Line Frequency Noise

Hi!
I am acquiring data from a digital readout unit using AI on my PCI-6034 card (with CB-68LP).
This signal is VDC (±10mV)
Lets say the output from the digital readout unit is solid 3mV. When I display the acquired signal, I see a random noise signal varying a few mV either side of 3mV (instead of a straight line at 3mV).
What could be the cause?
How can I find out if this noise is line induced voltage noise and if yes, how can I remove it?
Do I need to use averaging/filtering?
My system is Win2000, LV-PDS 6.1 and NI-DAQ 6.9.2
Thanks!,
Gurdas
[email protected]
Gurdas Singh
PhD. Candidate | Civil Engineering | NCSU.edu

LD,
Thanks. I tried what you suggested. The resulting screen shots are attached to this post.
As in the previous case, I have used 21210 numeric channel in MAX.
There is improvement but honestly I am not clear what is happening here. The signal still looks 'noisy' although the peak to peak levels have decreased.
Q) Shouldn't I see a solid zero line?
Also, there is NO difference (for the input ranges ±10V, ±1V, ±0.1V) when I see data in my VI. I've used AI config, AI start and AI read.
Feeling somewhat lost .....
Best regards,
Gurdas
Gurdas Singh
PhD. Candidate | Civil Engineering | NCSU.edu
Attachments:
PCI6034E_21210_1V.jpg ‏68 KB
PCI6034E_21210_0.1V.jpg ‏70 KB
PCI6034E_21210_0.01V.jpg ‏72 KB

Similar Messages

High Frequency Noise from Headphones Out Jack

I have isolated the following issue to audio that is monitored via the headphones output on the back of my iMac:
I've been encountering a very high-pitched (and at times a cycling through high frequencies) noise when working with headphones to monitor audio. It's not the headphones and the problem is not limited to any single application. The noise is sometimes barely audible, and it comes and goes - but repeatedly and often. Sometimes the frequency of the noise is so high that I can imagine that those with poor or compromised hearing wouldn't even notice it. But the highest frequencies are still detectable - kind of like a faint ringing in the ears or a ringing television set that has its volume turned all the way down.
I've done everything I can imagine to troubleshoot the problem including asking a Mac genius, but nobody seems to have encountered this before. The noise can be triggered off (not masked) by any other incoming audio, but eventually it reappears. I will be editing a file, the noise will appear, and I can literally silence it for the moment by pressing a volume key or playing back a portion of audio.
Anyone else experiencing this issue? Is there a fix? I do a lot of audio engineering and this problem is very distracting. I haven't purchased any outboard gear to monitor with yet, so I don't know if I will hear this noise through an external audio interface or not. Thankfully, this noise isn't being recorded to disk. It appears to be a little monster that is haunting only the playback.

OK, It is very easy to reproduce the problem, just follow this steps:
(1) Insert any headphones to iMac.
(2) Do NOT play any iTunes or any application with sound.
(3) Now, set volume with the volume control keys on your keyboard, set it to the MAX.
(4) You can keep pressing on the increase volume key and every time you hit the key you should hear a sound.
Just as when the sound stop, you will hear a high pitch. Keep repeat step 4 and wait a while, then occasionally you will hear a high pitch sound that will last to longer than 30 seconds. The high pitch will be even easier to reproduce if you alternate before decreasing volume and increase volume by 1 level, each time, wait and you will hear the high pitch too.
This high pitch sound can be heard on external speaker plug into the headphone jacks too.
BTW, I turned OFF WIFI, Bluetooth, removed all USB devices except keyboard and mouse, adjust monitor brightness, they have no effect on the high pitch, it is still there!
I am going to call the Apple Care tomorrow. Will keep you guys posted.
Message was edited by: chienlim

Regza 40" LCD TV emits high frequency noise

A few months ago I was lucky to win this television, a 106 cm Regza HD LCD.
I was very pleased because I could never have afforded it myself, and I am very happy with its performance generally.
What I find however is that it emits a high frequency noise that triggers tinitus to my hearing. (Tinitus is a high pitched squealing noise heard by people who have damaged their ears, sometimes called ringing in the ears).
I guess my hearing is already sensitive through listening to lots of live music over the years, but I think that this noise is excessive.
I figure that a monitor this size is using a fair amount of power and that maybe the power supply could be overworking itself.
The monitor emits this noise at a consistent level even before the sound from the tv show begins.
I am interested to find out what suggestion forum users may have for reducing this background noise?
The monitor is still under warranty as it is only 6 months old.
I wanted to be prepared to discuss it with Toshiba warranty people if forum users can suggest first of all what could be causing the noise, and secondly, possible ways of addressing the issue.
Thanks petekey4

Hello Pete
As you can see this is Toshiba computer forum and I don't believe you will find many people here who want to discuss about Toshiba LCD TV.
Anyway, if the TV is new and with valid warranty the best option for you is to contact service people and let them check your new TV.

HELP! Weird "Underwater" effect when reducing high and low frequency noise.

Hi everyone.
I am in a spot of bother with Soundtrack Pro. I hooked up a reel-to-reel player's audio line out to my PowerBook's line in. Then in Soundtrack Pro, I hit record.
So everything works out fine, except...
There is some hissing in the audio file which I can easily remove with the "Reduce Noise..." feature, but there is this low "rumbling" noise in the background. When I try to remove that, the entire song sounds like it was played "underwater". I tried selecting only the low noise, goin to "Process>Set Noise Print" then reducing the noise, and the underwater effect gets worse.
I need help pronto!
Thanks

Hmmm...OK. The hiss is removed, and the underwater effect is elimanated, but how do I get rid of this annoying low rumbling? I tried looking under the Analysis tab and selecting "Power Line Hum" but it couldn't find anything. High Pass Filter and Linear Phase EQ either kill the whole bass frequencies or they make the song sound "Tinny".
Any advise?
Thanks

Strange thin line of 'noise' across all video playback

Hey, another problem I'm currently having... for no reason my mac has started displaying a flashing line of what I can only describe as 'noise', it's very thin only a few pixels high but as wide as the video playback. This happens in FCP on my viewer window and also in quicktime, not all the time but most of the time.. it also displays on other video playback software.
Any ideas? I can take a screen shot if that helps...
Thanks!

There are many people using iMacs including myself who've developed random lines of random pixels, usually confined to the current window.
The machines have also become prone to hangs/freezes when these lines appear.
It is suspected that the problem is related to overheating in some way, as it can be improved by ramping up fans speeds using smcFanControl.
Most attribute it to overheating/faulty garphics cards but logic boards might also be implicated. It's been seen on the iMacs with ATI and nVidia cards, and on Leopard/Tiger.
It seemed to appear for me after a software update (early 2008 security update I think), and while that may be coincidence, I do wonder if a bug has been introduced somewhere.
AC
Message was edited by: Alley_Cat

Does Line Static Noise Affect Infinity 2 Speed?

Hi, I've had my Infinity installed just over a week now. Since the install I noticed static noise on the line, was told it could be a problem with my phone, went and bought a cheap phone which seemed ok.
The last 2 days the hubs been disconnecting with the orange light flashing and when I plug my phone in theres loads of noise on the line.
I rang customer services as I was also getting a 42Mb download on the speed test (the technician tested it at 70), he advised my to go to speedtest.btwholesale.com follow instructions (which i did). I then get 37MB on the download. BUT, during the call I asked if the line noise affects the speed, but he said just to ignore it as I hardly use my home phone.
The technician who installed it all said it tested fine but I dont think it is. Also I know they can't guarantee download speeds but 42mb is pretty far from 76mb advertised...

Yes noise on your line will have an adverse effect on your broadband speeds. You need to report a fault. Do not mention your broadband or you will end up with the same response you have had already. Just report it as a phone fault.
Once the line is clear from noise you should notice a rise in broadband speeds.
If you run this checker it will show the two ranges which your speeds should be within.
https://www.btwholesale.com/includes/adsl/main.html

Questions - Drop Lines & Responsibility, Noise, En...

Hi,
I wonder if you could answer a few questions:
#1 Are BT/OpenReach responsible for the wire from the back of the NTE5 master socket and beyond?
I believe I am only responsible for anything from the master socket "inwards" inside my home. #151 faults have told me I am responsible for everything within the boundary of my property.
#2 Our local area is all underground cabling. The phoneline comes under the front gardens (semi-detached), and appears at the wall, middle of both houses. Small circular junction box, line off to each house. The cable from the junction to our house is 6-core white cable, looks suspiciously the same as the internal extension wiring you can buy yourself. Should this quality of cable be used externally?
#3 There is a second phone line to our home from the junction box, we have never had a second line so presume the previous owners asked for this. The line is not connected, I have removed the wall socket it went to and clipped the cable back. This 2nd line cable is a simple grey 2-core, and I have noticed that it has a break in the outer sleeve, and can see the bare metal of the enclosed cable. Would this be a free of charge visit by an Engineer to remove?
Background:
Two weeks ago, I was prompted by failing internet connection to do the quiet line test using a corded phone in the master socket. To say there was noise on the line was an understatement! Unfortunately #151 fault did a line test and reported no problems. Then warned of £130 call out charge, and asked if I wanted an Engineer out. Of course I didn't want to risk it, replacement router seemed to coincidentally arrive when the line noise had subsided.
Back to testing today, same quiet line test, still have feint noise on line. Nothing spectacular but all the same, I'd rather it resolved.
#151, same routine. Do a line test, no fault, warn of £130 charge and ask if I want an Engineer out.
Here lies the rub, I am wondering if the broken second line cable and/or the internal quality cable on their own would be sufficient for an Engineer to visit anyway, ie FREE. Can I get an answer out of #151, no I can't. The ropey answer to question #1 above from #151 leads me to believe I can't get off the call centre script of "do line test, book engineer."
I wish I was responsible for the line within my property, I could happily remove and replace the cables!
edit: coincidentally two weeks the weather was very bad, torrential rain and wind. Now it's sunny, calm but **bleep** cold. This "noise" has been on and off over the years, but hasn't caused internet issues until now.
Solved!
Go to Solution.

chadders74 wrote:
Apologies, please subsitute "Test Socket" for "Master Socket" in my original post!
After reading other posts, I am just worried about an Engineer turning up for "line noise" and there being none on the day in question, and thus being on the receiving end of a £130 bill.
edit: I am trying to ascertain if the outside cables are in fact "an issue", and will lead to a guaranteed free Engineer visit regardless of line noise.
Well if the noise is still there at the test socket, then there is an external issue somewhere. The "internal" cable used outside does not sound right. It could have water ingress causing all manner of problems.
In theory, Openreach should do what they call a "Quality Check", at the cabinet and distribution point, especially if its a repeat fault.
It could be a high resistance connection or corrosion.
Charging is a difficult issue. It all depends on how the Openreach technician closes their job. Sometime charges can be raised by mistake.
I would report it as an intermittent noisy phone problem which happens when it rains, and mention the poor state of the external DP (Distribution Point). Do not report it as broadband fault
With luck they should repace the wiring, and remove any unwanted terminations, which could be introducing noise into the line.
If the Openreach technician does do work outside, then he should make sure that this is recorded as the possible fault, and not "fault not found (FNF)" or "right when tested (RWT)".
If that is done correctly, then you should not be charged. You may like to mention it to them
There are some useful help pages here, for BT Broadband customers only, on my personal website.
BT Broadband customers - help with broadband, WiFi, networking, e-mail and phones.

Line-In Noise

I recently discovered noise coming in on my line-in while getting ready to record some audio tracks. I have no audio input devices connected although I am seeing the VU meter pulse when I have the input volume set as little as a hair more than midway in Systems Preferences> Sound> Input. I have disconnected all cables besides the power cable and this still persists. I've tried switching between line-in and the internal mic (which doesn't reproduce the same problem), adjusting the audio MIDI setup and the noise persists. The pulsing on the VU meter in the sound preference isn't steady but somewhat irregular as if there were music or dialogue or some sort of signal playing in the background. Of course this seems to be causing a low level hiss in my audio recording playback (not audible while actually recording).
Any suggestions?

something tells me you're still picking up the internal Mic... My line in (course I'm on an Imac G5) is whisper quiet when not being used...

Mic audio line makes noise during recording

I have a condenser mic and have not had any problems until now. I don't think its the mic as when I plug the headphones into the "phones" jack on my mixer, its fine. However,when I plug the headphones into the line out (headphone on the back of my IMacG5 there is static like noise when I talk into or touch the mic.
What are the possibilities?

1.) You're in a Windows forum
2.) You're in an iTunes forum when your issue doesn't sound iTunes related in the least
May want to post this in the appropriate forum.

Line level noise (hiss) in meters

Should there be a level in the audio meters even when I am not capturing ? It's around the -24 to -30 db area.
Thanks
Tony B

**** wrote:
Well lowering your input impedance should help sonically with a ribbon but...
The button on the preamp is set on "high".
The mic specs says the mic impedance is <=200 ohms
<div class="jive-quote">But what puzzles me is this:
{quote:title=yattaman wrote:}On playback, I can here a noticeable difference - there is silence between the gaps of spoken words - there is "noise" under the spoken parts. It is not room noise.{quote}
Do you have a way to use another interface?
Only this preamp. Is the trouble with the USB Codec? I think I once saw a way to bypass the USB Audio Codec used by the preamp, and instead use the Mac "line in" setting while still using the preamp. Change the settings in the Sound Preference pane and/or Audio-MIDI Setup? Also, regarding Audio-MIDI Setup, no matter what I try, cannot make the 48000 setting stay enabled in Audio-MIDI Setup on the left side. It always reverts to 44000. I saw a thread here about it a year ago, and I guess this was never solved.
As an aside Phantom Power itself will not hurt Ribbons. The issue is if pin 2 or 3 were to short to ground with Phantom Power on. I've left Phantom Power on many times with ribbons.
The Nady manual (from here: http://www.nady.com/RSM4micspg.html) says phantom power will destroy the ribbon in this mic.)
How about this:
I decrease the preamp mic gain, and increase recording level in GB. And, can you confirm how to increase the recording level in GB? :-|

Problem with huge graphic - Lines become noise

Hi there,
I have a strange problem when drawing a huge graphic. Is is a kind of line-chart. The graphic (chart) is placed to a JPanel within a JScrollPane. The size can be configured and if it exceeds a size the lines are not visible anymore, but every pixel of the line is distributed within the whole graphic. It looks like noise or a snow flurry.
The line chart is updated (re-drawn) within a certain interval. I think no manual repaint is done and it happens and sometimes later is ok again and you can see the line chart and then its gone again.
Can can't exactly tell what the "critical" size is, but the chart is actually about 3000x300 pixels big.
The strange thing is, that never happens when unsing Java 1.4.XX, it is since Java 1.5, and does not happen with smaller size (at least I think so)
The lines are "PolyLines" with several thousand edges.
The code for creating this is like:
          m_bufImage = new BufferedImage(m_nWidth, m_nHeight, BufferedImage.TYPE_INT_RGB);
          m_imageG2D = m_bufImage.createGraphics();
          m_imageG2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
          m_imageG2D.setColor(m_colBg);
          m_imageG2D.fillRect(m_nWidth, m_nHeight, m_bufImage.getWidth(), m_bufImage.getHeight());
          m_pnlChart.add(new JLabel(new ImageIcon(m_bufImage)));
Any idea?
regards

Any idea?
Yes.
m_pnlChart.add(new JLabel(new ImageIcon(m_bufImage)));
Swing may have a hard time keeping up with repainting thousands of labels.
You could abandon the components and draw the polyLines directly into an image and draw that
for each repaint. Try this:
import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.swing.*;
public class SimpleDrawing extends JPanel {
    BufferedImage image;
    Random seed = new Random();
    protected void paintComponent(Graphics g) {
         super.paintComponent(g);
         if(image == null)
             initImage();
         g.drawImage(image, 0, 0, this);
    public Dimension getPreferredSize() {
        return new Dimension(3000, 300);
    private void draw() {
        Dimension d = getPreferredSize();
        int w = d.width;
        int h = d.height;
        int r = 20;
        int cx = r/2 + seed.nextInt(w - r);
        int cy = r/2 + seed.nextInt(h - r);
        int nPoints = 3 + seed.nextInt(4);
        int[] xPoints = new int[nPoints+1];
        int[] yPoints = new int[nPoints+1];
        double theta = 0;
        double thetaInc = 2*Math.PI/nPoints;
        for(int j = 0; j <= nPoints; j++) {
            xPoints[j] = (int)(cx + r*Math.cos(theta));
            yPoints[j] = (int)(cy + r*Math.sin(theta));
            theta += thetaInc;
        Graphics2D g2 = (Graphics2D)image.getGraphics();
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setPaint(Color.black);
        g2.drawPolyline(xPoints, yPoints, nPoints+1);
        g2.dispose();
        repaint();
    private void initImage() {
        Dimension d = getPreferredSize();
        int w = d.width;
        int h = d.height;
        int type = BufferedImage.TYPE_INT_RGB;
        image = new BufferedImage(w, h, type);
        Graphics2D g2 = image.createGraphics();
        g2.setBackground(getBackground());
        g2.clearRect(0,0,w,h);
        g2.dispose();
    private void start() {
        Thread thread = new Thread(new Runnable() {
            public void run() {
                do {
                    try {
                        Thread.sleep(50);
                    } catch(InterruptedException e) {
                        System.out.println("init interrupted");
                        System.exit(1);
                } while(image == null);
                while(true) {
                    try {
                        Thread.sleep(50);
                    } catch(InterruptedException e) {
                        System.out.println("interrupted");
                        break;
                    draw();
        thread.setPriority(Thread.NORM_PRIORITY);
        thread.start();
    public static void main(String[] args) {
        final SimpleDrawing test = new SimpleDrawing();
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(new JScrollPane(test));
        f.setSize(500,400);
        f.setLocation(200,200);
        f.setVisible(true);
        test.start();
}

Line mic noise preamp USB hiss eliminate how?

Setup: Garageband 08, Tube MP ART project Series USB preamp, and a professional-grade non-powered ribbon mic. There is a dedicated booth for the mic.
The preamp gain needs to be turned way up to get an acceptable but seemingly-low recording level from the mic into GB.
So the preamp is set at +35dB gain (max is +45dB) and the optional gain booster of +20d is enabled. The preamp functions Impedance, Filter, Phantom, Limit, and Phase are disabled. (I know that Phantom power should not be used with the mic I have.) High quality shielded mic cable.
On playback, I can here a noticeable difference - there is silence between the gaps of spoken words - there is "noise" under the spoken parts. It is not room noise.
I can use Bias' SoundSoap (or play with the Noise Gate plugins I have installed) but to totally eliminate the noise, both the above effects muffle the sound and it can also sound out of phase.
How can I maintain a clear recorded voice that does not have that noticeable difference between the gaps of the spoken parts?
There's so much information out there yet I can't find an answer for non-technies.

**** wrote:
Well lowering your input impedance should help sonically with a ribbon but...
The button on the preamp is set on "high".
The mic specs says the mic impedance is <=200 ohms
<div class="jive-quote">But what puzzles me is this:
{quote:title=yattaman wrote:}On playback, I can here a noticeable difference - there is silence between the gaps of spoken words - there is "noise" under the spoken parts. It is not room noise.{quote}
Do you have a way to use another interface?
Only this preamp. Is the trouble with the USB Codec? I think I once saw a way to bypass the USB Audio Codec used by the preamp, and instead use the Mac "line in" setting while still using the preamp. Change the settings in the Sound Preference pane and/or Audio-MIDI Setup? Also, regarding Audio-MIDI Setup, no matter what I try, cannot make the 48000 setting stay enabled in Audio-MIDI Setup on the left side. It always reverts to 44000. I saw a thread here about it a year ago, and I guess this was never solved.
As an aside Phantom Power itself will not hurt Ribbons. The issue is if pin 2 or 3 were to short to ground with Phantom Power on. I've left Phantom Power on many times with ribbons.
The Nady manual (from here: http://www.nady.com/RSM4micspg.html) says phantom power will destroy the ribbon in this mic.)
How about this:
I decrease the preamp mic gain, and increase recording level in GB. And, can you confirm how to increase the recording level in GB? :-|

MacBook: line out noise when sleep mode

Hi,
I have my MacBook hooked up to my hi-fi system with a line-out to cinch cable. whenever the macbook enters sleep mode or is turned off, a very loud noise is generated, as if I would have plugged the cable right off the computer.
Is there any way to circumvent this annoying noise? I fear that the permanent explosion-like-sound might damage my speakers.
Thank you!
Mark

thenk you for the answers so far. What I am doing at the moment is not perfect, because it does not work when I forget one step:
-I activate sleep mode only manually now
-before, I switch off the receiver (otherwise, the loud "pop" noise is still there)
I will try with a better quality-cable, but I can only imagine the sound quality of the loud "pop"-noise to be 'crystal-clear' with a better transmission (optical cable doesn't work on my system)
Thank you,
Mark

Mid-2009 13" MacBook Pro emits high-frequency noise when engaged for sound

Recently I noticed that when the MacBook Pro activates the sound output device for built-in speakers, a high-pitched whine or noise begins, and does not stop until the card deactivates again.
The sound is not proportional to brightness, hard drive activity, CPU load, or anything else I've been able to try, except for sound output. When I plug in headphones it cuts out when the sound transfers to the headphones (it's on the same slight delay that the sound change is on). This MBP leads a relatively tame life, although it does travel sometimes. I can't figure out what would have started this sound, but I noticed it start within the last month, and I have confirmed that others hear it in the same quiet environment as I hear it in.

Give it two or three more weeks to get below 80% and stay there, then take it to an Apple Store for testing. As long as it's still above 80%, it's going to be considered "within spec," so make sure it's below 80% when you take it in.

Line out noise

Whenever I hook my iMac up to my stereo I get a loud annoying buzz coming from my stereo speakers. I'm using a good quality cable and have tried different ones. My stereo sounds great with everything else I hook up to it. I'm just using a 1/8" to RCA cable (Belkin), same thing I've used with many other things including my iPod and nothing else makes this noise.
This also happened with my first iMac G5 (i bought it right before the iSight version came out so I got to return it for the new model) and I cannot figure out for the life of me what's happening and I'm really hoping I don't have to take it in for service since that's an hour drive (for the nearest Apple store anyway). If anyone could give me some help on this I would greatly appreciate it!
- Dan
iMac G5 iSight Mac OS X (10.4.4)

Dan, If your headphones work, the plug could be ruled out. One thing to check is wiggling the headphone plug as it's inserted in the iMac jack. If there is no buzz then begin to suspect the Y adapter; either at the 3.5mm end or the RCA ends. At the Y connection, disconnect first one RCA end from the extension cable and then try the other one. If the channel that is connected has no buzz, then either the other end is the culprit or maybe it's the Y adapter on the 3.5mm end. If you have access to another Y adapter try that one.
Troubleshooting cables is tricky, but if like you say, the headphones work, ie; no buzz, then the Mac is probably fine.
I just reread your reply and I'm not sure you understood what I meant when I said to try your headphones. Your reply doesn't make it clear if you tried your phones directly in the iMac or are you plugging your phones into your stereo headphone jack. Mind you, that might be something else you could try. With the iMac connected to the stereo, plug the phones into the stereo and see if the buzz goes away; ie, are you able to hear the buzz through the phones?
Good luck - this can be figured out.
Paul

Line Frequency Noise

Similar Messages

Maybe you are looking for