G.P.S. Basics

  • Basis of GPS technology is a set of 24 satellites that are continuously orbiting the Earth.
  • The satellites are equipped with an atomic clock and a radio transmitter that send out a signal as to the exact time and their location.
  • Once the receiver(GPS) locks into 4 or more of these satellites, it can triangulate its location from the known position of these satellites.
  • UTC time is the basis of all GPS calculations. If nothing else a GPS receiver is the most accurate time piece available.
  • Functionality of the receiver is dependent of the ability to receive signals from the satellites. Certain locations such as under very thick foliage of the bottom of a slot canyon will cause problems with location. Most newer receivers don’t have these problems.
  • Accuracy is dependent on the number and quality of the signals it is getting from the satellites and from a factor called “Selective Availability”.
  • Selective availability is an intentional error that is introduced into signals coming from the satellites that can create readings 300’ off. At worst even with selective availability turned on the readings are within 100’.
  • On May 1, 2000, President Clinton had Selective Availability turned off.
  • Accuracy is now <10 meters. GPS is more accurate than the accuracy standard for USGS topographic maps.
  • 18 additional satellites are now under construction to improve accuracy even further and to eliminate distortions caused by the ionosphere.

USES FOR GPS UNITS

FORESTRY APPLICATIONS

  • Mapping timber stands and calculating acreage for site prep and planting.
  • Mapping stands for timber sales.
  • Marking Southern Pine Beetle (SPB) spots.
  • Navigating to SPB spots.
  • Navigating quickly and easily to tracts in unfamiliar areas (how many times have we tried to locate a tract in an unfamiliar county?).
  • Marking and measuring areas for aerial spray contractors.
  • Marking and navigating back to the big whitetail deer scrape found while cruising timber!
  • Delineating stream management zones (SMZ’s)
  • Mapping forest roads
  • Creating maps for fire plans
  • Locating corners of property

HUNTING USES

  • Never get lost again. Plots a route back to your vehicle or camp.
  • Get to deer stands easily. (set as waypoint)
  • When trailing a deer you can mark to spot when you go for help or can plot the best route back to your vehicle.
  • Calculate acreage of game plots for efficient use of fertilizer and seed.
  • Mark scrape lines and rubs.
  • Can get you back to the camp in wilderness areas.
  • Some units include best hunting and fishing times.

FISHING USES

  • Navigate to a reef or a good fishing spot.
  • Man Overboard MOB (to save a life)

FARMING

  • Some combines have a GPS system which can monitor which parts of a field had the best yield.
  • Many of the same uses as forestry in precise measurements involving chemicals, seeds, and fertilizer.

AUTOMOBILE

  • Mapping units can help to navigate to a destination.
  • Some complex units even speak to you with directions

ARCHEOLOGY

  • Mark locations of found artifacts.
  • There are also many other uses too numerous to mention.

GPS RECEIVER BASIC USE

  • Initialization of unit—Units, location, etc. Time offset from Greenwich.
  • Save current position as a waypoint
  • GO-To to navigate to a waypoint
  • Trackback is a plotting function which plots your course of travel. It will create multiple waypoints to take you back to your point of origin.