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A two-dimensional GPS position fix that
includes only horizontal coordinates (no GPS elevation). It
requires a minimum of three visible satellites
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A three-dimensional GPS position fix that
includes horizontal coordinates plus elevation. It requires a
minimum of four visible satellites
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A measure of how
close an estimate of a GPS position is to the true location.
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The time it takes a
GPS receiver to acquire satellite signals and determine the
initial position
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An antenna that
amplifies the GPS signal before it sends it to the receiver
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The segment of a
route currently being traveled. A segment is that portion of a
route between any two waypoints in the route
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Information transmitted by each satellite on
the orbits and state (health) of every satellite in the GPS
constellation. Almanac data allows the GPS receiver to
rapidly acquire satellites shortly after it is turned on
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An instrument for determining elevation,
especially an aneroid barometer used in aircraft that senses
pressure changes accompanying changes in altitude. The GARMIN
eTrex Vista and Summit models contain a basic GPS with a
built-in barometric altimeter.
How To Use An Altimeter
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The principal feature of analog signals is
that they are continuous. In contrast, digital signals consist
of values measured at discrete intervals
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A basic computer document that contains only
text characters that are part of a standard set of characters
set by the American
Standards
Code
for Information
Interchange
( ASCII ). These files may be read and written by any text file
editor, or word processor program.
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Some GPS Models Come With The Ability To
Display A Background Map Image On Their Position-Plotter Map
Screen. This Background Map Is Called A Basemap by Some GPS
System Manufactures.
Basemaps can come in two different types. The first type is a
simple background map-image. These images vary greatly from
manufacturers and various GPS models, and their date of
manufacture. The second type of basemap can also included
extended system software navigation features that are integrated
into the GPS system's software. Such a feature is called
Autorouting.
Depending on the manufacturer and the model of
GPS system, it may be possible for the user to add additional map-detail to the built-in
basemap. Data can be transferred into the GPS unit using a PC and
a data-cable. Users may also be able to
purchase Data Cards or CD-ROMs that hold additional map detail.
This additional detail may include: highways, city borders, local
city streets, dirt roads, rivers, waterways, etc..; details that
are normally seen on paper maps, such as road maps, topographical
maps and marine charts.
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The quoted figure from GARMIN, reflects
battery life when using GARMIN's "Battery Saver" Mode.
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The art or technique
of making maps or charts. In GPS technology, cartography refers
to map details; points of detail on a map. These map details can
be roads, rivers, city marks, trails, points of interest marks,
and other marks found on different types of maps.
The major recreational
GPS manufacturers, such as GARMIN and Magellan, offer map
details as collections on CD-ROM or in memory chip form. These
details can be transferred to a Mapping GPS system for display
on its built-in basemap.
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A confluence is defined as a flowing together; a meeting
place (often of rivers).
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Continental United States.
Refers To The Connecting United States As A Group.
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Any element in a group of references to a
particular location, such as the intersection of a certain row
and column.
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Points on a plane (two dimensions) or in
space (three dimensions) that are located by their positions on
intersecting axes.
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A method of representing points in a space of
given dimensions by coordinates.
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The coverage provided by a radio navigation system is that
surface area or space volume in which the signals are adequate
to permit the user to determine position to a specified level of
accuracy. Coverage is influenced by system geometry, signal
power levels, receiver sensitivity, atmospheric noise
conditions, and other factors that affect signal availability.
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A Datum is a set of
parameters and control-points used to mathematically define and
model, the three-dimensional shape of the Earth; enabling
calculations to be carried out in a consistent and accurate
manner.
The datum is physically represented by a framework of ground
monuments, whose positions have been accurately measured and
calculated on this reference surface.
Lines of latitude and longitude on a
printed map or chart, are referenced to a
specific map datum. Every chart has a map datum reference.
The map datum selected on a GPS receiver needs
to match the datum listed on the corresponding paper map being
used for current reference, in order
for the position readings to match.
If the user is
navigating and comparing the GPS coordinates to a map, chart or
other reference, the map datum in the GPS unit should be set to
the same datum as the map or chart to insure the most accurate
navigation.
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Degree Confluence |
degree confluence is the exact spot where an integer
degree of latitude and an integer degree of longitude meet, such
as 43°00'00"N 72°00'00"W. An interesting
project finding and documenting degree confluences can be
found online
here
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Differential Global Positioning
System (DGPS) - A Broadcast Standard For Marine Navigation.
What is DGPS? Complete Detail Here
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Dilution of Precision (DOP). This Data
Field Measures 'Satellite Geometry Quality' (the number of
satellites received and their location in relation to each
other) on a scale from one to ten; the lower the number, the
better the accuracy.
Garmin Users' Note: DOP Data Is Not Available in The 'Garmin'
Serial Output Data Format.
Examples are HDOP for local horizontal, VDOP for local vertical, PDOP for all
three coordinates, and TDOP for time.
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The U.S. Department of
Defense. The DOD owns, manages and controls the Global
Positioning System.
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See Dilution of Precision (DOP)
DOP is a measure of the number of
satellites and quality of satellite positions.
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Drawing
Interface Format. An AC\SCII
file format used by various graphic and CAD programs. Each ASCII
line in a DXF file describes an object within the overall
drawing.
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Expanded
Memory System. Memory added to
your computer above, and beyond, conventional memory. The
expanded memory board, and supporting expanded memory manager,
should conform to the LIM (lotus/Intel/Microsoft) version 3.2
specification.
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Estimated Position Error; This Data Field
Indicates The Estimated Accuracy of The Horizontal Position Fix.
This Data Is Commonly
Displayed On A Modern GPS System's 'Satellite Information'
Screen Display.
This Data Is based upon the
'Dilution of Precision' (DOP).
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Global Positioning System. More Details
Click Here
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A Grid Refers To A Grid Projected Over The Earth's Surface
For The Purpose Of Referencing Points On The Earth's Surface.
Many Countries Have Produced Their Own Reference Grid And Use
Them For Navigation Coordinates. Grids Are Used With GPS
Systems And Maps. When Working With Coordinates, Its
Extremely Important To Make Sure That Any Grid System Used, Is
The Same On The Map Used And Any Navigation System Or GPS
Device.
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Horizontal Alert Limit (HAL). The Horizontal Alert Limit
(HAL) is the radius of a circle in the horizontal plane (the
local plane tangent to the WGS-84 ellipsoid), with its center
being at the true position, which describes the region that is
required to contain the indicated horizontal position with a
probability of 1-10-7 per flight hour, for a particular
navigation mode, assuming the probability of a GPS satellite
integrity failure being included in the position solution is
less than or equal to 10-4 per hour.
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Horizontal
Dilution Of Precision.
HDOP is an indicator of the quality of a horizontal position
(latitude and longitude) based on satellite geometry (or,
position of the satellites with respect to each other). A low
HDOP value indicates better position accuracy.
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No matter where a person happens to be on the
surface of the Earth, there is an exact reference description
for the person's present location, called a "location
coordinate". A location coordinate is the description for any
specific location on the Earth, determined by one of the many
types of Location Formats.
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A person's current location is given in the
form of location coordinates. Each location coordinate system
has a format for presenting its location data; this is the
location format. Maps and charts are based on different location
formats.
In GPS working terms, the location format is
the format used to display location coordinates on the GPS unit.
A GPS user may select the format used by the GPS unit, to
display the user's current position, and when working with
location coordinates within the GPS unit's system software.
A truly useful GPS-receiver system must allow
the user to choose the correct coordinate system for the type of
map being used. Maps and charts are based on different locations
formats. A good GPS unit allows the user to choose the correct
coordinate system for the type of map being currently used.
The most commonly know location format is
latitude and longitude, which is utilized by most GPS receiver
systems. Most GPS receiver systems provide the user with the
ability to change the location format to use with other
coordinate systems.
A much more easier, accurate, and practical
way to work with location coordinates is in using the more
modern UTM/UPS world grids. These grids are standard on most
USGS topographical maps and other country's topographical maps.
Several other grids, including a
user-definable grid, may also be selected.
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See Datum
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A graphic
representation of a geographic area and the features in it.
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Military Grid Reference System
DEPARTMENT OF DEFENSE INTERFACE STANDARD
Document: MIL-STD-2500C
3.2.43 Military Grid Referencing System
(MGRS). A means of expressing Universal Transverse
Mercator (UTM) or Universal Polar Stereographic (UPS)
coordinates as a character string, with the 100-kilometer
components replaced by special letters (which depend on the UTM
or UPS zone and ellipsoid).
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An error caused
when a satellite signal reaches the GPS receiver antenna by more
than one path. Usually caused by one or more paths being bounced
or reflected. The TV equivalent of multipath is "ghosting."
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NAVAID |
Navigation Aid; A Device Used For Assisting In Navigation,
But Not To Be Used As A Primary Navigation Tool!
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Navigation |
The Act Of Determining The Course Or Heading Of Movement Of
An Object (Person, Vehicle, Device). Traveling from a
position to another position, following a route with knowledge
of the current position in relation to the route and the
destination position.
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NATIONAL MARINE ELECTRONICS
ASSOCIATION
A U.S. standards
committee that defines data message structure, contents, and
protocols to allow the GPS receiver to communicate with other
pieces of electronic equipment aboard ships
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A NMEA standard
defines an electrical interface and data protocol for
communications between marine instrumentation.
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National Geodetic Survey. Information about
survey monuments on record with the National Geodetic Survey (NGS)
is published in a Digital Survey DATA (DSDATA) format.
CLICK HERE
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A screen display
feature that provides the user with a natural way to move
electronic screen-map displays on GPS receiver systems. The
feature provides the user with a way to move the screen
displayed map, in any direction with continuous motion. This
gives the user a more natural way to view the electronic map,
and allows for a large area of coverage, that is many times
larger than the small screen size can display.
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A continuous
tracking GPS receiver using multiple receiver circuits to track more
than one GPS satellite, simultaneously.
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The precise code of
the GPS signal typically used only by the U.S. military. It is
encrypted and reset every seven days to prevent use from
unauthorized persons.
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A Single Display
Element (dot) On A Display Screen. The More Pixels Within
A Given Area Translates To Higher Defined Graphics And Text. For
The Same Size Screen, A Higher Pixel Count Means A Better
Looking Screen, Easier To Read Text, And More Refined
Intelligent Looking Graphics.
Casanova's Computer Technology Lab Tip:
Higher Pixel Counts Cost More To Produce.
Always Select Higher Pixel Counts If You Can Afford To.
Higher Pixels Will Also Allow For More Data To be Displayed In
The Same Given Screen Size. Therefore, More Expensive
Models Offer more On-Screen Data Display Options For A More
Practical Functioning Tool. This Is A Proven Fact As A
Result Of Working With Computer technology And Digital LCD
Technology In CGI Science & Technology Labs Since 1979 - A
Division Of The Casanova Corp.
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Position
Dilution Of Precision.
PDOP is an indicator of the quality of a horizontal and vertical
position (latitude, longitude and altitude) based on satellite
geometry. A low PDOP value indicates better position accuracy.
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Points Of
Interest. When Working With GPS Systems, POI Stands
For "Point Of Interest"; A Simple Way To Refer To Publicly
Notable Locations On Earth on A Map; Predefined
Waypoints.
Basic POI Data Will
Contain: 1) A Name For The POI; 2) A Universal Global Coordinate
To The Point. POIs
Can Be The Center Of Towns, City Halls, Public Buildings,
Monuments, Famous Locations, Commercial Businesses, Buildings, Service
Stations, Food, Drink, Public Facilities, Marine Navigation
Markers, Radio Towers, Land Marks, Mountain Summits, Boat
Launches, Look Out Point, Scenic Point, Highway Rest Stop,
Highway Exits, Rivers, Lakes, Fishing Spots, etc..
POIs Are Predefined
Public Waypoints Offered by Cartography
Data Provider Companies. POIs Can Vary Between
Data-Providers, In The Name And Coordinates Provided For Any
Given Point Of Interest.
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Position refers to an exact, unique
location on Earth; identified by a unique set of grid coordinates.
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The exact grid coordinates
for a point on Earth.
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The way in which
a GPS receiver's software will give position information in.
Position format refers to geographic coordinate system.
Currently, most consumer GPS systems are set to display the
latitude/longitude geographic coordinate system in degrees and
minutes, with options for degrees, minutes and seconds, degrees
only, or one of several other geographic coordinate system grid
formats. The easiest to use and understand is the UTM geographic
coordinate system.
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The zero meridian,
used as a reference line from which longitude east and west is
measured. It passes through Greenwich, England.
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A type of GPS
antenna in which four spiraling elements form the receiving
surface of the antenna. For GPS use, quadrifilar antennas are
typically half-wavelength or quarter-wavelength size and encased
in a plastic cylinder for durability
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A serial
input/output standard that allows for compatibility between data
communication equipment made by various manufacturers.
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Radio Technical Commission Marine (RTCM)
is a name given to a specific data format. DGPS corrections are
often transmitted in a standard format specified by the Radio
Technical Commission Marine (RTCM).
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A group of
waypoints that mark a course in a specified sequence to be
navigated.
When working with
GPS receiver's system software or a GPS Mapping PC program, when
one is navigating a route, the software will indicate the course
to steer and may provide additional information on time, speed
and distance to destination.
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A waypoint that is a member of a 'route' is called a
'Routepoint'. In most GPS devices, standalone waypoints
may also be members of one or more routes
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A message shown
when a GPS receiver is gathering satellite almanac data. This
data tells the GPS receiver where to look for each GPS
satellite.
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The sequential
transmission of the signal elements of a group representing a
character or other entity of data. The characters are
transmitted in a sequence over a single line, rather than
simultaneously over two or more lines, as in parallel
transmission. The sequential elements may be transmitted with or
without interruption
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The random error,
which the government can intentionally add to GPS signals, so
that their accuracy for civilian use is degraded. SA is not
currently in use.
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The actual speed
the GPS unit is moving over the ground. This may differ from
airspeed or nautical speed due to such things as head winds or
sea conditions. For example, a plane that is going 120 knots
into a 10-knot head wind will have a SOG of 110 knots.
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The received GPS signal is a wide
bandwidth and low powered signal. The L-band signal is modulated
with a pseudo random noise code to spread the signal energy over
a much wider bandwidth than the signal information bandwidth.
This provides the ability to receive all satellites
unambiguously and to give some resistance to noise and
multipath.
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See Standard Position Service (SPS)
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(SPS) Three-dimensional position and time determination
capability provided to a user equipped with a minimum capability
GPS SPS receiver in accordance with GPS national policy and the
performance specifications.
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A unit of length
equal to 5,280 feet or 1,760 yards (1,609 meters) used in the
U.S. and some other English-speaking countries
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The act of going
from one waypoint to another in the most direct line and with no
turns.
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Suite |
The Word 'Suite' Is
Used To Identify A Computer Application Program That Contains
Several Different Application Programs Designed To Work Together
As One Central Tool Set.
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A "track" in a GPS system, refers to a system
software feature that has the capability to record or "track" your
movement. Think of a GPS track as an electronic bread crumb trail
you leave as you move.
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This file contains
a list of position data samples (each sample having a unique
time assigned to it) which indicates where you have been. Track
log files are created/stored in your GPS unit and downloaded to
the PC.
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A "Trackpoint" is the name given to a point (coordinate) that is a
member of a track. Some GPS
devices allow you to convert a 'track' to a 'route'; which
results in 'trackpoints' being converted into 'waypoints'.
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A transducer converts
electrical current energy into physical sound wave
energy, and also converts sound energy into electrical current.
Transducers are
used in underwater applications where they send and receive
sound waves underwater. Marine Sonar, Sounders, Depth
Finders, and Fishfinders, all use a transducer to transmit sound
waves into a focused direction underwater, and at the same time,
collect any of those sound waves that bounce off underwater
objects.
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A method of
determining the location of an unknown point, as in GPS
navigation, by using the laws of plane trigonometry.
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A universal global time
standard, referencing the time at Greenwich, England. Also
referred to as GMT or Zulu time And 'UTC-Time'.
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There are 25
standard time zones around the world that are all an integer
offset of hours to UTC-time. If UTC-time is 12:00
(Noon/PM), then people having offset +5 hours, have local time
17:00 (or 5:00 PM). There are also some countries/places
not using the standard time zones, they might be e.g. 5 hours
and 45 minutes ahead of UTC.
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Universal
Transverse Mercator. UTM is
a popular coordinate system used in survey and mapping
applications. UTM relies on grid zone designations, easting/northing
distances and provides one meter resolution.
More Details and How To Use & Read UTM -
Click Here
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A transmission path
by which radio or other signals are sent from the ground to an
aircraft or a communications satellite.
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The way in which
information is exchanged between the GPS receiver and the user.
This takes place through the screen display and buttons on the
unit
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The segment of the
complete GPS system that includes the GPS receiver and operator
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The rate of closure
to a destination, based upon your current speed and course
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Vertical Alert Limit (VAL). The Vertical Alert Limit is half
the length of a segment on the vertical axis (perpendicular to
the horizontal plane of WGS-84 ellipsoid), with its center being
at the true position, which describes the region that is
required to contain the indicated vertical position with a
probability of 1-10-7 per flight hour, for a particular
navigation mode, assuming the probability of a GPS satellite
integrity failure being included in the position solution is
less than or equal to 10-4 per hour.
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Wide
Area Augmentation System - Basically,
it's a system of satellites and ground stations that provide GPS
signal corrections, giving you even better position accuracy.
More WAAS Info
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Water Resistant |
- IPX2 - Light Mist, Do Not Immerse
-
- IPX4 - Rain, Splashing Water, Do Not Immerse
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- IPX7 - Submerged to 1 Meter For 30 Minutes
Electronics are protected if immersed, but
battery compartment may get wet. Be sure batteries and
compartment are dry before using.
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The distance between
points of corresponding phase of two consecutive cycles of a
wave.
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A specific location
saved in the memory of a GPS receiver. Waypoints can be saved
with information on that point depending on the GPS receiver's
limits and features.
Waypoints are
locations or landmarks worth recording and storing in your GPS.
These are locations you may later want to return to. They may be
check points on a route or significant ground features. (e.g.,
camp, the truck, a fork in a trail, or a favorite fishing spot).
Waypoints may be
defined and stored in the unit manually, by taking coordinates
for the waypoint from a map or other reference. This can be done
before ever leaving home. Or more usually, waypoints may be
entered directly by taking a reading with the unit at the
location itself, giving it a name, and then saving the point.
Waypoints may also be put into the unit by referencing another
waypoint already stored, giving the reference waypoint, and
entering the distance and compass bearing to the new waypoint.
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World Geodetic System -
1984. The primary map datum used by GPS. Secondary
datums are
computed as differences from the WGS 84 standard.
WGS-84 (Geodetic, 1984) is an
international reference system (map datum) which defines the
shape of an earth ellipsoid, its angular velocity, mass, and
gravity.
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Cross Track Error - The distance you
have deviated from the original straight line of travel when
navigating to a waypoint. Refers to how far off course you are.
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The encrypted P-Code
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An ASCII file
format used to define the orbital parameters for each
operational GPS satellite. YUMA format is used by a variety of
satellite tracking programs.
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