High-pass filter question

Hi all

I have a question about the high pass filtering in LabVIEW simply based on observation, have never been taught directly on the filters.

A signal of high pass filtering, with a Butterworth IIR filter (2nd order) for example, around the time Fortran, = 0 there is a transition from a high-intensity "false" at a rate expected, as the officer although this is achieved thanks to a program as I have nothing else to hand at the moment.  In order to minimize the importance, for the rest of the filtered signal, you can increase the sampling time, change the filter settings or even add time of additional levy in order to truncate it.

Is there an established method to get around this?  The reason why I ask is because I'm trying to distinguish accurately Laminar and turbulent parts of a signal of speed but on time = 0, in a completely laminar signal, our method returns false positives for the presence of turbulent structures.  I assume that this will always be the case, but it is better to ask first and concluded later!

Thank you.

All filters have a transient initial.  You must wait until it has settled on or try to compensate for the spike in some way.  Transitional measure also depends on the input (including any noise) signal, it is generally not possible to compensate exactly.

Lynn

Tags: NI Software

Similar Questions

  • 3 color separation - viewable problem with high-pass filter help

    Hello and thanks in advance for your time and help!

    I fix a color image created with color separation negatives, 3 images black and whites (captured on photographs) combined in the RGB layers to create a color image. The original negatives have been very badly damaged, so the alignment and the correction was quite complicated.

    I'm finally get closer, but there is still a lot of blotches that I have a problem fixed, where each of the channels have been under/over exposed, creating stained yellow or green, etc.

    I tried to use the high-pass filter and discovered, he shows me exactly my problems - of the high-pass filter usually makes all grayscale, however I see blue exactly where I need to make a correction - see screenshot.

    How can I selectively change this field! Other ideas for filters or way of singling out this broken capillaries to make adjustments? Editing is really not help color balance, I tried also to hue/saturation, but I am not able to isolate problem areas.

    Screen Shot 2016-04-25 at 1.40.21 PM.png

    < < second Image deleted by Mod, in accordance with the guidelines of forums > > >

    If a channel in the filtered image is useful and then load it and use it as a layer mask (and change with the curves and the additional filters needed).

  • How to apply the high pass filter on Smart Object

    Hi all

    I'm trying to apply a high-pass filter on a dynamic object. Is this possible? -When I select the high-pass filter, choose my RADIUS and click OK, it applied the results to the entire layer. I expect the image below...

    Screen Shot 2015-07-25 at 11.47.30 AM.png

    ... but I don't get it.

    Screen Shot 2015-07-25 at 11.49.52 AM.png

    I hope that makes sense, because I'm having a hard time to explain. Basically, I do not see my image (as in the first photo above), I see the high image passed instead.

    Jeff

    Be aware that happens if you hide the effect of the dynamic object, you will have just the layer mode to overlay, which isn't want you want if you will exacerbate. You want the mask on the layer itself.

  • CAN´t set up a low-pass filter properly

    Hello everyone,

    First of all, sorry for my bad English!

    Before asking this question, I ve tried to seek answers in the forum and couldn t find a useful for my case.

    I m new to LabView and I m test for the analysis of the signals.  I m using an Agilent signal generator and a NI USB 4431 to acquire the signal.

    OK, here´s my problem. I can´t use of a Butterworth or a Chebyshev filter (or any type) to create a low-pass filter filter. I Don t know if I didn t understand it s parameters correctly or if I m set something wrong. When I use the ExpressVI filter, I get the result I want to, but when I use the function of Butterworth, it doesn´t work.

    Can someone help me please?

    I m sending the project I ve designed, so that you guys can see what I ve done.

    Here some explanations: the "puro" labeled graph is the pure I m signal generation.

    The labeled graph "Spec. PURO"is the power spectrum of the signal current

    The graph "filtrado" is the signal after going through a low pass filter in the express VI (which works fine) and the graphic "filtrado Spec" is the power of it s spectrum.

    In the upper part of the loop is the function of Butterworth filter. I ve wired the pure data to its input signal and expect one out everything as the express VI creates, but he's not even conspire anything in the chart.

    The windowed FIR filter VI generates the error-20023, which constitutes a violation of Nyquist. Because this VI returns only an error code and not the cluster of standard error, you must connect explicitly an indicator or manipulation to the error output.

    The cause is that you have the frequency to zero.  OR use a somewhat confusing nomenclature for the inputs of the filter frequency screw these detailed help says:

    high cut-off frequency: fh is the high frequency in Hz. The default value is 0.45 Hz. The VI ignores this parameter when the type of filter (low pass) 0 or 1 (high-pass). When the filter type is 2 (bandpass) or 3 (Bandstop), high cut-off frequency: fh must be superior to low cut-off frequency: fl and respect theNyquist criterion.

    Thus, for the high pass filters and both low-pass cut-off frequency is the value wired to low cut-off frequency: fl. I regularly get this error. When I get strange results, I read the help and fix it. As soon as I wired 5000 to fl, the output looks like this:

    The differences in amplitude and transitory initial are likely due to different specifications of filter.

    The way I start it is to convert the flag to a Pure control, do default to the current value, and then put all the DAQmx screws in schema structures disable. I have disable placing the pure control (or a copy of it) in a case to permit the schema structure which has the DAQmx Read. Since you have only one data channel I added the Index table to get a unique waveform of the table. Then all the code signal analysis works.

    Lynn

  • Low-pass filter before the NI 5112

    Hello

    I currently use a 5112 AND measure the signal of an infrared detector in an experience of ring to the bottom of the cavity. Below are three examples of signals. My main question is how I can implement a low pass filter, passive preference, before my 5112 OR undistorted extremely my signal due to the impedance mismatch. Now a few details:

    Some unique captures for each wavelength are shown in color, while average 25 pulses appears offset in black. The range and offset are chosen in each case in order to minimize the noise of "scanning". In the case of 3.14um, the noise that you see is about 25 times noise from scanning. They were taken without the limitation of BW and 100 ms/s mode.

    The detector (Vigo MIPDC-F-10) has a bandwidth of 10 MHz. I think it is a low impedance and is intended to be harnessed with 50Ohms, however its documentation confuses me, and I'm waiting for a definitive answer from the provider. 2.4 part of the manual says 50Ohms recommended, however the Datasheet and our map calibration (below) seem to suggest 1 MOhm is recommended!

    There are a few strange oscillations with a period of almost 180ns in our signal that I thought were due to the impedance mismatch existed in the system before I changed it:

    -Detector

    -1 metre 50 Ohm SMC Cable BNC (RG-174)

    -Inline BNC connector

    -meter 5, 75 Ohm BNC to BNC cable

    -Digitizer, DC, no BW limit, 100 ms/s, 1MOhm | 30pF

    When I saw this configuration, I knew something wasn't right and I even he modeled in LTSpice and he showed the same period of oscillations. But now, the Setup is:

    -Detector

    -1 metre 50 Ohm SMC Cable BNC (RG-174)

    -BW digitizer, DC, limit, 100 ms/s, 50 Ohm

    And we still have oscillations, even if the period seems to have changed to 320ns all about. These oscillations, which remain are 99%, probably due to our drop-down ring cavity experiment, however if anyone has recommendations on possible causes or ways I can confirm it is not because of my chain of detection they would be more than welcome!

    Now, the main question. Between the 50 Ohm 1 meter cable and the scanner I would insert a low pass filter. The BW limit has helped reduce the noise, but it can certainly still be further reduced without any lose to our signal. That's because we cut the beginning of the signal and then measure just the the decay time, which is relatively long and smooth (1 to 2 times 1/e US). Thus, in the future I may even want to try to eliminate the oscillations 320ns, but I'm afraid that this much filtering will distort the signal too. Therefore, for the immediate future I'm just looking to 'replace' the filter BW 20 MHz, with something like 1 or 5 MHz.

    Of course, I would disable the BW limit on the digitizer to avoid additional confusion, but nevertheless, I'm not sure how to approach the problem. Usually I do a lot of research and try different solutions. However, I don't have access to all components to this work, so everything should be ordered, and I don't have a lot of time to experiment. Ferrites seem like a possible solution, however not sure how effective they are at this low frequency or the way they work with coaxial cables. I know that the filter passes low RC base, but the 50Ohms (or 1MOhm | 30 pF if I change it) seem to make it impossible. I guess an op-amp based one might work, however the large input impedance is the impedance of coaxial cable... etc...

    All of the recommendations of the technique or red resources wort would be welcome. Thanks for your time.

    A possible way to separate your artifacts electric and the cavity is relatively simple.  You take the data at three wavelengths.  For each of them, make a simple exponential decay (for example exponential Fit.vi) adjustment to your data, then subtract this signal.  You should have something that oscillates on an average.  Compare the residual signals for all three wavelengths, either visually or with something like a power spectrum.  Anything in the three is probably the electronic (and you could possibly model and subtract it rather than trying to eliminate it).  This could break if the rise time of the signals are different, because that will include elements of different frequency.

    I am not convinced that you need to filter your signal before taking data.  As you said, any filter will distort your final signal.  My preference would be to take the raw signal and apply a filtering in the analysis.  LabVIEW has a rich filter, so you can experiment later.  If you apply a filter before the digitization of data, you take you will never receive data.  However, if you know that your data has no component of your proposed cut filter frequency, you should be good.  An analysis of the power on your current spectrum should tell you this.  Be careful.  Your form of rise time may have information you want later.  If you filter, you will probably slow it down.

    Good luck!  Let us know if you need more information.

  • decimation (decimation.vi there a pass filter down?)

    Hello

    I have a question about the decimation (decimation (continuous) .vi) function in labview. Has a low pass filter to take care of the aliasing, if so it's a zero-phase filter. Basically, I'm looking for something that can decimate 20 kHz signals sampled at 5 kHz.

    Thank you

    Kitenge

    Depends on your version of LabVIEW and installed toolboxes.

    The Digital Filter Design Toolkit has a decimation VI which includes an AA LP filter.  Open the help of LabVIEW and search "decimation" and "filter" to see what tools are available.

  • I need a 50 Hz low pass filter for a 6 X 6 matrix

    I want my plate strength of the signals at 50 Hz to low-pass filter. I don't know how to apply a filter with my data types?

    Any help would be appreciated.

    See attached file

    I do not attach controls or subvi

    Thanks in advance

    Index on the channels you want filtered and run through 6 different copies of the VI filter.  You might be able to make the reentrant filters.  If so, make sure that all of the subVIs are reentrant also.  If your data acquisition is not continuous, look out for the transient filter.

    Although your speed needs are not too high, I move all the signal processing (zero, calibration, filter,...) and show the loop of consumer and have only the acquisition of raw data in the loop of the producer. If the treatment and the display can slow things down in your current configuration, you may eventually lose data.  With treatment in the consumer, the display or recording might be delayed, but you won't lose data.

    Lynn

  • 6 dB/octave high-pass Butterworth problem

    Hello!

    I want to do the pre-emphasis filter. I know that some specifications:

    First-order Butterworth, high pass cutoff frequency of 1200Hz, 6 dB per octave. I know how to use Butterworth filter.vi, but don t know how to apply my specifications. I Don t have Digital Filter Design toolkit. Can it be done without this kit?

    I checked finder help and examples, but he didn t give me a hint.

    I have LabVIEW 2013

    6 dB per octave, multiplied by the number of poles or to the order of the filter is the attenuation of a Butterworth filter. If you need a 1st order filter.

    Use the Filter.vi of Butterworth of the Signal Processing > range of filters. Set the order of 1. Set the type to pass.  The value low cut-off frequency: fl 1200 Hz.  Note that you set the frequency of low cuttof, not the high-frequency cut-off as you would expect. Read the detailed help for the confusing details.

    Lynn

  • Loss of information on the edges of the sample of low-pass filter

    Hello

    I use a low-pass filter elliptical command to address 6 to remove trend of signal in a measure of the pressure of data sampled before, however given that the program must deal with and calculate an index in a given period of time, I can't filter and store then the data for the calculation later.

    The size of the sampe is this 1250 or 10secs data with sampling frequency value is 125 samples/s.

    In the effort to eliminate the distortion of the filtered signal, I use a technique described for tag/add a start and a value final ampitude on the beginning and end of the sample of the same length (1250), I have also run the data in the order opposite to eliminate phase effects.

    However I want to say is still a slight distortion that can be seen in the start menu of the sample; first of all, here with the loss of amplitude, but more often it's worse than that and distortion occurs at the end of time to time.

    I have some experience of the DSP (but since 20 years ago!) and remembers Windowing may be a way, but I still think that the filter should not be so difficult to implement more I don't want to lose any information amplitude.

    Any help would be appreciated.

    See you soon,.

    Kevyn

    johnsold wrote:

    ..., you may need to use different techniqoes that are not in the information stored on the previous behavior of the signal.

    Lynn

    In some cases special where information that happened before all data you have is implicit, but data yo u have, you can go out with reflecting data about initial/final data set and then run the data through the filter first forward, then backward. After that mix data accompanying your data "pretend" and just look at the part that iss associated with the actuall data set.

    Ben

  • low pass filter in labview 7.1

    Hi all

    I would like to ask about the low pass filter.

    Is it possible to make a simple low-pass filter without any supplement on Labview 7.1.

    We strive to connect a micro-switch in a DAQmx device, but the thing is, because the switch is somehow Earth-connected to an engine step by step, each time the engine is running, it will have peaks and spikes were interpreted as logic 1 in the labview. Since we have no treatment signal Add ons in the labview, we try to do it ourselves.

    Thank you

    Although suggestions are significant

    But the solution has not been reached. So actually, we tried to change the analog to digital input in our DAQ hardware. I hope that the - top-of-10V-spike not to spoil our DAQ hardware. And it turns out OK. In the digital input, spikes has appeard not even once, and we think it does.

    @ t06afre: thanks for the material made up the suggestion, but since it is a testbox.foobar.com that we, his isn't going to be easy to put in engines and unlikely capacitors supposed to do. The cable twisted pair is not a bad idea though.

    We thought that the software solution filter would be the best (less time necessary and less messy) but is not as we have not thought of material assistance (R - C circuit, duuh) filter.

    And on the 'minimum pulse duration' setting, is not only applicable for some DAQ hardware? CMIIW

  • IMAQ Low pass filter failed with invalid image border.

    Hi Expert,

    I'm trying to use the imaqLowPass function. I expect that the input image would have been handled by the low pass filter.

    But it is a runtime error showed 'invalid image border.

    Can someone tell me what is happening?

    Problem solved.

    I add a border to the image.

    He must take care of the size of the border and the size of the filter.

  • all design pages suddenly have an orange for them cast as a pass filter above all. Preview mode seems to not be affected. Put in quotes in some texts and Bam! every thing is orange.

    All design pages suddenly have an orange for them cast as a pass filter above all. Preview mode seems to not be affected. Put in quotes in some texts and Bam! every thing is orange. What is this and how do I get out of it.

    Go to the menu "show/hide grid Overlay.

  • Lack of High-Low Pass filter/effect

    The high-low pass audio filter, Bass & treble and others are missing in my adobe after effects cs6. where are they? How can I get them?

    Reinstall the program. Do it with sufficient privileges to user and file permissions. Also to disable security tools. Even when running the program.

    Mylenium

  • How to get data not filtered as o/p of the low-pass filter Group

    Hello

    IM new to Labview and exploring it.

    IM implementation of a system in which I need to use a LPF and a series of filter pass band.

    The filtered o/p of the LPF is as I / p for 1 GMP...

    Later, the o/p UNFILTERED 1st BPF is as I / p for 2nd GMP.

    The problem im facing is: I do not see any box in treatment that gives the data filtered or unfiltered together in the time domain of the signal.

    Could you please help me with this asap... desperately need your help.

    Thank you

    PSADAP

    There is not direct the tool to do this, but there is a solution to your needs.

    Say that if you use a LPF (with cutoff frequency, say 50 Hz), now to get blocked (UNFILTERED in your terminology) signal, set a HPF (with cutoff frequency of 50 Hz).

    See the block diagram

  • Filter question of hosted service - seems to not work

    I have a configured filter and most of the time it seems to work correctly.  The goal was to create a filter TLD of sorts, but some still get through.  Read on.

    In our environment, we care only about 6 TLDS (COM, NET, ORG, GOV, US and CA).  Due to this luxury hotel, it is ideal for simply deleting all other areas.  I created a filter where the "from" field "does not contain" these 6 words (in a dictionary) and it works... for the most part.  Some still go and sit in our junk mail box.  Of course, an email like "[email protected]" that makes grace because the letters 'com' is in the word 'complete' and who is eligible to pass the filter.  However, an email with a 'to' of '[email protected]' is sitting in our junk mail box.  Why it has not been deleted?  (See below... I removed the field)

    From: "AIGDirect.
    TO:
    Object: $13,91 buy term life insurance of $250,000
    Date: Monday, may 18, 2015 18:12:20-0700
    Message-ID:

    Even the header information (RAW MODE) containing all the references to my dictionary.

    Unfortunately not. It is based on the search criteria.

    In this case "does not contain".

    It does not use the "." using anything else that ends with right now.

    But we are also on a new version 8.1 on hosted, so there must be a few things to fix.

    One thing I ask is the option for "ends not by.

Maybe you are looking for

  • Malfunction/M40 - 236 card reader problem

    Hello, we bought 2 m40 - 236 s, and both have the same problem: we put 'em out of the box and when an sd card is inserted in the card slot reader two computers laptops 'die '. Windows does not respond, led does not blink, cursor moves, but nothing wo

  • TPC - MatchRegExpEfficient is a missing file of VI or C

    Hello I'm creating a whole involved system that includes a touch screen (2106 t). I need 2 .exe for display. One for PC and one for the touch screen. Code would be exactly the same. So after having developed the software for the PC, I moved a VI in d

  • I can not reset my work going on in hotmail.

    I can not reset my work going on in hotmail.

  • Mounted the case for POWERSHOT SX50HS

    Hello -What someone has a suggestion for a case for my camera.  Amazon has an Everready case it seems to be described as a product of inner quality. Canon has one on the site of tneir as well. Thank you guys!

  • Is a person having problems with Morph Cut

    I have published an interview of 2 cameras multicam sequence and then created a new sequence to cut change the interview, dropping the Multicam sequence in this new sequence a video track, by cutting out the stuff I want not etc. Then I'm going to ap