Distributed Acoustic Sensing (DAS) is an innovative technology based on Rayleigh scattering, which uses fiber optic cables as acoustic sensors to provide distributed voltage detection.[1] This technology allows detecting vibrations, acoustic waves or movements along the cable, offering an advanced monitoring system used in various industries.[2][3]​.

Contenido

Los sistemas DAS funcionan emitiendo luz láser a través de un cable de fibra óptica.[4]​ Las vibraciones y los cambios mecánicos a lo largo de la fibra causan alteraciones en el índice de refracción del cable, lo que genera una dispersión de la luz. Este fenómeno se analiza para detectar eventos acústicos en tiempo real.

El valor máximo de deformación que se puede medir depende de la relación portadora/ruido de la señal óptica de retorno. El nivel de la portadora está determinado en gran medida por la amplitud de la señal óptica "Amplitud (física)"), mientras que el ruido es una combinación de una variedad de fuentes, incluido el ruido del láser, el ruido electrónico y el ruido del detector.

Spatial resolution and spatial sampling period

Spatial resolution is determined primarily by the duration of the transmitted pulse, with a 100 ns pulse giving a resolution of 10 m as a typical value. The amount of reflected light is proportional to the pulse length, so there is a trade-off between spatial resolution and maximum range. To improve maximum range, a longer pulse length would be used that increases the level of reflected light. But this leads to lower spatial resolution. For two signals to be independent, they must be obtained from two points on the fiber that are separated by at least spatial resolution. It is possible to obtain samples with separations smaller than the spatial resolution and, although this produces signals that are not independent of each other, this approach offers advantages in some applications. The separation between sampling points is sometimes called the spatial sampling period.

Acquisition rate