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Owning Palette: Adaptive Filters VIs

Installed With: Adaptive Filter Toolkit

Updates the coefficients of an adaptive filter point by point. Use this VI with the AFT Filter Signal VI to update the coefficients of an adaptive filter. You must use the least mean squares (LMS) or recursive least squares (RLS) algorithms to create the adaptive filter. Wire data to the e(n) input to determine the polymorphic instance to use or manually select the instance. The data type of the adaptive filter that you wire to the adaptive filter in input must match the instance of the AFT Update Coefficients VI.

Note  Do not use the AFT Update Coefficients VI with the AFT Create FIR Fast Block LMS and AFT Create FIR QR-RLS VIs.

Examples

Use the pull-down menu to select an instance of this VI.

Select an instance AFT Update Coefficients (Real, PtByPt)AFT Update Coefficients (Complex, PtByPt)

AFT Update Coefficients (Real, PtByPt)

	adaptive filter in specifies the adaptive filter that you create.
	e(n) specifies the error signal e(n) of the adaptive filter. The error signal is the difference between the input signal d(n) and the output signal y(n). Use the AFT Filter Signal VI to obtain y(n).
	error in describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node. status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE. code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
	step size specifies the step size for the adaptive filter. If this value is less than zero, this VI ignores this parameter and uses the step size that you specify when you create the adaptive filter. If this value is zero, this VI processes the input signal without updating the coefficients of the adaptive filter. If this value is greater than zero, this VI uses this value as the step size to update the coefficients of the adaptive filter. The default is –1. Note  This parameter is valid only if the adaptive filter uses a least mean squares (LMS) algorithm. If the adaptive filter uses the normalized LMS or normalized leaky LMS algorithm, the value must be less than 2.
	adaptive filter out returns the adaptive filter in unchanged.
	error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error. status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred. code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

AFT Update Coefficients (Complex, PtByPt)

	adaptive filter in specifies the adaptive filter that you create.
	e(n) specifies the error signal e(n) of the adaptive filter. The error signal is the difference between the input signal d(n) and the output signal y(n) of the adaptive filter. Use the AFT Filter Signal VI to obtain y(n).
	error in describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node. status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE. code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
	step size specifies the step size for the adaptive filter. If this value is less than zero, this VI ignores this parameter and uses the step size that you specify when you create the adaptive filter. If this value is zero, this VI processes the input signal without updating the coefficients of the adaptive filter. If this value is greater than zero, this VI uses this value as the step size to update the coefficients of the adaptive filter. The default is –1. Note  This parameter is valid only if the adaptive filter uses a least mean squares (LMS) algorithm. If the adaptive filter uses the normalized LMS or normalized leaky LMS algorithm, the value must be less than 2.
	adaptive filter out returns the adaptive filter in unchanged.
	error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error. status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred. code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code. source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

Examples

Refer to the following VIs for examples of using the AFT Update Coefficients VI:

• Adaptive Channel Equalization VI: labview\examples\Adaptive Filters\Applications\Adaptive Channel Equalization
• Control Coefficients Updating for Adaptive Filter VI: labview\examples\Adaptive Filters\Getting Started