Jw. Dooley et Mj. Nolan, COMMENT ON CHIRP EXCITATION OF ULTRASONIC PROBES AND ALGORITHM FOR FILTERING TRANSIT TIMES, IEEE transactions on ultrasonics, ferroelectrics, and frequency control, 42(4), 1995, pp. 799-801
Polkestad and Mylvaganam use a chirp technique to resolve an ambiguity
in time-of-flight measurements. An alternative is to trigger an oscil
loscope on one cycle of the initial tone burst, then vary the frequenc
y. In the delayed burst, the correct cycle for time-of-flight measurem
ents remains stationary.