Program examples of filtering software

　　We can use the C language program code subroutine of the digital filtering method to complete the software filtering function. We assume that the data is read from the 8-bit AD. If it is a higher-bit AD, the data type can be defined as int, and the subroutine is defined as get_ad().
　　
　　(1) Arithmetic average filtering program, call the function get_ad() to read the data.

　　(2) Determine the filtering program and call the data reading subroutine get_ad().

　　(3) Sliding average filter method C language program, calling the data reading subroutine get_ad().

 　　(4) Median average filtering method C language program, calling the data reading sub-function get_ad().

　　(5) Median filtering method: the N value can be adjusted according to the actual situation, and the sorting adopts the bubble method.

　　This example mainly introduces the method and program of using single-chip microcomputer to realize software filtering. The sliding average filter method has a good inhibitory effect on periodic interference, high smoothness and low sensitivity, but it has a poor inhibitory effect on occasional pulse interference, and it is not easy to eliminate the deviation of the sampling value caused by pulse interference. Therefore, it is not suitable for occasions with serious pulse interference, but is more suitable for high-frequency oscillation systems.
　　
　　Arithmetic mean filtering cannot eliminate obvious pulse interference, but can only weaken its influence, so that the output value of the average filter is closer to the true value. The program judgment filtering method can effectively overcome the shortcomings of pulse interference caused by accidental factors, but it cannot suppress that kind of periodic interference and has poor smoothness.