Update wfs-animation.ipynb

some suggestions
- imports into dedicated cell
- point source location farther and offset for more active speakers and ping pong pattern
- mod some comments, e.g. add physical units
- normalise with 4*pi*xs to be consistent with other examples
- time_stamps not hard coded
- due to normalise other vmin/vmax

Author: fs446

doc/examples/wfs-animation.ipynb

@@ -13,28 +13,38 @@
     "from matplotlib import animation\n",
     "from IPython.display import HTML\n",
     "from functools import partial\n",
-    "from scipy.signal import unit_impulse\n",
-    "\n",
-    "\n",
+    "from scipy.signal import unit_impulse"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "d5cf3220",
+   "metadata": {},
+   "outputs": [],
+   "source": [
     "# Point source\n",
-    "xs = 0, 2, 0\n",
-    "rs = np.linalg.norm(xs)  # distance from origin\n",
-    "ts = rs / sfs.default.c  # time-of-arrival at origin\n",
+    "xs = 0.1, 3, 0  # yields 11 active loudspeakers and \n",
+    "# a ping pong like excitation pattern\n",
+    "rs = np.linalg.norm(xs)  # distance from origin [m]\n",
+    "ts = rs / sfs.default.c  # time-of-arrival at origin [s]\n",
     "\n",
     "# Impulsive excitation\n",
-    "fs = 8000  # Adjust this to change the shape (width) of the impulse\n",
-    "signal = unit_impulse(512), fs  # Band-limited pulse (e.g. sinc) can be used instead\n",
+    "fs = 8000  # [Hz], determines width of the impulse\n",
+    "signal = unit_impulse(512), fs\n",
     "\n",
     "# Circular loudspeaker array\n",
     "N = 32  # number of loudspeakers\n",
-    "R = 1.5  # radius\n",
+    "R = 1.5  # radius [m]\n",
     "array = sfs.array.circular(N, R)\n",
     "\n",
     "grid = sfs.util.xyz_grid([-2, 2], [-2, 2], 0, spacing=0.02)\n",
     "\n",
     "delays, weights, selection, secondary_source = \\\n",
     "    sfs.td.wfs.point_25d(array.x, array.n, xs)\n",
-    "d = sfs.td.wfs.driving_signals(delays, weights, signal)"
+    "weights *= 4 * np.pi * rs  # normalise to origin\n",
+    "d = sfs.td.wfs.driving_signals(delays, weights, signal)\n",
+    "# note: no WFS pre-filter is utilised"
    ]
   },
   {
@@ -54,6 +64,7 @@
     "    sfs.plot2d.loudspeakers(array.x, array.n, selection * array.a, size=0.15)\n",
     "    return im\n",
     "\n",
+    "\n",
     "def update_frame_pressure(i, time_stamps):\n",
     "    t_i = time_stamps[i]\n",
     "    p = sfs.td.synthesize(d, selection, array, secondary_source, grid=grid,\n",
@@ -62,15 +73,16 @@
     "    return [im]\n",
     "\n",
     "\n",
-    "time_stamps = np.linspace(0.5/343, 5/343, 100)  # Time sampling is different from fs defined above\n",
-    "frames = 100\n",
-    "interval = 150\n",
-    "\n",
+    "# Movie time sampling is different from fs defined above\n",
+    "time_stamps = np.linspace(ts-R/sfs.default.c,\n",
+    "                          ts+R/sfs.default.c,\n",
+    "                          100)\n",
+    "frames, interval = 100, 150\n",
     "\n",
     "fig, ax = plt.subplots(figsize=(5, 5))\n",
     "p = sfs.td.synthesize(d, selection, array, secondary_source, grid=grid,\n",
     "                      observation_time=0)\n",
-    "im = plot(d, selection, secondary_source, t=ts, ax=ax, vmin=-0.01, vmax=0.01)\n",
+    "im = plot(d, selection, secondary_source, t=ts, ax=ax, vmin=-0.4, vmax=0.4)\n",
     "\n",
     "ani = animation.FuncAnimation(\n",
     "    fig, partial(update_frame_pressure, time_stamps=time_stamps),\n",
@@ -86,14 +98,14 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "# Save as gif file - This might take a few minutes.\n",
-    "ani.save(\"wfs-25d-td.gif\", writer='imagemagick',fps=10, dpi=200)"
+    "# Save as gif file - this might take a few minutes.\n",
+    "ani.save(\"wfs-25d-td.gif\", writer='imagemagick', fps=10, dpi=200)"
    ]
   }
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3 (ipykernel)",
+   "display_name": "sfs",
    "language": "python",
    "name": "python3"
   },
@@ -107,7 +119,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.5"
+   "version": "3.13.7"
   }
  },
  "nbformat": 4,