It can't avoid that the problem of transforming a continue signal into a discrete digital series in the process of design a digitalized signal sampling system,so it is importance to discuss the sampling error for Hi－Fi digital sampling system.

The Gauss width of focal spot which is too small results in the sampling error while using CCD as the centroid detecting device of Shack-Hartmann Wavefront Sensor(SHWS) in Adaptive Optics(AO) system.

For new technology research and commerial testing of various catalystic cracking,sampling analysis of cracking gas and checking the junctures of analysis method and its program have important effects on exploring the best operating parameters,and obtaining the reliable material balance data.

After discussing the Fourier analysis and the sampling analysis of the LR\|C impulse signal ,the sampling frequency and filter are defined, and then the design of the signal simulator is presented.

We also proposed a control mechanism for the width of BTP through stratified sampling method.

And then an analytical system of the oil contamination based on the separating flow sampling principle is developed.