Thanks for asking a question on our blog.

As the article states the initial problems with the tachometer are caused by extra erroneous pulses and missing pulses, which are probably caused by mechanical problems from the rotor inside the distributor on this particular automotive engine.

Also as you can see from the article the tachometer pulses themselves are very noisy and each pulse actually has a spike at the leading edge and the trailing edge of differing magnitudes over time.

This means any fixed amplitude peak detection is going to involve errors, if you simply count the peaks, as the article states.

The DATS tachometer repair function simply analyses the signal, this gives the software the ability to predict when the next pulse should occur, for example the speed is not going to change by half in less than one pulse, therefore any pulses detected earlier then 50% of expected time can be considered erroneous. The process is actually much more complex, but this analogy gives a brief understanding of the concept of the hold off time, as a percentage of how much of the pulse is going to be ignored, or held off. The DATS tachometer processing software suite has further advanced features not referenced in this article, for example variable tachometer amplitude tracking.

If you have any further questions, please feel free to ask.