In the development process of satellite control systems and solar sensors, conventional solar simulators can‟t show
variations in the solar shape and intensity in the state of solar occultation, so we set up a solar simulation and test
platform. A method is put forward to simulate the wavefront error based on deformable mirror (DM). In this paper, the
main relevant parameters which describe the atmospheric turbulence are introduced. The statistic characteristics of
optical wavefront phase influenced by atmospheric turbulence are presented, and analyzed by the method of Zernike
modes. A piezoelectric DM with 109 electrodes manufactured by OKO is used as the wavefront phase modulator. The
important technology parameter about the deformable mirror is tested. Owing to the linear superposition, we have a
research in the optical influence function and voltage deflection. The method of Karhunen-Loeve function is used in the
simulation of optical wavefront, because it is statistically independent and can be expanded into the form of Zernike
polynomials. We can get the coefficient matrix of random turbulence wavefront, and then link up with surface of the
mirror. According to the relationship between deformation of the mirror and the voltage, we can deduce the voltage
control matrix, and change the surface of the mirror as we conceive. The numerical results indicate that wavefront error
can be introduced to the distribution maps of solar shape and intensity in different orbital position and any tangent point
by DM in the light path.
A new method of pulse signal de-noising based on wavelet transform and coherent averaging method is proposed. Pulse
signal is complex and weak, generally submerged by the interference of baseline drift, motion artifact and high
frequency noise. Consequently, it’s difficult to measure the heart rate by processing only one single-channel pulse signal,
especially when the noise frequency and the pulse signal frequency are in the same frequency range. In this paper, multichannel
pulse signal processing based on wavelet transform and coherent averaging is proposed to solve the above
problem. First, the detail coefficients and approximation coefficients of each channel signal are obtained by N layer
wavelet decomposition, then reconstructing the signal with high layers coefficients as the high frequency noises always
exist in low layers coefficients. In this way we can filter out the high frequency interference. Second, the centerline of
the upper and lower envelope curve obtained by cubic spline estimation is subtracted from each reconstructed signal so
as to eliminate the baseline drift completely. Finally, the heart rate is acquired with the coherent averaging method which
results in the noise being offset each other and the pulse signal being enhanced in the frequency range of pulse wave. The
pulse signal and three kinds of noise signals simulated with the superposition of different frequency sin signal were
analyzed, besides the experiment of six channel pulse signals measured simultaneously based on PhotoPlethysmoGraphy
(PPG) were conducted. The simulation and experiment results showed that this method was superior to the traditional
single channel.
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