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Questions tagged [digital-filter]

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7
votes
3answers
887 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
46 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
34 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
45 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
85 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
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 ...
0
votes
2answers
114 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
336 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
235 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
81 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
347 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
66 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
145 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
86 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
50 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
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.
3
votes
1answer
110 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
101 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
163 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
371 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
107 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
124 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
618 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
250 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
196 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
496 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
272 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
319 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
804 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
80 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
388 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
7k 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
171 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
388 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
707 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
116 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
608 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
250 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
389 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
83 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
246 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
98 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
269 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
425 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
votes
1answer
684 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, ...