The horizontal positional accuracy of the SPEEDBOX20 is quite typical for a unit in its class, with accuracy to within 3m being obtained under most conditions. Position is output at 20Hz and uses the very latest processing techniques to eliminate jumps in position when the satellite constellation changes, whilst avoiding any lag in positional update when the unit moves. The example given shows the positional ‘walk’ whilst the unit was kept stationary for 1 hour, using a standard patch antenna mounted on the roof of a building, with a clear, unobstructed view of the sky.
The vertical positional (altitude) accuracy is typically only half as accurate as the horizontal positional accuracy, this is entirely due to the geometry of the satellites visible from the antenna and affects all GPS systems. From any point on the surface of the Earth, there is a maximum spread of visible satellites of approximately 180° in the horizontal plane, but only 90° in the vertical plane.
GPS positional data recorded during 1 hour static test