GPS and GNSS

The old Global Positioning System (GPS) is familiar to many. Today the GPS program has been incorporated into the more comprehensive Global Navigation Satellite System (GNSS) but the general idea is still the same - estimate location on the earth's surface by measuring distance to fast-moving objects 11,000 miles up.

GPS Navigation
Location information generated by GPS receivers has many uses. Real-time navigation is the GPS function that most of us are familiar with. Once a receiver has estimated it's location on the Earths's surface, it's computer can calculate numeric distances and directions to preprogrammed destinations. More advanced models display navigation information on built-in maps.

GPS Mapping
At the Biodiversity Center we use our GPS equipment to record the map coordinates of natural features that we observe in our fieldwork. Using GPS in this way is referred to as "GPS mapping". The information produced is part of the scientific record so the methods used are more rigorous than for navigation.

Marine-Recreation GPS Receivers
The majority of the Biodiversity Center's GPS mapping work is done with marine-recreation receivers. If recommended procedures are used, this equipment is capable of 5-10 meter accuracy. We have around thirty of these units of varying age and technical capability. They are in constant demand for classes and research projects. However, there are usually a few available to be loaned out. Biodiversity Center Program Assistant Kim McKeefry manages equipment sign-outs. About half of our receivers have the Garmin high-sensitivity antenna technology. Anyone planning to work in tree cover should try to get one of these (look for the "x" in the model number).

Submeter Mapping
In spring of 2011, the Biodiversity Center acquired submeter GPS mapping capability. A hardware and software package was purchased that supports positional accuracy down to 50 centimeters. The selected receiver includes several technical advances reported to improve performance in tree cover, which is a known weakness of submeter technology. Biodiversity Center GIS Technician Mike Stiefvater manages sign-out of this equipment. Coaching on the use of the equipment is availble with a little advance notice. Check out our Submeter GPS page for more information on the equipment and how to use it.

Mapping Methods
GPS mapping work results in latitude/longitude coordinate pairs called waypoints being written to the receiver's memory.

Downloading Waypoints From A GPS Receiver
Raw GPS waypoints are not particularly useful as-is. A number of processing steps are required starting with transfer of the waypoint data to a Windows PC. Check out our downloading options page for more info.