AmplitudeResponse (FPScript)
Calculates the amplitude response from the filter coefficients.
Syntax
AmplitudeResponse(FilterCoefficients, [ Length = 1024 ] [ , SamplingRate = 1 ])
The syntax of the AmplitudeResponse function consists of the following parts:
Part |
Description |
|---|---|
FilterCoefficients |
The filter coefficients for which the amplitude response is calculated. Permitted data structures are data series und list. All numeric data types are permitted, except calendar time und time span. |
Length |
Specifies the data length of the amplitude response. Permitted data structures are scalar value. Supported data types are 16-bit integer und 32-bit integer. The value must be greater than 0. If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated. If this argument is omitted, it will be set to the default value 1024. |
SamplingRate |
If you specify the sampling rate of the time signals to which you apply the filter, then the X component is scaled in such a way that it represents the physical frequencies. If you omit the argument, the amplitude response for normalized frequencies in a range from 0 to 0.5 will be calculated. Permitted data structures are scalar value. All real data types are permitted. The value must be greater than 0. If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated. If this argument is omitted, it will be set to the default value 1. |
Remarks
The result is a signal and the data type is always a real or complex 64-bit floating point value. The X component contains the frequencies from 0 to half of the sampling frequency.
The FilterCoefficients argument is either a list with the numerator and denominator coefficients (IIR) or a data series with the numerator coefficients (FIR) of a filter.
Available in
Option Digital Filters
Examples
AmplitudeResponse(IIRFilter(FILTER_BUTTERWORTH, FILTER_LOWPASS, 5, 0.1, 0.1, 0.1, FILTER_DELTA))
Calculates the amplitude response from the coefficients of a Butterworth low pass filter of the 5th order with the normalized cut-off frequency of 0.1.
AmplitudeResponse(IIRFilter(FILTER_ELLIPTIC, FILTER_LOWPASS, 5, 200 Hz, 0.1, 0.1, FILTER_DELTA, FILTER_COEFFICIENTS, 1 kHz), 2048, 1000 Hz)
Calculates the amplitude response of the length 2048 from the coefficients of a Cauer low pass filter of the 5th order with the cut-off frequency 200 at a sampling frequency of 1000 Hz.
See Also
FIR Filter Analysis Object (Equiripple Method)