Sample narrow waveform for a flat, uniform surface

The relative time axis represents two-way travel time. Two adjacent returns separated by a relative time difference (delta_t) in nanoseconds correspond to a height difference of delta_h in centimeters such that:

delta_h = c / 2 * delta_t

where:

c is the speed of light in cm/nsec
c = (3 x 10¹⁰ cm/sec) / (1 x 10⁹ nsec/sec)
c = 30 cm/nsec

So, a relative time difference of 1 nsec corresponds to a height difference of 15 cm.