π What is Continuous Wave Doppler Sonar?
Continuous Wave (CW) Doppler sonar continuously emits and receives ultrasound waves. This allows for the measurement of blood flow velocity along the ultrasound beam's path. Because it continuously sends and receives, it doesn't have the same limitations as pulsed wave regarding maximum measurable velocity.
- π‘ Continuous transmission and reception of ultrasound waves.
- π Measures velocity along the entire beam path.
- β¬οΈ Excellent for measuring high velocities.
- π Lacks depth specificity (range resolution).
π What is Pulsed Wave Doppler Sonar?
Pulsed Wave (PW) Doppler sonar emits ultrasound waves in short bursts or pulses. After each pulse, the system listens for the returning echo from a specific depth (sample volume). This allows for precise velocity measurements at a particular location.
- β±οΈ Emits ultrasound waves in pulses.
- π― Measures velocity at a specific depth (sample volume).
- β¬οΈ Subject to aliasing at high velocities.
- π Provides depth specificity (range resolution).
π Continuous Wave vs. Pulsed Wave Doppler Sonar: A Comparison
| Feature |
Continuous Wave Doppler |
Pulsed Wave Doppler |
| Wave Emission |
Continuous |
Pulsed |
| Velocity Measurement |
Along entire beam path |
Specific depth (sample volume) |
| Depth Specificity |
No |
Yes |
| High Velocity Measurement |
Excellent |
Limited by Nyquist limit (aliasing) |
| Cost |
Generally lower |
Generally higher |
π‘ Key Takeaways
- π― Depth Specificity: Pulsed Wave Doppler offers depth specificity, allowing you to measure velocities at specific locations.
- β¬οΈ High Velocities: Continuous Wave Doppler is better for measuring high velocities without aliasing.
- π¬ Applications: PW is used when you need to know the exact location of the blood flow being measured, while CW is used when high velocities are expected and location isn't critical.