Questions tagged [digital-filter]
The digital-filter tag has no usage guidance.
83
questions
2
votes
0answers
76 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
907 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
64 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
38 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
54 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
99 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
52 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
120 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
440 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
298 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
113 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
625 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
69 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
167 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
93 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
46 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
113 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
107 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
173 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
405 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
114 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
96 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
127 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
666 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
263 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
199 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 ...
2
votes
1answer
540 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 ...
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
282 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
333 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 ...
1
vote
0answers
872 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
votes
1answer
82 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
votes
1answer
408 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
votes
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 ...
7
votes
4answers
8k 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
votes
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 (...
1
vote
3answers
181 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 ...
1
vote
1answer
400 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 ...
0
votes
2answers
750 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
votes
1answer
119 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 ...
1
vote
1answer
630 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 ...
-1
votes
2answers
265 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-...
4
votes
1answer
397 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, ...
0
votes
1answer
88 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 ...
1
vote
1answer
253 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}{...
1
vote
1answer
106 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 ...
0
votes
2answers
277 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
votes
1answer
437 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 ...
