DFD NStage MRate Filter Design VI

	manual factorization specifies the factors for each stage. The product of all the factors in the manual factorization input must equal the factor input value.
	factor specifies the sampling frequency conversion factor of the multirate filter. factor must be greater than 1. The default is 8. If you set using CIC? to TRUE, factor must be greater than 4 and divisible by 4.
	using CIC? specifies if you want to use the cascaded integrator comb (CIC) filter design method to design one stage of the multistage multirate filters. The default is FALSE, which means this VI does not use the CIC filter design method. If the value is TRUE, this VI uses the CIC filter design method to design the first stage of the filter when you set filtering mode to Decimation, or the last stage of the filter when you set filtering mode to Interpolation.
	freq specs specifies the passband edge frequency and stopband edge frequency of the multistage multirate filters. fpass specifies the passband edge frequency of the multistage multirate filters. The default is 45. fstop specifies the stopband edge frequency of the multistage multirate filters. The default is 52.
	ripple specs specifies the ripple level in the passband and stopband of the filter. passband specifies the ripple level in the passband. The default is 0.1. stopband specifies the ripple level in the stopband. The default is 60. dB/linear? specifies whether this VI applies a decibel scale or a linear scale to the ripple levels. If the value is TRUE, this VI applies a decibel scale to the ripple level. If the value is FALSE, this VI applies a linear scale to the ripple level. The default is TRUE.
	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.
	fs in specifies the input sampling frequency of the multistage multirate filters in hertz. The default is 800.
	filtering mode specifies the processing mode of the filter that this VI creates. 0 No Rate Change—Does not change the sampling frequency of a signal. 1 Interpolation—Increases the sampling frequency of a signal to a higher sampling frequency that differs from the original frequency by an integer value. Interpolation also is known as up-sampling. 2 Decimation (default)—Reduces the sampling frequency of a signal to a lower sampling frequency that differs from the original frequency by an integer value. Decimation also is known as down-sampling.
	multirate filters out returns the new multistage multirate filters.
	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.

DFD NStage MRate Filter Design Details

Use the DFD NStage MRate Filter Design VI to create multirate filters with large multirate factors. This VI distributes a large factor into each stage of the multirate filter, as shown in the following example. A multistage design requires less computation and storage than a single-stage design.

For example, if the sampling frequency conversion factor M contains the factors M₁, M₂, and M₃, such that M = M₁*M₂*M₃, and M₁>M₂>M₃>1, you can design a three-stage multirate filter in which all three stages use the same multirate processing mode that filtering mode specifies.

If you set using CIC? to TRUE, the factor M must be divisible by 4, for example, M = 2*2*M₁. In this case, the filter with the largest factor M₁ is a CIC filter.

The overall response of cascading the multirate filters is a lowpass response.

Examples

Refer to the following VIs for examples of using the DFD NStage MRate Filter Design VI:

• Analyze Coefficients-Quantized Multistage Multirate Filter VI: labview\examples\Digital Filter Design\Fixed-Point Filters\Multirate

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• Multistage Decimation Filter Design VI: labview\examples\Digital Filter Design\Floating-Point Filters\Multirate

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• Multistage Multirate Filter Design (with CIC) VI: labview\examples\Digital Filter Design\Floating-Point Filters\Multirate

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• Multistage Multirate Filter Design VI: labview\examples\Digital Filter Design\Floating-Point Filters\Multirate

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