k-Wave
A MATLAB toolbox for the time-domain
simulation of acoustic wave fields
- Getting Started
- Examples
- Initial Value Problems
- Example: Homogenous Propagation Medium
- Example: Using A Binary Sensor Mask
- Example: Defining A Sensor Mask By Opposing Corners
- Example: Loading External Image Maps
- Example: Heterogeneous Propagation Medium
- Example: Saving Movie Files
- Example: Recording The Particle Velocity
- Example: Defining A Gaussian Sensor Frequency Response
- Example: Comparison Of Modelling Functions
- Example: Setting An Initial Pressure Gradient
- Example: Simulations In One Dimension
- Example: Simulations In Three Dimensions
- Example: Photoacoustic Waveforms in 1D, 2D and 3D
- Time Varying Source Problems
- Example: Monopole Point Source In A Homogeneous Propagation Medium
- Example: Dipole Point Source In A Homogeneous Propagation Medium
- Example: Simulating Transducer Field Patterns
- Example: Steering A Linear Array
- Example: Snell's Law And Critical Angle Reflection
- Example: The Doppler Effect
- Example: Diffraction Through A Slit
- Example: Simulations In Three-Dimensions
- Sensor Directivity
- Example: Focussed Detector in 2D
- Example: Focussed Detector in 3D
- Example: Modelling Sensor Directivity in 2D
- Example: Modelling Sensor Directivity in 3D
- Example: Sensor Element Directivity in 2D
- Example: Focussed 2D Array with Directional Elements
- Photoacoustic Image Reconstruction
- Example: 2D FFT Reconstruction For A Line Sensor
- Example: 3D FFT Reconstruction For A Planar Sensor
- Example: 2D Time Reversal For A Line Sensor
- Example: 2D Time Reversal For A Circular Sensor
- Example: 3D Time Reversal For A Planar Sensor
- Example: 3D Time Reversal For A Spherical Sensor
- Example: Image Reconstruction With Directional Sensors
- Example: Image Reconstruction With Bandlimited Sensors
- Example: Iterative Image Improvement Using Time Reversal
- Example: Attenuation Compensation Using Time Reversal
- Example: Attenuation Compensation Using Time Variant Filtering
- Example: Automatic Sound Speed Selection
- Diagnostic Ultrasound Simulation
- Example: Defining An Ultrasound Transducer
- Example: Simulating Ultrasound Beam Patterns
- Example: Using An Ultrasound Transducer As A Sensor
- Example: Simulating B-mode Ultrasound Images
- Example: Simulating B-mode Images Using A Phased Array
- Numerical Analysis
- Example: Controlling The Absorbing Boundary Layer
- Example: Source Smoothing
- Example: Filtering A Delta Function Input Signal
- Example: Modelling Power Law Absorption
- Example: Modelling Nonlinear Wave Propagation
- Example: Optimising k-Wave Performance
- Using The C++ Code
- Elastic Wave Propagation
- Example: Explosive Source In A Layered Medium
- Example: Plane Wave Absorption
- Example: Shear Waves And Critical Angle Reflection
- Example: Simulations In Three Dimensions
- Functions - By Category
- Functions - Alphabetical List
- Release Notes
- License
k-Wave Toolbox |
The Doppler Effect Example
On this page… |
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Overview
This example demonstrates the doppler effect in which a stationary sensor point records a shift in frequency as a moving source travels past. It builds on the Monopole Point Source In A Homogeneous Propagation Medium Example.
Creating a moving source
The moving source is created by using a line of source points and then gradually moving the active points along this line. To create a smoother source transition from point to point, the source strength is interpolated between pairs of points using linear interpolation. The input pressure signal to each source point along with the total input pressure is plotted below.
A snapshot of the moving source is given below. In this example the source is moving to the right. Notice that the wavefronts are slightly closer together on the right hand side than on the left.
As the source approaches the receiver, the amplitude gradually increases and the perceived frequency is shifted upwards according to the relative velocity between them. The amplitude of the recorded signal reaches a maximum when the source is adjacent to the receiver. The amplitude then gradually decreases as the source moves away, with the perceived frequency similarly shifted downwards. The shift in frequency can clearly be seen by analysing the parts of the time series corresponding to the approach of the source to the receiver and its retreat away again.
Snell's Law And Critical Angle Reflection | Diffraction Through A Slit |
© 2009-2014 Bradley Treeby and Ben Cox.