The GPS position update rate is 10 Hz because the GPS satellites orbit the Earth at a speed of about 4,600 mph. This means that the satellites are constantly moving so they can relay positioning information to receivers on the ground. Therefore, receivers need to be able to receive signals from multiple satellites in order to calculate their location. And since there are only so many GPS satellites orbiting the Earth at any given time, receivers need to be able to track them quickly in order to receive positioning updates at a frequency of 10 Hz.