Technique for measurement of the noise of a sensor in the presence of large background signals

Abstract

This work reports on a method to measure the instrumental noise of a sensor in the presence of large background signals, based on measuring the coherence and output of two identical sensors exposed to the same input stimulus. The technique can be applied to any sensor characterization problem where there is interest in distinguishing random noise from common-mode noise. The method is demonstrated using geophones, a single-axis seismometer that has been an important sensor for geophysical measurements for decades. Previous experimental work has not published measurements of the geophone’s instrumental noise at frequencies near the geophone’s resonance because of the presence of large background seismic signals compared to the predicted instrumental noise, which is a minimum at the geophone’s resonant frequency. With this coherence technique, measurements performed in the presence of 1 μg/Hz seismic signals showed that the minimum instrumental noise was within a factor of 2 of the predicted minimum noise of 0.6 ng/Hz.

On the Systematic Long-Period Noise Reduction on Ocean Floor Broadband Seismic Sensors Collocated with Differential Pressure Gauges

“…The amplitude response at this period systematically increases by a factor of about 2 from northern hemisphere summer (April through September 2009) to winter (October through December 2009 and January through February 2010). One possible explanation for this systematic change is that it is due to a temperature effect (Barzilai et al, 1998). A systematic temporal variation is not observed during the time interval July 2011 to June 2012 although the variability of the amplitude of the transfer function is comparable to that observed during the time interval April 2009 to February 2010.…”

Stability of Silicon Microelectromechanical Systems Resonant Thermometers

“…As such temperature control is not achievable, a measurement technique was employed to distinguish the resonator stability from temperature variation. As detailed previously, the inherent noise of a sensor can be distinguished from large external signals by placing two sensors side-by-side and assuming that both sensors experience the same environment and are thus subject to identical external signals [27]. The common-mode signal present in the output can be eliminated to yield the inherent sensor noise.…”

Prototype of a Small Low Noise Absolute Displacement Sensor

“…A possible embodiment is disclosed in [15]. In [16], [17] a home made capacitive sensor has been mounted in a GS-11D to develop an affordable feedback accelerometer. In [18], two capacitive sensors are used in a piezoelectric low frequency feedback displacement sensor.…”