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The electrocardiogram signal consists in a character of smaller amplitude together with a larger interference range and the reconstructed signal, according to the classical compressed sensing theory, cannot be accurately conveyed by the signal. To solve this problem, compressed sensing based on the wavelet transform was stressed on. We carry out a compressed sensing algorithm based on wavelet transform, thus is to use the wavelet decomposition to separate the electrocardiogram, to reduce the noise pollution, to compress and reconstruct the high-frequency coefficient and to recover the signal by inversing the wavelet transform. Meanwhile, analysis on the data effect was also made. The result of the simulation shows that it obviously proves the noise suppressing effect on combining wavelet transform with compressed sensing to recover the signal. The integrity of useful information is enhanced, as well as obtaining a higher signal-to-noise ratio.

The effect of Yb3+ concentration on the fluorescence of 12CaO·7 Al2O3:Ho3+/Yb3+ polycrystals is investigated. The Raman spectra of pure C12A7 under 633-nm excitation show that the highest photon energy is 787.267 cm−1, which is not much bigger than general fluorides, so it can realize high efficiency upconversion. The upconversion emission spectra suggest that the green upconversion emission centered at 548 nm and the red upconversion emission at 662 nm correspond to the 5F4/5S2→5I8 and 5F5→5I8 transition of Ho3+ ions, respectively. The intensity of the upconversion luminescence and the ratio of red to green are changed with Yb3+ ion concentration. The pump dependence and luminescence decay dynamics spectra show the green and red upconversion emissions are populated by a two-photon process, and the upconversion mechanisms are analyzed. The relative luminous efficiencies of green and red emissions are 2.035% and 0.7%, respectively. The normalized efficiency obtained for green emission of Ho3+ at RT when the sample is excited by 980-nm light with an absorbed intensity of 7.5 W/cm2 is 0.27 cm2/W. This result is comparable to the values obtained in YF3 for the Yb3+, Er3+ green emission. The C12A7 with upconversion red and green light will be a promising luminous material.

The effect of Yb 3 + concentration on the fluorescence of 12 CaO·7 Al 2 O 3 :Tm 3 + /Yb 3 + polycrystals is investigated. Under the excitation of 980 nm laser, the strong blue (477 nm) emission band is observed and attributed to 1 G 4 → 3 H 6 of Tm 3 + . The ratio of blue to red emission increases with the increasing of Yb 3 + and remains constant at 10 mol% Yb 3 + . The pump dependence and upconversion mechanisms show that the two-photon cooperative upconversion process is responsible for the enhancement of the blue upconversion emission. The Commission Internationale de l'eclairage chromaticity coordinates (x, y) illustrate that the 12 CaO·7 Al 2 O 3 :1 mol% Tm 3 + /10 mol% Yb 3 + can emit high-purity blue light.