http://www.k-wave.org/forum/topic/question-about-influence-of-zero-values-of-signal-of-extractampphase-function Support for the k-Wave MATLAB toolbox en-US Tue, 12 May 2026 21:37:32 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/question-about-influence-of-zero-values-of-signal-of-extractampphase-function#post-9059 Wed, 20 Mar 2024 20:35:02 +0000 Bradley Treeby 9059@http://www.k-wave.org/forum/ <p>The assumption of this function is that you’re sampling a periodic signal. Take a look at the “Heating By A Focused Ultrasound Transducer” example to see how you can change when to start recording (so you skip the zeros at the beginning) and how to set the sampling appropriately. </p> http://www.k-wave.org/forum/topic/question-about-influence-of-zero-values-of-signal-of-extractampphase-function#post-9041 Tue, 20 Feb 2024 03:49:49 +0000 lyz2001 9041@http://www.k-wave.org/forum/ <p>Hi everyone,<br /> I found that if there are some zero values in the front of the signal, the amplitude of fft will be reduced,in the case of a single-frequency signal.<br /> I want to study the propagation of the sound field of the parametric array loudspeaker. I set up sensors at each point of the axial direction,and use extractAmpPhase function to calculate the sound pressure of the difference frequency.<br /> But the sensor signals which are far away from the source will have some zero values before the sound propogates there, which affects the computation of the sound pressure value of the difference frequency.<br /> I have read the sourcecode of this function,and it seems that it doesn't remove the zero values at the beginning of the signal.I would like to ask if k-wave have considered this phenomenon and how to solve this problem. </p>