Abstract: A method providing an increased signal-to-noise (SNR) characteristic for coherent distributed acoustic sensing (DAS) systems, the method employing fiber coils (microphones) made from sections of an optical sensing fiber that collect acoustic signals and uses multiple differential pairs of the microphones for signal averaging to improve the SNR. An analysis determines complex products (beating products) for a pair of locations that are part of a fiber microphone along the length of the optical sensing fiber that are used to determine a phase change in-between locations along the length of the optical sensing fiber.

Abstract: An advance in the art is made according to aspects of the present disclosure directed to a DAS method that utilizes a differential phase to detect phase change(s) between two locations of a DAS sensing fiber to ascertain vibrational/acoustic activities/environment at intermediary fiber location(s) between the two locations. Additionally, systems, methods, and structures according to aspects of the present disclosure may employ a fiber coil comprising a segment of fiber wrapped in acoustic sensitive material (“acoustic signal collector”). The material responds to an environmental acoustic signal, which results in strain(s) applied to the fiber. Furthermore, rather than using a measured phase difference between the two ends of the fiber coil, systems, methods, and structures according to aspects of the present disclosure utilize all samples collected from one end of the fiber coil to the other end of the fiber coil (the left side of the coil to the right side of the coil)—which may be extended further.