System Identification Method – applied to Seismic Detectors

Seismic detectors, both geophones and hydrophones, are considered to be the most vulnerable part in the seismic data acquisition chain. They are in need of constant quality control and maintenance. Reliable quality control of these detectors depends upon accurate measurement of the electro-dynamical parameters, such as sensitivity, resonance  frequency and damping.

These can in principal be derived from the detector’s dlmamic response to a step-wise varying current. The measured response can be fitted to a physical model of the detector by means of System Identification techniques.
This makes it possible to estimate the quality of the design, or the present state of the detector, and assess whether it meets the manufacturer’s specifications.
The analysis method presented here yields asymptotically unbiased estimates of the electro-dynamical characteristics in the presence of white noise. Dynamic responses from under-critically, critically, and overcritically damped detectors may be analyzed.