Practical Considerations for Field Deployable DAS Systems

Over the past 20 years fiber-optic Distributed Acoustic Sensing (DAS) units have been deployed in telecommunication centres, control rooms and field cabinets across the world for a wide variety of applications.  These locations typically have ample space for mounting equipment with air conditioning and power. They also tend to be quite environment with low vibroacoustic background noise. However, geophysical research often presents a stark contrast, necessitating the deployment of DAS systems in remote and challenging locations devoid of basic amenities, extreme weather conditions, lacking mains electricity, and with scarce communication options. Consideration therefore needs to be given to attributes of DAS systems that facilitate easy field deployment while maintaining data integrity. Presented will be details on the advantages of fully integrated small DAS sensing units that are light weight and require low power. These systems also need to operate in challenging environments with extreme temperatures and humidity, be sealed against dust and have high levels of immunity to environmental vibro-acoustic noise. Additionally, the logistics of transporting these systems to remote locations are considered, emphasizing features that streamline setup, such as automated configuration and fiber diagnostics, and the capability for remote operation over low-bandwidth connections, which is critical in long duration unmanned monitoring projects. Whilst these features are important there must be no compromise in the performance characteristic of the DAS which should be optimised for the acquisition of low frequency small magnitude geophysical signals. The ability to perform at-the-edge processing is also considered so that the high volumes of data acquired by DAS can be reduced before the recording or transmission of data. Whilst in the field it is also important to ensure the data acquired and stored is quality assured. In addition to the sensing unit there may also be the requirement for additional equipment such as network attached storage and a field kit containing items such as spare patch leads, and connector inspection and cleaning equipment. Looking forward, the evolution of DAS technology is anticipated to continue towards smaller, lighter, and more energy-efficient units without sacrificing performance, promising enhanced capabilities for geophysical research and beyond.