Alternating noise canceling method of equi-status normal mode noise for encoder

One of the significant and difficult problems in engineering is the cancellation of equi-status normal mode noises (NMNs). The authors previously proposed an alternating noise canceling (ANC) method for removing NMNs even in the presence of the equi-status noise in instrumentation since 1990. As an example, they made two signals as a sensor output and its opposite output signal by alternating the switching. The sensor output includes the true signal and its opposite output signal and noise from the electromagnetic environment. The data processing of the two signals made a reliable signal without any noise on the transmission line. In this case, “any noise” means normal mode noise (NMN) under a quarter frequency of switching. In this paper, the authors discuss a canceling method of equi-status NMNs in instrumentation by a rotary encoder based on the ANC method. They conduct experiments and verify that this method prevents the miscounting of the instrumentation. Naturally, this method also works even if the power spectra between the signal and NMNs are not different i.e. equi-status NMNs