Merge branch 'master' of https://github.com/sfstoolbox/sfs

Author: hagenw

README.md

@@ -323,6 +323,40 @@ sound_field_mono_nfchoa([-2 2],[-2 2],0,[0 -1 0],'pw',800,conf);
 ![Image](doc/img/sound_field_nfchoa_25d.png)
 
 
+#### Local Wave Field Synthesis
+
+In Near-Field Compensated Higher Order Ambisonics aliasing frequency in a small
+array inside the listening area can be increased by limiting the used order. A
+similar outcome can be achoieved in Wave Field Synthesis by applying so called
+local Wave Field Synthesis. In this case the original loudspeaker array is
+driven by Wave Field Synthesis to create a virtual loudspeaker array consisting
+of focused sources which can then be used to create the desired sound field in a
+small area.
+The settings are the same as for Wave Field Synthesis, but a new struct
+<code>conf.localsfs</code> has to be filled out, which for example provides the
+settings for the desired position and form of the local area with higher
+aliasing frequency.
+
+```Matlab
+conf = SFS_config_example;
+conf.resolution = 1000;
+conf.dimension = '2D';
+conf.secondary_sources.geometry = 'box';
+conf.secondary_sources.number = 4*56;
+conf.secondary_sources.size = 2;
+conf.localsfs.vss.size = 0.4;
+conf.localsfs.vss.center = [0 0 0];
+conf.localsfs.vss.geometry = 'circular';
+conf.localsfs.vss.number = 56;
+% sound_field_mono_localwfs(X,Y,Z,xs,src,f,conf);
+sound_field_mono_localwfs([-1 1],[-1 1],0,[1.0 -1.0 0],'pw',7000,conf);
+axis([-1.1 1.1 -1.1 1.1]);
+%print_png('img/sound_field_localwfs_2d.png');
+```
+
+![Image](doc/img/sound_field_localwfs_2d.png)
+
+
 #### Stereo
 
 The Toolbox includes not only WFS and NFC-HOA, but also some generic sound field

SFS_analysis/freq_response_localwfs.m

@@ -85,7 +85,7 @@
 
 %% ===== Computation ====================================================
 % Get the position of the loudspeakers
-x0 = secondary_source_positions(conf);
+x0_real = secondary_source_positions(conf);
 % Generate frequencies (10^0-10^5)
 f = logspace(0,5,500)';
 % We want only frequencies until f = 20000Hz
@@ -95,7 +95,7 @@
 % Get the result for all frequencies
 for ii = 1:length(f)
     if showprogress, progress_bar(ii,length(f)); end
-    D = driving_function_mono_localwfs(x0,xs,src,f(ii),conf);
+    [D, x0] = driving_function_mono_localwfs(x0_real,xs,src,f(ii),conf);
     % calculate sound field at the listener position
     P = sound_field_mono(X(1),X(2),X(3),x0,greens_function,D,f(ii),conf);
     S(ii) = abs(P);

doc/generate_doc_plots.m

@@ -151,6 +151,7 @@
 conf.localsfs.vss.geometry = 'circular';
 conf.localsfs.vss.number = 56;
 sound_field_mono_localwfs([-1 1],[-1 1],0,[1.0 -1.0 0],'pw',7000,conf);
+axis([-1.1 1.1 -1.1 1.1]);
 print_png('img/sound_field_localwfs_2d.png');
 
 % --- spatio-temporal snapshots of the sound field ---