Questions tagged [digital-filter]
The digital-filter tag has no usage guidance.
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0answers
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Time delay using IIR filters
I am trying to implement a cardioid pattern with two microphones.
I was reading this paper titled "Digital Filter Array Optimization for Directivity Pattern". The link to download the paper is this. ...
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6answers
2k views
Extremely low frequency filters
I have a data acquisition board(A/D+Digital Signal Processor) and I want to check if a digital high-pass filter(implemented in DSP) at an extremely low cut-off frequency(0.05Hz) is actually working.
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1answer
51 views
Inverse Z-transform Problem [closed]
I'm rather stuck trying to compute the inverse Z-transform y[n] of the function below. I'm having trouble selecting the correct formulas from the table to achieve the right solution.
Any help with ...
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2answers
97 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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0answers
205 views
FIR filter in dsPIC with DSP Library
I have to make a digital filter with a dsPIC30F, but I don't know much about it. I've read part of the documentation about the dsPIC30F and the DSP Library, and I found a page on Microchip website ...
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1answer
161 views
DSP Library not working in MPLAB X
I have to make a digital filter with a dsPIC30F4011 (I'm completely new to microcontrollers). I was reading the documentation about the DSP Library to figure out how to use it. I created a simple C ...
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1answer
52 views
Filtering Audio Signals in MATLAB
I'm trying to apply a filter to an audio signal in MATLAB and having some trouble processing it.
So far, I have a transfer function that describes a K-weighted filter, and I am able to create a bode ...
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1answer
153 views
Is this alternator W RPM input circuit ok and how can I improve it?
I need a robust and reliable way of taking a RPM signal from the W terminal of a standard automotive alternator. Most of the time the signal will come from a 12V alternator but there is a requirement ...
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0answers
54 views
Why do we need an (adaptive) equalizer when we have a matched filter at the receiver?
When both can perform the same task of reducing the effects of ISI, why use both and not just one at the receiver end?
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3answers
113 views
Predicting decay time of a resonant bandpass filter?
In a typical resonant bandpass filter, resonance is set as none at 0 and full at 1, such that the filter rings infinitely at 1 and not at all at 0.
If there is a two-pole resonant bandpass filter, ...
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2answers
80 views
Digital vs Analogue Filters From an Non-Audio Perspective
Recently I have been reading about the use of digital filters. By deriving the transfer function of the desired filter (in the s-domain) and multiplying holds (ZOH or FOH).
What is the general ...
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1answer
49 views
Filter gyroscope's error from linear acceleration?
I need to use 3-axis angular velocity data for my application, but the gyroscope outputs angular velocity when under linear acceleration (not rotating). Is there a way to filter this error?
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1answer
40 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.
3
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1answer
107 views
Understanding digital filters, specifically their effects on time domain information, how to preserve the waveform of a signal being filtered?
According to Steven W. Smith, in his book: The Scientist and Engineer's Guide to Digital Signal Processing, when designing a digital filter, "Good performance in the time domain results in poor ...
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1answer
98 views
Same z transformed function, but different answers of inverse z transform?
Given z transformed function is
E(z)=1/(z+4)
I know there are several ways to get the inverse z transform of this function.
use partial fraction
E(z)=1/(z+4)
E(z)/z=1/z(z+4) apply partial fraction ...
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2answers
146 views
Efficiency of FIR filter in verilog language
Implementing a 4-tap FIR unity coefficients, is this code efficient in power and area ?
...
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1answer
346 views
Anti-Aliasing Filter example
I need help in solving the below question.
Bandwidth of the signal is 1KHz. Use a 12-bit ADC with SNR of 78dB for sampling. the sampling frequency is 12KHz. Choose suitable filter order and cut-off ...
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1answer
102 views
Decimate ADAR7251 Sigma-Delta ADC Output
I'm working with a Analog Devices ADAR7251 Sigma-Delta ADC. It has multiple sample rates to choose from (1800 kSPS, 1200 kSPS, 900 kSPS, 600 kSPS, 450 kSPS, and 300 kSPS) but my application requires ...
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3answers
95 views
ADC power supplies monitoring - How to reject short overvoltage pulses
I have an MCU application where the MCU switches on/off and monitors the various power supplies of the board (3.3V, 1.8V, 1.0V etc.). When an under- or over-voltage is detected, an alarm to the system ...
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2answers
121 views
How to DSP filter a signal that has a variable time base?
I am measuring frequency on a microcontroller by measuring the time between pulses on an input.
DSP filter theory requires the time base of an input signal to be regular, e.g. IIR and FIR filters. ...
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2answers
557 views
How to determine appropriate lowpass filter for Sigma-Delta modulator?
My question may be a bit naive, as I don't know this stuff well, but bear with me.
I'm looking a encoding a time-varying signal x(t) into a pulse-stream ...
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1answer
216 views
Problems with implementation of a band-stop filter on an MCU (dsPIC) using fixed-point arithmetic
I'm trying to implement a band-stop (notch) filter on a microcontroller dsPIC33EP64GS506 to filter out a 100 Hz component from ...
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1answer
194 views
What reduced the noise when multiplying neighbor samples?
Is this a common filtering technique? I multiplied each sample with it's neighbor.
I was trying to distinguish the spikes from the noise. Low-pass filtering wasn't as helpful maybe because both the ...
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1answer
449 views
DSP/dsPIC Getting Started
I am a last class eee student and I started to study on digital filters. I want to design a 0-150 Hz band pass filter for getting started(I have not determined certain parameters, I want to do ...
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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 ...
2
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0answers
261 views
RC filter - compute output as a function of input for generating waveform
I'm not so deeply into the theory about all this, I may use strange terminology...
If I put a square wave through a simple lowpass RC filter, the output will be a sort of "rounded sawtooth", well not ...
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1answer
293 views
FPGA filter - sinusoidal wave at clock frequency observed in filtered signal
I am using an FPGA to implement FIR filters, specifically for this question I have implemented a 12 point moving average filter. At the moment I am just using a signal generator as an input to the ...
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0answers
727 views
Low-pass digital filter for 0-10 V, 4-20 mA input
I'm looking for a little direction or recommendations in how to select and implement a low-pass filter in software as my background in signals and systems is quite weak. In particular, I'm interfacing ...
0
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1answer
78 views
How do we balance an FIR around its center?
How do we balance an FIR around its center? I was asked this question in an interview. What does this mean? Is the center point the point corresponding to the peak of impulse response?
0
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1answer
376 views
Designing Butterworth Filter [closed]
I want to design butterworth filter in matlab only based on order of the filter and the cutoff frequency in Hz.
the syntax is for returning the ABCD matrix of statespace is
...
2
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4answers
1k views
Remove spikes from Load Cell readings
I have developed load indicator interfaced with load cell to display the value of load. The device is to be used in on-line weighing of a bag that is moving over the conveyor. Due to the mechanical ...
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4answers
6k views
Performing FFT at low frequencies but high resolution?
To put this in context, I'm looking to achieve both high speed and high accuracy for measuring biosignals through the FFT. I'll describe a quick example to see if I understand this properly as well as ...
2
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4answers
2k views
Advantages of filtering signals using analog or digital methods?
In my understanding, it seems that there are, broadly speaking, two primary ways in which signals are filtered for analysis by computers, which are software-side filters and hardware-side filters (...
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3answers
163 views
Sharp and Simple Analog Filter suggestions
I'm looking for schematics of some simple opamp-based analog filter, which has a sharp band-pass functionality. I want it to control small robot with sounds of different pitch.
The matter is like ...
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1answer
360 views
Digital filter implementation in C (embedded)
I am a recent grad and my new project at work deals with taking the signal from an electret microphone and getting SPL values for 10 standard frequency bands.
The analog amplification/conditioning is ...
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2answers
644 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 ...
0
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1answer
107 views
Changing the data logging rate on a Tektronix DSO
Currently, for a continuous waveform, i am able to log data from the Tektronix TBA 1064 DSO as .csv files. The time interval between two samples currently is around 4 * E-08 (by default).
My ...
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1answer
580 views
FIR Filter 16-Bit
I am trying to implement a 32-tap filter on an FPGA, I can have only 16-bits for the coefficients, and 16bits for the input samples, and my output should also be 16 bits. Multiplying a 16bit ...
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2answers
238 views
Derive Zero-Input Response for High-Pass Filter
Given a simple series RC circuit where the output is measured across the resistor (i.e. a high-pass filter), how would one derive a general zero-input response for the system?
I can do it for a low-...
2
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1answer
363 views
digital bandpass filter with parallel inputs
I have a high speed ADC connected to an FPGA. The ADC is designed such that you get 16 samples every FPGA clock cycle (that's samples, not bits). The 16 samples are from a single ADC input channel, ...
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1answer
71 views
What is a Thresh filter?
I was looking at this site and saw the term. While I'm a bit familiar with some DSP terminology, I have never heard of this before. Google did not really help at all.
From what the site explores, it ...
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1answer
236 views
Distinguishing between FIR and IIR filters from transform function
I was good at this but unfortunately I have forgot almost everything... So the question is what are the steps to tell if a transform function is for IIR or FIR filter:
$$H(z) = \frac{z^3+5z^2+3z+1}{...
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1answer
93 views
Finding the system function of a digital filter
I am studying for exams and I need help with a question I came across in a textbook.
Given a digital filter $$y_n = a(x_{n-1} + x_{n+1}) + bx_n$$ find the system function of this filter and the ...
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2answers
258 views
Gain Resolution after delta-sigma (ΔΣ) analog-to-digital converter (ADC)
Is it possible (effective) to do oversampling and apply extra Moving Average Filter with a delta-sigma (ΔΣ) analog-to-digital converter (ADC)?
More detailed: The ADC (ADS1258) I chose has an ...
0
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1answer
406 views
Digital Low-Pass Filter When Oversampling Audio
The human ear can hear sounds up to ~ 20KHz. Some ADC's oversample. For example, to capture frequencies up to 20KHz, an ADC converter might sample at 160KHz. The steps are: 1. Filter the audio with an ...
2
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1answer
658 views
Low Pass IIR filter attenuating all frequencies
I am trying to make a Low pass IIR filter in dsPIC(dsPIC33FJ12MC202) using mikroC compiler. I have generated filter coefficients using Filter Design Tool. My filter specifications are as follows:
LPF, ...
0
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1answer
194 views
filter whose gain increases from minimum to maximum for frequency 400Hz to 1kHz
I want to design high pass filter whose gain should increase from minimum to maximum ( minimum upto 400 Hz maximum for 1 kHz) linearly or exponentially. It must be an active filter and my input signal ...
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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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3answers
699 views
Linear Phase Response
In many cases it is demanded that the filter has a linear phase response. (like in case of FIR ). Why linear is so important? Why not constant or anything else(any other shape)?
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3answers
485 views
Physical significance of group delay
What is the physical significance of the group delay of a system/filter?. Why is the slope of the phase response critical in a communication system.
