GPS wildlife tracking - terminology
2-axis information: Stored activity data that relates to animal head movement up and down and from left to right (indicating walking).2D positions: A two-dimensional GPS position fix that includes only horizontal coordinates (no GPS elevation) requiring at least three visible GPS satellites.
3D positions: A three-dimensional GPS position fix that includes horizontal coordinates, plus elevation requiring a minimum of four visible GPS satellites.
Activity data: Information stored in the GPS collar memory and/or transmitted over the VHF beacon that indicates the level and the type of movement by the study animal.
Almanac Data: 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.
Back-up battery: An alternative power source in the GPS collar that provides current to the drop off mechanism and the VHF recovery beacon even after the primary power source has gone flat.
Collar schedule: A user created timetable that indicates to the GPS collar when to attempt GPS position fixes and when to transmit a VHF signal, among other things.
Data transmission range: The distance from which a user can successfully retrieve GPS position data that is stored in the GPS collar memory and transmitted to the user on command.
Date and time of mortality event: When an animal died.
Datum: A mathematical model that depicts a part of the surface of the earth. Latitude and longitude lines on a paper map are referenced to a specific map datum. The map datum selected on a GPS receiver needs to match the datum listed on the corresponding paper map in order for position readings to match.
Differential correction: An extension of the GPS system that uses land-based radio beacons to transmit position corrections to GPS receivers. DGPS reduces the effect of selective availability, propagation delay, etc. and can improve position accuracy to better than 10 meters.
Dilution of precision (DOP): A measure of the GPS receiver/satellite geometry. A low DOP value indicates better relative geometry and higher corresponding accuracy. The DOP indicators are GDOP (geometric DOP), PDOP (position DOP), HDOP (horizontal DOP), VDOP (vertical DOP), and TDOP (time clock offset).
Drop off mechanism: A device built into the GPS collar that will allow the user to remotely cause the GPS collar to fall off of the study animal on command.
Glosnass: The Global Orbiting Navigational Satellite System; the Russian counterpart to the United States' GPS system.
GPS: A global navigation system based on 24 or more satellites orbiting the earth at an altitude of 12,000 statue miles and providing very precise, worldwide positioning and navigation information 24 hours a day, in any weather. Also called the NAVSTAR system.
GPS acquisition time: The time it takes a GPS receiver to acquire satellite signals and determine the initial position.
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.
Longitude: The distance east or west of the prime meridian (measured in degrees). The prime meridian runs from the north to South Pole through Greenwich, England.
Magnetic on/off switch: This device enables a user with a magnet to turn off a GPS collar after programming but prior to deployment.
Maximum number of locations: The most locations that a GPS collar can acquire before its primary battery is depleted.
Missed positioning opportunities: The instances of no location data acquired by a GPS collar when a GPS position was attempted.
Mobile phone data download: GPS position data that is stored in the GPS collar memory and transmitted to the user over the GSM mobile phone network.
Non-volatile memory: A memory chip that does not require a power source in order to retain information.
Output: Information supplied to the user by the GPS collar whether supplied by mobile phone download, radio download or direct download via a custom USB cable.
Radio download: GPS position data that is stored in the GPS collar memory and transmitted to the user via a 433 MHz transceiver.
Remote data download: GPS position data that is stored in the GPS collar memory and transmitted to the user.
Store-On-Board: A GPS collar that acquires GPS positions and stores them but does not transmit them to the user remotely. A user must recover this collar to extract the data manually via a wireless or a USB connection between the collar and the user's PC.
Temperature Range of Operation: The lowest and highest temperatures at which a GPS collar will still continue to operate properly. The collars are not guaranteed to operate properly outside of this temperature range.
UTM: Universal Transverse Mercator. A nearly worldwide coordinate projection system using north and east distance measurements from reference point(s). UTM is the primary coordinate system used on U.S. Geological Survey topographic maps.
WGS-84: World Geodetic System, 1984. The primary map datum used by GPS. Secondary datums are computed as differences from the WGS 84 standard.