对连续时间正弦信号x(t) sin(2π t+ )，可以按抽样频率 1/ 对x(t)抽样来获得离散时间信号x[n] x(t) sin( ).

以不同的组合f0和fs绘出x[n],可以说明混叠问题。以下，去抽样频率fs 8kHZ.

(a)绘出一个被抽样的正弦波单图。正弦波频率300Hz，10ms间隔上抽样，相位任意指定。使用stem绘图。

(b)使用plot绘图。

(c)将正弦波频率从100Hz变至475Hz，每次增加125Hz。绘图。

(d)将正弦波频率从7525Hz变至7900Hz，每次增加125Hz。绘图。

(e)将正弦波频率从32100Hz变至32475Hz，每次增加125Hz。绘图。

讨论显现频率是增加还是减少

-For the continuous time sinusoidal signal x (t)　 sin (2π t+), the discrete time signal x [n]　 x (t)　 sin () can be obtained by sampling the sampling frequency　 1/x (t).

The x [n] is plotted with different combinations f0 and fs, which can explain the aliasing problem. Here, the sampling frequency fs　 8kHZ.

   　(A) Draw a sampled sine wave single graph. Sine wave frequency 300Hz, 10ms interval sampling, the phase specified arbitrarily. Use stem drawing.

   　(B) use the plot plot.

   　(C) change the sine wave frequency　100Hz to 475Hz, each increase 125Hz. Drawing.

   　(D) change the sine wave frequency　7525Hz to 7900Hz, each increase 125Hz. Drawing.

   　(E) change the sine wave frequency　32100Hz to 32475Hz, each increase 125Hz. Drawing.

         　Discuss whether the apparent frequency is increased or decreased