| Home | Highlights | Intro | Objective | System | More |

| General Issues And Design Goals | Basic System Components |

Basic System Components > Front-end unit

Hibernation Mode

The hibernation mode is a special mode of operation intended to optimize the system´s performance under unfavorable circumstances:

• In all cases of prolonged line power failure--when the system falls back from regular power supply to temporary battery operation
• In cases where a user may decide to accept a somewhat reduced performance in order to profit from the advantage of autonomy (i.e. the convenience of operating a fully battery-powered front-end in a problematic environment)

During hibernation, the system operates based on only one dimension of the 3D acceleration sensor.

In hibernation level one, there is regular sampling in the Z dimension, but with a reduced sampling rate.

In level zero hibernation, the digital signal processing is frozen completely and no regular sampling occurs. The Z sensor itself is still powered, and an Analog Motion Trigger (AMT unit) monitors for any seismic signal beyond a programmable threshold. A faint seismic signal will instantaneously wake up the whole system, which will resume normal operation mode within just a few milliseconds of lag time. During level zero mode, the total power consumption shrinks to roughly 10% of normal operation, thus offering a tenfold increase in battery backup time!

An important operational advantage that could be gained by using the hibernation mode at the lowest level would be a period of ten years of total autonomy (when powered by an <external lithium battery pack). The initial investment required to integrate a lifetime power pack like this would be around $300--not really a cheap option, but a reasonable figure compared to the total effort of providing (and regularly maintaining) a solar power utility in today´s generation of stand-alone stations under open skies.

The hibernation mode stands out as a uniquely cost-efficienct solution for those early warning sensors that are placed more or less in the middle of nowhere. The system‘s early warning capability is not compromised when the whole front-end unit is allowed to fall into a level one hibernation state.