Renesas H8 Series Hardware Manual page 331

In this example, high-level input of less than five times the width of the sampling clock at the
input capture input pin is eliminated as noise.
Input capture
input signal
Sampling clock
Noise canceler
output
Eliminated as noise
Figure 9.10 Noise Canceler Timing (Example)
Rev. 7.00 Mar 10, 2005 page 289 of 652
Section 9 Timers
REJ09B0042-0700