一連の信号のパワースペクトル
ダイヤルパッドからのデュアルトーン信号のスペクトログラムを可視化する．
Manipulate[Row[{Grid[Partition[MapIndexed[Button[First[#2] /. {10 -> "*", 11 -> 0, 12 -> "#"}, (EmitSound[Play[Sin[2 Pi #[[1]] t] + Sin[2 Pi #[[2]] t], {t, 0, .2}]];
signal = Join[signal, Table[Sin[2 Pi #1[[1]] t] + Sin[2 Pi #1[[2]] t], {t, 0, .2, 1 / 8000.}]];
p = Spectrogram[signal, 256, 128, BartlettWindow, SampleRate -> 8000, AspectRatio -> 1, ImageSize -> {Automatic, 180}]), ImageSize -> {40, 40}]&, Flatten[Outer[List, {697, 770, 852, 941}, {1209, 1336, 1477}], 1]], 3]], Spacer[30], Dynamic[p]}, Alignment -> Top],
Initialization :> (
signal = Table[Sin[2 Pi 697 t] + Sin[2 Pi 1209 t], {t, 0., 0.2, 1 / 8000.}];
p = Spectrogram[signal, 256, 128, BartlettWindow, SampleRate -> 8000, AspectRatio -> 1, ImageSize -> {Automatic, 180}])]