Glossary of terms - GPS, SatNav & Maps

The world of GPS SatNav (Sat Nav) and maps is full of technical terms, acronyms and other abbreviations. Here's a glossary or dictionary of the most commonly used words/terms relating to satellite navigation systems and mapping/route software. Please let me know of any others that should be included.

See also, GPS & SatNav Jargon Buster further doen the page

See also: Garmin: GPS Glossary (external link)


Acquisition the ability to find and lock on to satellite signals for ranging.
Basemap a map or GIS that is pre-loaded in a GPS receiver
Coordinate a location on the surface of the earth. 'All Topo Maps: GPS' converts all coordinates to a Latitude Longitude pair, but will import coordinates in UTM notation.
Datum The model of the earth's surface. The datum for the map you are using is found the map legend. Most of the maps included in 'All Topo Map' map sets are NAD27. See [ Datum Configuration ].
GIS Geographic Information System is a system for capturing, storing, analyzing and managing data and associated attributes which are spatially referenced to the earth
GLONASS Global Navigation Satellite System is the Russian counterpart to GPS. GLONASS provides worldwide coverage, however, its accuracy performance is optimized for the northern latitudes and is specificed as identical to that of GPS SPS.
GPS Global Positioning System
GPS receiver An electronic device used to measure ranges to GPS satellites and determine geographic coordinates.
Latitude The distance in degrees above or below (North or South) of the equator.
Longitude The distance in degrees east or west of the Greenwich Meridian.
MapSource a detailed mapping program that can load map information into a Garmin GPS receiver. The Mapsource software includes functionality to backup personal waypoints and routes.
NAVSTAR the name given to GPS satellites. NAVSTAR is an acronym for NAVigation Satellite Timing and Ranging
NMEA National Marine Electronics Association. NMEA, POBox 3435, New Bern NC 28564.
POI Points of Interest
Route an ordered group of waypoints (points ot tracks), with an optional route name and number.
Routepoint a waypoint that is a member of a route. In most GPS devices, standalone waypoints may also be members of one or more routes.
SatNav or Sat Nav short for Satellite Navigation system; A civillian GPS receiver
TMC Traffic Message Channel - an RDS radio data service providing traffic information. Some sat navs come with a built in TMC radio receiver, and for others it is an option
Track an ordered group of coordinate locations automatically accumulated in GPS memory as your position changes. Moving a track from your GPS to the 'All Topo Maps' viewer will result in a trail annotation showing the path you have traveled.
Trackpoint a coordinate that is a member of a route. Some GPS devices allow you to convert a track to a route which will result in trackpoints converting to waypoints.
UTC Universal Coordinated Time, formerly GMT or Greenwich Mean Time
UTM Universal Transverse Mercator, zone based metric grid.
Via Point / ViaPoint Via points let you direct your navigation system to create a route that passes through a particular place. Via points are especially useful for longer trips where you want to pass through a particular city or use a favorite road or highway.
Better GPS systems let you add a via point to the current route for things such as food stops or site seeing detours.
Waypoint the combination of a coordinate location, a coordinate name, a coordinate description and a coordinate note.
Waypoint Description A longer description of a waypoint, the description may contain more characters and may include spaces. Two or more waypoints may have the same exact description. You may turn waypoint description annotations on and off in the 'All Topo Map' viewer using the Alt-D shortcut.
Waypoint Name A six character, alpha-numeric name associated with a coordinate. Spaces are not allowed. The GPS tool will convert a name like 'Grass Creek' to 'GRASSC', if another waypoint name exists with the same name, the second occurrence will be changed to 'GRASS1'. Waypoint names are forced to be unique. You may turn waypoint names on and off in the 'All Topo Map' viewer using the Alt-N shortcut.
Waypoint Note Generated automatically by 'All Topo Maps: GPS' the note generally has a reference to where a waypoint came from. Waypoint notes are not sent to the GPS but are sent to the All Topo Map viewer. You may turn waypoint note annotations on and off in the 'All Topo Map' viewer using the Alt-T shortcut


GPS & SatNav Jargon Buster:

What is SatNav (Sat Nav)?
Satellite navigation systems use radio time signals transmitted by satellites to enable mobile receivers on the ground to determine their exact location. The relatively clear line of sight between the satellites and receivers on the ground, combined with ever-improving electronics, allows satellite navigation systems to measure location to accuracies on the order of a few metres in real time.

What does GPS mean?
GPS stands for Global Positioning System (GPS). A global positioning sytem allows you to pinpoint your exact location anywhere on the surface of the planet utilising a series of satellites that are constantly orbiting the earth. So long as you are above ground and can see the sky it should work.

What is SiRF
SiRF is a company that manufactures GPS chips. Their newest chip, the SiRF Star III, is super-sensitive and achieves a TTFF of one second. This makes real-time navigation practical, even in many indoor environments, through urban canyons, and under dense foliage. They are currently the most popular manufacturer of GPS chips.

NMEA stands for National Marine Electronics Association, and the NMEA 0183 standard is a data specification used for GPS receivers.

TTFF stands for Time To First Fix, the time taken for the receiver to obtain a satellite position from at least three satellites.

What does GPRS mean? 
GPRS, stands for General Packet Radio Service, and is a protocol for passing data over a mobile phone network. GPRS offers what has become known as "always on" data connection for GSM mobile phones, allowing for faster browsing of Internet content, and faster access to online services such as WAP and email.
As well as being faster than the older dial-up method of connecting from a mobile, the main advantage is that you don't pay your online time per-minute, you pay for the amount of data you transfer. Another bonus of GPRS, is that sessions can be suspended when an incoming voice call is detected, so you don't lose calls.

What is 'polling'?
Interrogation of devices for purposes such as to avoid contention, to determine operational status, or to determine readiness to send or receive data.

What is 'geofencing'?
Restricting the movement of a vehicle or other object to within a specified area. The location of the vehicle is monitored by telemetry and an alarm raised if it goes outside that area.

What does SMS mean?
Short Message Service: SMS is available on digital GSM networks allowing text messages of up to 160 characters to be sent and received via the network operator's message center to your mobile phone, or from the Internet, using a so-called "SMS gateway" website. If the phone is powered off or out of range, messages are stored in the network and are delivered at the next opportunity

What does GSM mean?
Global System for Mobile communications, the most widely used digital mobile phone system and the de facto wireless telephone standard in Europe. Originally defined as a pan-European open standard for a digital cellular telephone network to support voice, data, text messaging and cross-border roaming. GSM is now one of the world's main 2G digital wireless standards

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