Archive for October, 2008

ODTS versus PPP coordinates

October 9th, 2008 by Ricardo Píriz

As explained in the previous entry of this blog, the ODTS algorithm inside magicGNSS is able to calculate precise station coordinates. Another technique that is becoming increasingly propular to calculate receiver coordinates is Precise-Point-Positioning (PPP).

The main difference between ODTS and PPP is that ODTS is a multi-station global solution that calculates also satellite orbits and clocks, and PPP is a single-station technique where satellite orbits and clocks are solved beforehand using an independent software (or are fixed to IGS solutions). ODTS is based on a batch least-squares algorithm whereas PPP is normally based on a sequential filter that solves for the user reciever coordinates, clock, tropo, and phase ambiguities.


Refine station coordinates: when?

October 3rd, 2008 by Álvaro Mozo

One of the available scenario settings is the “Refine Station Coordinates” check box. When this is checked, magicGNSS will estimate the station coordinates, yet keeping a constraint to their initial value, as provided by ITRF (or the IGS). This refinement can compensate for some inaccuracies, such as some mismodelling of the Earth motion, thus helping to achieve better performances.

On the other hand, when the observability is not good enough (e.g. when the number of stations/data is insufficient or their distribution is poor) the estimation of the coordinates may be correlated with other parameters and lead to a degradation of performances! So, should one check the box or not?


Looking for something on the blog?

October 2nd, 2008 by Ricardo Píriz

As the magicGNSS blog gets more entries it obviously becomes increasingly difficult to find some specific information on it. But do not worry, that is why the Search window is there at the top right. Just type what you are looking for (e.g., “presentation” or “paper”) and click on Search. Enjoy!