IEEE UCSD [tutorials:fixed_point_filtering_library] - Waterfox. We have written a fixed-point filtering library in three different flavors: C, C++, and ARM assembly. The C version is the most versatile, but uses more memory and instructions than the C++ or ARM version. The C++ version uses templates to eliminate a few pointers and constants by evaluating them at compile time. The hand-written ARM assembly version is the fastest and most memory efficient, and leverages the smlal 64-bit single cycle multiply accumulate instruction. We provide an online tool that takes a Matlab coefficient file as input and will produce an assembly file and header file as output. It is assumed that the reader has a background in DSP.
You will need Designing Fixed-Point IIR Filters with Matlab's FDATool At the matlab prompt, type fdatool Use the filter specification tab to input your filter's specifications. Click on the Filter Quantization tab and set Filter Arithmetic to “Fixed-point”. Go to File → Export. Export To: Coefficient File (ASCII) Format: Hexadecimal qiir.S. Audio Weighting Filters - MATLAB & Simulink Example - MathWorks United Kingdom - Waterfox. This example shows how to obtain designs for the most common weighting filters - A-weighting, C-weighting, C-message, ITU-T 0.41, and ITU-R 468-4 - using the audio weighting filter designer, fdesign.audioweighting, in the DSP System Toolbox™. In many applications involving acoustic measurements, the final sensor is the human ear. For this reason, acoustic measurements usually attempt to describe the subjective perception of a sound by this organ. Instrumentation devices are built to provide a linear response, but the ear is a nonlinear sensor.
Therefore, special filters, known as weighting filters, are used to account for the nonlinearities. A and C Weighting (ANSI® S1.42 standard) You can design A and C weighting filters that follow the ANSI S1.42  and IEC 61672-1  standards. The ANSI S1.42 standard requires that the filter magnitudes fall within a specified tolerance mask. The following code obtains an IIR Class 1 filter design for A-weighting with a sampling rate of 48 kHz. Audio weighting filter specification object - MATLAB fdesign.audioweighting - MathWorks United Kingdom - Waterfox. Audio weighting filter specification object Syntax HAwf = fdesign.audioweightingHAwf = fdesign.audioweighting(spec)HAwf = fdesign.audioweighting(spec,specvalue1,specvalue2)HAwf = fdesign.audioweighting(specvalue1,specvalue2)HAwf = fdesign.audioweighting(... ,Fs) Description Supported audio weighting filter types are: A weighting, C weighting, C-message, ITU-T 0.41, and ITU-R 468–4 weighting. HAwf = fdesign.audioweighting constructs an audio weighting filter specification object HAwf with a weighting type of A and a filter class of 1.
Use the design method to instantiate a dfilt object based on the specifications in HAwf. HAwf = fdesign.audioweighting(spec) returns an audio weighting filter specification object using default values for the specification string in spec. 'WT,Class' (default spec)The 'WT,Class' specification is valid for A weighting and C weighting filters of class 1 or 2.The weighting type is specified by the string: 'A' or 'C'.
HAwf = fdesign.audioweighting(... Input Arguments. IEEE UCSD [tutorials:fixed_point_filtering_library] - Waterfox. Why does my IIR filter become unstable when I change Filter arithmetic to Fixed-point using FDATOOL in Filter Design Toolbox 4.3 (R2008a)? - MATLAB & Simulink - MathWorks United Kingdom - Waterfox. Date Last Modified: Friday, June 26, 2009 Subject: Why does my IIR filter become unstable when I change Filter arithmetic to Fixed-point using FDATOOL in Filter Design Toolbox 4.3 (R2008a)? Problem Description: I noticed that my filter is stable for Double-precision floating-point and Single-precision floating-point but unstable for Fixed-point. The reproduction steps are provided below: a) Start FDATOOL b) Select Bandpass for Response Type, Elliptic in IIR for Design Method, Filter Order 20.
Using FDATool - MATLAB & Simulink - MathWorks United Kingdom - Waterfox. To open FDATool, type fdatool at the MATLAB® command prompt. The Filter Design and Analysis Tool opens with the Design Filter panel displayed. Note that when you open FDATool, Design Filter is not enabled. You must make a change to the default filter design in order to enable Design Filter. This is true each time you want to change the filter design. Choosing a Response Type You can choose from several response types: LowpassRaised cosineHighpassBandpassBandstopDifferentiator Multiband Hilbert transformer Arbitrary magnitude Additional response types are available if you have DSP System Toolbox™ software installed. To design a bandpass filter, select the radio button next to Bandpass in the Response Type region of the GUI. Choosing a Filter Design Method You can use the default filter design method for the response type that you've selected, or you can select a filter design method from the available FIR and IIR methods listed in the GUI.
Setting the Filter Design Specifications Filter Order. A-weighting Sound Filter - MATLAB Answers - MATLAB Central - Waterfox. Real time octave analysis: oct3dsgn(Fc,Fs,N); - File Exchange - MATLAB Central - Waterfox. Audio Weighting Filters - MATLAB & Simulink Example - MathWorks United Kingdom - Waterfox. DSP System Toolbox Examples - MathWorks United Kingdom - Waterfox. Floating-Point to Fixed-Point Conversion of IIR Filters - MATLAB & Simulink Example - MathWorks United Kingdom - Waterfox. Design a Lowpass Chebyshev Type I Filter We will use a minimum-order lowpass Chebyshev Type I design for the purpose of the example.
The design specifications of the filter are: Passband frequency edge: 0.4*piStopband frequency edge: 0.45*piPassband ripple: 0.5 dBStopband attenuation: 80 dB f = fdesign.lowpass('Fp,Fst,Ap,Ast',0.4,0.45,0.5,80); Hdf1sos = design(f, 'cheby1', 'FilterStructure', 'df1sos'); Step 1: Select a Second-Order Structure We will illustrate why converting to transfer function is a bad idea when fixed-point arithmetic will be used (and even when floating-point is to be used). [b,a] = tf(Hdf1sos); Hdf1 = dfilt.df1(b,a); Now we set arithmetic to fixed. Hdf1.Arithmetic = 'fixed'; hfvt = fvtool(Hdf1,'legend','on'); legend(hfvt,'Direct-Form I') So converting to transfer function is not advisable. Hdf1sos.Arithmetic = 'fixed'; setfilter(hfvt,Hdf1sos); axis([0 1 -120 5]) legend(hfvt,'Direct-Form I SOS', 'Location','NorthEast') Hdf1sos.AccumWordLength = Hdf1sos.ProductWordLength;
Numerical integration question - Newsreader - MATLAB Central - Waterfox. Floating-Point to Fixed-Point Conversion of FIR Filters - MATLAB & Simulink Example - MathWorks United Kingdom - Waterfox.