What is the maximum velocity limit for a 3 MHz CW Doppler unit operating at a depth of 4 cm?

What is the maximum velocity limit for a 3 MHz CW Doppler unit operating at a depth of 4 cm?

• A. None of the above
• B. 40 cm/s
• C. 200 cm/s
• D. 2.5 m/s

Answer: (A)

In continuous-wave Doppler, the velocity you’re measuring is tied to how large a Doppler shift the instrument can display. The Doppler shift is Δf = 2 f0 v cos θ / c, so velocity scales with the observed shift. The key limit is the system’s bandwidth (the maximum Doppler frequency shift the receiver can handle), not the depth. Depth affects signal strength and the beam angle but does not set a fixed velocity ceiling. Without knowing the instrument’s Doppler-bandwidth limit (and the angle to flow), you can’t pin down a single maximum velocity. Depth at 4 cm doesn’t determine v_max, and the provided numbers assume a specific bandwidth that isn’t given. Therefore none of the listed values can be guaranteed as the maximum measurable velocity.

In continuous-wave Doppler, the velocity you’re measuring is tied to how large a Doppler shift the instrument can display. The Doppler shift is Δf = 2 f0 v cos θ / c, so velocity scales with the observed shift. The key limit is the system’s bandwidth (the maximum Doppler frequency shift the receiver can handle), not the depth. Depth affects signal strength and the beam angle but does not set a fixed velocity ceiling.

Without knowing the instrument’s Doppler-bandwidth limit (and the angle to flow), you can’t pin down a single maximum velocity. Depth at 4 cm doesn’t determine v_max, and the provided numbers assume a specific bandwidth that isn’t given. Therefore none of the listed values can be guaranteed as the maximum measurable velocity.