Calculate engine speed using the charging signal from the battery on a diesel engine

Universe12

Calculate engine speed using the charging signal from the battery on a diesel engine [Copy link]

The engine speed is 1500 rpm, the AD sampling rate is 70K, and a total of 1024 points are collected. The time domain waveform is as follows:

The red circle is the interference waveform, which has a large amplitude and sometimes cuts up and down. It is also close to the effective signal frequency. How can I remove the interference? Please give me some advice! ! !

chunyang

The engine rotor is an object with high rotational inertia, that is, the speed will not change suddenly. Compared with the previous speed, if the period changes suddenly and the rate of change is greater than the preset threshold, the current value is abandoned and the previous value is maintained. As for the amplitude problem, the amplitude does not affect the frequency, only the frequency can be judged. The amplitude can be processed into 0 or 1 according to the threshold and normalized, which makes it easier to judge the frequency.

Universe12

My next step is to do Fourier transform, and this large interference seriously affects the result of my Fourier transform, causing interference when I look for the spectrum of the effective signal. I want to get rid of this interference in the time domain first. I have tried to cover this waveform with a useful signal, but the final Fourier transform result is not ideal.

maychang

Universe12 posted on 2020-5-25 15:02 My next step is to do Fourier transform, and this big interference seriously affects the result of my Fourier transform, causing me to have problems when looking for the spectrum of the effective signal...

What you want is the diesel engine speed, and you can get the speed value accurately, so why do you need to do Fourier transform?