Northstar 941X Reference Manual SOFTWARE VERSION 2.05 30 SUDBURY ROAD ACTON, MASSACHUSETTS 01720 (508) 897-6600 Copyright 1994, 1995, 1996 Northstar Technologies P/N GM1100 Doc.
WARRANTY Northstar Technologies, a Division of CMC Electronics, Inc., warrantees its products to be free from defects in material and workmanship for a period of two (2) years from the date of shipment to an authorized dealer. This warranty applies to the original purchaser or subsequent owner.
IMPORTANT NOTICE Although Northstar products are designed to be very useful navigation tools, they are not substitutes for good seamanship. The prudent navigator should never rely on any single device as the sole source of navigation guidance. Exercise caution and good judgment whenever underway.
! 1 CONTENTS ! The Northstar 941X Introduction ................................................................. 2 Upon First Start-up ...................................................... 2 Using This Manual........................................................ 3 941X Features ............................................................... 4 941X Functions ............................................................. 5 Comparing GPS and Loran ..........................................
4 Creating Waypoints and Routes Entering Data.............................................................. 36 Creating Waypoints .................................................... 37 Avoidance Areas ......................................................... 39 Waypoint Lists ............................................................ 41 Coordinate Options .................................................... 42 Updating Waypoint Coordinates ............................... 42 Editing Waypoints ...........
8 9 Other Special Functions Alarms .........................................................................68 Screen Backlighting .....................................................71 TideTrack™..................................................................71 Internal Differential Beacon Receiver ....................... 74 Customizing the 941X Time of Day................................................................. 78 Display Options ..........................................................
Figures FIGURE 1—MAX. POSITION VARIANCES WITH UNCORRECTED GPS.... 8 FIGURE 2—YOKE MOUNT DRILLING DIMENSIONS ........................... 102 FIGURE 3—REAR CONNECTORS ...................................................... 103 FIGURE 4—941X GPS-ONLY ANTENNA (AN145 & AN150).......... 105 FIGURE 5—941X COMBO GPS/DGPS ANTENNA (AN190)............. 105 FIGURE 6—STRIPPING THE COAX CABLE JACKET ............................ 107 FIGURE 7—FLARED CABLE BRAID ..................................................
1 Introducing the Northstar 941X Introduction 2 Upon First Start-up 2 Using This Manual 3 Features 4 Functions 5 Comparing GPS and Loran 5 Mounting 9 Special Functions 9 The Display Screen 10 Interfacing Capability 11 T his section introduces you to the Northstar 941X navigator, outlining its various operational functions, installation configurations, and specifications.
Introduction T HE NORTHSTAR 941X combines 12-channel GPS navigation with Differential GPS capability, a high-definition display, loran compati- bility, built-in tide data up to the year 2010, and many other navigation features. For the ultimate in GPS accuracy, the 941X may be purchased as the 941XD, featuring an internal DGPS (Differential GPS) receiver.
The alarm message NO GPS POSITION FIX, along with its time and date, are shown in the RECENT ALARMS box. The word NEW in the upper right corner of the box indicates that this is a previously unacknowledged message. This sequence is a normal part of powering-up the 941X for the first time, as it notifies you that it is in the process of acquiring satellite information necessary for navigation. It normally takes only two to five minutes to acquire this data, after which the 941X is ready to navigate.
Features Upon using the 941X, you’ll see that you can actually learn to operate the system’s various features without constant referral to this manual. After you’ve read through it once, you won't have to refer to it very often again. Since the 941X anticipates your most frequent requests for navigation information, accessing most functions requires only one or two button pushes. By minimizing the attention needed to navigate, you can now devote more time to other aspects of your trip.
Functions Five keys on the 941X instantly select the most commonly used functions, as described below: POSITION displays position coordinates as 1) GPS lat/lon coordinates 2) loran TDs, if you have a loran receiver interfaced to the unit 3) or calculated “Phantom Loran” TDs if you don't. Speed- and Course-Over-Ground, and Time and Date are also displayed. An alternate position screen plots your position graphically, along with any nearby waypoints and your track history.
from a chart or other reference. Repeatable accuracy refers to the ability to return to a position whose coordinates you have previously recorded with the same equipment.) Developed by the United States Department of Defense (DOD) the GPS system of 21 active satellites (with 3 additional spares) literally encircles the earth with navigation information. GPS is offered in two forms: for military users and for civil users.
“beacons,” the transmitters are being situated at various locations along the U.S. coastline and Great Lakes, most of which are former marine radiobeacon sites.) With DGPS, navigators are guaranteed position accuracy on the order of 2-5 meters 50% of the time, and to 10 meters 95% of the time (usually, much better). Lat/lon positions displayed to thousandths of minutes (roughly 6 feet) are common with DGPS.
Loran, however, isn’t as proficient as GPS in absolute accuracy, or visiting a spot for the first time. Since it transmits at a relatively low frequency (100 kiloHertz—similar to that on your AM radio), your ability to get an accurate position “fix” is directly related to: 1) your distance from the loran transmitters, and 2) the weather between you and the transmitters. It’s in these two areas that GPS consistently excels when it comes to absolute accuracy.
getting more If you need a higher level of accuracy than what basic GPS provides, accuracy there are two choices available to you: 1. Use Differential GPS by installing a Northstar internal differential beacon receiver (or use an externally-located Northstar differential beacon receiver), or other source of differential corrections for your 941X. DGPS should provide better than 10-meter accuracy (repeatable and absolute) 95% of the time. See “Using GPS” on page 25 for more information. 2.
real-time loran TDs. These features greatly ease the transition from using loran to using GPS. See page 30 for further details on using loran TDs. plotter functions The 941X’s plotter provides a picture of your position, and of what is around you. Nearby waypoints, avoidance areas, and a lat/lon grid may be displayed along with an image of your boat.
any oil or grease on the screen. Whenever possible, avoid touching the window with your fingers, as natural oils from your hand will temporarily degrade the characteristics of the window and cause your fingerprints to appear as bright reflections. These will disappear when the screen is cleaned as described above. CLEANING HINT Pre-packaged moist towellettes (especially those containing a small amount of alcohol) are excellent for cleaning the display window.
Page 12 1 — Introduction Rev.
2 Using the Controls POWER Key 14 CONTRAST Key 14 SAVE/MOB Key 15 Function Keys 16 Menu Keys 17 Cursor Keys 17 Keypad 17 Special Display Windows 18 T HIS SECTION describes each of the Northstar 941X's controls. Use this section for learning what each control does and for an overview of using its various functions. Rev.
T POWER Key HE MAJOR FUNCTIONS of each of the 941X's controls are described in this section. Press the POWER switch briefly to turn on the 941X. The unit displays a special startup screen that includes an owner-identification message which you may customize to aid in theft-prevention. Next, the 941X displays the results of the internal self-tests that are automatically run each time the unit is turned on. Finally, navigation data is displayed.
SAVE/MOB Key The SAVE/MOB key is used to save your current position as a waypoint. It does this in either of two ways, depending on whether you press the key briefly, or press and hold it. saving a waypoint Press the SAVE/MOB button briefly to simply store your position. This new waypoint will automatically be given a name, such as –S002–, where the letter S indicates a saved waypoint, and the 3-digit number increases by one every time you save a waypoint.
To leave MOB mode and return to normal navigation, press SAVE/MOB for at least three seconds. Function Keys The five function keys located below the display screen control what the 941X is doing. Any function key may be pressed at any time to display the information you need to see. POSITION key The POSITION key displays your position coordinates, or displays a plotter screen to show your position graphically, relative to nearby waypoints and your track history.
NAV LOG key The NAV LOG key displays the waypoints you have passed, and allows you to change those ahead of you. See “What NAV LOG Does,” on page 64, for more information. “How am I doing?” Menu Keys The five round MENU keys on the right side of the display screen are used for different purposes depending on what function is currently being used or displayed. The function of each key is labeled on the screen, and pressing the key performs the displayed function.
right side of the field. If you make a mistake, you can press CLEAR to clear the entire number and re-enter it, or you can press the left-arrow cursor key to reenter particular digits, one at a time. entering letters When the 941X is expecting letters to be entered, such as waypoint names and descriptions, the operation is slightly different. Each key is labeled with three letters (or other special characters) and a digit.
information Information windows are displayed while you are entering data or using windows control functions. They give you extra details pertaining to what is about to happen, or let you acknowledge a command. Information windows always appear with the word “INFO” in a small box. question windows Question windows appear when the 941X needs to know more about what you want to do. A question mark will always appear in this type of window.
Page 20 2 — Using the Controls Rev.
3 Basic Navigation Displaying Position, Heading & Speed 22 Position Plotter 22 Using GPS 25 Using Loran 30 Using Phantom Loran 32 T HIS SECTION describes the most basic—yet important—navigation function available in the Northstar 941X: determining your position. Position coordinates may be determined from the GPS satellite system, or you may display loran coordinates if you have connected a loran receiver.
Displaying Position, Heading & Speed T O DISPLAY the coordinates of your current position, simply press the button marked POSITION. A screen is displayed showing your position coordinates at the top, and your Course-Over-Ground (COG) and Speed-Over-Ground (SOG) at the bottom. (If you see the PLOT screen displayed instead of your position coordinates, just press the POSITION button again). GPS position coordinates are displayed as latitude and longitude.
The image of your boat displayed on the screen points in the direction of your Course-Over-Ground. Remember, this direction may be different from your heading. The boat image shows your actual direction of travel over the bottom, not the direction your boat is headed. If your boat is not moving, the Course-Over-Ground cannot be determined by the 941X, and the direction of the boat on the screen has no meaning.
plotter options To set up the parameters for the display of data on the plotter screen, press the OPTIONS menu key.
You may also choose to freeze the track, so that no more points will be stored and the track will remain unchanged. Pressing the CLEAR TRACK menu key clears the track history displayed on the screen. Press the RETURN menu key to go back to the plotter screen. Using GPS Your 941X contains an internal GPS receiver which is used as the primary source of position data. GPS data is displayed directly on the GPS POSITION screen.
NOTE The 941X’s speed and course readings are the result of instantaneous measurements derived from satellite signals. GPS speed is updated every second. However, you may average these readings by changing the “GPS speed averaging” value (see page 87). datum In the center of the screen, the name of the datum currently in use is displayed. The datum describes the reference of the chart you are currently using (the reference datum used is indicated on each chart).
For further information on operating in DGPS mode, refer to “Internal Differential Beacon Receiver,” on page 74. With DGPS active, you will often see position measurements accurate to about 2-5 meters, speed measurements accurate to about 0.1 knot, and Course-Over-Ground measurements accurate to about 0.5 degree. DGPS corrections remove the errors caused by Selective Availability (SA) and the atmosphere, and provide an accuracy exceeding that obtained by military users of the GPS system.
NOTE On five-channel 941Xs, the last bar at the bottom of the screen will sometimes “jump” around once per second as the 941X receiver sequences among other satellites. The following GPS data is also displayed: ACCURACY: ACCURACY The estimated accuracy of the GPS system to be expected at the current time. Your position readings should be more accurate than this estimate 95% of the time. HDOP: HDOP This is a technical measure of the “quality” of your fix.
The lower part of the screen shows three bar graphs: 1. SNR The Signal to Noise Ratio (SNR) is a good overall measure of overall signal quality, and should be as high as possible. Values of 15 and higher are preferred, while anything below 10 could indicate poor reception. 2. SIGNAL The actual strength of the received signal—should be as high as possible. Varies with distance from beacon transmitter. 3.
MESSAGE OLD CORRECTIONS NOT INSTALLED UNHEALTHY BEACON UNHEALTHY SATS ACQUIRING SATS DGPS IN USE/ OK MEANING No DGPS corrections have been received within the DGPS DATA TIMEOUT limit set in RECEIVER OPTIONS (default is 1 minute), and the navigator has returned to nondifferential operation. See “GPS data timeout” on page 89 for details. A beacon receiver is not installed. The beacon transmitter reports it has problems. Data received from satellites cannot be relied upon.
4. Press the up and down cursor arrow keys to display EXTERNAL LRN as the position source. If you change your mind, press CLEAR to restore the original setting; otherwise, press ENTER, then the RETURN menu key. loran TDs The loran display screen looks like this: Press the L/L TDS menu key several times to select either the particular pair of TDs you wish to use, or the loran-derived latitude/longitude.
INDICATOR SNR BLNK CYC LOCK MEANING Signal-to-Noise Ratio is low—use caution Coast Guard is transmitting a blink signal indicating a probable transmitter problem the receiver has detected a possible cycle slip the receiver has locked onto the loran track point. This is not a warning indicator but an indication of normal performance. Note: These indicators are available only from Northstar 800 lorans.
ber, however, that these calculated TDs will not match exactly the positions of previously recorded TD coordinates obtained directly from actual loran signals. In most areas, errors should not exceed 0.2 microsecond. However, larger errors are possible in areas for which the 941X does not contain accurate, factory-programmed ASF correction points. selecting Phantom Loran " To display Phantom Loran TDs as position coordinates, first select Phantom Loran as the position source, as described below. 1.
choosing L/L or TDs Press the L/L TDS menu key several times to select the particular pair of Phantom Loran GRI Press the SET GRI menu key to change the GRI to be used in calculating TDs you wish to use or to display GPS latitude/longitude. the displayed TDs. Press the up and down cursor keys to display the available GRIs one at a time. When the GRI is correct, press ENTER.
4 Creating Waypoints and Routes Entering Data 36 Creating Waypoints 37 Avoidance Areas 39 Waypoint Lists 41 Coordinate Options 42 Updating Waypoint Coordinates 42 Editing Waypoints 43 Transferring Waypoints to a PC 44 Creating Routes 44 Saving a Route 47 Changing a Route 50 In this section, we’ll learn how to create waypoints, use them to form routes, and change them as necessary. Rev.
Entering Data Before we move on to the sections describing how to enter waypoints and routes into the 941X’s memory, let’s take a break and review the methods for entering data into the unit. Some screens, such as coordinate entry screens, allow entry of numbers only. Others, such as waypoint names, allow entry of letters, digits and " punctuation characters. A typical entry screen will have several items of data displayed.
4. String these waypoints together to form routes 5. Follow these routes 6. Edit or erase waypoints or routes 7. Plot waypoints or routes 8. Transfer waypoints and routes from the 941X to a personal computer, and back again. Creating Waypoints To enter waypoints, press the WAYPTS/ROUTES key. Press the WAYPT LIST menu key and then the ADD menu key. A screen similar to the following is displayed: To store a waypoint permanently in the 941X's memory, first assign it a name.
waypoint coordinates " Waypoint coordinates can be entered as lat/lon coordinates, loran TDs, or as distance and bearing from your present location or from any waypoint in the 941X’s memory. To change the coordinate type from what is currently displayed, press the COORD TYPE menu key until you see the option you want. Enter the waypoint coordinates as previously described on page 36.
avoidance area If this new waypoint is to be used as the center of an avoidance area, enter the warning radius at the bottom of the screen in the WARN RADIUS box. If no radius is entered, the point will be treated as a regular waypoint, and not as an avoidance area. Avoidance Areas You may designate new or existing waypoints as avoidance areas. Avoidance areas are depicted on the PLOT screen as waypoints with circles around them.
As a precaution, once you have designated a waypoint as an avoidance area, the 941X does not allow you to navigate to it. avoidance area alarm " Once you have designated a waypoint as an avoidance area, the 941X will alert you upon penetration of that area. To set the audible avoidance area alert feature: 1. Press the STAR key once to display the ALARMS & BACKLIGHT screen. 2. Be sure that the cursor arrow is in front of the ALARM AUDIO option. 3. Press the EDIT ALARM menu key. 4.
Waypoint Lists Waypoints contained in your 941X can be displayed in any of four ways. Press the WAYPTS/ROUTES function key, then the WAYPT LIST menu key to display waypoint lists. Use the NEXT LIST menu key to select the list that is best for your current situation. Each press of the NEXT LIST menu key displays a waypoint list in the following order: ALPHA, SAVED, AVOID and LOCAL, then starting again at ALPHA.
saved list All saved waypoints (stored by pressing the SAVE/MOB button, and having a name such as –S001–) are listed in order of the time at which they were saved, with the most recent first. avoid list Up to 30 avoidance points within 100 nautical miles are listed in order of their distance from your position. local list In the LOCAL list, up to 30 of the closest waypoints within 100 nautical miles are listed in order of distance from your position.
" To update a waypoint’s coordinates, first sail to the spot where the waypoint will be located. Press WAYPTS/ROUTES, then the WAYPT LIST menu key, to display a list of waypoints on the screen. Press the NEXT LIST menu key, if necessary, to show the local waypoints (in order of distance from your position). Your waypoint should be at or near the top of this list. Use the up and down arrow keys to point to the desired waypoint.
Transferring Waypoints to a PC If you store a large number of waypoints or routes in the 941X, or if your waypoints are the only records you have of important locations, you should consider making a copy of them by transferring them into a personal computer using special transfer software (provided by a third party vendor) and a Northstar loader cable (part #1100-LC).
Press the NEW menu key. A screen is displayed asking you to enter the name of the new route. route name Enter the name of the new route using the keypad and cursor arrow keys, as described on page 36, and press ENTER. The NEW ROUTE waypoints screen will be displayed, ready for you to begin selecting waypoints to add to the route. Rev.
inserting waypoints To add waypoints to the route, press the INSERT menu key. A list of stored waypoints is displayed. Scroll the waypoint list up or down using the cursor keys to designate the desired waypoint, and press ENTER. The selected waypoint is now in the route. Press the NEXT LIST menu key, if you wish, to select different waypoints from the alpha, alpha local or saved lists. (Avoidance points cannot be used as waypoints in a route.) Repeat for each waypoint you wish to enter.
verifying entry As waypoints are entered, the distance and bearing of each leg of your route are displayed on the NEW ROUTE screen. To see an overhead plot of the entire route, press the QUICK PLOT menu key. It is good practice to use these two features to check that the route matches your expectations, ensuring that no errors were made in selecting waypoints. The entire route is displayed, with the plotter scale automatically adjusted to show all of the waypoints.
Press the SAVE menu key on the lower right of the display to instruct the 941X to begin saving a route automatically. A screen is displayed asking you to enter the name of the new route to be saved. route name Enter the name of the new route to be saved, using the keypad and cursor arrow keys, and press ENTER. The 941X displays the message “SAVING TO: [route name]” at the bottom of the ROUTES screen confirming that your route is now being saved. Page 48 4 — Creating Waypoints and Routes Rev.
storing waypoints As you pass the location of each new waypoint, press the SAVE/MOB key to the left of the display (not the SAVE menu key in the lower right of the screen). The boat's location will be saved as a waypoint in the unit's memory, and the waypoint will automatically be added to the route being saved. The waypoint will be stored with a name similar to (0001).
Changing a Route To make a change to a route stored in the 941X's memory, use the EDIT ROUTE function. Press WAYPTS/ROUTES and then the ROUTE LIST menu key to display the ROUTES screen. Use the up or down cursor keys to point to the route you wish to change. Press the EDIT key. The route name is displayed. If you wish to change the route’s name, do so now, then press ENTER. If not, press ENTER to continue.
inserting waypoints To insert a new waypoint, use the up and down cursor keys to move the pointer to the spot between the two existing waypoints where you want to make the insertion, and press the INSERT menu key. A screen listing waypoints is displayed. Move the cursor to select the waypoint from the displayed list, and press ENTER. You will see the selected waypoint now in your route.
To plot an overhead view of the route, press the QUICK PLOT menu key. Page 52 4 — Creating Waypoints and Routes Rev.
5 Waypoint and Route Navigation Quick-Start Waypoint 54 Navigating to Waypoints 55 Navigating Along Routes 59 Restarting the Course Line 61 In this section, we’ll begin navigating to specific waypoints and along routes, and show you how to get back on course, or follow a new course line to your destination. Rev.
Quick Start Waypoint T he 941X’s “Quick Waypoint” feature allows you to enter coordinates and start navigating in one quick and easy sequence. Press the WAYPTS/ROUTES key, and then press the QUICK WAYPT menu key. A screen for entering waypoints appears. Key-in the coordinates of the waypoint (just as you would normally store a waypoint) and press ENTER twice. The 941X stores the waypoint as a “–QUIK–” waypoint, and will immediately begin navigating to it.
WAYPOINT TIP You can specify a waypoint to navigate to, and store it permanently in the 941X’s database in one operation, if you like. While in the QUICK WAYPT entry screen, just move the cursor arrow up to the waypoint’s name and change it from -QUIK- to its permanent name before pressing ENTER. To make a previously-entered QUICK waypoint become a permanent waypoint, just go to a waypoint list screen and edit the name (and description, if you wish).
choosing a steering screen The first STEERING screen is a traditional display showing cross-track distance at the bottom of the screen (how far off your intended course line you may be) combined with numeric information depicting the distance to your destination waypoint, your present bearing to that waypoint, your present SOG, and your present COG.
1 2 3 In the first steering screen above, a line extends from the data box in the center of the screen to a menu key. Each press of the menu key changes the data displayed in the box among three choices, as follows: 1. Estimated Time En Route (ETE) to the waypoint, and Estimated Time and Date of Arrival (ETA) 2. Speed of Advance (SOA) and Heading Correction 3.
Two vertical lines near the edge of the screen indicate the limits of offcourse distance. An alert message will be given if these limits are exceeded, and the image of your boat will flash on and off. Press the STAR button to display the alert message, then the CLEAR ALARM menu key to acknowledge and clear it. NOTE As you pass a waypoint while following a route, the image of the boat may swing around vigorously as it points to the waypoint you are passing.
Navigating Along Routes To follow a route that has been stored in the 941X’s memory, press the WAYPTS/ROUTES key, then the ROUTE LIST menu key. Use the cursor keys to select the route you wish to follow, and then press the GO menu key. The first four waypoints of the route are displayed. starting the route 1 2 Notice that the arrow shape alternates as you move the cursor up and down. The first arrow shape designates a single waypoint of the route. The second designates a leg connecting two waypoints.
changes to a connecting arrow between the two waypoints, as in screen #2 above. Press the GO menu key, then ENTER. To start following the route, select the waypoint or leg you want to start on, press the GO menu key, then ENTER. planning ETA to any waypoint Before you actually start the route, you can display planning information about the route in the GO ALONG ROUTE screen. An estimate of the time required to travel to the selected waypoint is displayed near the top.
distance & bearing The distance and bearing of each leg are displayed near the center of the waypoint coordinates To display the coordinates of each waypoint in place of the name and de- quick plot screen. scription, press the NAME/COORD menu key. To plot an overhead view of the route, press the QUICK PLOT menu key. When displaying the plot, you may use the NEXT WAYPT and PREV WAYPT menu keys to advance along the route or move back towards the beginning.
If you do not need to return to the original course line, you can continue directly to the waypoint (Course 2) using the restart function described " below. To restart your course line from your present position, display the NAV LOG screen or the POSITION PLOTTER screen. Press the RESTART menu key, then the ENTER key. The 941X will recompute the course line to extend from your present position directly to the next waypoint, resetting your cross-track error to zero.
6 The NAV LOG Function What NAVLOG Does 64 Logging Your Trip 65 Changing Your Trip 65 Adding Waypoints to the Trip 66 The Northstar 941X’s NAV LOG function provides a quick and easy way to check on your progress along a trip, and to make changes to it while you travel. Rev.
What NAV LOG Does T HE Northstar 941X’s NAV LOG feature helps you plan and log your trip. It contains the actual series of waypoints that you follow along your route. When you navigate to a waypoint or along a route from the 941X’s memory, the string of waypoints are copied into the NAV LOG, which acts as a kind of “scratchpad” for monitoring your progress. You can modify NAV LOG’s route in any way you want without affecting the original route, which remains safely stored in the unit’s memory.
reversing the trip You can reverse the trip at any time (navigating to route waypoints in appending waypoints Waypoints may be added to the trip by pressing the APPEND WAYPT reverse order) by pressing the REVERSE menu key. menu key. Any waypoints added to the trip in NAV LOG are not permanently appended to the route in the 941X’s memory. To make permanent changes to the route, you must use the EDIT ROUTE functions, as described on page 50.
Under NAV LOG, the distance and bearing of each leg are displayed. You can easily read the direction of the next leg of your trip from this display. Adding Waypoints to the Trip Press the NAV LOG key to display the waypoints of your current trip. To add a waypoint to the end of the trip, press APPEND WAYPOINT. A list of the waypoints stored in memory is displayed. Use the up and down cursor arrow keys to select the desired waypoint.
7 Other Special Functions Alarms 68 Screen Backlighting 71 TideTrack™ 71 Internal Differential Beacon Receiver 74 This section covers several special functions that enable you to: change the 941X’s audible alarms and screen appearance; navigate using the unique TideTrack™ feature; get the most out of the high-precision positioning capabilities of your internal or external Differential GPS (DGPS) receiver. Rev.
S everal special 941X functions are controlled by the STAR function key ( ). These include alerts and alarms, TideTrack™ functions, and setup functions. Alarms The Northstar 941X has a number of automatic alarms that can alert you of special situations. For example, when you are approaching a waypoint, the 941X signals you with a distinctive “beep” and a flashing exclamation point symbol on the screen.
Though most alarm conditions are “auto clearing” after approximately five seconds, and do not require any user action, two alarms— AVOIDANCE AREA and ANCHOR WATCH—must be acknowledged before the exclamation point can be cleared from the screen. The most recent instance of an alarm type (waypoint, communications, avoidance area, anchor and cross-track alarms) is retained in the 941X’s memory.
When ALARM AUDIO is set to ON, the 941X will audibly alert you to any of the alarm conditions turned ON at the ALARMS & BACKLIGHT screen. anchor watch The anchor watch feature of the 941X will sound an alarm if the unit detects that the boat has moved a specified distance away from an initial " position. 1. Press the DROP ANCHOR menu key at the spot where the anchor is dropped. 2. Press ENTER in response to the question window prompt. 3.
arrive radius The ARRIVE RADIUS alarm signals you when you come within a specified distance of the next waypoint. You can specify the distance of the " radius around waypoints down to 0.01 nm. 1. If you want to change the limit at which the arrive radius alarm will alert you, move the cursor arrow to ARRIVE RADIUS. 2. Press the EDIT ALARM menu key. 3. Using the keypad, specify the distance at which you want to be alerted, and press ENTER.
displayed for any date from 1994 to 2010. Data is from the official tide table predictions and should be as accurate as the printed tables. (Please refer to Tide Tables, published by the NOS/NOAA, Rockville, Maryland 20852, for more information on tides.) " To use TideTrack, press the STAR key until the TideTrack graphic is displayed. The water height for any 24-hour period is displayed for the selected NOAA tide station.
" To choose a nearby tide station, press the CONFIG key while viewing the TIDE TRACK screen. Press the CHOOSE CLOSEST TIDE STATION menu key. The 941X will search for the nine closest stations to your present position and present a list like the following, organized by closest station at the top: Use the up and down arrow keys to point to the desired station, and press ENTER twice to return to the TIDE TRACK screen and display the tides for that station.
Use the up or down cursor arrow keys to point to the desired waypoint, and press ENTER. The 941X will search for, and present, the nine closest tide stations to this waypoint. Now, use the up and down arrow keys to point to the desired station, and press ENTER twice to return to the TIDE TRACK screen and display the tides for that station. selecting a day " The TIDE TRACK screen normally displays tide information for today’s date.
These corrections are used by your 941X to improve its position accuracy to 10 meters—or better—with 2-5 meters accuracy commonly available. Differential corrections are invaluable when navigating in narrow or congested areas (such as ports and waterways), or whenever extreme accuracy is required for locating a precise area (retrieving lobster pots, returning to a diving spot, etc.). Northstar beacon receivers require no manual operation.
ual mode, the beacon receiver will output DGPS corrections only from the selected station. Though the need for manual operation is rare, it is easily accessed from your 941X keypad. To manually choose a beacon, you must select the frequency and baud rate (the beacon’s data transmission speed) of the desired beacon. " 1. To first change the frequency, press the STAR key until you display the USER CUSTOMIZATION screen. 2. Press the RECEIVER OPTIONS menu key.
8 Customizing the 941X Time of Day 78 Display Options 78 Navigation Options 82 Port Setup Options 90 Service Options 91 Geodetic Datum 94 T his section explains the various options available to you for customizing the way your 941X displays information to you, computes navigation data, and “talks” to other devices. Each option is changeable at any time, according to your specific needs. Rev.
Time of Day Press the STAR key until you display the TIME OF DAY screen. The time, date, local time zone, and time of today’s sunrise and sunset are shown. Also displayed is the current time expressed as “GMT” (Greenwich Mean Time). Note that the day of the week in Greenwich, England may be dif- " ferent from the day in your local time zone (right screen, above).
" To change any of the options (described below), select it by using the cursor keys to move the arrow at the left of the screen, and then press the EDIT menu key. The field will begin to flash, waiting for you to change it using the up/down cursor keys or the keypad. distance, bearing as The 941X offers you the choice of calculating the distance and bearing to your intended destination as either a GREAT CIRCLE route or a RHUMB LINE.
NOTE This option determines whether feet or meters will be used in the STEERING screen’s CROSS-TRACK display, and in both steering screens’ distance-to-waypoint displays when HIGH is selected as the STEER DIST PRECISION option (both selected under NAVIGATION OPTIONS—see pages 85 and 86, respectively). time display (DISPLAY OPTIONS) Time of day may be displayed in either 12- or 24-hour format.
" To change the maximum saved waypoint number: 1. Move the cursor to this option and press the EDIT menu key. The cursor will begin to flash in the first digit field. 2. Using the numeric keypad, enter the value you want—up to a maximum of 199—and press ENTER. For one- or two-digit values, enter a zero as the leading digit(s).
Press the RETURN menu key to return to the USER CUSTOMIZATION screen. Navigation Options The following options control aspects of navigation and the use of GPS and Differential GPS. Press the STAR key until you display the USER CUSTOMIZATION screen. Press the NAVI-GATION OPTIONS menu key to display the following choices: To change any of the displayed options, move the cursor arrow to that item and press the EDIT menu key.
• • GPS can be selected as the navigation source at any time. • PHANTOM LORAN can be used if no loran receiver is interfaced to the system, but you’d like to see your position displayed in TD coordinates. • DEMO mode is used to simulate a stationary position—namely, the unit’s last position fix—if you want to practice using the 941X without being on your boat or connected to an antenna. You may enter a waypoint with the name “DEMO” to establish a new demo position at that waypoint’s coordinates.
" Press EDIT to change the 941X’s magnetic variation setting. Use the up/down cursor keys to choose AUTO, MANUAL or TRUE. When choosing MANUAL, move the cursor to the right to enter the value you want. Press ENTER when you are done, or CLEAR to leave the option unchanged. waypoint switching (and the arrive radius) (NAVIGATION OPTIONS) The 941X can be set to advance automatically to the next waypoint upon arrival at each waypoint, or it can be set to require manual switching.
" The ARRIVE RADIUS factory default is 0.02 nautical miles (approx. 120 ft.). To change it: 1. Press the STAR key to display the ALARMS & BACKLIGHT screen. 2. Move the cursor arrow down to ARRIVE RADIUS and press the EDIT ALARM menu key. 3. Enter the new value you want, then press ENTER, or CLEAR to leave the value unchanged. geodetic datum (NAVIGATION OPTIONS) The geodetic datum option contains all referenced datums according to " Defense Mapping Agency publications.
NOTE The CROSS-TRACK FULL SCALE display formats apply only to the STEERING screen, and not to the 3-D steer screen. The options represent the entire distance limit on your screen, from complete left to complete right. Therefore, a cross-track distance setting of 1,000 feet will display 500 feet to either side of your track line, while a " choice of ½ mile will display limits of ¼ mile to either side, and so forth.
" To change the STEER DIST PRECISION option, press the EDIT menu key and use the up/down cursor keys to scroll among the choices of HIGH or NORMAL. Press ENTER when you are done, or CLEAR to leave the option unchanged. Both steering information screens will now reflect your preference when you are less than one mile or kilometer from your destination. Receiver Options The 941X’s RECEIVER OPTIONS provide you with advanced control capability over several of the unit’s GPS and DGPS navigation functions.
" To change the speed averaging value: 1. Move the cursor arrow in front of the GPS SPEED AVERAGING option and press the EDIT menu key. 2. Use the up/down cursor keys to select an averaging time of two to 10 seconds—or OFF. 3. Press ENTER to make the change, or CLEAR to leave the value at it previous setting. You may change the speed averaging value at any time without affecting other 941X navigation functions.
GPS data timeout (RECEIVER OPTIONS) This setting determines how long the 941X will continue to use existing DGPS corrections if no new corrections are being received (due to bad weather, extreme distance from beacon, etc.). If this time period elapses with no new DGPS data received, the 941X reverts to standard GPS navigation, and displays OLD CORRECTIONS as the DGPS status. Under normal operating conditions, this “time-out” should be set to one or two minutes to guarantee the highest accuracy.
After this “timeout” period elapses with no DGPS data having been received, the 941X will revert to navigating with normal GPS, the DGPS display indicator (shown at left) will be turned off, and the “DGPS lost” alarm will sound, if enabled (see “Alarms,” beginning on page 68). DGPS navigation will resume automatically as soon as valid corrections are received again. lowest sat elevation (RECEIVER OPTIONS) NOTE It is recommended that this option be left at the factory default of 10°.
Refer to “Programming the Output Ports,” on page 115, for detailed information on how to interface your 941X with other equipment. Service Options To view your 941X’s serial number and hardware specifications, press the STAR key until the USER CUSTOMIZATION screen is displayed.
main board soft ver (SERVICE INFORMATION) This number indicates the revision level of your 941X’s operating software program. beacon rx soft ver (SERVICE INFORMATION) If your 941X has an internal beacon receiver installed, this line will contain a number indicating the software revision of the beacon receiver. If none is installed, the line will be blank.
the message FAILED is displayed, return the 941X to the factory for service. keypad test (SERVICE INFORMATION) A built-in test feature allows you to verify the integrity of your 941X keypad. Each key you press here will be identified in the KEY PRESSED display box. This function works for all but the POWER, CONTRAST control, and SAVE/MOB keys located to the left of the display screen (pressing SAVE/MOB during the keypad test will save a waypoint instead of testing the key).
Geodetic Datum " Different regions of the world use various models for lat/lon coordinates on their charts, called “datum.” You should always be sure that your 941X is using the same datum as your charts. Press the STAR key until you display the USER CUSTOMIZATION screen, then press the NAVIGATION OPTIONS menu key. Move the cursor down to GEODETIC DATUM and press EDIT. Use the up or down cursor keys to scroll through the list of datums (organized alphabetically, as in the list below).
Rev. D AB4 Astro B4 Sorol Atoll (Hawaiian Islands) INTL 114 -116 -333 AD714 Astro Dos 71/4 (Atlantic Isl.
Page 96 NAH_O Nahrwan—Masirah Island (Oman) CL1880 -247 -148 NAH_UA Nahrwan—United Arab Emirates CL1880 -249 -156 381 NAH_SA Nahrwan—Saudi Arabia CL1880 -231 -196 482 NAP Naparima BWI (Trinidad and Tobago) NAD27_MN North American 1927—CONUS mean value 369 INTL -2 374 172 CL1866 -8 160 176 NAD27_WU North American 1927—Western U.S. CL1866 -8 159 175 NAD27_EU North American 1927—Eastern U.S.
SA69_AG South American 1969—Argentina SA1969 -62 -1 -37 SA69_BO South American 1969—Bolivia SA1969 -61 2 -48 SA69_BR South American 1969—Brazil SA1969 -60 -2 -41 SA69_CH South American 1969—Chile SA1969 -75 -1 -44 SA69_CO South American 1969—Colombia SA1969 -44 6 -36 SA69_EC South American 1969—Ecuador SA1969 -48 3 -44 SA69_GY South American 1969—Guyana SA1969 -53 3 -47 SA69_PA South American 1969—Paraguay SA1969 -61 2 -33 SA69_PR South American 1969—Peru SA
Page 98 8 — Customizing the 941X Rev.
9 Installation and Interfacing Mounting the 941X 100 Wiring the 941X System 102 GPS Antenna Location 104 DGPS Antenna Coupler (ACU) 108 Interfacing the 941X 112 Programming the Output Ports 115 RS-232 Port 126 This section includes all the information needed to install your 941X and interface it to other equipment on your boat. Rev.
Mounting the 941X Proper installation of your Northstar 941X receiver is of utmost importance to accurately receive and effectively use GPS signals under a wide variety of weather conditions. To get the best performance from your Northstar, we strongly recommend that you have an authorized Northstar dealer install it for you. However, if you prefer to perform the installation yourself, please follow these instructions carefully.
The shipping carton contains the following components: • • • the 941X • beacon receiver Antenna Coupling Unit (ACU) (for units with internal differential GPS receiver only) • • • • • • 10’ interface cable GPS antenna 25’ coaxial antenna cable (for passive-patch antennas; 50’ supplied with optional active-patch antenna) 10’ power cable flush-mount drilling template sunshield this Reference Manual connectors and parts kit Save all packing material in the event it is necessary to return the unit to th
wipe the unit dry, especially the rear connectors. When not in use, cover the 941X with the sunshield to protect it from excessive heat. Figure 2—Yoke Mount Drilling Dimensions Wiring the 941X System Your Northstar is designed with an internal fusible link to protect against faulty power wiring. The link consists of a short length of 30 AWG wire located on the I/O board. If this link becomes open-circuited, carefully check all power wiring, especially the white and black wires on the power cable.
We strongly recommend (as a good safety practice) that your 941X be connected to an external circuit breaker or fuse located near the battery or breaker box. The internal fuse is designed to protect the 941X itself; the external fuse or breaker is intended to protect the vessel wiring and prevent electrical fires. The power wiring should be connected directly to the battery when possible for optimum noise immunity.
Antenna Location Three antennas choices are available for your 941X: two for reception of GPS-only signals (standard #AN145 and “active” #AN150), and one to receive both GPS and DGPS signals (#AN190 combo antenna). The antenna is a vital link between the 941X receiver and the outside world. Aesthetics and easy access should be secondary to providing strong and reliable GPS signals to the 941X receiver.
3.00 ANTENNA .91 O-RING ADAPTER 1.82 CAPTIVE SCREW Figure 4—941X GPS-Only Antenna (AN145 & AN150) 7.00 2.5 TNC 3.5 Figure 5—941X Combo GPS/DGPS Antenna (AN190) mounting the GPS-only antenna Tools needed: 1) flat-bladed screwdriver 2) knife blade 3) Amphenol crimp tools. The RG-59 cable supplied with your 941X has one TNC connector attached to the antenna-end of the coax. Connection to the antenna itself involves the following steps: Rev.
1. Remove the antenna base by loosening the four captive screws in the base. 2. Screw the base onto the top of the antenna mount (standard 1"14 marine thread). 3. Feed the open end of the supplied coax cable down through the antenna base and through the hollow core of the antenna mount. 4. Affix the TNC connector-end of the coax to the mating connector inside the upper half of the GPS antenna. 5. Align the upper half of the antenna with the bottom half and tighten the four screws.
without appreciable signal loss. However, the splitter is not weatherproof and should be placed in a protected area where it will not be subjected to direct water splash or spray. combo antenna location The combo antenna should be located where it has a clear view of the horizon, but is not the highest point on the vessel. Keep the antenna at least six feet away from objects that can “shade” GPS or differential signals. GPS antenna cables Avoid tight bends when installing any antenna cable.
Figure 7—Flared Cable Braid 3) Place center contact onto center conductor so that it butts against the cable dielectric. Crimp the contact in place using Amphenol tool handle #227-944 and Cavity B of Die Set 227-980-3. 4) Figure 8: 8 Install cable assembly into body assembly so inner ferrule slides over dielectric and under braid. Push cable assembly forward until contact seats in insulator. Slide outer ferrule over braid and up against connector body.
is molded into the lower portion, or base, of the ACU body into which the upper half is secured (see Figure 9 on page 110). The bottom of the base is threaded (1"–14) to mount onto the antenna mast or onto a standard deck mount. A gasket and rubber O-ring provide weathertight sealing at the ACU base. The ACU connects to the receiver by a single 25-foot length of RG-58U coaxial cable which carries signals to the beacon receiver and DC power to the ACU amplifier.
Figure 9—ACU Assembly WARNING WHENEVER ANY ANTENNA IS DISCONNECTED FROM ON-BOARD EQUIPMENT, BE SURE TO GROUND THE ANTENNA SHIELD IN ORDER TO DISCHARGE EXTREMELY LARGE STATIC VOLTAGES THAT CAN QUICKLY BUILD UP ON AN UNGROUNDED ANTENNA SYSTEM. THESE VOLTAGES ARE HAZARDOUS TO PERSONNEL AND EQUIPMENT! Page 110 9 — Installation and Interfacing Rev.
differential GPS antenna cable connectors Both ends of the differential beacon receiver antenna cable terminate in UHF connectors. Follow the assembly instructions in Figure 10 for preparing UHF connectors. For best results, coat these connectors with silicone gel to retard corrosion. Figure 10—PL 259 (UHF) Connector Rev.
DGPS antenna mounting The Northstar 8410 differential beacon receiver antenna should be mounted as high as conveniently possible (but not at the highest point) and as far away as possible from other antennas. If you have several possible antenna locations, you may evaluate each by operating the 941X with the DGPS antenna temporarily mounted in each location.
The 941X has two programmable NMEA input/output ports and one RS232 input/output port that you can customize for outputting data to other instruments, and two ports for inputting data from other devices. connector pin wiring (PORT SETUP OPTIONS) A list of wire connections for the interface connector is built-into the 941X’s PORT SETUP OPTIONS screen, accessed from the USER CUSTOMIZATION menu. Press the WIRING INFO menu key to display the following screen: Figure 11—Interface Connector (mating side) Rev.
Wire Color Pin NMEA PORT 1 INPUT A Description BROWN 3 NMEA PORT 1 INPUT B BLUE 1 NMEA PORT 1 INPUT GROUND WHITE w/BLUE STRIPE 4 VIOLET 12 NMEA PORT 1 OUTPUT A NMEA PORT 1 OUTPUT B GRAY 7 BLUE w/WHITE STRIPE 8 NMEA PORT 2 INPUT A WHITE w/BROWN STRIPE 6 NMEA PORT 2 INPUT B BROWN w/WHITE STRIPE 2 NMEA PORT 1 OUTPUT GND NMEA PORT 2 INPUT GROUND WHITE 5 NMEA PORT 2 OUTPUT A YELLOW 15 NMEA PORT 2 OUTPUT B ORANGE 11 BLACK 10 NMEA PORT 2 OUTPUT GND RS-232 GROUND RS-232 INPUT RS
Figure 12—200 PPNM Output Block Diagram Programming the Output Ports Each output port can be programmed to meet most any special requirements of devices that conform to the NMEA 0183 data format specification. The SETUP function described below allows the selection of the specific 0183 sentences that will be transmitted by the 941X. Press the STAR key until you see the USER CUSTOMIZATION menu. Press the menu key marked PORT SETUP OPTIONS, then press the PORT 1 SETUP or PORT 2 SETUP key.
Check the installation instructions for the equipment to which you are interfacing for any special requirements.
(NMEA) 0180 is an infrequently-used format, developed in the late 1970’s and is required by many older autopilots. 0183 V2.1 is the most popular interfacing format and is used by most autopilots, radars, plotters and other equipment. After pressing ENTER to select 0183 as the output format, you will be presented with a list of all 0183 sentences which may be individually turned on or off. The 1.
input to the 941X, the checksum is ignored. (It should be noted that, with the checksum ignored on input, there is a possibility of the 941X receiving contaminated NMEA data when it is connected to an external Raytheon loran.) Format is supported on PORT 1 and PORT 2. The setting NONE is used when the 941X is not connected to an external device.
will be output are followed by the word ON. Those that will not be output are followed by two dashes, signifying that they are turned OFF. 1. Move the cursor arrow to the sentence you wish to change and press the EDIT menu key. 2. Use the up/down cursor keys to toggle the sentence ON or off (dashes) and press ENTER to make your selection, or CLEAR to leave it unchanged. 3. Repeat for each sentence requiring modification. Press the RETURN menu key to go back to the PORT SETUP screen when you are done.
The meaning of the NMEA 0183 three-letter identifiers are: 0183 IDENTIFIER APB BOD BWC GGA GLC GLL GSA GSV HSC RMA RMB RMC RNN VTG WCV WPL XTE ZDA ZTG MEANING Autopilot Sentence “B” Bearing to Destination Bearing & Distance to Wpt. (Great Circle) GPS Fix Data Geographic Position, Loran-C Latitude/Longitude GPS DOP and Active Satellites GPS Satellites In View Heading Steering Command Recommended Min. Sentence A Recommended Min. Sentence B Recom. Min.
the listener device is expecting. Check the listener device’s instruction manual to determine which “talker ID” codes it will respond to. Use the EDIT menu key, then scroll through the three choices using the up/down cursor arrow keys to make your choice. Press ENTER when done. The interfaced equipment will then receive the 0183 data in the correct nav-source format.
function with two-place precision. Refer to the manufacturer’s instructions for how many digits of precision are required for that particular device. output rate (PORT 1 / PORT 2 SETUP) The 941X defaults to a two-second update interval for data transmission. There are some applications where a longer update period is required, and the 941X allows you to increase that span to 999 seconds.
connecting to a Northstar 800 series loran If you presently own a Northstar 800 series loran, you may connect it to your 941X to serve as an ideal source of Loran-C TDs and previouslystored waypoint locations. Use the appropriate pin/wire connections and the 800’s setup sequence, each listed below, to initialize the data output to be received by the 941X. Port 1 or Port 2 of the 941X, or A or B of the 800, may be used. Wire colors refer to the 941X’s interface cable.
connecting to other devices Interfacing to other devices requires slightly different pin/wire connections. For example, use the following table to enable the 941X to communicate with a Yeoman electronic chart plotter.
8800 DGPS Sensor Pin 21 (receive) Pin 20 (transmit) Pin 17 (ground) 941X Interface Connector red (RS-232 output) #18 green (RS-232 input) #16 tan (RS-232 ground) #17 8400 beacon receiver black (receive) white (transmit) orange (ground) 941X Interface Connector red (RS-232 output) #18 green (RS-232 input) #16 tan (RS-232 ground) #17 8401 beacon receiver yellow (receive) blue (transmit) orange (ground) 941X Interface Connector red (RS-232 output) #18 green (RS-232 input) #16 tan (RS-232 ground) #17 Tabl
Use this same EDIT procedure to set the baud rate to match that of the external device, if necessary. (Refer to the external device’s instructions for correct baud rate setting.) The 941X is now configured to accept differential corrections from an outside source. RS-232 Port The RS-232 port is used for interfacing to an external DGPS beacon receiver, an external device that accepts SC-104 differential corrections, or a personal computer.
copy port 1 copy port 2 The COPY PORT function enables you to interface the 941X to many Personal Computers without the need for an RS-422-to-RS-232 converter. Many PC application programs for waypoint/route loading, chart programs, data logging, etc. can be used. The function “copies” the output of the specified port 1 or port 2 data format (NMEA 0180, NMEA 0183, DATAMARINE CDX, or RAYTHEON 0183) to the RS-232 port’s output for direct connection to your computer. " 1.
Page 128 9 — Installation and Interfacing Rev.
APPENDIX Northstar 941X Specifications System Features Position Data • Latitude/longitude (158 datums) from GPS with 1-second updates • Phantom Loran-C TDs (calculated from GPS) Loran-C TDs (from your existing loran: 1 second from Northstar 800 series, 2 seconds from other lorans) • Real-time receiver status screens Steering Screens • Large, easy-to-read graphical presentation • Waypoint name, position • Bearing and distance to waypoint • Cross-track error (numeric and two graphic screens: traditional an
Waypoint & Route Management • Avoidance Waypoints • Enter wpts as lat/lon, distance and bearing, or loran TDs • Displays 30 closest waypoints • Store 1,000 waypoints • Store up to 500 routes • Stores waypoints/route • Update waypoint coordinates to ship's position • Edit/erase waypoints or routes • Plan Route function • Plot any route with automatic chart scale selection • Time-To-Go Waypoint Navigation • Navigate to coordinates, waypoints and along routes • Save current position • Steer to new point funct
• Time To First Fix: 30 seconds (typical) • Dynamics: Velocity: 1800 km/h • Acceleration: 4m/sec; Jerk: 2m/sec2 • Operating Modes: Modes 2D Nav, 3 or more satellites; 3D Nav, 4 or more satellites visible • SC-104: Processes all USCG SC-104 message types, including 1 and 9 • EMI: FCC Part 15 subpart J Interfaces • Two bi-directional NMEA I/0 ports • One bi-directional RS-232 port • Waypoint upload/download capability • Operating software upload • NMEA output sentences: APB, BOD, BWC, BWC (1.
Dimensions Figure 13—941X Dimensions Page 132 Appendix Rev.
Internal Beacon Receiver (optional) Signal Processing • Number of Channels: 2 • Frequency Range: 283.5–325.
Combo GPS / DGPS Antenna IEC Compliance • Frequency: • Finish: Outdoor Weatherable Polymer • Polarization: Right-Hand Circular • Weight: 22 Ounces • Axial Ration 3 dB Max. • Altitude: 12,000 Feet • Noise Figure: 2.5 dB Max. • Temperature: -40º C to +70º C • Impedance: 50 Ohm • VSWR: <2.0 : 1 • Band Rejection 35dB @ 1625 MHz • Power Handling: 1 Watt Immunity to electromagnetic environment (1988/’92 amend.
GLOSSARY accuracy: accuracy absolute accuracy—the accuracy of displayed lat/long coordinates of your present position as compared to lat/long determined from a chart or other reference source. repeatable accuracy—the ability to return to the same location using a receiver’s previously-obtained coordinates. acquisition: acquisition The procedure during which a GPS receiver attempts to track satellites before a position fix can be computed.
ETA: ETA Estimated Time of Arrival at the next waypoint, as calculated by the 941X according to your present speed of advance (SOA) and distance to the waypoint. ETE: ETE Estimated Time Enroute to the next waypoint, as calculated by the 941X according to your present speed of advance (SOA) and distance to the waypoint. GPS: GPS Global Positioning System. A navigation system using signals from earth-orbiting satellites. The system is capable of providing high accuracy under all weather conditions.
tion and uses it to display bearings as magnetic north. The variation at any location changes slowly over a period of years, and the 941X compensates, according to the current calendar year. master: master The one loran transmitter in a “chain” of at least three stations which initiates the series of coded pulses emulated by the secondaries. precipitation static: static Also known as “P-Static.
INDEX A absolute accuracy......................................................... See accuracy, absolute ACCURACY repeatable........................................................................135 ACCURACY absolute .......................................................................5, 135 absolute, GPS..............................................................6, 8, 9 absolute, loran .................................................................... 8 Coast Guard requirement......................
COG .................................................................................................22, 23, 104 contrast ......................................................................................................... 14 COPY PORT function .................................................................................. 127 cross-track display limits................................................................................ 85 cursor (flashing)................................................
checking status ............................................................32, 34 comparing to Loran ......................................................... 5, 7 converting coordinates from Loran TDs ............................ 42 converting coordinates to Loran TDs..............................9, 32 converting coordinates to Phantom Loran ....................16, 82 displaying lat/lon ............................................................... 25 interfacing with Loran ..............................
LORAN absolute accuracy ............................................................... 8 comparing to GPS............................................................... 5 converting TDs to lat/lon ................................................... 42 displaying TDs ................................... 5, 9, 10, 16, 22, 30, 31 interfacing with GPS ....................................................30, 31 Phantom operation.......................................................32, 33 repeatable accuracy.....
overview............................................................................ 90 programming the ports .............................................115, 125 RS-232 port .....................................................................126 POSITION key......................................................................................... 16, 22 P-static ........................................................................................................ 112 Q QUESTION windows ................
SOG ........................................................................................................ 22, 23 STAR key .....................................................................5, 16, 30, 33, 68, 76, 82 STEER key.............................................................................................. 16, 55 steering distance precision ............................................................................ 86 STOP SAVE function.......................................................
removing from a route ....................................................... 51 saved as you travel ......................................................42, 49 saving as part of a route...............................................44, 49 switching to next (auto) ..................................................... 84 switching to next (manually) .............................................. 84 transferring to a personal computer................................... 44 updating coordinates................
