http://www.k-wave.org/forum/topic/time-gain-compensation-for-plane-wave Support for the k-Wave MATLAB toolbox en-US Tue, 12 May 2026 23:42:12 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/time-gain-compensation-for-plane-wave#post-7181 Mon, 20 Jan 2020 17:43:44 +0000 Bradley Treeby 7181@http://www.k-wave.org/forum/ <p>Hi Farnaz,</p> <p>It looks like there's a bug in this script - the attenuation value should be in Nepers not dB. Try dividing tgc_alpha by 8.686.</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/time-gain-compensation-for-plane-wave#post-7118 Wed, 06 Nov 2019 13:35:19 +0000 Farnaz 7118@http://www.k-wave.org/forum/ <p>Hi, </p> <p>I am using : </p> <p> t0 = 120 * kgrid.dt / 2;<br /> r = c0*( (1:length(kgrid.t_array)) * kgrid.dt / 2 - t0); % [m]</p> <p> % create time gain compensation function based on attenuation value,<br /> % transmit frequency, and round trip distance<br /> tgc_alpha = 0.48; % [dB/(MHz cm)]<br /> tgc = exp(2 * tgc_alpha * 5e6 / 1e6 * r *100);</p> <p> % apply the time gain compensation to each of the scan lines<br /> scan_lines2 = bsxfun(@times, tgc, transducer_data);</p> <p>for time gain compensation of single Plane-wave.</p> <p>120 is the length of my input signal, and the center frequency is 5e6 Hz, attenuation was 0.5 dB/MHz cm while simulating the raw data. I have a single plane wave and I do time compensation before cutting the near transducer signal (transmit pulse). </p> <p>The result of this looks strange, it seems that the signal from end of the medium is extremely amplified. As the result the b-mode image is also looks quite disturbed. The effect is so high that I can not even afterwards normalize the data so I end up with quite large values. </p> <p>The question is that whether this formula can be applied for plane-waves as well? Am I setting any parameter wrong here? </p> <p>Best, </p>