# Questions tagged [iir]

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### Problem with I2S and IIR-filter

I am working on a system that receives audio data over Bluetooth using a BM83. This is transmitted to an STM32F7 over ADC, an IIR-filter is applied and the data is transmitted out over I2S. The ADC ...
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### IIR digital filter: samples not matching the frequency response

I am working on a small project in Mathematica involving a Chebyshev 4th order highpass filter, trying to obtain its digital IIR filter with the bilinear transformation. I implemented the differential ...
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1 vote
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### IIR filter design: detect limit-cycle oscillations

I am studying IIR filters read about limit-cycle oscillations in IIR filters. From what I understand, there are two types of oscillations Granularity limit-cycle: when signal levels become very low ...
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### How to classify filters

I deal with digital signal processing which also deals with filters. There are 2 main types of filters: Analog and Digital. To each type there are several classifications such as:FIR/IIR/RCSR(...
502 views

### What sampling rate to use when making IIR filters with an audio sample rate of 44.1kHz?

I am kind of confused as to which sampling rate to use when making an IIR filter if the sampling rates for audio are 44.41kHz, or 96kHz, etc.. My concept and what has been working for me. When people ...
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1 vote
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### How can I prevent my IR sensor from sensing the sunlight?

I want to use an IR sensor for object detection. An LED will be turned on if an object is detected. But because of sunlight, it's malfunctioning (i.e. always getting logic 1). So, how do I omit the ...
105 views

### Is my IIR implementation (in C) correct for this difference equation?

I recently started developing a digital regulator for a DCM boost (Digital regulator for DCM Boost - How does it relate to duty cycle?) And I've implemented the difference the following controller in ...
148 views

### Why won't my IIR filter work?

I have a cascaded IIR filter that has a sampling frequency of 1kHz and consist of a highpass filter with a cutoff frequency of 0.8Hz and a lowpass filter with a cutoff frequency of 5Hz. I have ...
196 views

### Error implementing IIR filter on FPGA

I want to implement several IIR filters on an FPGA, using VHDL. The filters is for audio. I start out by implementing a single filter with the following transfer function: H_1(z)=\frac{304 -304z^{-...
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### How does an IIR filter change depending on the approximation used? [closed]

What are the main differences between the filters when using Butterworth, Chebyshev type I, Chebyshev type II or Elliptic aproximations.
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1 vote
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### Find filter's frequency characteristics from its impulse response

Impulse response is defined as . Its plot looks like this: Now I am basically supposed to say what does filter do with incomming signals based on this formula or plot. How can I approach this ...
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### Implement IIR SOS structure into FPGA

I try to implement an IIR into my FPGA project. I've got the coefficients from my matlab program and implement the gain directly into the coefficients, though I don't need an additional gain ...
1 vote
360 views

### problem with fixed point butterworth implementation

I have designed a 2nd order Butterworth filter with MATLAB fdatool for VHDL implementation. the cuttoff frequency is less than Fs/10, which should be okay since fdatool uses prewarping. Indeed, the ...
2k views

### ADC sampling frequency - Noise filtering

I have to take the reading of two analog sensors temperature & Fuel level. Both of them are analog signal & i have to remove noise from this reading. And i want to use the Digital filter for ...
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### Implementing a very sharp IIR (125Hz sampling rate, 0.2Hz bandwidth)

I am trying to design a IIR lowpass filter. The purpose of this filter is to get pure DC from noises. The sampling rate is: 125Hz. The bandwidth of the filter: 0.2Hz. I designed the filter with ...
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1 vote
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### How to improve my digital filter to extract DC from noises?

Digital filter description: The filter's input are sensor data and output will be provided to a PID controller. Sampling rate: 64kHz Noises spectrum: from DC to 10kHz Filter target: to get DC ...
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### IIR filter concerns in PID control systems

The following diagram represents the system: Here comes some more description: The system input (ref or reference is zero). And actually the goal of the controller is to maintain the output of the ...
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### Relationship between order of filter and impulse response?

I see that the slope of the frequency response of a filter (such as the Elliptic, Butterworth...) becomes steeper as its order increases; for instance, a low pass Elliptic filter with an order of N=3 ...
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### Is it possible to create an IIR filter in an FPGA that's clocked at the sample frequency?

This question is about implementing a IIR filter in a FPGA with DSP slices, with very specific criteria. Lets say you're making a filter with no forward taps and only 1 reverse tap, with this ...
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1 vote
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### IIr filter layout to formula problems

I am trying to create the formula for this layout but I have the feeling that I made a mistake. The formula that I have at the moment is: Can someone tell me if this is correct?
231 views

### Conditions for realizing a filter

I was reading a chapter in a textbook on Infinite Impulse Response filters. The author in the beginning of the chapter states that" impulse response h(n) for a realizable filter is " h(n)=0 for n<=...
1 vote
1k views

### Is it possible to compute delay with an IIR filter between peaks?

I am developing a project which receives accelerometer signals as input, which must then be analysed via peak-detection algorithms (among other techniques). In order to do so more effectively, I ...
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### Is a IIR digital filter with a0=1 effectively a FIR digital filter?

I have been experimenting with several digital filters for my thesis recently, and while learning about the FIR and IIR kind, they seem to have similar output expressions. While using a Java class I ...
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### low pass filter design for accelerometer

I find the following code for a simple implementation of a low pass filter. #define alpha 0.1 accelX = (acceleration.x * alpha) + (accelX * (1.0 - alpha)); I have been experimenting with the value ...
55k views

### Code example for FIR/IIR filters in VHDL?

I'm trying to get started with DSP in my Spartan-3 board. I made a AC97 board with a chip from an old motherboard, and so far I got it to do ADC, multiply the samples for a number <1 (decrease ...
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### IIR filters what does infinite mean?

I am having difficulty understanding what "infinite" in IIR means in practice..In theory the impulse response is used for feedback..If this feedback never ends how output is generated?
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### IIR filter on a 16bit MCU (PIC24F)

Im trying to implement a simple first order IIR filter on a MCU (PIC24FJ32GA002), without success until now. The filter is a DC tracking filter (low pass filter) whose purpose is to track DC component ...
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