Method of estimating the position of a device

(canceled)

Data processing apparatus for estimating the position of a device, the data processing apparatus comprising:

• two or more positioning modules including a satellite positioning module configured to receive satellite positioning signals from one or more satellites of a satellite positioning system, to determine a satellite positioning based estimate of the position of the device from the received satellite positioning signals and to obtain orbital positioning data indicative of an orbital position of each of the said one or more satellites;
• and a controller in communication with the positioning modules, the controller being configured to determine an indicator of the accuracy of the satellite positioning based estimate taking into account the said orbital positioning data.

A method of estimating the position of a device, the method comprising:

• obtaining a first satellite positioning based estimate of the position of the device, the first satellite positioning based estimate being determined from first satellite positioning signals received from one or more satellites of a satellite positioning system;
• obtaining a second satellite positioning based estimate of the position of the device, the second satellite positioning based estimate being determined from second satellite positioning signals received from one or more satellites of a satellite positioning system;
• and determining an indicator of the accuracy of the satellite positioning system by comparing the first and second satellite positioning based estimates.

-39. (canceled)