Free GPS Guidance

When you compare benefits of GPS devices, a feature commonly noted is the number of “channels” a GPS has. What are channels, and are they important to help determine which GPS system to purchase? First, it might be helpful to have a basic understanding of how GPS works. Sometimes taking it down to a very basic level is quite helpful. At the most basic level, your GPS needs one channel for every satellite it is communicating with. You need to realize that there are exceptions to this, but we are going for simplicity here. The more channels your GPS has, the more satellites it can communicate with at one time. The GPS satellite system is designed to provide similar levels of service anywhere in the world, so at any given moment your GPS unit will only be able to “see” a few of the satellites at one time. At least half of the satellites will on the other side of the earth, while others could be out of view due to mountains, trees, buildings, and so on. Sometimes channels are reserved for more than just tracking a visible satellite, but also for searching for other satellites which are predicted to come into view. If you continue to watch the screen over time you will see that some satellites disappear from view while other satellites appear on the horizon. While your GPS might be tracking only 8 satellites, it might be using a couple of other channels to search for new satellites which it predicts will come into view.

Some very basic GPS navigation systems have a single or dual channel scanning receiver that can read and ‘lock’ onto 8 to 12 satellites. If a device can give me a fairly accurate location with only 4 satellites, why would I want more than 5 parallel channels? Since 5 would only allow for a margin of 1 visible satellite, having more channels would permit your unit to maintain a position when you moved behind a building where you suddenly lost contact with several satellites. Ideally you would like to be able track all available satellites simultaneously to maintain a fix under the worse possible conditions. If you turn a corner and several satellites are now obscured from view there is a good likelihood that the extra channels will instantly bring several others into view, thus maintaining continuous accuracy. I hope this has been useful information to help make your decision as you purchase your new GPS navigation system.