A low-pass filter is a filter that passes signals with a frequency lower than a selected cutoff frequency and attenuates signals with frequencies higher than the cutoff frequency. The exact frequency response of the filter depends on the filter design. The filter is sometimes called a high-cut filter, or treble-cut filter in audio applications. A low-pass filter is the complement of a high-pass filter.
In optics, high-pass and low-pass may have different meanings, depending on whether referring to frequency or wavelength of light, since these variables are inversely related. High-pass frequency filters would act as low-pass wavelength filters, and vice versa. For this reason it is a good practice to refer to wavelength filters as short-pass and long-pass to avoid confusion, which would correspond to high-pass and low-pass frequencies.Low-pass filters exist in many different forms, including electronic circuits such as a hiss filter used in audio, anti-aliasing filters for conditioning signals prior to analog-to-digital conversion, digital filters for smoothing sets of data, acoustic barriers, blurring of images, and so on. The moving average operation used in fields such as finance is a particular kind of low-pass filter, and can be analyzed with the same signal processing techniques as are used for other low-pass filters. Low-pass filters provide a smoother form of a signal, removing the short-term fluctuations and leaving the longer-term trend.
Filter designers will often use the low-pass form as a prototype filter. That is, a filter with unity bandwidth and impedance. The desired filter is obtained from the prototype by scaling for the desired bandwidth and impedance and transforming into the desired bandform (that is low-pass, high-pass, band-pass or band-stop).
In filters usually you can find two different specifications: number of poles and dB/octave.
I know that the poles gives you the transfer functions using this equation for a low pass filter
H(f)=1/\sqrt{1+(f/f_{C})^{2P}}
Where P is the number of poles of the filter. But how can I translate...
i have got a problem with a calculation involving a filter, i hope you all with lend me a helping hand.
to calculate a diameter of a cylinder is rather easy, but how to determine the size of the water filter knowing only the flow rate of the pipe, diameter of the piping and the pressure of...
Dear all,
I'm trying to implement an Extended Kalman Filter for position, velocity and orientation tracking of a rigid body and I am using quaternions for representing the orientation in the state vector. As this is the first time I have to work with a Kalman Filter, and the project is on a...
Hello everyone! Thank you for looking at this thread.
I am trying to design a 10th order Butterworth filter using passive elements (i am using the Insertion Loss Method, and using prototype numbers). So far, I have designed a 5th order Butterworth filter, and I am planning to cascade two of...
Homework Statement
A band Pass filter is given with the following configuration, R-Resistor, C-Capacitor:
See Attatchment 1 - Circuit.jpg
https://www.physicsforums.com/attachment.php?attachmentid=16241&stc=1&d=1225999965
R1 = R2 = 10 kΩ
C1 and C2 are unknown
Cut off Frequencies...
Homework Statement
You drop a single coffee filter of mass 1.4 grams from a very tall building, and it takes 47 seconds to reach the ground. In a small fraction of that time the coffee filter reached terminal speed.
a) What was the upward force of the air resistance while the coffee filter...
It is well-known that the step-response of an ideal low-pass filter (Gain = 1 for f = 0 to F and = 0 for f = F to infinity) is non-causal, in that the output appeares before t = 0.
But what if the filter's Gain is = 1 for f = 0 to F and = e (some small non-zero value) for f = F to infinity...
Homework Statement
A linear time-invariant filter is described by the difference equation
y[n] = x[n] - x[n-2]
a) Obtain an expresson for the frequency response of this system.
b) Sketch the frequency response (magnitude and angle) as a function of frequency.
2. The attempt at a...
I have run into a problem... The language filter we have been using is out of date and it periodically does not work. I was hoping I could get some help on making a new one.
The old one:
import java.io.File;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.net.SocketAddress...
Hi PF Designers,
Wasn't too sure if this would belong in the Electrical engineering forum but here goes.
I'm designing a prototype for my thesis that will read in sensory data wirelessly to a MATLAB script. This sensory data is riddled with noise, however important data is contained in...
I am trying to make my own Reverse Osmosis water filter, and I need some help. Can someone tell me where I can find parts for it so I can make it myself instead of spending $150 on it? Thank you.
I'm having some trouble calculating the values I need for a capacitor and inductor for a passive filter. The values that I know to use are current, voltage and frequency. But I have a voltage <1 volt and a frequency of 60Hz but no current. Can someone help me figure out what value of capacitor...
What is the best way to filter out Gaussian noise from points in a data curve? (i.e. each point of the x-y-graph is displaced in y by a random amount)
A simple running mean does it, but on the other hand it also changes the shape of the underlying real curve.
Is it possible to use the...
Hi
I am working with current meter data (oceanographic) and have to filter my timeseries to remove the tidal component (frequency 12h). I have not worked with filters before and would appreciate any help.
Thanks
Hi,
I'm working with distributions of weights that are predominently "normal". The weights on the upper end of the distribution are in error and I'd like to find a method that I can use to automatically "chop" off this portion of the distribution. Based on my inexperienced inspection of these...
Hi,
Just when I thought I'd grasped the Discrete Fourier Transform properly,something comes along and messes me up ... and my books don't seem to treat it.
Say you have a square 2D image and you want to do an Ideal LowPass Filter. Well, in general, filters need to be odd-number-sized so...
I'm wanting to build a RC bandpass filter to pass only 60Hz. But I do not know what capacitors and resistors to use. Can anyone tell me what capacitor and resistors I should use?
given that x has an exponential density function ie p(x) = exp (-x) and x(n) & x(m) are statistically independent.
Now y(n) = x(n-1)+x(n)
what is the pdf (probability density function) of y(n)
I did a lab using an active low pass filter with an op amp and at the end we were instructed to remove the capacitor that was in parallel with the resistor. The result was an extremely high voltage compared to the voltage with the capacitor in the circuit. We are asked to explain what kind of...
hi guys,
i know something about math and physics and a lot about electronics and signal processing, but chemistry is the natural science that i have always been weakest about.
first, how do most cities chlorinate their water? i presume they mix in some solid or liquid chemical that has Cl as...
Homework Statement
Homework Equations
The Attempt at a Solution
Hi all, i have some doubts on how to find the impedances for active filter circuits.
Let's start with a simple low pass filter :
http://img85.imageshack.us/img85/6484/52244578oo4.th.jpg
The input impedance should be...
Homework Statement
Given a simple RC high pass filter, I need to find the value of C that will give the output as shown on a scope capture.
Input Voltage: 2.5 + 10.01cos(\omega t) (10.01V wave shifted up 2.5V)
Output Voltage: 3.46cos(\omega t - 60^\circ)
R = 5k
\omega = 2\pi 100...
Homework Statement
Q] The figure below shows a typical circuit for a low-pass filter. An AC input V_i~=~10~mV is applied at the left end and the output V_o is received at the right end. Find the output voltage as a function of \nu~(\textrm{frequency})...
hi,
May I know if we were to pass a signal into a 5th order butter worth filter, why would its magnitude decrease? Should the magnitude decrease, or it should remain the same?
thank you.
Hi, I need to construct a filter to pass 5Hz and above. I'm also using this circuit to prevent any DC signals from passing (I have a DC offset that I need to get rid of). I'm using the equation f = 1 / 2*pi*RC (in which I found after derivation).
As of right now, I have two designs:
1) Series...
Question: Prove that if any convergent filter on a space X converges to a unique limit, then X is Hausdorff.
I think the solution in my textbook is faulty. It says "Suppose X is not Hausdorff. Let Nx and Ny be the collection of all neighbourhoods of x and y, respectively. Then Nx U Ny...
in my textbook, they've said that a capacitor is used to filter an input from a full wave rectifier.. So that the output does not fluctuate (much) and hence convert an a/c current to d/c current. But, the textbook isn't clear about how this happens.
It just says that the time constant for the...
I wanted to make a negativer full bridge rectifier circuit and filter it, so that after it went past the bridge, the output voltage would be full wave but negative. Tried reversing the diodes on the actual full bridge rectifier but doesn't work.
Refer to the diagram on the left,is it...
I have some chip emi filter capacitor type. Its parameters are size 0603 , 1000pF , tollerance +/-20%. I would like to replace it by filter of another vendor, with the difference of tollerance -20/+50%.
As I'm understanding from attenuation characteristics chart, the replacement maybe even...
Hi,
I'm trying to find the transfer function to this circuit (see attached image). I put together a MATLAB script file which I will paste the code below. I found the transfer function to be...
Homework Statement
I am trying to design a passive filter for a home power conditioning device. It is for a standard 120V 60Hz outlet with a 15A fuse. I have decided to go with 'pi' or 'T' filter, but I am having trouble locating the specifications needed to choose the necessary parts.
It is...
I am trying to build the Schaffner line filter FN410 out of discrete parts. The datasheet for that part can be seen here:
http://www.schaffner.com/corporate/en/register_log.asp?language_id=12&fN=http%3A%2F%2Fwww%2Eschaffner%2Ecom%2Fcomponents%2Fen%2F%5Fpdf%2FDatasheet+FN410+e+6%2Epdf...
Hi,
I'm working on a UHV STM. Recently I opened the multigain switch to set higher gains and I also changed the bandwidth.
In the manual I read that the bandfilter is a so called 'single pole filter' and has a 6dB/Octave roll off.
Can someone help me to understand what a single pole...
Homework Statement
You drop a single coffee filter of mass 1.2 grams from a very tall building, and it takes 47 seconds to reach the ground. In a small fraction of that time the coffee filter reached terminal speed.
(a) What was the upward force of the air resistance while the coffee...
You drop a single coffee filter of mass 1.4 grams from a very tall building, and it takes 47 seconds to reach the ground. In a small fraction of that time the coffee filter reached terminal speed.
(a) What was the upward force of the air resistance while the coffee filter was falling at...
Homework Statement
I have a signal that I want to interpolate 625 times, and then decimate 12 times to get the decired result. I've read that the best way of doing this is to use a polyphase FIR filter with zero stuffing. I was planning to use steps of 5 for the interpolation, and steps of 4...
Homework Statement
I have data for an ECG and I want to filter it.
Homework Equations
The problem tells me to run the signal through a low pass filter.
I tried a single pass double pole filter (essentially the average of three averages). If we have data points A, B, C, D, E, and F...
I have a digital signal from EEG recording. I need to filter 50 Hz frequencies and 0.5 to 120 Hz, so I've tried this:
1. I designed a notch filter with Matlab.
2. I used fft to transform the signal to frecuency domain.
3. I applied the notch filter.
4. I used ifft to get back to time domain...
I want to work on a bandpass filter program, but I'd like some realistic data to try it on. There's got to be something on the web to write/test programs with.
Any suggestions?
Hello All,
I have been doing some experiments where I need to make a very short pulse to switch on and off a MOSFET I am using (IRF840) but all I have as a pulse source is a small function generator which outputs square waves fixed at 50% duty cycle.
So I had an idea to use a simple high...
given that light can be polirized at any plane while the polirized
filter has only a precise orientation, I assume there is a range of
angles of polirizzation that go though the polirized filter others are cut out.
how large is the angle selectivity of the polirized filters ?
how is this...
Homework Statement
Hey guys, quick EE question for ya.
This is the end of a signals and noise assignment and i think I've got it but I am not sure so i thought id check. Attached is the question, doing the 2nd part of 13
The part that isn't shown that we need is that the band pass is between...
Homework Statement
Show that a series LR circuit is a Low Pass filter if the output is taken across the resistor. Calculate the corner frequency, f_c, if L = 2mH and R = 10k\Omega.
Homework Equations
H(\omega)\,=\,\frac{V_0(t)}{V_i(t)}
H\left(\omega_c\right)\,=\,\frac{1}{\sqrt{2}}...