Setting the Receiver Display – The only information on the receiver screen essential to data collection success are items that indicate whether or not the receiver is happy. These include the satellite status page, 2d vs 3d indication, estimated position error (EPE), etc. But there are many display settings that can be configured for the convenience of the user. Most noteworthy are the Position Format and Map Datum settings. The reasonable initial cost of recreation grade receivers allows for purchase of enough receivers that each technician engaged in mapping work has their own. We’ve observed that technicians are able to work more effiently and accurately when they use the same piece of equipment session after session.
Compass and Notebook
As wonderful as the GPS technology is, there are some things that it doesn’t do very well. For one thing it’s a very poor substitute for a compass. We suggest that field technicians always carry a real compass and not bother with the compass that is built in to a typical recreation-grade receiver.
Mapping work with recreation-grade GPS also requires a field notebook. The note-taking feature built in to the receiver has limited capacity and is ridiculously clumsy to use. Plain old pencil and paper is much more efficient. Most field work requires hand-written field notes anyway so mapping-related information can be captured as part of note-taking that is already being done. This isn’t as detrimental as it sounds since the technician is making entries into a notebook or data sheet anyway. It should be a simple matter to include waypoint info in the note-taking that’s already being done.
Even though we are advocates of note-taking, we are opposed to the practice of transcribing coordinate pairs from the receiver screen to field notes. A more robust practice is to use the Mark Waypoint function to write coordinate pairs to the receiver’s memory, thus eliminating the risk of transcription error. That being said, we know that transcription is a strongly entrenched practice. Some organizations flat-out require it as a matter of policy and under those circumstances there are some practices that should be followed. First, the Mark Waypoint function should be used to store the coordinates in the receiver’s waypoint memory before they are copied from the screen into field notes. Second, the coordinate pair should be written in Decimal Degrees referenced to the World Geodetic System of 1984. That means the receiver display must be configured correctly (Position Format and Map Datum settings).
Taking Care of the Data
Good practice requires that users download marked waypoints as soon as possible. For this first data handling step, no effort should go into categorizing the data. The first priority is to get it onto a PC hard drive that has a rigorous back up protocol. Once the security of the data is assured, the receiver’s waypoint memory can be erased.
Satellite Navigation Systems
Satellite navigation systems are used extensively in GIS mapping work. The are a number of satellite arrays operational or in the works including the US Global Positioning System (GPS), the Russian GLONASS system and the European Union’s Galileo program. The individual satellite arrays are referred to collectively as the Global Navigation Satellite System (GNSS). GNSS receivers can use any well-positioned satellite for calculating a fix, regardless of which country the satellite belongs to.
Natural Resources Mapping With GPS Receivers
The great majority of natural resurces mapping work can be accomplished with recreation grade handheld receivers. These receivers utilize radio signals originating from an array of navigation satellites referred to as the United States Global Positioning System or GPS. The recreation-grade GPS approach is not the only option, but it’s the one that usually comes out on top when a common sense based comparison is made. Since the results of GPS mapping work wind up in the scientific record, the error control and data integrity requirements are more rigorous than those for navigation. For example, receivers used for mapping must be new enough to have “high-sensitivity” technology. The cut-off year is around 2010. There aren’t many of the old klunkers around, but it’s definitely something to watch out for.
These receivers utilize radio signals originating from an array of navigation satellites referred to as the United States Global Positioning System or GPS. The recreational GPS approach is not the only option, but it’s the one that usually comes out on top when a common sense based comparison is made.