Editing Animal echolocation (section)

==== CF signal advantages ====

The structure of a CF signal is adaptive in that it allows the CF-bat to detect both the velocity of a target, and the fluttering of a target's wings as Doppler shifted frequencies. A [[Doppler shift]] is an alteration in sound wave frequency, and is produced in two relevant situations: when the bat and its target are moving relative to each other, and when the target's wings are oscillating back and forth. CF-bats must compensate for Doppler shifts, lowering the frequency of their call in response to echoes of elevated frequency – this ensures that the returning echo remains at the frequency to which the ears of the bat are most finely tuned. The oscillation of a target's wings also produces amplitude shifts, which gives a CF-bat additional help in distinguishing a flying target from a stationary one.<!--<ref name="Simmons_1980"/><ref name="Grinnell 1995"/>--><ref name="Neuweiler_2003">{{cite journal |last=Neuweiler |first=G. |year=2003 |title=Evolutionary aspects of bat echolocation | journal=Journal of Comparative Physiology A |volume=189 |issue=4 | pages=245–256 |doi=10.1007/s00359-003-0406-2 |pmid=12743729 |s2cid=8761216 }}</ref><ref name="Jones_2006"/> The horseshoe bats hunt in this way.<ref name="Schnitzler Flieger 1983">{{cite journal |last1=Schnitzler |first1=H. U. |last2=Flieger |first2=E. |year=1983 |title=Detection of oscillating target movements by echolocation in the Greater Horseshoe bat | journal=Journal of Comparative Physiology |volume=153 |issue=3 | pages=385–391 |doi=10.1007/bf00612592 | s2cid=36824634 }}</ref>

Additionally, because the signal energy of a CF call is concentrated into a narrow frequency band, the operational range of the call is much greater than that of an FM signal. This relies on the fact that echoes returning within the narrow frequency band can be summed over the entire length of the call, which maintains a constant frequency for up to 100 milliseconds.<ref name="Grinnell 1995">{{cite book |last=Grinnell |first=A. D. |date=1995 |chapter=Hearing in Bats: An Overview. |title=Hearing in Bats |editor1=Popper, A. N. |editor2=Fay, R. R. |publisher=Springer Verlag |location=New York |pages=1–36 }}</ref><ref name="Fenton_1995"/>