Have you had an instance where you cannot get the correct position of your asset in a built up area? Is your vehicle showing as being somewhere you know it isn't? This can often happen in the city, especially in underground carparks.
GPS Bouncing or Multipath as it is called in the industry, occurs when the GPS signals refract off of objects such as concrete, glass and roofing. Multipath is most prevalent when parking vehicles inside of buildings, or driving through city’s high-rise areas, such as downtown Auckland.
The issue of GPS Bouncing (Multipath) is a common problem and is not easily fixed – however, Argus Tracking has reduced multipath events on our system by 98% by using our hardware and software smarts. We use 8 satellite positions for important data such as speeding and BI. We are the only GPS company in New Zealand who has taken an initiative to try and overcome this annoying issue.
Another example where you see multipath is with vehicle navigation system. If you leave the navigation device stationary in the same position for an extended period of time you will see it recalculating your position and the map moving. The multipath problem happens to all types of GPS devices.
The other possible reason for seeing some bouncing is atmospheric conditions such as solar flares or the electromagnetic GPS signals being slowed and refracted by the different atmospheric layers. When issues like this happen, the hardware will sometimes try and hold onto any good GPS positions it is receiving, hence making it look as if the asset is moving.
This website explains in more detail about GPS errors.