Traditional differential GPS, generically referred to as relative positioning, relies upon reference stations, which derive corrections for each GPS satellite measurement that are then applied at the user end to cancel out common errors. Whilst this technique is very robust and well proven there are limitations, the main one being that as the users distance to the reference station increases, the accuracy decreases due to the errors becoming increasingly de-correlated.
In contrast to having a unique set of satellite corrections specific to each reference site, Veripos Ultra consists of one set of corrections for the satellites, which are valid globally. These are used at any location with no dependence on distance to reference stations.
Veripos Ultra delivers a high accuracy position using a proprietary PPP algorithm developed by Veripos that minimises or removes all of the main GPS errors sources such as satellite orbit, satellite clock, troposphere, ionosphere and multi-path.
To carry out this absolute positioning technique orbit and clock correction information is broadcast for each and every GPS satellite to allow removal of satellite based error components. Use of dual-frequency GPS hardware at the user-end permits the calculation and removal of local ionosphere errors, whilst troposphere delays are estimated within the calculation.
Other sources of error are also modelled and include ocean loading, earth tides and phase windup. To obtain the high-accuracy solution, multi-path and GPS receiver noise errors are minimised through use of carrier phase observables, which are precise to the millimetre level.
In all, Veripos Ultra provides a truly global, seamless high-accuracy position, which is not only robust but effective in all areas of operation, including areas of ionosphere disturbance
