Time-Synchronized Geophysical Investigations in Denied GPS-Time Spaces

Summary Without doubt much more can be done to utilize underground workings for site investigations. A few years ago, we realized this offered a unique opportunity with important applications and benefits of providing synchronized surveys in underground spaces using receivers typically used at the surface. However, technical limitations were hindrances. We have now been able to pioneer a prototype system that can provide accurate GPS-time (micro-second accuracy) to an array of various sensors placed in different tunnels and in different depth levels. The solution will be useful for any deep mines, tunneling industry and anywhere that a synchronized survey is needed but accurate timing is not available directly via satellites. The system does not need extensive cabling or accessibility to mine communication and operational facilities. It is a mobile system, transportable to underground workings using a couple of small boxes, and easy to set-up. Add-on options and modularity are also possible to provide greater flexibilities. Such a solution can bring for example 3D surveys to underground. No need to revise existing sensors implies also millions of saving and possibility to dual use sensors used for surface measurements.