. Krikorian, P. Maes. Impulse: Location-based Agent Assistance, in Software Demos, Proceedings of the Fourth International Conference on Autonomous Agents. June 2000. 5. J. Youll, R. Krikorian. Wherehoo Server: An interactive location service for software agents and intelligent systems, in Workshop on Infrastructure for Smart Devices. Sept. 2000.
Since we use GPS as the only means for sensing position, DealFinder only works in outdoor areas where the system has a clear view of the sky. To handle the case when the shopper is inside a store, we cache the users last known position when the system no longer receives location data from the receiver. We are also exploring different indoor position detection methods, including using RF tags and IR beacons. Furthermore, because of the limited bandwidth of our wireless data connection (4800-9600 bps), DealFinder is restricted to retrieving and sending only text data from the remote database. The system is, however, designed to support additional multimedia content (photographs, audio,