Angle Factor Reduces Shift - Biophysical Ultrasound: Echo Timing and Acoustic Interfaces Step by Step

Only along-beam velocity enters the Doppler ledger. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Full along-beam motion gives the anchor shift

With projection factor 1, the shift is 4 hertz.

4\ \text{Hz}

A half projection halves the shift

With projection factor 1 over 2, the same speed gives shift 2 hertz.

4\cdot \frac{1}{2}=2\ \text{Hz}