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1、1、限幅滤波法(又称程序判断滤波法)（1, limiting filter method (also known as program judgment filter)）1, limiting filter method (also known as program judgment filter)A and method:Based on experience judgment, determine the maximum deviation allowed for the two sampling (set to A)Each time a new value is detected:If
2、 the difference between this value and the previous value is A, then the value is invalid, the value is dropped, and the last value is used instead of the valueB, advantages:It can effectively overcome the pulse interference caused by accidental factorsC and shortcomingsThat periodic interference ca
3、n not be suppressedPoor smoothness2 median filteringA and method:Continuous sampling N times (N odd number)Arrange the values of the N sub sampling by sizeTake the middle value as the valid valueB, advantages:It can effectively overcome the fluctuation disturbance caused by accidental factorsThe tem
4、perature and level changes slowly, and the measured parameters have good filtering effectC and shortcomings:It is not suitable for fast changing parameters such as flow rate and speed3 arithmetic average filtering methodA and method:N sampling values are continuously taken for arithmetic average ope
5、rationWhen the N value is large, the signal smoothness is higher, but the sensitivity is lowerN value is small: the signal smoothness is lower, but the sensitivity is higherN value selection: general flow, N=12; pressure: N=4B, advantages:The utility model is suitable for filtering signals with rand
6、om disturbance in generalIn this way, the signal is characterized by an average value that fluctuates near and below a certain range of valuesC and shortcomings:It is not suitable for real-time measurement with slow measurement or fast data calculationRelatively wasteful, RAM4, recursive mean filter
7、ing (also known as moving average filtering)A and method:Take the successive N values as a queueThe length of the queue is fixed to NEach sample to a new data into the team tail, and throw out the original data of the team (first in first out principle)We can obtain new filtering results by arithmet
8、ic average operation of N data in the queueN value selection: flow rate, N=12, pressure: N=4, liquid level, N=412, temperature, N=14B, advantages:It has a good inhibitory effect on periodic interference, and has high smoothnessSystem suitable for high frequency oscillationC and shortcomings:Low sens
9、itivityThe inhibition of accidental impulsive interference is poorIt is difficult to eliminate the sampling value deviation caused by pulse interferenceNot suitable for occasions where pulse interference is severeRelatively wasteful, RAM5, median value average filtering method (also called anti puls
10、e interference average filtering method)A and method:It is equivalent to median filtering and arithmetic average filteringContinuous sampling of N data, remove a maximum and a minimumThen calculate the arithmetic mean of the N-2 dataN value selection: 314B, advantages:The advantages of the two filte
11、ring methods are fusedFor accidental pulse interference, the sampling value deviation caused by pulse interference can be eliminatedC and shortcomings:The speed of measurement is slower than that of arithmetic average filteringRelatively wasteful, RAM6, limited average filtering methodA and method:I
12、t is equivalent to limiting filter method + recursive average filtering methodEach new data is sampled by amplitude limiting,Then send the queue for recursive average filter processingB, advantages:The advantages of the two filtering methods are fusedFor accidental pulse interference,The sampling va
13、lue deviation caused by pulse interference can be eliminatedC and shortcomings:Relatively wasteful, RAM7 、 first order lag filtering methodA and method:Take a=01The filter results = (1-A) * this sampling value +a*, the last filter resultsB, advantages:It has a good inhibitory effect on periodic inte
14、rferenceIt is suitable for occasions with high fluctuation frequencyC and shortcomings:Low phase delay and low sensitivityThe degree of lag depends on the size of the AAn interference signal that does not eliminate the 1/2 of the filter frequency higher than the sampling frequency8 weighted recursiv
15、e mean filterA and method:It is the improvement of recursive mean filtering, that is, the data at different times have different weightsUsually, the closer to the present time, the greater the power.The higher the weight coefficient of the new sampling value is, the higher the sensitivity is, but the lower the signal smoothness isB, advantages:
