Bessel_Coef

Advanced Analysis Library Only

AnalysisLibErrType Bessel_Coef (int type, int order, double samplingFreq, double lowerCutoffFreq, double upperCutoffFreq, double aCoefficientArray[], int numberACoefficients, double bCoefficientArray[], int numberBCoefficients);

Purpose

Generates the set of filter coefficients to implement an IIR filter as specified by the Bessel filter model.

aCoefficientArray and bCoefficientArray are the reverse and forward filter coefficients. Use IIRFiltering to achieve the actual filtering.

Parameters

Input
Name Type Description
type integer Controls the filter type of the Bessel IIR filter coefficients.

type has the following valid values:

lowpass = 0 (default)
highpass = 1
bandpass = 2
bandstop = 3
order integer Order of the IIR filter.

Default Value: 3.
samplingFreq double-precision Sampling frequency in Hertz.
lowerCutoffFreq double-precision Lower cutoff frequency of the filter in Hertz.
upperCutoffFreq double-precision Upper cutoff frequency of the filter in Hertz.
numberACoefficients integer Number of coefficients in aCoefficientArray.

numberACoefficients = order + 1 for low or highpass filters numberACoefficients = 2 × order + 1 for bandpass or bandstop filters
numberBCoefficients integer Number of coefficients in bCoefficientArray.

numberBCoefficients = order + 1 for low or highpass filters numberBCoefficients = 2 × order + 1 for bandpass or bandstop filters
Output
Name Type Description
aCoefficientArray double-precision array Array that contains the reverse coefficients of the designed IIR filter.
bCoefficientArray double-precision array Array that contains the forward coefficients of the designed IIR filter.

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.