Digital Signal Processing
Overview of Digital Signal Processing Subroutines
All subroutines and functions available in SAS Viya are listed in Table 1, Table 2, and Table 3. A subset of these routines is available in SAS 9.4. The routines whose names are marked with an asterisk (*) in the tables are not available in SAS 9.4. In each table, the subroutines and functions are divided into categories by functionality, and within each category they are listed in order of most common usage.
The subroutines and functions in Table 1 are supported for digital filters.
Table 1: Subroutines and Functions for Digital Filters
| Category | Name | Functionality |
|---|---|---|
| Filter design | DFORDER | Computes the minimum order that is required for a specific digital filter |
| DFDESIGN | Designs a digital filter that meets the design specification | |
| Data filtering | DFFILT | Filters a signal by using a digital filter (designed by the DFDESIGN subroutine), with its direct form |
| DFSOSFILT | Filters a signal by using a digital filter (designed by the DFDESIGN subroutine), with its second-order section form | |
| DFMEDFILT | Filters a signal by using a nonlinear median filter | |
| Filter visualization | DFFREQZ | Generates a digital filter’s frequency response by using transfer function coefficients |
| DFSOSFREQZ | Generates a digital filter’s frequency response that corresponds to its second-order section form by using transfer function coefficients | |
| DFFREQZZPK | Generates a digital filter’s frequency response by using the transfer function’s zeros, poles, and gain | |
| DFSOSFREQZZPK | Generates a digital filter’s frequency response that corresponds to its second-order section form by using the transfer function’s zeros, poles, and gain |
The subroutines and functions in Table 2 are supported for signal transforms and operations.
Table 2: Subroutines and Functions for Signal Transforms and Operations
| Category | Name | Functionality |
|---|---|---|
| 1-D Fourier transform | FFT | Computes the discrete Fourier transform |
| IFFT | Computes the inverse discrete Fourier transform | |
| FFTC | Performs the discrete Fourier transform for complex signals | |
| IFFTC | Computes the inverse discrete Fourier transform for complex signals | |
| 2-D Fourier transform |  | Computes the two-dimensional (2-D) fast Fourier transform of a real 2-D signal |
 | Computes the two-dimensional (2-D) inverse fast Fourier transform of a 2-D signal | |
| Hilbert transform | TFHILBERT | Computes the Hilbert transform of a discrete time series |
| Wavelet transform | WAVFT | Computes a wavelet transform of one-dimensional (1-D) data |
| WAVGET | Returns requested information about a wavelet transform | |
| WAVIFT | Inverts a wavelet transform after applying thresholding to the detail coefficients | |
| WAVPRINT | Displays information about a wavelet transform | |
| WAVTHRESH | Applies specified thresholding to the detail coefficients of a wavelet transform | |
| SCALOGRAM | Creates a wavelet scalogram, which shows the relative magnitudes of detail coefficients and the energy in each level | |
| Cepstral analysis | RCEPSTRUM | Computes the real cepstrum |
| CCEPSTRUM | Computes the complex cepstrum | |
| ICCEPSTRUM | Computes the inverse complex cepstrum | |
| Vector convolution | DFCONV | Computes the convolution of two one-dimensional (1-D) vectors |
| Instantaneous properties |  | Calculates instantaneous frequency, phase, and amplitude |
| Peak finder |  | Outputs information about the peaks in a series |
 | Finds the peaks in a series |
The subroutines and functions in Table 3 are supported for time-frequency analysis.
Table 3: Subroutines and Functions for Time-Frequency Analysis
| Category | Name | Functionality |
|---|---|---|
| Short-time Fourier transform | TFSTFT | Computes the short-time Fourier transform |
| TFWINDOW | Computes a window function for a short-time Fourier transform | |
| Short-time power spectral density transform | TFSTPPSD | Computes the short-time power spectral density |
| Pseudo-Wigner-Ville transform | TFPWV | Computes the pseudo-Wigner-Ville transform |
| Empirical mode decomposition |  | Decomposes a time series into multiple intrinsic mode functions and a residual |
| Hilbert-Huang transform |  | Applies the Hilbert-Huang transform to calculate instantaneous amplitude, phase, and frequency |
 | Applies the Hilbert-Huang transform to calculate instantaneous energy as a function of time and instant frequency | |
| Time-frequency visualization | SPECTROGRAM | Displays a spectrogram of a short-time Fourier transform |
 | Displays a spectrogram of a time-frequency analysis |