Questions tagged [iir]

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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 ...
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0answers
27 views

Noise reduction and signal affect in IIR filter

I have found two equations which describe affect on signal and noise when using IIR filter: For signal: For noise: Can someone explain how to get these equations?
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2answers
102 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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1answer
41 views

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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2answers
80 views

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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1answer
407 views

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 ...
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2answers
168 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 ...
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2answers
1k 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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1answer
87 views

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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2answers
671 views

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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1answer
737 views

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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2answers
2k views

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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2answers
2k views

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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2answers
125 views

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?
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1answer
121 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<=...
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1answer
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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3answers
525 views

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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2answers
4k views

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 ...
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6answers
45k 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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5answers
5k views

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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6answers
2k views

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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3answers
3k views

Does somebody know about a tool to design filters for DSPIC?

I have to make a filter with DSPIC33 and I want a program that design the filter (there are a lot), yet export code to DSPIC (in c, any compiler or assembly).
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4answers
6k views

Good filter design software for Mac OS X/Unix?

I need to implement a simple lowpass filter for a data acquisition circuit (using stretch conductive fabric as a resistive sensor). Various sources have recommended that the best way to go about this ...