  This study proposes a method to determine the filter parameters required for
the topology method, which is a radar-based noncontact method for measurement
of heart inter-beat intervals. The effectiveness of the proposed method is
evaluated by performing radar measurements involving both human participants
and chimpanzee subjects. The proposed method is designed to enable setting of
the filter cutoff frequency to eliminate respiratory components while
maintaining the higher harmonics of the heartbeat components. Measurements
using a millimeter-wave radar system and a reference contact-type
electrocardiogram sensor demonstrate that the smallest errors that occur when
measuring heart inter-beat intervals using the proposed method can be as small
as 4.43 and 2.55 ms for humans and chimpanzees, respectively. These results
indicate the possibility of using noncontact physiological measurements to
monitor both humans and chimpanzees.
