2D Mode

A two-dimensional position fix that includes only horizontal coordinates. It requires a minimum of three visible satellites.

二維定位模式, 只有平面的座標. 必需至少取得三個衛星的資料.

3D Mode

A three-dimensional position fix that includes horizontal coordinates plus elevation. It requires a minimum of four visible satellites.

三維定位模式. 除了平面位置之外加上高程. 必需至少取得四個衛星的資料

Acquisition Time

The time it takes for a GPS receiver to acquire satellite signals and determine the initial position. Three satellites are needed for a 2D and four for a 3D-position fix.

GPS 接收機從收到衛星訊號到計算出座標的時間. 最少三個衛星才能取得二維定位, 最少四個才能取得三維定位.

Active Leg

The segment of a route currently being traveled.

Almanac Data (星歷)

Information transmitted by each satellite on the orbits and state (health) of the entire constellation. Almanac data allows the GPS receiver to rapidly acquire satellites as soon as it is turned on.

Anti-Spoofing

Encryption of the P-code to protect the P-signals from being "spoofed" through the transmission of false GPS signals by an adversary.

Atomic Clock (原子鐘)

A very precise clock that operates using the elements Cesium or Rubidium. A Cesium clock has an error of one second per million years. GPS satellites contain multiple Cesium and Rubidium clocks.

一種極為精確的時鐘, 它是使用銫或銣元素運轉的原子鐘. 銫原子鐘的誤差為每百萬年一秒. GPS 衛星包含了多個銫原子鐘與銣原子鐘.

Azimuth

The horizontal direction from one point on the earth to another measured clockwise in degrees (0-360) from a north or south reference line. An azimuth is also called a bearing.

Beacon

Stationary transmitter that emits signals in all directions¾ also called a non-directional beacon. In DGPS, the beacon transmitter broadcasts pseudorange correction data to nearby GPS receivers for greater accuracy.

Bearing

The compass direction from a position to a destination, measured to the nearest degree¾ also call an azimuth. In a GPS receiver, bearing usually refers to the direction to a waypoint.

Coarse Acquisition Code (C/A Code)

The standard positioning signal the GPS satellite transmits to the civilian user. It contains the information the GPS receiver uses to fix its position and time. Accurate to 100 meters.

Cold Start (冷啟始)

The power-on sequence when the GPS receiver downloads almanac data before establishing a position fix. Also called initialization.

Control Segment

A worldwide chain of monitoring and control stations that control and manage the GPS satellite constellation.

Coordinate

A set of numbers that describes your location on or above the earth.

Coordinated Universal Time (UTC)

Replaced Greenwich Mean Time (GMT) as the World standard for time in 1986. It is based on atomic measurements rather than the earth's rotation. Greenwich Mean Time (GMT) is still the standard time zone for the Prime Meridian (Zero Longitude). It is the time kept by GPS satellites.

Course

The direction from the beginning landmark of a course to its destination (measured in degrees, radians, or mils).

Course Deviation Indicator (CDI)

A technique for displaying the amount and direction of crosstrack error (XTE).

Course Made Good (CMG)

The bearing from the 'active from' position (your starting point) to your present position.

Course Over Ground (COG)

Your direction of movement relative to a ground position.

Course To Steer

The heading you need to maintain in order to reach a destination.

Crosstrack Error (XTE/XTK)

The distance you are off the desired course in either direction.

Datum (座標系統格式)

A math model designed to fit part of the earthÕs surface. Latitude and longitude lines on a paper map are referenced to a specific map datum. The map datum for a GPS receiver needs to match the datum listed on the corresponding paper map.

一種用設計來表示部份地球表面位置的數學運算式. 在地圖上的經緯線是參考到一個特定的地圖投影座標系. GPS 接收機所表示出來的位置的座標值若要吻合於一般的地圖或是地圖軟體, 那麼它的座標系必需要設定與該地圖或軟體相同的座標系才行.

Desired Track (DTK)

The compass course between the "from" and "to" waypoints.

Differential GPS (DGPS)

A technique used to improve the accuracy of the GPS. DGPS reduces the effect of selective availability, propagation delay, etc. and can improve position accuracy to greater than 10 meters.

Dilution of Precision (DOP)

A measure of the GPS receiver-satellite geometry. A low DOP value indicates higher accuracy. The DOP indicators are GDOP (geometric DOP), PDOP (position DOP), HDOP (horizontal DOP), VDOP (vertical DOP), and TDOP (Time clock offset).

DOD

The U.S. Department of Defense. The DOD manages and controls the Global Positioning System.

Elevation

The distance above or below average sea level.

Ephemeris (星歷表, 衛星的天文歷表)

Current satellite position and timing information transmitted as part of the satellite data message. A set of ephemeris is valid for several hours.

　

Estimated Position Error (EPE)

A measurement of horizontal position error in feet or meters based upon a variety of factors including DOP and satellite signal quality.

Estimated Time Enroute (ETE)

The time left to your destination based upon your present speed and course.

Estimated Time of Arrival (ETA)

The time of day of your arrival at a destination.

Format (座標格式)

我們內政部的地圖所使用的座標格式為二度分帶, 這是由大麥卡多楕球投影座標系位移所換算過來的座標系統, 在民國 67 年時所制定的稱為 T67, 在我們的 GPS 中即顯示為 Taiwan Grid.

Global Positioning System (GPS 全球定位系統)

A global navigation system based on 24 satellites orbiting the earth at an altitude of 1,200 miles and providing very precise, worldwide positioning and navigation information 24 hours a day, in any weather. Also called the NAVSTAR system.

一種以24個在地球上空約1,200英里的軌道上運行的衛星定位系統, 提供精確, 全時, 不受天候影響, 全球通用的導航資訊. 也稱之為 NAVSTAR 系統

GLONASS

The Russian Global Positioning System.

俄國的全球衛星定位系統

GOTO

A route consisting of one leg with your present position being the start of the route and a single defined waypoint as the destination.

Greenwich Mean Time

The mean solar time for the meridian at Greenwich, England, used as a basis for calculating time throughout most of the world. Also called universal time.

Grid

A pattern of regularly spaced horizontal and vertical lines forming square zones on a map used as a reference for establishing points.

Heading

The direction in which a ship or an aircraft is moving. This may differ from actual COG due to winds, sea conditions, etc.

I/O (Interface Option) 輸出/入界面

The one-way or two-way transfer of GPS information with another device, such as a nav plotter, autopilot, or another GPS unit.

與其它的設備單向或雙向傳送 GPS 資訊的接口或接頭規格, 這些設備通常有; 電腦, 數位地圖顯示器, 自動駕駛系統, 無線電數據機, 行動電話, 或是另一台 GPS.

Initialization

The first time a GPS receiver orients itself to its current location. After initialization has occurred, the receiver remembers its location and acquires a position more quickly because it doesn't need a large amount of satellite information.

Invert Route

To display and navigate a route from end to beginning for purposes of returning back to the route's starting point.

L1 Frequency

One of the two radio frequencies transmitted by the GPS satellites. This frequency carries the Coarse Acquisition Code, P-Code, and the nav message and is transmitted on a frequency of 1575.42 MHz.

L2 Frequency

One of the two radio frequencies transmitted by the GPS satellites. This frequency carries only the P-Code, and is transmitted on a frequency of 1227.6 MHz.

Latitude

A position's distance north or south of the equator measured by degrees from 0 to 90. One minute of latitude equals one nautical mile.

Leg (route)

A portion of a route consisting of a starting (from) waypoint and a destination (to) waypoint. A route that is comprised of waypoints A, B, C, and D would contain three legs. The route legs would be from A to B, from B to C, and from C to D.

Liquid Crystal Display (LCD)

Produced by applying an electric field to liquid crystal molecules and arranging them to act as light filters.

Local Area Augmentation System (LAAS)

The implementation of DGPS to support aircraft landings in a local area (20 mile range).

Longitude

The distance east or west of the prime meridian (measured in degrees) which runs from the North to South Pole through Greenwich, England.

Long Range Radio Direction Finding System (LORAN)

A radio navigation aid operated and maintained by the U.S. Coast Guard. It is used as a supplemental system for harbor approach navigation and inland navigation. LORAN C is used in civil aviation.

Magnetic North

Represents the direction of the north magnetic pole from the observer's position. The direction a compass points.

Magnetic Variation

Errors in magnetic compass readings caused by changes in the earth's magnetic field at different locations on the planet. Navigational charts list the variation and a yearly level of increase.

Map Display

A graphic representation of a geographic area and the features in it.

Multiplexing Receiver

A GPS receiver that switches at a very rapid rate between satellites being tracked. Typically, multiplexing receivers require more time for satellite acquisition, and are not as accurate as parallel channel receivers. Multiplexing receivers are also more prone to lose a satellite fix in dense woods than parallel channel GPS receivers.

Multipath

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."

　

Nautical Mile

A unit of length used in sea and air navigation, based on the length of one minute of arc of a great circle, especially an international and U.S. unit equal to 1,852 meters (about 6,076 feet).

Navigation

The act of determining the course or heading of movement. This movement could be for a plane, ship, automobile, person on foot, or any other similar means.

Navigation Message

The message transmitted by each GPS satellite containing system time, clock correction parameters, ionospheric delay model parameters, and the satelliteÕs ephemeris and health. The information is used to process GPS signals to give the user time, position, and velocity. Also known as the data message.

NAVSTAR

The official U.S. Government name given to the GPS satellite system. NAVSTAR is an acronym for NAVigation Satellite Timing and Ranging.

NMEA (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.

NMEA 0183

A standard data communication protocol used by GPS receivers and other types of navigation and marine electronics.

North-Up Display

A GPS receiverÕs display screen always showing North on top.

Parallel Channel Receiver

A continuous tracking receiver using multiple receiver circuits to track satellites simultaneously.

P-Code

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.

Pixel

A single display element of an LCD screen. The more pixels, the higher the resolution and definition.

Position

A geographic location on the earth commonly measured in latitude and longitude.

Position Fix

The GPS receiver's computed position coordinates.

Position Format

The way in which the GPS receiver's position will be displayed on the screen. Commonly displayed as degrees and minutes, with options for degrees, minutes, and seconds, degrees only, or one of several grid formats.

Prime Meridian

The zero meridian (0¡), used as a reference line from which longitude east and west is measured. It passes through Greenwich, England.

Pseudo-Random Code

The identifying signature signal transmitted by each GPS satellite and mirrored by the GPS receiver in order to separate and retrieve the signal from background noise.

Pseudorange

The measured distance between the GPS receiver and the GPS satellite using uncorrected time comparisons from satellite transmitted code and the local receiver's reference code.

RS-232

A serial input/output standard that allows for compatibility between data communication equipment made by various manufacturers.

Radio Technical Commission for Maritime Services (RTCM)

A commission established for the purposes of establishing standards and guidance for interfacing between radiobeacon-based data links and GPS receivers, and to provide standards for ground-based differential GPS stations.

Route

A group of waypoints entered into the GPS receiver in the sequence you desire to navigate them.

Search the Sky

A message shown when a GPS receiver is gathering data from satellites to compute a position without almanac data.

Selective Availability (SA)

The random error which the government intentionally adds into GPS signals so that their accuracy, for civilian use, is degraded. The level of SA is subject to accuracy degradation to 100m.

　

Space Segment

The satellite portion of the complete GPS system.

Speed Over Ground (SOG)

The actual speed the GPS unit is moving over the ground. This may differ from airspeed or nautical speed due to such things as sea conditions or head winds. For example, a plane that is going 120 knots into a 10-knot head wind may have a SOG of 110 knots.

Statue Mile

A unit of length equal to 5,280 feet or 1,760 yards (1,609 meters) used in the U.S. and other English-speaking countries.

Straight Line Navigation

The act of going from one waypoint to another in the most direct line and with no turns.

　

Taiwan Grid

二度分帶, 是台灣專用的一種座標格式, 以 X, Y 的數值表示, 每一單位為一公尺.

TracBack

The GARMIN feature which takes your current track log and converts it into a route to guide you back to a starting position.

Track-Up Display

The direction to be followed, is always located at the top of the display.

Track (TRK)

Your current direction of travel relative to a ground position (same as COG).

Triangulation

The location of an unknown point, as in GPS navigation, found by using the laws of plane trigonometry.

True North

The direction of the North Pole from your current position. Magnetic compasses are slightly incorrect due to effects of the Earth's magnetic field. GPS units correct for magnetic influences.

Turn (TRN)

The degrees which must be added to or subtracted from the current heading to reach the course to the intended waypoint.

Universal Time Coordinated (UTC)

A universal time standard, referencing the time at Greenwich, England. Also referred to as GMT or Zulu time.

Universal Transverse Mercator (UTM)

A worldwide coordinate projection system utilizing north and east distance measurements from reference point(s). UTM is the primary coordinate system used on U.S. Geological Survey topographic maps.

U.S.C.G.

United States Coast Guard. The Coast Guard is responsible for providing all of the navigation aids in the U.S. including DGPS.

User Interface

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.

User Segment

One segment of the entire GPS system that includes the GPS receiver.

Velocity Made Good (VMG)

The rate of closure to a destination, based upon your current speed and course.

趨近目的地的比值, 取決於您目前的速度與方向

Waypoint

A permanently stored and named position in the GPS receiver's memory.

指可以存放在 GPS 或是電子地圖中的用戶自定地標點

Wide Area Augmentation System (WAAS)

A U.S. Federal Aviation Authority (FAA) system of equipment and software that supplements GPS accuracy, availability and integrity. The WAAS provides a satellite signal for WAAS users to support enroute and precision approach aircraft navigation.

美國聯邦航空系統的軟硬體設備. 可增加 GPS 的精準度. WAAS 為 WAAS 用戶提供衛星號以取得精準的航空導航需求. 這裡有整理一些較詳細的資料

WGS-84

World Geodetic System - 1984. The mathematical reference ellipsoid used by GPS.

世界地理系統於 1984 年制定. GPS 使用的數位楕球投影系統之一. 參考上述的 Datum (座標系統格式) 幾乎所有的的導航軟體都支援 WGS-84, 在我們台灣, 另一個被支援的座標系為虎子山系統, 為民國 67 年所制定的, 在 Garmin 的 GPS 產品中有些機種在座標系統設定欄下會有 TW67, 或是英譯的 Hu Tsu Sam. 不過現在有所喟的 TW97, 其實就是回去用 WGS-84, 配合二度分帶的座標格式. 我們若配合GPS使用電子導航軟體時, 要注意GPS的座標系必需與軟體所設定的座標系一致或是和地圖一致才不會產生過大的誤差.

Y-Code

The encrypted P-Code.

加密過的格式碼, 為軍用, 或是被援權製造的高精度測量專用的 GPS, 價格很昂貴.