Abstract
The demand from industry to produce accurate acceleration measurements down to ever lower frequencies and with ever lower noise is increasing. Different vibration transducers are used today for many different purposes within this area, like detection and warning for earthquakes, detection of nuclear testing, and monitoring of the environment. Accelerometers for such purposes must be calibrated in order to yield trustworthy results and provide traceability to the SI-system accordingly. For these calibrations to be feasible, suitable ultra low-noise accelerometers and/or signal processing functions are needed. <br />Here we present two digital signal processing (DSP) functions designed to measure ultra low-noise acceleration in calibration systems. The DSP functions use dual channel signal analysis on signals from two accelerometers measuring the same stimuli and use the coherence between the two signals to reduce noise. Simulations show that the two DSP functions are estimating calibration signals better than the standard analysis. <br />The results presented here are intended to be used in key comparison studies of accelerometer calibration systems, and may help extend current general low frequency range from e.g. 100 mHz down to ultra-low frequencies of around 10mHz, possibly using somewhat same instrumentation.
Highlights
In the field of dual channel signal analysis there are some very powerful functions for analysing signals, such as the well-known frequency response function and coherence
There are other functions like the coherent power function (COP) and non-coherent power function which are very powerful for decomposing noisy signals into the coherent part and the non-coherent part [10][11][12]
We have tested the two digital signal processing (DSP) functions on simulated data and our findings based on the simulations shows promise to the functions as good tools for accurately measuring amplitudes and phases of a multi-sine wave in a noisy environment
Summary
In the field of dual channel signal analysis there are some very powerful functions for analysing signals, such as the well-known frequency response function and coherence. For the COA to work in a proper manner, it is crucial that the signal applied to the shaker is a continuous signal, like a sine or a multi-sine, and that the frequencies of the sines are very precise and phase synchronized with the frequencies of the Fourier transformation, to prevent the phase from drifting or even make jumps. The degree to which the COP, and the COA can separate a signal into coherent and noncoherent parts increases with the length of the measurement, and generally depends on parameters like how many time-samples the measurement is divided into, how long each time-sample is, the sampling rate, and the Fourier transform used
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
