

stft(e1071)                                  R Documentation

_C_o_m_p_u_t_e_s _t_h_e _S_h_o_r_t _T_i_m_e _F_o_u_r_i_e_r _T_r_a_n_s_f_o_r_m _o_f _a _V_e_c_t_o_r

_D_e_s_c_r_i_p_t_i_o_n_:

     This function computes the Short Time Fourier Transform
     of a given vector `X'.

     First, time-slices of length `win' are extracted from
     the vector. The shift of one time-slice to the next one
     is given by `inc'. The values of these time-slices are
     smoothed by mulitplying them with a window function
     specified in `wtype'. For the thus obtained windows,
     the Fast Fourier Transform is computed.

_U_s_a_g_e_:

     stft(X, win=min(80,floor(length(X)/10)), inc=min(24,
     floor(length(X)/30)), coef=64, wtype="hanning")

_A_r_g_u_m_e_n_t_s_:

       X: The vector from which the stft is computed.

     win: Length of the window. For long vectors the default
          window size is 80, for short vectors the window
          size is chosen so that 10 windows fit in the vec-
          tor.

     inc: Increment by which the window is shifted. For long
          vectors the default increment is 24, for short
          vectors the increment is chosen so that 30 incre-
          ments fit in the vector.

    coef: Number of Fourier coefficients

   wtype: Type of window used

_V_a_l_u_e_:

     Object of type stft. Contains the values of the stft
     and information about the parameters.

  values: A matrix containing the results of the stft. Each
          row of the matrix contains the `coef' Fourier
          coefficients of one window.

windowsize: The value of the parameter `win'

increment: The value of the parameter `inc'

windowtype: The value of the parameter `wtype'

_A_u_t_h_o_r_(_s_)_:

     Andreas Weingessel

_S_e_e _A_l_s_o_:

     plot.stft

_E_x_a_m_p_l_e_s_:

     x<-rnorm(500)
     y<-stft(x)
     plot(y)

