High-precision GNSS algorithms have a complexity that requires a high computational load, so not all mobile devices will be capable of calculating position through their use, and without compromising their efficiency and wasting battery. The development of an app will provide the opportunity to research the possibility of controlling 100% of the raw data from the GNSS sensor from smartphones. Oriented to “cloud computing”, since the main objective is to provide a real-time computing tool to achieve a navigation solution, we use GNSS algorithms for this purpose, and thus avoid the computational load on the smartphone.

In 1870, the newly created Instituto Geográfico of Spain, the precursor of the current Instituto Geográfico Nacional (IGN), began to carry out work for the preparation of the National Topographic Map of Spain, a major project that would take almost 100 years to be completed. This work began with the measurement of geodetic bases throughout the national territory. Subsequently, the necessary topographic surveys were conducted to delimit the boundaries of municipalities, and to represent all the planimetric elements. As a part of this, surveys were carried out with topographic compasses, which allowed work to be performed at a good pace and with sufficient accuracy for cartographic purposes. The current IGN keeps in its archives all the documentation generated in the work related to the completion of this major project. The objective of this study is to extract information from this documentation on the magnetic declination measured at that time, and to evaluate it as a possible source of historic geomagnetic information for use in future works. To achieve this, we compared the recovered declination dataset with those generated for the same locations and dates using two independent sources: the Cov-Obs.x2 geomagnetic field model, which spans the last two centuries, and the declination data used to produce the first Spanish declination chart developed by the IGN at the beginning of the 20th century. The results show a clear agreement between the recovered dataset and both sources of independent declination data, suggesting that this dataset is valuable for improving our understanding of the recent geomagnetic field history and for refining main field models for the last centuries.