Portable navigation systems pinpoint location using a networks of satellites, so they can save you from becoming stranded even when you’re in the wilderness, out of cell service range. Two systems exist: the Global Positioning System (GPS) is a satellite-based navigation system that includes 24 satellites. It’s available worldwide and is funded by the United States government; and the Russian-funded Global Navigation Satellite System (GLONASS), or Globalnaya Navigazionnaya Sputnikovaya Sistema, the second-largest navigational system in the world. It works essentially the same way as the GPS system, just using different satellites. Using both networks improves the speed and accuracy of a navigation system, though it’s common for a device to use one or the other.