Features Common to GPS Recievers
You see people using GPS receivers in cars, boats, while tracking through the wilderness, and out on the opening road. And if you go down to your local electronic store, various brands and models with loads of features are represented. But before you lay down your money, you better be sure which features you are going to need on the road or trail. Otherwise, you may be unhappy with what it can or can't do for the bicyclist or hiker.
General Features
Before I discuss key features for biking and hiking with GPS, I need to mention a few general features that separate receivers immediately:
As long as a receiver is on, it will search for and acquire location information constantly. But not all receivers obtain and process this information at the same speed, especially if the unit has been powered off. The on-screen simulation test is not an accurate indication of the speed in the field. So the 'Time-to-First-Fix' (TIFF) should be noted for each receiver that you are researching. Factors that affect TIFF include the number of channels the receiver has, its type of antenna, and if the unit has a high-sensitivity processor chip like the SiRF Star III.- In general, less weight and/or small size comes at cost. This cost is reflected either by higher price or less features. Small units often double-up functions on unlabeled buttons or display small screens. Conversely, large models have dedicated and clearly labeled buttons for primary functions and wide screens.
In basic terms, a receiver locks onto each available satellite's transmission, determines the distance away from each satellite by measuring the time it takes the radio wave to reach the receiver, and calculates its location on Earth by triangulation of the satellites, each in its own orbit. The distance from a fourth satellite enables the receiver to determine its exact position on Earth.
Maps
A little warning about maps: Don't expect to buy a handheld receiver with preloaded maps and take off on your bike or trail while the receiver guides you along. This fact is what angers new GPS owners the most. Most out-of-the-box handheld receivers come with a general map of your country with highways and freeways and not secondary roads. You will have to purchase a navigator or trip GPS receiver, the one most people buy for their cars, with the pre-load maps for this type of navigation. Or you will have to buy the appopriate maps and preload them on your handheld receiver. The following is a general description of the types of maps available for handheld receivers:
- Base Maps: These maps are usually pre-loaded in most handheld receivers. They offer very little detail and are chosen so that no added costs is applied to the receiver. You will just see highways and freeways with general detail. You won't be able to navigate with 'turn-by-turn' directions.
- World Maps: They are normally a step up in detail from the basemaps. You may see more minor roads and more detail, but you won't be able to navigate with 'turn-by-turn' directions.
- Navigator and City Maps and Premium MetroMaps: These are maps you will need for secondary roads, rural roads, and 'turn-by-turn' route navigation. Most of the automobile navigation GPS receivers come with these levels of maps preloaded. For handheld receivers, you will have to purchase these maps separately. They are not cheap, but they are worth the costs for route planning.
- Topographic Maps: These maps are based on government survey maps and show elevations, trails, streams, and landmarks. The amount of detail depends on the scale of the maps. If you are a hiker, mountain biker, or adventurer, these are the maps you will need to purchase.
- Country Maps: The detail of these maps very drastically, depending on the initial maps they were based on. If you are going to travel in different countries, you will need to verify the quality of the maps. In general, the more detail the map the greater the costs. The cost of the maps is directly related to the royalties that have to be paid. Maps, even of small areas, can cost hundreds of US dollars.