To solve the problem of broadband signal waveform prediction under mobile underwater acoustic channel, mobile broadband propagation model based on ray model and a waveform prediction method based on BELLHOP model is established. The model takes the frequency-dependent propagation loss and non-uniform Doppler effect into account. The principle of this prediction method and the anechoic tank experiment's results are discussed in this paper. Anechoic tank experiment's results show that the waveform predicted by the method proposed in this paper is much more similar to real waveform than traditional method.
Correlating Shack-Hartmann wavefront sensor is widely used in solar adaptive optics in which the relative shift between
different subapertures by correlation algorithm is computed, and then the control voltage by wavefront
reconstruction can be estimated to use for correcting the wavefront distortion induced by atmospheric turbulence. In this
paper, several different correlation algorithms including Cross-Correlation Coefficient, Absolute Difference Function,
Absolute Difference Function-Squared and Square Difference Function are used to estimate relative shift in correlating
Shack-Hartmann wave-front sensor with the different observed solar structure such as sunspot, solar pore and solar
granulation. The measurement noise RMS error is computed to compare the performance of the correlation algorithms.
The results show the correlation algorithm precision is directly related to the solar structure. The measurement noise is
relatively small with the relatively high contrast target, and vice versa. At the same time, the size of reference image also
could influence the measurement noise, the larger size of the reference image, the smaller the measurement noise is.