The new generation, low-cost U-blox ZED-F9P receiver was evaluated and statistically compared by GNSS observations on a geodesic monument, through both Precise Point Positioning and Static relative positioning techniques with a distance of 33 km from the references station. This was done with the purpose of checking the use feasibility of the low-cost receiver of similar gamma in topographic-geodesic works. To that end, four scenarios were considered: in the first scenario, the static relative positioning with the low-cost equipment was applied; in the second scenario, the static relative positioning with a geodetic receiver was applied. Both scenarios were processed with commercial software. The third and fourth scenarios were processed with Precise Point Positioning techniques through the RTKLIB software. The results show that Precise Point Positioning techniques get a precision of 1 cm through the use of low-cost equipment which is suitable to apply in geodetic works. In the static relative method, the precision obtained is 7 mm, indicating the possibility of using the low-cost equipment in both survey and geodetic high precision works, considering a line base ≤30 Km, according to the Instituto Nacional de Estadística y Geografía normative.

Nowadays, with the incursion of low-cost GNSS receivers with modern characteristics, it is common to investigate and apply new methodologies and solutions with different receivers of this nature. Based on this fact, the performance of the solution obtained from the low-cost GNSS receiver is evaluated compared to a geodetic grade GNSS receiver at different sampling frequencies for the PPP-static and PPP-kinematic modes. For this, the original RINEX observation files were analyzed and decimated into different sampling rates as 0.1, 0.2, 1, 5, 15 and 30 s with TEQC software. All RINEX files were submitted to the Canadian Spatial Reference System Precise Point Positioning (CSRS-PPP) online service for processing with static and kinematic modes. The PPP-derived coordinates from the low-cost GNSS receiver were compared with the geodetic receiver to evaluate the obtained solution. The results reveal that the behavior of all studied sampling rates from the low-cost GNSS receiver are constant in achieved positioning. In addition, the achieved precision shows that it is recommendable to use a high sampling rate to obtain a cm level in PPP-static mode by using a low-cost GNSS receiver, this mode being the most accurate and potential alternative for structural health monitoring studies, mapping and positioning in urban areas.

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La distribución de velocidades entre las placas del Pacífico y de Norteamé-rica, así como su posible relación con los sismos ocurridos en la zona del Golfo de California en México ha sido estudiada mediante mediciones continuas GPS en el periodo 2010-2016. Los datos GPS fueron procesados con Gamit/Globk para estimar la posición y velocidad de las estaciones continuas. El análisis posterior ha mostrado que el movimiento relativo promedio entre las placas de Pacífico y de Norteamérica es consistente con estudios anteriores, estimando en 40 mm/año en la dirección norte y 30 mm/año en la dirección oeste, con un valor absoluto de 50 mm/año. Se presenta una posible relación entre los cambios repentinos en la velocidad asociados con los eventos cosísmicos y una tendencia que indica que la probabilidad de que se presente un sismo de magnitud Mw ≥ 5.0 crece con el aumento de la velocidad relativa entre las placas.