Schuller, Gerd; Suga, Nobuo (1976): Storage of Doppler-Shift Information in the Echolocation System of the "CF-FM"-Bat, Rhinolophus ferrumequinum. In: Journal of Comparative Physiology A, Vol. 105: S. 9-14




The greater horseshoe bat (Rhinolophus ferrumequinum) emits echolocation sounds consisting of a long constant-frequency (CF) component preceeded and followed by a short frequency-modulated (FM) component. When an echo returns with an upward Doppler-shift, the bat compensates for the frequency-shift by lowering the emitted frequency in the subsequent orientation sounds and stabilizes the echo image. The bat can accurately store frequency-shift information during silent periods of at least several minutes. The stored frequency-shift information is not affected by tone bursts delivered during silent periods without an overlap with an emitted orientation sound. The system for storage of Doppler-shift information has properties similar to a sample and hold circuit with sampling at vocalization time and with a rather flat slewing rate for the stored frequency information.