EquiRpl_BSFiltering
Advanced Analysis Library Only
AnalysisLibErrType EquiRpl_BSFiltering (double inputArray[], ssize_t numberOfElements, int numberOfCoeffs, double samplingFrequency, double f1, double f2, double f3, double f4, double outputArray[]);
Purpose
Filter the real array using a optimal bandstop FIR linear phase filter with equi-ripple characteristics.
Example Code
/* Design a 51-point bandstop FIR filter and filter the real incoming signal. */
double x[256], y[306];
double fs, f1, f2, f3, f4;
int n, ncoef;
fs = 1000.0; // sampling frequency
f1 = 200.0; // first pass band [0, 200]
f2 = 250.0; // stop band [250, 350]
f3 = 350.0;
f4 = 400.0; // second pass band [400, fs/2]
n = 256; // input signal length
ncoef = 51; //filter length
WhiteNoise (n, 1, 17, x);
EquiRpl_BSFiltering(x, n, ncoef, fs, f1, f2, f3, f4, y);
Parameters
| Input | ||
| Name | Type | Description |
| inputArray | double [] | Array containing the raw data to filter. |
| numberOfElements | ssize_t | Number of elements in the input array inputArray. |
| numberOfCoeffs | int | Length of the FIR filter. numberOfCoeffs must be greater than 2. The algorithm introduces a large error when designing a bandstop filter for an even number of ncoef. To avoid this error, the EquiRpl_BSFiltering adjusts the ncoef to the next higher odd value if ncoef is even. |
| samplingFrequency | double | Sampling frequency in Hertz. |
| f1 | double | Highest frequency of the lower pass band. The lower pass band is [0, f1]. |
| f2 | double | Lowest frequency of the stop band. The stop band is [f2, f3]. |
| highestStopFreq | double | Highest frequency of the stop band. The stop band is [f2, f3]. |
| lowestPassFreq | double | Lowest frequency of the upper pass band. The upper pass band is [f4, samplingFreq/2]. |
| Output | ||
| Name | Type | Description |
| outputArray | double [] | Filtered data. This array must be at least (n + ncoef - 1) elements long when ncoef is odd. This array must be at least (n + ncoef) elements long when ncoef is even. |
Return Value
| Name | Type | Description |
| status | AnalysisLibErrType | A value that specifies the type of error that occurred. Refer to analysis.h for definitions of these constants. |
Additional Information
Library: Advanced Analysis Library
Include file: analysis.h
LabWindows/CVI compatibility: LabWindows/CVI 2012 and later