Data Hacking

168 Part III — Data Hacking
This coordinate system gives us the ability to pinpoint locations. 51° 30.075 North, 0° 08.545
West is the location of Buckingham Palace in London, England. If you enter this into your
GPS (see Figure 8-3), you will get information about how to get there.
As you move, the GPS will plot your position in relation to where you want to go, so you
always know exactly where you are.
FIGURE 8-3: Coordinates
entered into the GPS
Velocity
Velocity isn’t the same thing as speed. Speed is a measure of how fast you are going in any
direction. Velocity is more specific than that. Velocity measures how fast you are going and in
what direction you are going. In a GPS, this is normally computed as a track angle (the direction
of travel with respect to True North).
A GPS solution for velocity enables it to calculate whether you are moving toward or away
from a particular point, and from this information a number of calculations can be computed,
such as the following:
Distance to waypoint
Information about whether you are on course or not
Real-time plotting on a map of your direction of travel
Estimated arrival time
Estimated journey time
Different units display this information differently. Figure 8-4 is a screen capture from a
Garmin eTrex Vista.