So let's start the measurement with the encoder. The recorder is set up to show all three channels in one graph. The first observation is that the PAD module (green curve) has a long delay and updates the values only once per second. The other two curves (analog and counter) are aligned very well.

Measurement

If we store and analyze the data and zoom in on the record, we can see that the analog curve (also green) and counter the curve (blue) show the differences only at high magnification of time and amplitude. We can believe that the counter measurement is more exact, since it relies only on the accuracy of the base clock. The analog values are wrong because of the internal error of the circuit as well as the measurement error of the AD card. It is also delayed, but in this case when using the encoder, the delay is minimal.

Analysis

The second challenge for our competitors in the award of having the best frequency measurement technique (just want to check if someone is still reading this) is to measure the frequency from one pulse per revolution.