The LabVIEW Digital Filter Design Toolkit includes a variety of tools to help you design digital filters. For example, the Digital Filter Design Toolkit includes Express VIs that you can use to interact graphically with filter specifications to design appropriate digital filters.
In addition to the tools that help you quickly create digital filters, the Digital Filter Design Toolkit includes tools for single-rate and multirate digital filter design, floating-point to fixed-point conversion, filter analysis, simulation on a desktop computer, and filter bank design and analysis. The following sections describe the major features that the Digital Filter Design Toolkit provides.
You can use the Filter Analysis VIs to evaluate the characteristics of digital filters. You can examine the frequency response, group delay, phase delay, impulse response, step response, and pole-zero placement of a digital filter.
When you design digital filters with the Digital Filter Design Toolkit, you can select from one of 23 possible filter structures, which range from the direct form and cascaded form structures to the lattice auto-regressive (AR), lattice moving average (MA), and lattice ARMA structures.
Filter structures are mathematically equivalent when you use floating-point computation. However, different structures can perform differently in fixed-point implementations and can lead to different computation complexity and memory usage in fixed-point or floating-point implementations. Selecting an appropriate filter structure is critical for digital filter design, especially for fixed-point digital filters in which the precision of the filter coefficients and filtering operations is more limited than for floating-point digital filters.
The Multirate Filter Design VIs help you design, analyze, and implement single-stage multirate filters, multistage multirate filters, halfband filters, Nyquist filters, raised cosine filters, and cascaded integrator comb (CIC) filters.
The Fixed-Point Tools VIs and Multirate Fixed-Point Tools VIs help you quantize, analyze, model, and simulate the fixed-point filter design, including single-rate and multirate filters. You can save the resulting fixed-point filter information as C code, which you then can implement on digital signal processing (DSP) chips. You also can save the resulting fixed-point information as LabVIEW code, which you then can implement on NI Reconfigurable I/O (RIO) targets.
You can use algorithms such as the generalized Remez method and the least pth norm method to specify an arbitrary magnitude and a phase response for a digital filter. The Digital Filter Design Toolkit includes automatic order-estimation VIs to assist you in estimating the filter order.
The Digital Filter Design Toolkit includes VIs that you can use to design and analyze filter banks. You can use the VIs to design a 2-band quadrature mirror filter (QMF) or M-band cosine-modulated filter bank, analyze the characteristics of a filter bank, decompose or reconstruct signals with filter banks, retrieve filter bank parameters, and create a filter bank from a prototype filter.