Questions tagged [digital-filter]
A digital filter is a system that performs mathematical operations on a sampled, discrete-time signal
101
questions
1
vote
1answer
52 views
Digital control stability for more than impulse response stability?
I have a digital control system which is described by the transfer function
$$
Y(z) = \frac{-\beta}{z - 1 + k \beta} X(z)
$$
where \$\beta\$ is a real parameter I can adjust to modify the ...
0
votes
1answer
104 views
Software oscilloscope
I have been developing a C language software for software oscilloscope
which is part of a control software. From timing point of view the
software consists of two execution loops.
The first execution ...
2
votes
1answer
156 views
Why does this part of an OLED filter light only when orientated correctly?
Note: The screen is an OLED screen. I had assumed it was LCD, therefore the post mentions it as such.
I was disassembling a Samsung phone (GT-I9305) and was able to seperate the LCD into two sections....
2
votes
0answers
91 views
How to amplify the output of a digital low pass filter?
I have used the transfer function of a RC low pass filter to design a IIR Digital low pass filter.
\begin{equation}
H(s)=
\frac{1}{sRC+1}
;First
\space
order
\end{equation}
\begin{equation}
H(s)=
\...
3
votes
4answers
450 views
How to pick correct filter for a given signal processing task?
I did a study on digital signal processing and I found many theories.
But I don't know how to figure out which filter to use when I get a practical signal processing task.
Is there a procedure for ...
1
vote
5answers
517 views
Calculate cutoff frequency of a digital IIR filter
I have an ADC with 1 kS/s and would like to append a digital anti-aliasing filter to it as I have to downsample the data to 10 Hz.
As it's on an FPGA and I don't have any multipliers, I thought ...
4
votes
1answer
109 views
How to make my difference equation make the deadline constraint?
Back at it again.
STM32L43KC Datasheet:
The question this time is I am finally starting to implement my digital filter which can been see as:
Z - Transform:
$$LPF_D=\frac{Y}{U}=\frac{0.3957z^2+0....
0
votes
2answers
26 views
Truncation noise in digital circuits
I was reading a chapter of my book (I am not putting it as reference since it is not in english) about the quantization noise problem in digital filters. Specifically, it writes about a filter that ...
1
vote
2answers
36 views
“Order” of a digital filter (FIR and IIR)
I have some doubts about the meaning of order for digital filters. All I'll put here is taken from these slides.
1) Let's start from the definition of FIR filters:
From this definition we see that ...
2
votes
2answers
39 views
Physical operations of discrete - time circuits
I have a basic doubt about discrete time circuits.
A discrete - time signal is a sequence of values which are taken at specific time instants (let's call them sampling instants), as we can see from ...
2
votes
2answers
137 views
Doubts about IIR filters definition and transfer function
I have some basic doubts about IIR digital filters.
My first question is about its definition. IIR means Infinite impulse response, so my question is: is it physically possible to realize such ...
0
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0answers
27 views
How do I write a requirement of an asynchronous input signal, when the sampling clock has a certain resolution?
Let's say I have an asynchronous input (let's call it enable_h). This signal is supposed to be active high for 100us.
My 2mhz clock is double-registering this async input. So once it is in my clock ...
1
vote
0answers
61 views
Converting an analog Butterworth filter into a discrete filter
Here again to ask about another question. This time asking how to convert an analog transfer function to a discrete transfer function using standard continuous to discrete methods.
The application ...
3
votes
2answers
244 views
How can I design a low pass filter using Z transform in Microcontroller?
I have generated a signal which is a mixture of 50 Hz and 250 Hz sine waves using a microcontroller and DAC. Check the screenshot of the excel file:
The values of row 4 (i.e. f1+f2) are feed to an 8-...
0
votes
0answers
28 views
When to choose ZoH method over Tustin in Discrete design?
Hey guys I am kinda confused as to which method to pick from, in terms for a digital filter. Which method is appropriate for this application and how did you come to pick it?
I want to convert a ...
2
votes
2answers
265 views
How to implement a discrete transfer function into an arduino?
I am here asking how does one transfer a difference equation into a MCU? I have never done it personally and looking into this topic I was never able to find a good answer. Its usually used with ...
1
vote
1answer
98 views
What is the difference between a 1st and 2nd Order Digital Filter
I was just curious as to the differences between the two order filters?
How I created these discrete filters for references
Designed in Continuous first then converted into Discrete
Using Tustin's ...
3
votes
2answers
162 views
Why use convolution for pulse compression in radar instead of correlation?
I have not understood the way to process pulse compression in radar signal processing. I think it's correct to use correlation for pulse compression, but I saw many materials about pulse compression. ...
2
votes
0answers
77 views
Accelerometer to detect when product has been picked up by user
I have a 3-axis accelerometer on my board and i was hoping to use it to detect when a user lifts the device up.
I would like to avoid false triggers when the table shakes or when the user nudges the ...
7
votes
3answers
932 views
The term Feed-forward and its meaning?
I am trying to understand the technical meaning of the term 'feed-forward', when and where it can be used and where it cannot be used? I have seen this term in various different areas.
For example:
...
2
votes
1answer
79 views
LM567 or Custom bandpass filter
I'm using a array of hydrophones to localize an underwater pinger (37.5 kHz and 45 kHz) and I'm thinking of using LM567 tone decoder as a frequency filter. The other option is to design a custom ...
0
votes
0answers
39 views
Filtering analog audio signal using TLV320AIC3111-EVM
I'm working on a project to filter analog microphone data using the audio codec from TI, the TLV320AIC3111. We are using the EVM However, I'm facing problems with implementing the filters on the ...
1
vote
1answer
61 views
Xilinx FIR filter behavior
We're currently simulating some Xilinx AXI Stream Finite Impulse Response (FIR) IP cores.
https://www.xilinx.com/support/documentation/ip_documentation/fir_compiler/v7_2/pg149-fir-compiler.pdf
The ...
0
votes
0answers
116 views
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. ...
13
votes
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.
...
0
votes
1answer
56 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 ...
0
votes
2answers
125 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^{-...
1
vote
0answers
587 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 ...
1
vote
1answer
369 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 ...
1
vote
1answer
145 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 ...
0
votes
1answer
1k 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 ...
0
votes
0answers
74 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?
0
votes
3answers
186 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, ...
0
votes
2answers
106 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 ...
0
votes
1answer
51 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?
0
votes
1answer
64 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
votes
1answer
117 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 ...
0
votes
1answer
118 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 ...
0
votes
2answers
190 views
Efficiency of FIR filter in verilog language
Implementing a 4-tap FIR unity coefficients, is this code efficient in power and area ?
...
0
votes
1answer
437 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 ...
1
vote
1answer
118 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 ...
0
votes
3answers
98 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 ...
0
votes
2answers
138 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. ...
0
votes
2answers
742 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 ...
1
vote
1answer
283 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 ...
4
votes
1answer
200 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 ...
1
vote
1answer
595 views
DSP/dsPIC Getting Started [closed]
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 ...
0
votes
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
votes
0answers
306 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 ...
0
votes
1answer
352 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 ...
