Finding a Location Using a GPS Unit Introduction to GPS GPS technology is frequently used for general navigation. People regularly use GPS technology in every day life and in some cases they may be unaware that it is a modified GPS unit. A great example of this is satellite navigation systems in cars, these use GPS technology along with map information to give you road directions. SatNavs and GPS units utilize a network of satellites. These satellites transmit precise microwave signals to the GPS unit, which enables a GPS receiver to determine its' location; speed and direction. A GPS receiver calculates its position by measuring the distance between itself and three or more GPS satellites using a method called triangulation. In triangulation, a microwave signal is sent out from three or more satellites to the GPS receiver, the length of time it takes to receive a single signal relates to a distance measurement. These measurements allow the GPS unit to make an accurate approximation of its location.
Figure 1. Method of Triangulation and Global Satellite Distribution In this tutorial we will give you an idea of tools and functionality of a GPS unit. This should give you all the basic knowledge you will need to change the options and settings of your GPS unit and produce map locations for your study site.
GPS Layout Before you start using your GPS unit it is important that you understand the layout of the device. There are many brands and models of GPS on the market but this tutorial features the Garmin GPS 76 (figure 2). Although different GPS software creates slight variations in their functionality, they are generally very similar. Our study (and this tutorial) only uses a few of the basic tools that are available on GPS units and it therefore, should be a fairly reliable as a guide across all makes and models. Buttons When you look at a GPS, you will realize that it has very few buttons. Each button can actually perform many different actions. Once you know and understand what each button does you can move around the software in the devise and carryout various GPS tasks. Information on uses of each button is described in the diagram bellow, and later this tutorial will explain how to use them in various contexts.
Figure 2. Garmin GPS 76 Layout - Buttons and their functions
Screens The Garmin GPS software divides the GPS device onto different screens or pages, which you can move between using the 'Page' button. The basic Garmin set up is divided into five screens, their basic layout and description can be seen bellow in figure 3 (order and additional screens may vary between units).
Figure 3. Screen Layouts
The Satellite screen provides a visual reference of satellites being tracked. The Map screen displays your movements and nearby map features. The Navigation screen provides guidance to your destination. The Trip Computer screen provides a variety of trip and navigation data. The Main Menu screen provides a directory of advanced features...