I am reasonably new to ham radio and I understand that they depend on the antennas "seeing" each other. That is, the signal won't go through the earth. My use has been limited to local repeaters around town and direct to another users. But I am wondering what the availability is of repeaters when you are out west on the trail. For example, in Colorado, Utah, Arizona, etc. Or are the repeaters mostly at the cities and unreachable from the trail? I'm asking because I am planning a trip to Colorado and hoping to use APRS to allow my wife to see where I am. But not sure how often I can get a signal out.