User manual GARMIN GPS 75

GPS 75 Personal Navigator TM OWNER'S MANUAL (Software Version 2.20 or above) © 1992-1993 GARMIN, 9875 Widmer Road, Lenexa, KS Printed in Taiwan. 66215, USA All rights reserved. No part of this manual may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording, for any purpose without the express written permission of GARMIN. Information in this document is subject to change without notice. GARMIN reserves the right to change or improve their products and to make changes in the content without obligation to notify any person or organization of such changes or improvements. October, 1993 190-00046-00 Rev. D PREFACE GARMIN thanks you for selecting our high performance, full featured Personal NavigatorTM. The GPS 75 represents our continued commitment to provide you with a portable navigation unit that is versatile, extremely accurate, and easy to use. We are confident you will enjoy using your unit for many years to come. The GPS 75's rugged construction and quality components offer the reliability demanded by the harshest operating environments. It may be used in marine and land vehicles, as well as by hunters, hikers, and military forces. The unit may be operated portably using its own battery pack, or it may use a 5-40 volt DC external power source for fixed mounted applications. You can even use a 115- or 230-volt battery charger for planning trips at home. This manual and accompanying quick reference guide provide complete information on safely operating the GPS 75 to its full potential. A practice voyage has been planned for you to practice your navigation skills using the built-in simulator. Afterwards, try a trip of your own to realize the value of the GPS 75 as your Personal NavigatorTM. If you have any questions or comments, our Product Support Department is eager to serve you. GARMIN is fully committed to your satisfaction as a customer. GARMIN International, Inc. 9875 Widmer Road Lenexa, KS 66215 1-800-800-1020 (913) 599-1515 i CAUTION The GPS system is operated by the government of the United States which is solely responsible for its accuracy and maintenance. The system is under development and is subject to changes which could affect the accuracy and performance of all GPS equipment. Although the GPS 75 is a precision electronic NAVigation AID (NAVAID), any NAVAID can be misused or misinterpreted, and therefore become unsafe. Use the GPS 75 at your own risk. To reduce the risk, carefully review and understand all aspects of this Owner's Manual and thoroughly practice operation using the simulator mode prior to actual use. When in actual use, carefully compare indications from the GPS 75 to all available navigation sources including the information from other NAVAIDs, visual sightings, charts, etc. For safety, always resolve any discrepancies before continuing navigation. NOTE: This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation. ii TABLE OF CONTENTS CHAPTER 1 INTRODUCING THE GARMIN GPS 75 1.1 Capabilities 1.2 Operations 2 GETTING STARTED 2.1 2.2 2.3 2.4 2.5 2.6 2.7 3 Front Panel Softkey Operation Cursor and Fields Keypad Operation Entering Data Viewing Messages Operating Modes PAGE 1-1 1-1 1-2 2-1 2-1 2-1 2-2 2-2 2-4 2-4 2-5 3-1 3-1 3-2 3-3 3-5 3-6 3-6 3-7 3-8 3-11 3-11 4-1 4-1 4-2 4-3 4-4 4-4 4-5 4-5 iii BASIC OPERATION 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 Power On Satellite Status Pages Present Position Waypoints Waypoint List Autostore TM Getting There Fast--GOTO Navigating To A Waypoint Man Overboard Sample Trip 4 ROUTES 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Navigating Using Routes Creating and Copying A Route Activating Routes Editing Routes Deleting Routes Active Route Route List 5 ADVANCED WAYPOINT FEATURES 5.1 5.2 5.3 5.4 Nearest Waypoints Proximity Waypoints Reference Waypoints Waypoint Scanning 5-1 5-1 5-1 5-2 5-3 6-1 6-1 6-2 6-3 6-4 6-5 6-6 6-6 6-7 6-8 6-9 6-10 6-11 6 AUXILIARY FUNCTIONS 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 6.10 6.11 6.12 Operating Mode and Filters Plotting Setup Units/Heading Setup Alarms and CDI Setup Date/Time Audio and Display Setup Interface Setup Map Datum Selection Beacon Receiver Setup Sunrise/Sunset Planning Trip & Fuel Planning Messages APPENDICES A B MESSAGES GLOSSARY AND NAVIGATION TERMS B.1 Definitions B.2 Course To Steer (CTS) C INSTALLATION AND MAINTENANCE C.1 C.2 C.3 C.4 C.5 C.6 C.7 D E iv Specifications Electrical Wiring Universal Mount Installation Universal Mount Operation Battery Pack Operation Maintenance Product Support A-1 B-1 B-1 B-3 C-1 C-1 C-3 C-5 C-8 C-10 C-11 C-12 D-1 E-1 MAP DATUMS LOCAL TIME TO UTC TIME OFFSET CHAPTER 2 GETTING STARTED 2.1 FRONT PANEL Page Options Page Annunciator Softkeys Message Annunciator PWR STAT GOTO MOB AUTO STO ABC 1 JKL 4 STU 7 DEF 2 MNO 5 VWX 8 GHI 3 PQR 6 YZ 9 NAV WPT RTE CLR 0 ENT The front panel consists of a 20-key keypad with a 85 x 64-pixel LCD display. Both the display and keypad may be illuminated for nighttime operation. 2.2 SOFTKEY OPERATION Information displayed on the LCD is commonly referred to as a "page." The GPS 75 works with softkey operation. At the bottom of the screen is a list of page options. To select a different page, press the appropriate softkey below the desired menu option. Please note that the menu options must be highlighted in order to use the softkeys. On the bottom line, extreme right, is the page annunciator, which indicates the current page you are viewing. 2-1 2.3 CURSOR AND FIELDS Confirmation Field Bar Field Cyclic Field The area of the page which is highlighted in reverse video is called the cursor. The cursor may be moved to locations on the page called fields which allow you to enter data or change options. You will encounter five types of fields. · Numeric fields accept numbers only. · Alphanumeric fields accept numbers as well as letters. · Cyclic fields allow selection from several available options. A cyclic field is preceded by a prompt ( ). You may cycle through the choices by pushing CLR. · Confirmation fields allow you to indicate your approval. For example, you will be asked to confirm that you want to delete a waypoint. Confirmation fields always end with a "?" character. Press ENT to approve the confirmation field. · Bar fields allow an adjustable scale entry with the length of the bar representing the minimum to maximum setting. Use your arrow keys to make adjustments in bar fields. 2.4 KEYPAD OPERATION The PWR/STAT key is a dual function key that controls unit power and system status. Pressing this when the unit is off will turn the unit on. To turn the unit off, press and hold PWR/STAT until the display is blank. Pressing PWR/STAT momentarily while the unit is on will take you to the status pages (see Section 3.2). If the message annunciator is flashing and the tone sounds, you may push PWR/STAT to view the message. 2-2 Pressing GOTO/MOB once allows you to initiate the GOTO function, setting an instantaneous course to any waypoint (see Section 3.7). Pressing GOTO/MOB twice allows you to initiate the Man Overboard function, setting an immediate course to the captured position (see Section 3.9). Pressing AUTOSTORE allows you to capture your present position instantaneously (see Section 3.6). Pressing NAV selects the Navigation Pages which allow you to view navigation information and the Plot Page (see Section 3.8). Pressing WPT selects the Waypoint Pages which allow you to create, edit, delete, and rename waypoints. In addition, you may view nearest waypoints or proximity waypoints (see Sections 3.4, 3.5 and Chapter 5). Pressing RTE selects the Route Pages which allow you to edit, review, activate, and delete routes (see Chapter 4). Pressing either of the arrow keys allows you to move the cursor, scroll through information lists, and enter letters of the alphabet. The alphanumeric keys allow you to enter letters and numbers. Use the arrow keys to select the desired letter or number. Pressing this key while the cursor is not on a numeric or alphanumeric field allows you to change the backlight level. There are two backlighting levels. Pressing CLR erases information in the cursor field. If the cursor is over a cyclic field, pressing CLR will toggle through several available options. Pressing ENT confirms an entry or selection. 2-3 2.5 ENTERING DATA To enter data you must first move the cursor under the desired field by pressing the right or left arrow key. To enter a number... · Press the key that is labeled with the desired number. The numbers will fill in from the right side of the field and move to the left as each new number is entered. For example, if you wish to enter "51" in a three space field, you must press the 5 and 1 keys in that order. · Press CLR if you enter an incorrect number. · Press ENT when you have filled all significant digits of the field with numbers. To enter a letter... · Press the key that is labeled with the desired letter. · Press the right or left arrow key until the desired letter is displayed. · Press CLR if you enter an incorrect letter. · Press ENT when all the characters are entered. The GPS 75 features a keypad feedback tone which will sound each time you press a key. If you enter data which is not appropriate for the field, the feedback tone will quickly sound three times indicating an error. The keypad feedback tone can be turned off if you wish (see Section 6.6). 2.6 VIEWING MESSAGES From time to time, the GPS 75 will use a message to tell you of conditions needing attention. When the GPS 75 has a new message, the MSG annunciator will flash. When this occurs, press PWR/STAT to view the new message(s). Press PWR/STAT again to see the page you were viewing prior to reading your message. While the MSG annunciator is flashing, the GPS 75 will also generate a tone to alert you of the message (if your unit is connected to an external alarm, it will also be activated). Messages that demand immediate attention such as an arrival alarm generate a quick tone that will not stop until you view the message. All other messages generate a slow tone that will cease after 15 seconds. The message tone may be turned off if you 2-4 wish (see Section 6.6). Important messages will remain on the Message Page after being viewed. If this occurs, the MSG annunciator will be in view but will not flash (if no messages exist, the MSG annunciator will not be visible). To review these messages, press PWR/STAT to reveal the status menu options. Then press the key underneath the "AUX" page option. With the arrow keys, scroll to "Messages" and press ENT. Refer to Appendix A for a complete list of GPS 75 messages. 2.7 OPERATING MODES Three modes are available which will allow you to operate your GPS 75 in the way which best suits your needs (see Section 6.1). Normal mode is most suitable for high dynamics applications. The GPS 75 will typically operate up to 5 hours on a single pack of alkaline batteries, or 6 hours using the rechargeable battery pack. Battery Saver mode is suitable for most applications and will extend the battery life to 7 hours on a single pack of alkaline batteries, or 9 hours using the rechargeable battery pack. Simulator mode allows you to simulate the operation of the GPS 75 while at home or in your office. The simulator mode can be used while learning to use your GPS 75 and is ideal for planning routes and entering waypoints. Keep in mind that the GPS 75 is not tracking satellites in the simulator mode. YOU SHOULD NEVER ATTEMPT TO USE THE SIMULATOR MODE FOR ACTUAL NAVIGATION. If you are using your GPS 75 for the first time, you are encouraged to review Chapter 3 which introduces the GPS 75's basic features, and Chapter 6 on custom setups. Afterward, you may want to read through the rest of this manual and make further use of the built-in simulator to practice with the advanced features. 2-5 CHAPTER 3 BASIC OPERATION 3.1 POWER ON After you turn your GPS 75 on, it will conduct a series of self tests and display the following notice: Following completion of the tests, the Satellite Bar Graph Page (see Section 3.2) will be displayed, and the GPS 75 will begin acquiring satellites. After a position is found (and if no keys have been pressed), the Position Page (see Section 3.3) will be displayed, and the unit is ready for normal operation. When four or more satellites with good geometry are available, the GPS 75 will automatically operate in the 3D mode in which latitude, longitude, and altitude are computed. If only three satellites are available, the unit will operate in 2D mode in which only latitude and longitude are computed. When operating in the 2D mode, the unit will use the last computed altitude or your last entered altitude. (Section 3.3 describes how you may enter the altitude.) Your GPS 75 will automatically update satellite orbital data as it operates. If you have not operated your unit for a period of six months or longer, it will take approximately 15 minutes to search the sky and collect new orbital data. You will be informed when your unit is searching the sky with the message "Searching the Sky." Once satellite orbital data is collected, it will be stored in memory. The memory is maintained by an internal battery, therefore the data will not be lost when you turn your GPS 75 off. 3-1 3.2 SATELLITE STATUS PAGES There are four status pages available by pressing PWR/STAT. Three pages display satellite tracking status, and the fourth is a menu of auxiliary functions (messages, setups, and utilities). The softkeys at the bottom of each page allow selecting pages: BAR (bar graph), STAT (status), SKY (skyview), and AUX (auxiliary menu). You may also cycle through these pages by repeatedly pressing PWR/STAT. Satellite Bar Graph The Satellite Bar Graph shows the signal quality of each visible satellite graphically. The receiver status is also shown at the top of the screen. In this example, the unit is simulating navigation. The satellite numbers (1-32) are represented along the bottom of the graph; signal quality (1, weakest to 9, strongest) is represented along the side. If a satellite is visible but not tracked, the signal quality will be blank. If differential corrections are available for a satellite, a "D" will appear at the bottom of the signed strength bar for that satellite. (See Section 6.7 for DGPS setup instructions.) Satellite Status Page The Satellite Status Page shows the ID, azimuth, elevation, and signal quality of each visible satellite in a table format. The receiver status, again, is displayed at the top of the screen, as well as the dilution of precision (DOP) and estimated position error (EPE). (For more information about unfamiliar terms, see Appendix B.) * To view the Satellite Status Page, press softkey underneath the STAT banner. * Press SKY Softkey To display Satellite Skyview. 3-2 Satellite Skyview * Press AUX Softkey to display the Auxiliary Menu Page. The Satellite Skyview Page shows the azimuth and elevation of each visible satellite in a graphic skyview format. Additionally, the DOP and EPE are displayed. The azimuth and elevation are useful in determining whether a satellite signal is blocked by buildings, mountains, or other obstructions. If a satellite is not currently being tracked, it will be displayed in reverse video on the screen Auxiliary Menu The Auxiliary Menu Page enables the selection of various setup and utility functions by moving the cursor to an item with the arrow keys and pressing ENT. Each setup and utility page is described in detail in Chapter 6. 3.3 PRESENT POSITION Position Page As mentioned earlier, the Position Page is automatically displayed once a position is obtained. This page displays track, ground speed, latitude and longitude relative to the selected map datum (see Section 6.8), as well as a choice of altitude above mean sea level (MSL) or time (cyclic field). (Note: Time information will not be displayed when the GPS 75 is acquiring satellites.) 3-3 When the GPS 75 is performing 2D navigation, the last known altitude will be used in the latitude/longitude computation. If the altitude is not accurate within a few hundred feet, you should manually enter your altitude. To enter the altitude (2D only)... · Use an arrow key to move the cursor under the altitude. · Enter the altitude. If your antenna is mounted on a high mast, make sure you add the mast height. (Remember to complete the data entry by pressing ENT.) During initial satellite acquisition, the displayed position is the last computed position stored in the GPS 75. If your position has moved several hundred miles or more with the power off, the unit may go into the Autolocate mode. This process can take up to ten minutes. Alternatively, you may enter a more accurate initial position to speed up the acquisition process. (You may also change the position at any time while you are in simulator mode.) To enter the latitude/longitude... · Use an arrow key to place the cursor on the latitude hemispheric designation (far left). · Check the hemispheric designation ("N" or "S") of the latitude. If it is correct, go to the next step. If it is incorrect, press CLR until the correct hemispheric designation is displayed. · Place the cursor on the latitude field and enter the latitude. Depending on the position format selected (see Section 6.3), you will enter the latitude in one field (degrees only), two fields (degrees/minutes), or three fields (degrees/minutes/seconds or UTM). You must press ENT for each field to confirm the data entry. · Check the hemispheric designation ("E" or "W") of the longitude in the same manner as above for latitude. · Enter the longitude (remember to complete the data entry by pressing ENT). 3-4 3.4 WAYPOINTS The GPS 75 allows you to create, store, and use 250 alphanumeric waypoints. A waypoint consists of a name (up to six letters and/or numbers), its latitude/longitude location, last time/date of modification, and a one-line comment. There are four waypoint pages. The softkeys at the bottom of each page allow the selection of each page: WPT (waypoint definition), NRST (nearest waypoints), PROX (proximity waypoints), and LIST (waypoint list). To start the waypoint pages, press WPT. The Nearest and Proximity Waypoint Pages are covered in Chapter 5. Waypoint Definition If you are not already on this page, press the WPT softkey. It allows you to review, create and modify waypoints. The cyclic field allows you to display one of the following: 1) the date and time the waypoint location was last modified, 2) a oneline comment of the waypoint (up to 20 characters), or 3) range and bearing from a reference waypoint. To create, modify or review a waypoint · Move the cursor to the waypoint name field, then enter the desired waypoint name. · To create or modify position, enter the waypoint latitude and longitude as described in Section 3.3 on the previous page. (NOTE: If a waypoint is being used for navigation, its position cannot be modified. An attempt to modify the position of such a waypoint will result in the message "Can't Chg Activ WPT.") 3-5 3.5WAYPOINT LIST The Waypoint List Page allows viewing of the stored waypoints in the unit. The list may be scrolled, with the arrow keys, to view all the waypoints. From this page, waypoints may be selected for deletion, renaming, or to activate a direct GOTO. (See Section 3.7.) To delete a waypoint... · With the arrow keys, place the cursor on the desired waypoint. · Press CLR and ENT. · The Confirmation Page is displayed. Press ENT to confirm or CLR to cancel. NOTE: If you attempt to delete a proximity or route waypoint, a message will be displayed. You must delete the proximity alarm or the route before you can delete the waypoint. To rename a waypoint... · With the arrow keys, place the cursor on the desired waypoint. · Type in a new name for the waypoint and press ENT. · The Confirmation Page is displayed. name change or CLR to cancel. To delete all waypoints... · With the arrow keys, place the cursor over the "Delete All?" field and press ENT. · The Confirmation Page is displayed. Press ENT to confirm the deletion of all waypoints or CLR to cancel. NOTE: The "Delete All?" selection will delete all routes and proximity waypoints as well. 3.6AUTOSTORE function allows you to capture your position at the The AutoStore touch of a button for future reference. This function saves your current position in a waypoint. Additionally, you may record your navigation path by inserting the captured waypoints into a route (see Section 4.6). TM Press ENT to confirm the 3-6 The AutoStoreTM Page displays the waypoint name, captured position, TM and optional storage route. An AutoStore waypoint name is preassigned as a three digit number. You may change this to any name you desire. AutostoreTM waypoints may be used for any waypoint operation and will be part of the 250 available waypoints. Waypoint Name Longitude Latitude Route Storage Number To capture present position... · Press AUTOSTO. The pre-assigned waypoint name is on line 1. NOTE: The AutoStoreTM location is captured as soon as you press AUTOSTO. This allows you all the time you need to change the waypoint name and/or confirm the Autostore. · If you wish to give the waypoint a different name, move the cursor to the waypoint name field and enter the name of your choice. If you enter a waypoint name already used, you will be informed with the message, "WPT Exists [name]." Enter a different name if this occurs. Press ENT. · Press ENT on a blank route storage number field to save the waypoint. If the route storage number field is not blank, the waypoint will be added to the route shown. (In Chapter 4, we will discuss building a route with AutoStore.) 3.7GETTING THERE FAST--GOTO The GOTO function allows you to quickly set a course from your position to any waypoint. 3-7 To activate the GOTO function... · Press GOTO. The above page will be displayed with the cursor on the GOTO waypoint field. If the GPS 75 is currently navigating to a waypoint, that waypoint will be offered as the default GOTO waypoint. If the waypoint field is blank or the waypoint shown is not the desired destination, type the new name right over the old name. NOTE: If a non-existent waypoint name is entered, the Waypoint Definition Page will appear to give you the opportunity to create the waypoint (see Section 3.4). · Confirm the default GOTO waypoint by pressing the ENT key. The NAV Page will be displayed. (The D-Bar on the CDI will be recentered at this point, see Section 3.8 below.) Alternatively, the GOTO function may be quickly activated from many pages (e.g. the Nearest Waypoint Page or the Waypoint List) by placing the cursor over the desired waypoint name and pressing the GOTO key. The GOTO Page will be displayed with the cursor on the GOTO waypoint name. The GOTO function will be activated when the ENT key is pressed. To cancel the GOTO function... · Press GOTO. · Press CLR. The GOTO waypoint name will become blank. · Press ENT. The GPS 75 will start to navigate using the active route, if it has been programmed (see Chapter 4). Otherwise, the GPS 75 will stop computing waypoint navigation data. 3.8NAVIGATING TO A WAYPOINT There are four navigation pages available from the NAV key. You may cycle through the following with softkeys at the bottom of each page: NAV (navigation summary), CDI (graphic course deviation indicator), PLOT (graphic plotter), and POSN (Present Position Page). Active Leg Cyclic Fields D-Bar Relative Bearing Pointer 3-8 Cyclic Fields Scale Setting Course Deviation Indicator (CDI) Navigation Summary The Navigation Summary Page displays direction, distance and speed information to direct you along a route or a GOTO destination. The active leg (route) waypoints or GOTO waypoint is shown at the top of the screen. The CDI is at the bottom of the page. Current CDI scale setting is shown at each end of the scale. This is replaced by the cross track distance if the D-Bar goes off the scale. A relative bearing pointer at the center of the CDI indicates the bearing to the waypoint relative to the current track (TRK). Notice that this page has four cyclic fields available. The field options are as follows: Field #1 (top left) provides a choice of: (a) bearing to destination waypoint (BRG), (b) course to steer (CTS), (c) desired track (DTK), (d) ground track (TRK), or (e) turn (TRN). * Press the softkey under CDI. Field #2 (top right) provides a choice of: (a) range to destination waypoint (RNG), (b) cross track error (XTK), (c) along track distance (ATD), or (d) distance made good, back to starting point (DMG). Field #3 (bottom left) provides a choice of: (a) ground track (TRK), (b) course made good (CMG), or (c) ground speed (GS). Field #4 (bottom right) provides a choice of: (a) ground speed (GS), (b) estimated time enroute (ETE), (c) estimated time of arrival (ETA), or (d) velocity made good (VMG). (See Appendix B for a description of navigation terms.) Course Deviation Indicator The CDI Page shows a graphic "highway" display. The active waypoint is shown at the top of the screen. Navigation values for Track (TRK), Ground Speed (GS), Bearing (BRG), Range (RNG), and Estimated Time Enroute (bottom right) are shown. The center-line of the highway represents the desired 3-9 * Press the softkey under PLOT. track. The outer lines give a perspective view of the distance to a waypoint. As the waypoint comes into range, it will be displayed and the outer lines will become parallel. Plot Page The Plot Page shows a graphic top view of your course. The destination waypoint is shown at the top right of the screen. Your present position is shown as a plus ("+") sign in the middle of the page. The track history and/or the active route are shown as · Press the POSN a solid line. (Plotting of ground softkey . track and active route is userselectable, see Section 6.2.) Nearby waypoints are displayed as diamonds. You may view the waypoint name by scrolling to the point with the arrow keys. A GOTO may be performed by pressing GOTO while the cursor is on the waypoint. The scale distance for the screen (distance represented by height of screen) is at the lower left corner of the screen. The scale number (directly above the scale distance) may be changed by moving the cursor to the scale number and pressing CLR, or by entering a new number (09). Finally, the Plot Page can be oriented as a "North up", "Ground Track Up", or "Desired Track Up" display (see Section 6.2). Position Page The Position Page is described in Section 3.3. Please refer to that section for further information. 3-10 3.9MAN OVERBOARD The Man Overboard function allows you to set an instantaneous course to a captured position, providing rapid response to an emergency situation. To activate the Man Overboard function... · Press MOB twice. The above page will be displayed and the present position will be captured in a waypoint named, "MOB." · Press ENT to navigate to the Man Overboard waypoint. A navigation page will be displayed; select the desired page with the softkeys. 3.10 SAMPLE TRIP Now that you have gained a basic understanding of the GPS 75, you are ready to embark on a sample trip. Your GPS 75 is factory initialized with a position of N39°, W095°. A waypoint named GARMIN, located at GARMIN's Lenexa, Kansas facility, is also provided. Just for fun, let's go to GARMIN! Turn on your GPS 75. The power on notices will be displayed followed by the Satellite Bar Graph. The GPS 75 is ready to accept your commands. 3-11 Select the simulator mode... · Press PWR/STAT to select a Status Page. · If the Auxiliary Page is not displayed, press the softkey underneath the AUX banner to select it. · Use the right arrow key to highlight "Op Mode", press ENT. ENT · If the operating mode field does not already display "Simulator", move the cursor with the arrow keys to that field, and press CLR until it does, followed by ENT. The unit is now ready to start the simulation. NAV Check the present position... POSN Softkey if needed *Plus · Press NAV to display a navigation page. · If the Present Position Page is not displayed, press the POSN softkey to select it. Note the present position. We will change the position to N39° W95°. (If the unit is set to display UTM coordinates, refer to Section 6.3 to change the coordinates to latitude and longitude.) 3-12 · Move the cursor to the latitude hemispheric designator with the arrow keys. Press CLR if you need to change this designator from "S" to "N". Press ENT. · With the cursor on the latitude degrees, press "3" and "9", then ENT. (You may need to enter "0" for minutes and/or seconds to clear these fields, if they are shown.) · Move the cursor to the longitude hemispheric designator. Follow the same sequence as above to complete longitude entry. NOTE: The sample illustrations in this section assume that the factory default settings, including the selection of nautical units (knots, nautical miles), have not been changed. If these settings have been changed, the unit may display slightly different data than presented here. Changing the unit set-ups is covered later in Chapter 6. Check the GARMIN waypoint... WPT *Plus LIST softkey if needed · To verify that the "GARMIN" waypoint is in memory, press WPT to select a waypoint page. · If the Waypoint List Page is not displayed, press the LIST softkey to select it. Verify that the waypoint, "GARMIN", is on the list. If it is, you may skip the next three steps. NOTE: If the Waypoint List Page is full, use the arrow keys to scroll through the rest of the list until you locate the "GARMIN" waypoint. · If the "GARMIN" waypoint is not listed, you must add it to the GPS 75's memory before you can activate the GOTO function. Press the WPT softkey. · Move the cursor over the waypoint name field with the arrow keys. Enter "G", "A", "R", "M", "I", "N". Press ENT. Remember to use the arrow keys to select the letter you WPT 3-13 want (e.g., to get the letter "G", press the "3" key and then the left arrow). · Enter the coordinates for the "GARMIN" waypoint using the same method described for setting the present position (see Section 3.3). Note, however, that depending on the unit setups, Lat/Lon coordinates will be entered in one (degrees only), two (degrees/ minutes) or three (degrees/minutes/seconds) fields. These setups are covered later in Chapter 6. Refer to the table below for the proper location numbers to enter: Setup Degrees Only Degrees/Min/Sec Latitude N38.94992° N38° 56' 59.7" Longitude W94.74638° W94° 44.782' W94° 44' 46.9" Degrees/Minutes N38° 56.995' · With the coordinates entered, you are ready to proceed with the GOTO function. GOTO MOB GOTO GARMIN... · Press GOTO/MOB. The GOTO Page is displayed with the cursor under the GOTO waypoint name. · Enter the waypoint name, "GARMIN" with the alphanumeric keys and the arrow keys. Press ENT. Enter "GARMIN" with · A navigation displayed. page is then alphanumeric and arrow keys. ENT · If the Navigation Summary Page is not shown, select it with the NAV softkey. *Plus NAV softkey if needed 3-14 A Faster GOTO... At this point, we will take a very brief detour. You may recall from Section 3.7 that there is an alternative to typing all those letters in. Let's try it. · First we must cancel the existing GOTO by pressing GOTO/MOB, CLR, and ENT. This calls up the GOTO Page, clears the destination and then confirms that no GOTO destination is desired. · Select the Waypoint List Page by pressing WPT and then the LIST softkey, if needed. · With the right arrow key, move the cursor to the GARMIN waypoint. GOTO MOB · Press GOTO/MOB. The waypoint "GARMIN" is automatically carried over to the GOTO Page. (You can "import" waypoints to the GOTO Page from several other pages, including the Nearest Waypoint Page and the Plot Page, simply by highlighting the desired waypoint.) ENT · Press ENT. A navigation page is 3-15 then displayed. · Select the NAV Summary Page with the NAV softkey. Now back to our trip. Set the Simulation Speed... · With the arrow keys move the cursor to the ground speed field. (If this field does not currently indicate "GS", for ground speed, highlight that field with the left arrow key and press CLR until it does.) ABC 1 MNO 5 ENT · Enter a ground speed of 15 knots by pressing "1", "5", and ENT. (The GPS 75 will accept speeds of up to 90 knots.) The simulation speed is now set and the GPS 75 is simulating a trip from coordinates N39° W95° to the "GARMIN" waypoint (our Lenexa, KS facility). Examine the Navigation Information... At this point, you can explore the capabilities of the GPS 75. While you are on the Navigation Summary Page, you may want to examine other information not currently displayed (see Section 3.8). · As the unit is navigating, you will notice the Range (RNG) to GARMIN decreasing. If you wish to see the distance back to where you started from, highlight this field (top right) with the arrow keys, and press CLR until distance made good (DMG) is displayed. · Highlight the ground speed (GS) field (bottom right) and press 3-16 CLR until the estimated time enroute (ETE) is displayed. · Highlight the ground track (TRK) field (bottom left) and press CLR until groundspeed (GS) is displayed. · Highlight the bearing (BRG) field (top left) and press CLR until ground track (TRK) is displayed. You now have an entirely different Navigation Summary Page that should look something like this: Let's Look at a Different Navigation Page... · Move the cursor to the page options with the arrow keys. · Select the Graphic CDI Page with the CDI softkey, (the "3" key in this case). 3 · The Graphic CDI Page shows the "highway" display. Note the ground track (TRK), destination waypoint, and ground speed (GS), on the top line. On the bottom line, bearing (BRG), range (RNG), and estimated time enroute (ETE), are displayed. 2 3-17 Our Next Stop, Position Page... the Present CLR · Select the Present Position Page with the POSN softkey. Note that ground track (TRK) and ground speed (GS) are shown on the top line, followed by the current latitude and longitude on the next two lines. · Highlight the cyclic field at the bottom of the page and toggle between current time and altitude with CLR. The Plot Page (last one)... · Move the cursor to the page options with the arrow keys. · Select the Plot Page with the PLOT softkey. 1 The Plot Page will plot your ground track and/or an active route. (The setups for this page are covered in Section 6.2.) The top left corner indicates a "Track Up" display. A "North Up" display would be shown as "000" and a "Desired Track Up" display is also available. The top right corner shows the destination waypoint. 3-18 The scale setting is shown in the bottom left corner. · Highlight the scale setting field with the arrow keys and change the scale setting with CLR. You may also change the scale settings with the number keys (0-9). Finally, you may identify waypoint shown on the Plot Page. · Select a scale setting that allows you to see the destination waypoint (GARMIN). · With the arrow keys, highlight the waypoint shown on the Plot Map. Once highlighted, the waypoint name is shown. CLR Experiment with your GPS 75. You are on your way to mastering the GPS 75. If you let the simulator run, you will eventually get a message, "Approaching GARMIN", just prior to reaching the waypoint. Press PWR/STAT to view the message; and again to return to the Plot Page. You may also want to: · Press NAV, WPT, GOTO, or any other key to become more familiar with the available pages. · Practice using the softkeys and cyclic fields to display new information. · Change the simulation speed (faster or slower). · Read Chapter 6 on Unit Customization and set up the unit to your preference. · Stop the simulation. You can stop the simulation by turning the unit off (press and hold PWR/STAT), or go to the "OP Mode" set up and change to the "Normal" or "Battery Saver" modes (see Section 6.1). 3-19 There are 3 route pages in the GPS 75. The softkeys at the bottom of each page allow cycling through each page: RTE (route definition), ACTV (active route), and LIST (route list). 4.2CREATING AND COPYING A ROUTE The Route Definition page allows you to create, change, review, copy, and activate routes. Remember that route 0 is always the active route. If you create a route in route 0, you should copy it into an empty storage route (1-9). When you activate a storage route 1-9, it will be copied to route 0 for activation. Route Definition Route # Field Route Action Field Desired Track Waypoint List Leg Distance Press the RTE key. If you are not already on the Route Definition Page, press the RTE softkey. On the route number field, you may choose between routes 0 through 9 with CLR. Next to this is another cyclic field which allows you to activate the route, clear the route, copy the route to another location, or invert the order of the waypoints in a route and activate it. The arrow keys allow you to scroll through the list of waypoints in a route. To Create a Route... · Move the cursor to the route number field and press CLR until you find an empty route. · Scroll to the first blank waypoint name field and type in a waypoint you wish to put in the route. · Press ENT. · Repeat this process for each waypoint you want to add, up to a total of 20. 4-2 To copy a route... · Select the Route Definition Page (RTE). · Highlight the route number field and select the route number to copy from with CLR. · Highlight the route action field with the arrow keys and press CLR until ">Copy To>" is displayed. · A third field now appears in the top right corner. Highlight this field and select the destination route number with CLR. · Press ENT. The route is now copied. 4.3ACTIVATING ROUTES Routes are activated on the Route Definition Page also. You may activate any route in the displayed order, or in reverse order. (NOTE: Remember, when a new route is activated, the previous contents of route 0 will be overwritten. If you wish to save route 0, be sure to copy it to an empty route first.) To activate a route... · Select the Route Definition Page (RTE). · Highlight the route number field and select the route number to activate with CLR. · Highlight the route action field, and with CLR select ">Activate?". · Press ENT to activate the route. To invert a route... · Follow the same steps as above for activating a route, but select, ">Invert?" at the route action field. · Press ENT to activate the route in an inverted order. 4-3 4.4EDITING ROUTES To Edit an Existing Route... · Select the Route Definition Page (RTE). · Highlight the route number field and select the route you wish to edit. · To insert a waypoint into the route, highlight the waypoint you want to place the new waypoint in front of. Type in the new waypoint name. Press ENT. The new waypoint is added to the route. · To delete a waypoint from the route, highlight the waypoint you wish to delete. Press CLR and ENT. · If you attempt to add a waypoint to a route that already contains 20 waypoints, you will be informed with the message, "Route is Full". NOTE: You may also edit a route from the Active Route Page (see Section 4.6). 4.5DELETING ROUTES You may delete an unwanted route from the Route Definition Page. To delete a route... · Highlight the route number field and select the route you wish to delete with CLR. · Highlight the route action field and select ">Clear?" with the CLR key. · Press ENT to delete the route. 4-4 4.6ACTIVE ROUTE Active Leg Range Waypoint List Cyclic Column: - ETE - ETA - DTK The Active Route Page displays the waypoints of the active route starting with the "active from" and "active to" waypoints on the top line. Press the ACTV softkey to select this page. The Waypoint List displays route waypoints starting with the "active to" waypoint. For each waypoint, additional information is available. The first column displays Range (RNG). The second column is a cyclic field that displays Estimated Time Enroute (ETE, in hours/minutes or minutes/ seconds, as appropriate), Estimated Time of Arrival (ETA), or Desired Track (DTK). You may scroll through the waypoint list with the arrow keys. To edit the active route... · To insert a waypoint, highlight the waypoint you want to place the new waypoint in front of. Type in the new waypoint name. Press ENT. The new waypoint is added to the route. · To delete a waypoint, highlight the waypoint you wish to delete. Press CLR and ENT. 4.7ROUTE LIST The Route List Page displays a list of all routes currently stored in memory. Press the LIST softkey to select this page. The Route List Page displays the route numbers (far left), beginning waypoint, and final destination waypoint. You may also activate or delete a route from the Route List Page. 4-5 To Activate a Route... · Highlight the route you wish to activate with the arrow keys. · Press ENT. The Route Definition Page is displayed with the ">Activate?" action highlighted. · Press ENT to Activate the route. To Delete a Route... · Highlight the route you wish to delete with the arrow keys. Press CLR. The Route Definition Page is displayed with the ">Clear?" action highlighted. · Press ENT to delete the route. Building Routes with AutoStore... The GPS 75's AutoStoreTM feature is the quickest and easiest way to build a route as you go. With autostore, each time you turn on a new track, pass a significant landmark, or reach some location of interest, you can save the location and create a route at the same time. Each autostore waypoint can be added to the same route as you are traveling. · With the unit operating in 2D or 3D Navigation mode, press the AUTOSTO key to save your starting location. · At this point, you may change the AutoStore name, if you wish (see Section 3.6). · Select an empty route to store the waypoint by highlighting the "Append to Route >_?" field and pressing CLR until the desired route number is displayed. · Press ENT to add the waypoint to the selected route. · Repeat these steps each time you arrive at a location you wish to add to the route, up to a total of 20 waypoints per route. 4-6 CHAPTER 5 ADVANCED WAYPOINT FEATURES 5.1NEAREST WAYPOINTS An important feature of the GPS 75 is the ability to display up to nine nearest waypoints, within 100 nautical miles of your present position. In an emergency, you may use the nearest waypoint feature to find the closest point of safety in your area. As was discussed in Section 3.4, you may access the waypoint pages by pressing the WPT key. If the Nearest Waypoint Page is not currently displayed, press the NRST softkey. This page displays the waypoint names including bearing and range from present position. You can scroll through the waypoints listed by using the arrow keys. To GOTO a Nearest Waypoint... · Move the cursor to the desired waypoint name with the arrow keys. · Press GOTO and ENT. 5.2PROXIMITY WAYPOINTS The Proximity Waypoint Page allows you to define an alarm circle around a waypoint. This feature is useful in defining an area around a rock, reef, or restricted waters. When you approach one of these waypoints, the GPS 75 will notify you with an alarm tone and the message, "Prox Alarm-[waypoint name]," if you enter the alarm circle. The GPS 75 allows you to define a maximum of nine proximity waypoints. Scroll through the proximity waypoint list using the arrow keys. 5-1 To set a proximity waypoint... · Select the Proximity Waypoint Page with the PROX softkey. · Select a blank waypoint name field with the arrow keys. · Enter the waypoint name. (NOTE: If neither the waypoint name nor the location exists in memory, the Waypoint Definition Page will be displayed. You must then enter the waypoint location. See Section 3.4 to create a waypoint.) · Press ENT. · Enter the proximity alarm distance. · Press ENT to enable proximity alarm. If the newly created proximity alarm circle overlaps with an existing proximity alarm circle, you will be informed of the overlap with the message "Proximity Overlap". As long as the overlap remains, this message will be displayed each time the GPS 75 is turned on. (WARNING: If you enter the overlap area, the unit will only inform you of the nearest waypoint.) 5.3REFERENCE WAYPOINTS In section 3.4, we discussed creation of waypoints by entering the latitude and longitude position. Another way to create a waypoint is by referencing an existing waypoint. By indicating the bearing and range from a reference waypoint, the GPS 75 is able to compute a latitude and longitude location for the new waypoint. To create a waypoint referencing another... by · Select the Waypoint Definition Page with the WPT softkey. · Highlight the WPT name field and enter the new waypoint name. · Press ENT. · Highlight the ">Ref:" field and enter the existing waypoint that will be used as reference. (If the reference field is not currently shown, highlight that cyclic field and press CLR until it is displayed.) · Press ENT. 5-2 · Enter the bearing and distance from the existing waypoint to the new waypoint. · Press ENT. A latitude and longitude location for the new waypoint should now be displayed. 5.4WAYPOINT SCANNING Throughout this manual, each time we have encountered a waypoint name field, we have entered the waypoint name with the alphanumeric keys. An alternative is to use the waypoint scanning feature. To Scan for a Waypoint... · As an example, use the GOTO waypoint field. Press GOTO. · The waypoint name field is highlighted and may be blank or may already show a GOTO destination. If the waypoint name field is not blank, press CLR. · Press WPT. A waypoint name is now displayed. · Scan for the desired waypoint with the arrow keys. (NOTE: As you are scanning, up to nine nearest waypoints will be shown first; followed by the entire list in numeric and alphabetical order.) To limit the scanning range, you may specify the first letter(s) or number(s) of the waypoint name. To Perform a Limited Scan... · For this example, select the Waypoint Definition Page with WPT and the WPT softkey, if needed. · Highlight the waypoint name field with the arrow keys. · If this field is not blank, press CLR. · Enter the first character of the waypoint name. enter the letter "G". For this example, · Press WPT. Use the arrow keys to scan through all waypoints that begin with the letter "G". 5-3 CHAPTER 6 AUXILIARY FUNCTIONS The GPS 75's auxiliary pages allow you to do utility and setup functions to customize your unit. The 11 auxiliary pages are accessible from the auxiliary menu (see Section 3.2) by highlighting the page you want and pressing ENT. The softkeys allow changing to previous (PREV) and next (NEXT) pages. The AUX softkey takes you back to the Auxiliary Menu Page. 6.1OPERATING MODE AND FILTERS From this page, you may change between various operating modes by highlighting the "OPERATING MODE" field and pressing CLR. You may select simulator mode, normal mode, or battery saver mode. (See Section 2.7 for a description of each mode.) Also from this page, the position and velocity filters may be changed. Changing the filter settings will alter the GPS 75's response time to changes in track or ground speed. To change the filter settings, highlight the appropriate field and cycle through the filter settings (automatic, fast, medium, and slow) with CLR. The "Fast" setting will provide instantaneous response (three seconds maximum response time) to changing conditions. The "Medium" (approximately 20 seconds) or "Slow" (approximately 120 seconds) settings may be more desirable for slow speed operation where frequent ground track changes will occur (e.g. sailing or hiking). It is highly recommended that you select the "Automatic" setting for most applications. 6-1 6.2PLOTTING SETUP The Plotting Setup Page is used to configure the Plot Page and select the types of information that will be displayed. The first cyclic field defines the orientation of the plot map. The top of the plot map may be North (North Up), the direction of your current ground track (TRK Up), or the direction of the active leg of a route (DTK Up). To select the desired option, highlight this field and press CLR. Your present position and nearby waypoints are displayed on the plot map at all times. The second cyclic field determines what additional information will be displayed on the plot map. You may display the active route and a stored ground track showing where you have been, only the active route, only the ground track, or neither. The ground track is stored at a frequency that you can define either by: Time "Interval", "Resolution", or "Distance". Select the desired frequency unit by highlighting this field and pressing CLR. To store the Ground Track at selected time Intervals... · Highlight the storage frequency field (third line) and select "Interval" with CLR. · Press ENT. · Enter the time interval between stored positions starting with hours, then minutes, then seconds. Press ENT after entering data in each numeric field. To store the Ground Track by Distance... · Highlight the storage frequency field and select "Distance" with CLR. · Press ENT. · Enter the distance, and press ENT. When your position moves this distance in any direction, a new position is added to the stored ground track. NOTE: "Distance" storage may be preferable to "Resolution" storage if the ground track will include a large number of turns. 6-2 If the planned course will be primarily straight line travel, you should select "Resolution" storage. In this application, considerably less memory is used for the same distance traveled. To store the Ground Track by Resolution... · Highlight the storage frequency field and select "Resolution" with CLR. · Press ENT. · Enter the resolution range, and press ENT. When your position moves this defined range off a projected courseline, a new position is added to the stored ground track. The track storing function may be turned on and off by highlighting the "Track>" field and pressing CLR. From this same field, the track may be set to "wrap" around through available memory (deleting the oldest track information and using the memory to store the new track position). The amount of memory, used at any given moment, is shown on the bottom line. When available memory is filled or the track is no longer needed, it may be cleared by highlighting "Clear?" and pressing ENT. 6.3UNITS/HEADING SETUP The Units/Heading Page is used to select the units to display for position, distance, speed and heading information. Select the desired position units by highlighting the "POSN" field and pressing CLR. You may choose between degrees only (hddd.ddddd°); degrees and minutes (hddd°mm.mmm'); degrees, minutes and seconds (hddd°mm'ss.s"); UTM/ UPS; or various regional grid coordinates. Select the desired distance and speed units by highlighting the "NAV" field and pressing CLR. You may choose between nautical (nautical miles/knots/feet), statute (statute miles/miles per hour/feet), or metric (kilometers/kilometers per hour/meters) units. Heading information can be displayed referencing magnetic north (automatically calculated or user-defined), referencing true north or referencing calculated grid headings. Select the desired heading reference by highlighting the "HDG" field and pressing CLR. When the "Auto Mag Var[iation]" option is selected, heading information will reference the 6-3 automatically calculated magnetic variation shown. For most applications, the "Auto Mag" feature will provide accurate heading information. If the auto-magnetic variation is not correct, you may define the magnetic variation by selecting "User Mag Var". If the "User Mag Var" option is selected, the magnetic variation is then entered. To enter a user-defined magnetic variation... · Highlight the "HDG" field and select "User Mag Var" with CLR. · Press ENT. · The variation direction is highlighted. press CLR. · Press ENT. · Enter the variation degrees and press ENT. 6.4ALARMS AND CDI SETUP From the Alarms/CDI Page, you may define three alarms (and turn them on or off) and configure the graphic CDI to your preference. Alarms are available for anchor drift, arrival at a destination waypoint, and an alarm clock. To set the anchor alarm... · Highlight the anchor alarm distance and enter the maximum allowable drift. CAUTION: Setting the anchor alarm to its smallest value (.01 unit) may result in a false alarm. Please note that under certain circumstances (below average satellite geometry, degraded reception, etc.) the position error of the GPS 75 may be greater than the lowest scale settings available for this alarm. · Press ENT. · The on/off cyclic field is highlighted. If the alarm is not turned on, press CLR. To set the arrival alarm... · Highlight the arrival alarm distance and enter the distance from a destination at which you want the alarm to sound. 6-4 To change the direction, · Press ENT. · The on/off cyclic field is highlighted. If the alarm is not turned on, press CLR. To set the alarm clock... · Highlight the alarm clock time and enter the desired alarm time. NOTE: The alarm time may be either UTC or local time depending on the setting on the Date/Time Page. (See Section 6.5.) · Press ENT. · The on and off cyclic field is highlighted. If the alarm is not turned on, press CLR. The graphic CDI may be configured to the desired scale and steering orientation. Scale settings of ±.10, .50, 1.00, 5.00, 10.0, or 50.0 units (nautical miles, statute miles, or kilometers) are available. The scale setting represents the distance from center of the CDI to either end. You may change the scale setting by highlighting the "CDI Scale" field and pressing CLR. The CDI "Steer To" orientation determines how you interpret the "D-Bar" when it moves. You may select "Steer to >Center" or "Steer to >D-Bar" by highlighting that field and pressing CLR. A "Steer to Center" orientation, in effect, displays your position as the "DBar" and the center of CDI is the desired track. Thus, when you are off course, you would steer towards the center of the scale. A "Steer to DBar" orientation is just the opposite. The "D-Bar" represents the desired track and the center of the scale represents your position. When you are off course, you then steer towards the "D-Bar". 6.5DATE/TIME The Date/Time Page displays the UTC (Coordinated Universal Time or Greenwich Mean Time) date and time. The local offset or time difference is shown on the next line. For time zones west of the UTC zone, enter a negative offset. (The minus sign is on the "9" key.) Appendix E contains a list of time offsets. The cyclic field for "Display" options determines which time, UTC or Local, will be displayed on other GPS 75 pages. To change this option, highlight this field and press CLR. 6-5 The timer field can be selected as "Count Up" or "Count Down" by highlighting and pressing CLR. To clear the count up timer, highlight each time field, press CLR, then ENT. To set the count down timer, enter the hours, minutes, then seconds to count down from. The "Timer Expired" message will be displayed when the timer reaches zero. 6.6AUDIO AND DISPLAY SETUP From the Audio and Display Page, you can turn the message and/or keypad tones on and off, change the display contrast, and change the timeout for the display backlighting. Select the desired tone option by highlighting the "Tone>" field and pressing CLR. To change the display contrast... · Highlight "Change Contrast?" and press ENT. · The contrast bar is highlighted. to change the contrast level. Press the left or right arrow key · When the desired contrast level is reached, press ENT. The Backlighting Timeout determines the length of time the display and keypad backlighting will remain on. If no keys are pressed for the specified time, the backlighting will automatically shut off. Set the timeout interval by highlighting that field, entering the desired timeout and pressing ENT. 6.7INTERFACE SETUP From the Interface Page, you may select the input or output format needed to connect your GPS 75 to other equipment: plotter, autopilot, another GPS 75, a PC, etc. You may select no input/output (NONE/ NONE), NMEA output, GARMIN input/output, or RTCM input by highlighting the cyclic field and pressing CLR. When the NMEA 6-6 output is selected, a second cyclic field appears. From this second field, you may select the desired NMEA format: NMEA 0180, NMEA 0182 or NMEA 0183. A second cyclic field also appears when the GARMIN input/output is selected. The GARMIN option allows you to exchange data such as waypoints, routes, track logs and satellite almanac data with another GPS 75 or with a PC-compatible computer. You may select between acting as a HOST to data exchanges, REQUESTing data, or SENDing data by highlighting the cyclic field and pressing CLR. When the HOST option is selected, all interface operations are controlled by another GPS 75 or PC-compatible computer. When the REQUEST or SEND options are selected, the GPS 75 will control the data exchange. With the REQUEST or SEND options, a third cyclic field appears where you may define the type of data to be exchanged: routes, track log, waypoints, almanac, or proximity waypoints. Select the desired type of data by highlighting this field and pressing CLR. Press ENT to begin the data transfer. During the data transfer process, the number of data packets being exchanged will be displayed. Note: When exchanging data between two GPS 75s, one should be set to HOST and the second should be set to the desired data transfer option (REQUEST or SEND). The GPS 75 can use Differential GPS (DGPS) corrections in RTCM SC104 version 2.0 format. DGPS corrections in this format can be received from an external device (capable of output in 6 of 8 byte format as specified by RTCM SC-104, version 2.0) by connecting the device to the input port on the back of the GPS 75 and selecting an RTCM input interface mode. Two RTCM input modes are available, one which allows no output and another which allows NMEA output in 0180, 0182, or 0183 format. 6.8MAP DATUM SELECTION Select the desired map datum reference from the Map Datum Page. You may choose from 102 pre-defined map datums, or you may define your own. If the map/chart you are using specifies a reference datum, select that datum on your GPS 75. If the map/chart does not specify a reference datum, you may select each datum applicable to your region until you find the datum that provides the best positioning at a known point. NOTE: The GPS 75 is shipped from the factory with the WGS 84 datum selected. 6-7 To change the pre-defined datum... · Highlight the "Change?" field and press ENT. · With the arrow keys, find the desired datum and highlight it. · Press ENT. The new datum is selected The user-defined datum option allows you to custom-tailor a datum reference from which all position coordinates are calculated. All entries are defined as differences from the WGS 84 standard datum. CAUTION: Selection and use of the user datum function is for individuals experienced in the use of map datums. If the pre-defined map datums do not correspond to the chart you are using and you are unsure of the correct entries required to correspond to that chart, contact the chart manufacturer. Incorrect entries for a user-defined datum may result in substantial position errors. 6.9BEACON RECEIVER SETUP The Beacon Receiver Setup Page allows you to control a GARMIN Beacon Receiver for Differential GPS (DGPS) position corrections. Before the beacon receiver can be controlled by the GPS 75, it must be connected to the I/O port on the back of the unit and the "RTCM/ NMEA 0183" mode must be selected on the Interface Setup Page. If this interface mode is not selected, the GPS 75 will only display the message "No RTCM/NMEA 0183 interface selected" on the Beacon Receiver Setup Page. Once the correct interface is chosen, the Beacon Receiver Setup Page will display as shown above. The "Tuned To:" field is the frequency in kHz to which the beacon receiver is currently tuned or is attempting to tune. Below this field is a bit rate cyclic field which allows you to choose between bit rates of 25, 50, 100, and 200 bps by pressing the "CLR" key which the "Bit Rate" field is highlighted. When you first select the Beacon Receiver Setup Page from the Auxiliary Menu, (after selecting an RTCM/NMEA 0183 input/ output interface mode), the GPS 75 will automatically try to tune the last 6-8