Close Reflectors Fail Resolution Gate - Biophysical Ultrasound: Echo Timing and Acoustic Interfaces Step by Step

The same pulse rejects and accepts by exact separation. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Close reflectors fail the resolution gate

Depths 12 and 14 meters are separated by 2 meters, below the 4 meter limit.

\Delta d=2\ \text{m}<4\ \text{m}

Farther reflectors pass the same gate

Depths 12 and 18 meters are separated by 6 meters, above the 4 meter limit.

\Delta d=6\ \text{m}>4\ \text{m}