Calculation of speed in GPS

In GPS module, i are getting information about

  1. latitude and longitude
  2. Time
  3. Horizontal Estimated Positional Error
  4. Heading
  5. vertical speed
  6. horizonatl speed
  7. Altitude
  8. Location uncertainty angle
  9. Standard deviation of axis along
  10. Standard deviation of axis perpendicular to

How can we calculate the velocity of GPS device based above information?
Can any one explain it? if possible with example.

Best Regards
Sukhdeep Singh

You are already provided with the velocity:

  1. Heading
  2. horizontal speed

I have confusion here.

  1. what is role of vertical speed? where is it useful?
  2. why they are giving vertical speed. I am not sure that speed should be =square root of (square of vertical speed+square of Horizontal speed).
  3. What is heading point?


You will get good altitude and vertical speed data when you have a good 4 (or more) satellite fix. Great if you’re in an airborne object (plane, balloon, rocket…), probably not so useful if you’re in a land based object (car, bike, person…).

As far as I’m aware, the receiver does all the hard maths for you - so the horizontal speed is just that - speed in the horizontal plane - which is all most people want for a land based object (i.e. am I going faster than the speed limit).

Heading is the calculated true (not magnetic) compass heading - done by the receiver by using successive fixes and approximations. Note that you need both speed and heading to get velocity.

ciao, Dave