Royal Institute and Observatory of the Spanish Navy

About: Royal Institute and Observatory of the Spanish Navy is a facility organization based out in San Fernando, Spain. It is known for research contribution in the topics: Gamma-ray burst & Magnetic anomaly. The organization has 50 authors who have published 106 publications receiving 2565 citations. The organization is also known as: Instituto y Observatorio de Marina de San Fernando.

A Simple Technique to Extend the Bandwidth of Electromagnetic Sensors

Abstract: Electromagnetic sensors are typically loaded with an external resistance value that provides an effective damping factor of 0.7. The velocity response of the sensor is given by a third-order equation but can be approximated by an equation of second order if the coil inductance is neglected. We propose to use a capacitor in series with the resistance (series RC load) instead of a resistance only. The transfer function is then given by a fourth-order equation that can be reduced to a third-order one, as a zeros-poles analysis shows. This is the simplest and cheapest way to extend the response of an electromagnetic sensor. If appropriated values of R and C are selected, then the flat band of the frequency response is increased by moving the corner frequency down by a factor of 1/4 without any effective gain reduction.

On the Ag-photodissolution phenomenon in As0.35S0.65 chalcogenide glass films

Abstract: The results of a systematic study of the photodissolution of silver in As0.35S0.65 chalcogenide glass films are reported. The silver and chalcogenide glass films were prepared by thermal evaporation. The kinetics of the photodoping process have been investigated in detail by monitoring the time dependence of the electrical resistance of the Ag layer, under illumination by He-Ne laser light, with a view to the determination of the dependence of the electrical resistivity of the silver film on its thickness. In contrast with the behaviour found in other amorphous chalcogenide materials, an induction period was not observed before the onset of the photodissolution effect; instead, the process consisted of a phase of acceleration, followed by one of deceleration. The maximum photodissolution rate and duration of acceleratory period were studied as a function of the light intensity and of the temperature of the sample.

GPS carrier phase and precise point positioning time scale comparisons using different software packages

Abstract: Precise point positioning (PPP) software combines dual frequency code and phase GPS observation data with precise information about the satellite clocks and orbits provided by the International GNSS Service (IGS). It is also a very interesting method for time metrology. Error sources like tropospherical path delay and site displacements have to be modeled or estimated, while the error induced by the first order ionosphere terms can be canceled due to the usage of both GPS frequencies. In case of long baselines the atmospherical effects dominate. Here the physical correction models become important. In this work we compare several precise point positioning (PPP) software packages and study not only the clock solution but also other estimated parameters like positions and zenith tropospheric zenith path delays in order to find the software that is most suitable for time transfer. Especially the repeatability of the position could be a good indicator for quality. We use Dicom GTR50 time and frequency transfer receivers connected to local time scale realizations on baselines with different lengths.

Bouguer anomalies of the NW Iberian continental margin and the adjacent abyssal plains

Abstract: The NW Iberian margin is a hyperextended continental margin, formed during the opening of the North Atlantic Ocean, where a subsequent partial tectonic inversion has undergone during the Alpine Oro...

EURAMET Project 1156, GPSCALEU: Results of two years GPS receiver calibration campaign

Abstract: Since 2010 ROA has supported the coordination of the EURAMET Technical Committee for Time and Frequency (TC-TF) Project 1156, GPSCALEU, a reaction from EURAMET TC-TF to Recommendation 2 of CCTF 2009: to study the characterization of GNSS equipment in use for establishing the time links between institutes contributing with their clocks to TAI. Starting that year, it was organized a GPS calibration campaign between three contributing laboratories: ROA (Spain), PTB (Germany) and INRIM (Italy). The time transfer results were achieved by using P3, and also carrier phase PPP comparison techniques. These results were also used to re-calibrate the TWSTFT (Two-Way Satellite Time and Frequency Transfer, TW for short) links between the involved laboratories, with an uncertainty slightly higher than GPS links.