Different frequencies of signalexpress with oscilloscope

Hello

I'm new to the signal processing. I am facing some difficulties to measure the signal of a sensor of acoustic emission for my project. I use the PXI-6115 module with 1042 q and terminal block is TB2708. I used AI0 and AI1 for main signal and trigger respectively. I acquired the signal of 6115 in SignalExpress (v3.0) and convert to linear spectrum (Hanning window) and conversion of RMS with RMS on average 200. Same parameters are used in the oscilloscope (LeCroy LC564DL) too. I plugged the two signals of oscilloscope as well as for comparison. I saved data from the spectrum of SignalExpress and oscilloscope and plotted. You can see the graph as an attachment. It's totally different. Why is it so?

And one more thing, that is if I disconnect my connector NI DAQ system, spectrum in oscilloscope changed in amplitude at a certain frequency and vice versa.

Thank you in advance.

Myo

My apologies for the late reply. I've been sick for a few days.

I generated an amplitude 1V (2V peak-to-peak), 100 kHz, 10MS/s 20ksample sine wave to help to create an analog Signal.  I treated it with the power spectrum using 200 linear medium with RMS algorithm.  Value at 100 kHz - 3dB, as expected and as it should.

However, at a given time in the process, forced SignalExpress my frequency of 100 kHz to 50 kHz (probably due to a shift of frequency and the number of points).  This would result in what you see.  Check your project to see if this has happened to you.  If so, you would get - 350dB to 100 kHz (essentially a pure signal noise floor) and - 3 dB to 50 kHz.

Tags: NI Products

Similar Questions

  • Simultaneous release of digital waveform at different frequencies - cDAQ-9174 with two 9477 maps error-50103

    Hello

    I'm working on a project that requires two outputs digital signals at different frequencies. Frequency of the phase 1 is about 1 kHz and is modulated on and off to a pace that will change during the execution of the program. Wave 2 passes from 1 kHz to about 6 kHz while needing to be pretty accurate to the tenth of a Hertz.

    Initially, I tried to manage the simultaneous output of signals at different frequencies using a single task on a single 9477 daqmx in a cdaq-9174 chassis. As far as I know, the best way to get a specific frequency in a waveform output is to set the sampling frequency up to 2 times the frequency of the wave that is generated and generate a waveform that is given to each clock cycle. This works very well when it comes to a gesture, but I was unable to get the frequency of the modulated wave (wave 1) remains constant when the frequency of wave 2 modified or vice versa.

    I have a few other modules lying around (another 9477, 9403 and 9476) and I thought I would try another task running on a separate module. I find myself receive error-50103 message if I add these modules to my cdaq chassis and run one of the waveforms of a task set to run on the add-on. Is there a way to bypass this error? I guess it would cause by running two digital output on the cdaq-9174 tasks at the same time, but it seems to me that this wouldn't be a problem with an additional module.

    How can I have two outputs digital signals, running at the same time, maintaining their independent frequency frequency of the clock of the other sampling rate changes. In addition, because the wave 1 is enabled and disabled at a defined frequency, I use it to set the number of samples to write when you write a range of waveforms in the module (when generating these two waveforms on the same module).

    I'm sorry if the explanation was difficult to understand. I've attached an example of error 50103 lifting. This isn't really a part of my project as a whole, but it is the easiest way to reproduce the error.

    Thank you

    Hi awol.

    I have a follow up for you. You encounter the error because the cDAQ chassis has only a timing engine of. You will not be able to perform simultaneous tasks of the call by the hardware. Please see the following knowledge base: http://digital.ni.com/public.nsf/allkb/5E0B829E50ADE1BC86257AC50062B2D2

    Mike

  • How to structure the DMA buffer for SMU 6341 DAQ card for analog output with different frequencies on each channel

    I use the outgoing/incoming analog DDK with the DAQ 6341 SMU map.

    The examples, for example aoex5, show a single timer (method outTimerHelper::loadUI), but the example shows the DMA loaded with same size of vector data.

    There is a comment in the outTimerHelper:call rogramUpdateCount, which implies that memory sizes different pad per channel can be used.

    (the comment is: switching between the sizes of the various buffers is not used)

    Nobody knows what should be the format the DMA buffer for data from multiple channels with different frequencies?

    For example, we want a0 with a sinusoid at 1 kHz and a1 with a sine wave of 1.5 Khz.  What looks like the DMA buffer?

    With the same frequency for each channel, the data are interleaved, for example (ao0 #0, ao1 #0; ao0 ao1 #1, #1,...), but when the frequencies for each channel is different, what the stamp looks like?

    Hello Kenstern,

    Data are always intertwined since each card has only a single timing for each subsystem engine.

    To AO, you must specify the number of samples that will be released to the AO. You also specify the number of channels. Because he didn't is that a single engine timing for AO, each AO will be channel will be updated at the same time to update clock tick. Data will be interlaced exactly as shown in the example because each channel AO needs output at each tick of the clock to update. The data itself can change depending on the frequency you want to copy.

    kenstern wrote:

    For example, we want a0 with a sinusoid at 1 kHz and a1 with a sine wave of 1.5 Khz.  What looks like the DMA buffer?

    With the same frequency for each channel, the data are interleaved, for example (ao0 #0, ao1 #0; ao0 ao1 #1, #1,...), but when the frequencies for each channel is different, what the stamp looks like?

    In your example, you must come with an update rate that works for the two waveforms (sine waves of 1 and 1.5 KHz). To get a good representation of a sine wave, you need to update more than 10 x faster than your fastest frequency... I would recommend x 100 if possible.

    Update frequency: 150 KHz

    Channels: 2

    Then create you stamps that include complete cycles of each wave you want to produce based on the frequency of update. These buffers must also be of the same size.

    Buffer 1: Contains data for the sine wave of 1 KHz, 300 points 2 cycles of sine wave

    Buffer 2: Contains data for the sine wave of 1.5 KHz, 300 points, 3 cycles of sine wave

    You can Interleave them as before. When the data are performed through the ADC, they are out different sine waves, even if the AO channels are updated at the same speed.

  • Generating analog output signals 4 with different frequencies

    Hi all

    I was trying to say to generate 4 different signals at different frequencies

    1. first waveform is a sine wave with 5000 Hz,

    2. other with 8000Hz,

    3. third, one is a square with 25 Hz waveform and

    4. fourth one with triangular waveform 50 Hz

    all waveforms must be generated simultanoeusly.

    I tried to generate with the task unique analog output and sample clock (clock rate is 100000). Cross in scope that I see only 5000 and 8000 Hz we generated correctly and the rest two waveforms show the incorrect frequency.

    I guess that's due to the frequency of high clock to sample for more low frequencies for ex 25 Hz and 50 Hz. If I reduce the clock rate to get the lower frequencies properly so I can't generate frequencies higher correctly. (there's a clsh between frequencies and the clock frequency)

    Is it possible to use DAQ board master sample clock and its magnitude downward revision (everywhere where it is necessary for each waveform separately) to generate all the signals at different frequencies at the same time in a single task?


  • Several channels with different frequencies

    Hello

    I use card NI USB-6221.

    The C API using, I need to generate 6 digital output channels, with frequencies of diffrenet and Heavy duty.

    To be more precise, the 2 are totally identical, but I need them to be reversed, and the other 4 are similar to another, but should be shifted in time (I.e. There is a delay between each of the channels).

    I used the 2 channels of CO that the USB-6221 takes charge for the first two signals, and it works very well (the two signals are synchronized and are reversed).

    Now I need an additional 4 channels for the other vague square.

    I saw an articale NOR by JohnP web site with the title:

    Generate multiple channels of digital output with different frequencies and Heavy Duty

    The following example shows how to create and generate a digital with the non-regeneration wave form so that you can change the frequency and the duty cycle on the fly with the M Series DAQ hardware X.  The example uses output digital rather than counters to achieve this, so if you need more output than the available counters, it would be a good option (Note: on the materials of the M series an external sample clock must be provided, this may be caused by one of the counters if you want).

    that seems to be exactly what I need, but the examples are for LabView which I did not.

    Can someone explain how to do this with the C functions?

    Best regards

    Danny.

    Hey Danny,

    The important thing to note is that you can clock of arbitrary digital waveform (up to 1 MHz on the 6221).  The real data acquisition programming is pretty easy once you have the waveform.  My Example LV used LabVIEW Base generating function VIand then converted to a digital waveform to generate the signal from each channel.

    The functions of LV helped tremendously with to achieve the waveforms to be updated on the fly (the basic function generator keeps track of phase for you).

    If you do not need to be updated on the fly, then the construction of the waveform in C should not be too bad.  For example:

    P0.0 [1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0] * 1

    P0.1 [0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 0 0 0 0] * 2

    P0.2 [0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1] * 4

    P0.3 [1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1] * 8

    [9 9 9 9 9 3 3 3 3 3 6 6 6 6 6 12 12 12 12 12]

    The table above U8 would give you 4 output waveform of 50% duty cycle at Fs/20, shifted 90 degrees to eachother.  The lines would be p0.0 by p0.3 (the bit rate of the U8 corresponds to what line goes high).

    Best regards

  • Same result for different frequencies?

    Hi all

    I'm new to labview and the communication kit, so I'm trying to test the examples.

    When the example of 'Rx Continuous Sync or Async' opening and it works I get the same output on the "power spectrum".
    i'm checking different frequencies in the range of 1.2 GHz to 6 GHz.

    How is it possible then that there is nothing transmitted? -> checking with the android application for wifi channels (channels 1 to 8 are used, all others are not...) and yet labview gives me the same result... (attached file = 2 GHz, the other is a comparison of the 5 GHz, 2,412 GHz and 2,484 GHz)

    material:

    NEITHER USRP N210 (rev 4)
    CBX 1200-6000 MHz Rx/Tx (40 MHz)
    Antenna VERT900

    connecting via gigabit

    PC: W7 64 bit, i7-2600 to 3.4 GHz, 4 GB RAM

    Thanks in advance

    Hey insiderbe,

    I did some research on the Ettus forum and found the following:
    https://lists.gnu.org/archive/HTML/discuss-gnuradio/2010-08/msg00237.html
    https://www.Ruby-Forum.com/topic/214890

    I suspect that the IPS you see on 0Hz is the DC offset that is introduced to the ADC of the USRP N210. We can confirm this by removing air and closing the RX. If the tip is still there, it's a feature of the analog input circuit.

    Brian of Ettus recommends tuning your frequency slightly out of your signal of interest and using a high pass filter to remove DC offset. I recommend looking at the second link for more information.

    With respect to obtaining the value of art through many different frequencies, I think that it is a property of the antenna used. The VERT900 is valid from 824-960 MHz and 1710-1990 MHz. can you listen to one of these groups and test your power, even if you have a known signal? You have another USRP generator or a function to generate a known signal?

    https://www.ettus.com/product/details/VERT900

    My last concern use the N210 with the CBX in LabVIEW Communications. According to the Readme, it's an unsupported hardware configuration, which means that R & D has not tested the configuration, and we do not know how the configuration will occur.

    http://download.NI.com/support/softlib//RF/NI%20USRP/15.0/niUSRP_readme.html

    Thank you for this post!

    Kind regards

  • PCI, I / AO at a different frequency

    Hello

    As a newbie, I met a problem when I tried at the entrance and the analog output signal at a different frequency.

    I followed PID-control - Multichannel .vi to build a control program, so input/output can be synchronized. However, the project requires that the frequency of I be tenfold of the AO. I could re-write the while loop to make the output value constant for 9 of 10 cycles. However, in my view, it is simplest way to do.

    Anyone provide an example?

    Thank you in advance.

    Sincerely yours

    Ming

    lmuri wrote:

    Hello

    As a newbie, I met a problem when I tried at the entrance and the analog output signal at a different frequency.

    I followed PID-control - Multichannel .vi to build a control program, so input/output can be synchronized. However, the project requires that the frequency of I be tenfold of the AO. I could re-write the while loop to make the output value constant for 9 of 10 cycles. However, in my view, it is simplest way to do.

    Anyone provide an example?

    Thank you in advance.

    Sincerely yours

    Ming

    Hello Ming!

    Please use the Forums of NOR. You'll be happy to know DAQmx allows what I/O tasks such as these to be not run not only at the same time, but at different rates.

    The problem with the solution that you have imagined is that this implementation will remove the delegation of tasks to the hardware level, and your program would become software-driven; This becomes a problem when you perform tasks of acquiring data at very high speeds as it becomes limited to the speed of your operating system (OS).

    You can coordinate your tasks to operate synchronously and perform the output and the acquisition at different rates by creating a maintask. This means generally that you configure a task by DAQmx that keeps a clock frequency and you create tasks that use this clock frequency, or a division thereof, to exploit to their own individual frequency. This facilitated not only the execution of DAQmx tasks synchronous but also provide a material entirely focused on the solution of performance maximimse.

    Thanks to LabVIEW, if you go to help > examples find to open the Finder of example of OR. If you are browsing material input and output > DAQmx > synchronization > multifunction > Multi - multifunction - Synch Dig read write with Counter.vi, you will find an example of how to set up a counter as a master of the task to control the operation of operation both a reading and writing . (This example shows a digital but implementation may be easily replaced by analog).

    By setting the meter to the maximum frequency rate that you will require for your task (in this case, the speed at which you want to copy values) and apply it to the output of the SampleClocktask, you will drive the clock output task with the counter as the clock source. You can then use the meter as the source of the SampleClock for the task of entry, however to set the rate at any division of the driving frequency. In the case of your example, you can set the bit rate to 0.1 times the frequency counter to acquire a 10th of the rate.

    If you want to acquire at the same rate, but only to retrieve values on the 10th of the speed, this same solution can be configured to produce instead a trigger to return an acquisition in the buffer. With a master synchronizing the task, the possibilities are endless!

    I hope you find it useful, and if you need a precision more do not hesitate to let me know. Have fun with your DAQ!

  • Why you do not have your products with different colors? compatible with the colors of the iPhone or the iPad? Example: Gold Earpods, silver, BLACK and Rose Gold.

    Why you do not have your products with different colors? compatible with the colors of the iPhone or the iPad? Example: Gold Earpods, silver, BLACK and Rose Gold.

    You say Apple your wishes on the link below.

    http://www.Apple.com/feedback/

  • I want to buy an iBook. There are 2 different books with the same name, author, and the book cover. They are different number of pages with different prices. Specifically, all the light that we do not see. " How do you know that we purchase?

    I want to buy an iBook. There are 2 different books with the same name, author, and the book cover. They are different number of pages with different prices. Specifically, all the light that we do not see. " How do you know that we purchase?

    I would get one that has 4700 comments already.

  • Generate 2 Trains of pulses with different frequencies and Heavy duty with a PCI-MIO-16XE-10

    Hello

    I use a Board PEAK-MIO-16XE-10 DAQmx with LabView 8.6 to run a door for a piece of equipment controller. I need to create 2 separate, all pulse trains both trigger simultaneously, each with their own cycle frequency and duty. So far, I can create 1 pulse train and it works exactly as I need, however, whenever I try to enable the second train (called a door in this VI), I get an error saying: "the specified resourse is resevered," even though the first door is configured to use counter 1 and the second must be set to use counter 0. As I understand it, this map contains 2 separate counter/timer modules, so this should be possible. A large part of the rest seen in the attached VI's preparation for the signal processing and other controls that I use that I finished this VI.

    Thank you

    <><>

    Hi Eric - you forgot to attach your VI.  I did what you're trying to do with a similar card, but who has been using NOR-traditional DAQ (before DAQmx).  It should be possible with DAQmx as well.  A quick search on the forums turns up these two links, which suggests that your problem is that you try to create two tasks separate DAQmx, one for each counter.  What you need to do is create a single task DAQmx which includes the two counters, then together, that their frequency and duty cycle regardless.

    http://forums.NI.com/NI/board/message?board.ID=170&message.ID=241602

    Causes of error NEITHER-DAQmx-50103

  • Measure the resistance with PXI DMM 4072 on different frequencies

    Hi all

    I tried to get on board various and unable to find solutions for that. I'm trying to measure resistance using NI PXI-4072 on frequencey 1 kHz, but not luck. When I try to use Agilent LCR meter I see the correct value of the resistance.

    I've seen a few posts on this but don't have no satisfactory solutions.

    http://forums.NI.com/T5/Digital-Multimeters-DMMs-and/LCRmeter-test-frequency-for-resistance-measurem...

    In above post, someone said that I can use 4072 DMM OR digitizer, does not have a lot.

    Can someone please provide the right path for me to solve this problem.

    Thank you

    Hello Puneet_K,

    I checked the data sheet and the method of measurement described in the specifications of the NI 4070/4072 http://www.ni.com/pdf/manuals/371304g.pdf; indicates that the ability is measured using an alternating signal and select the test frequency range, for example 3 kHz, 1kH or 91 Hz. The resistance is simply measured using a DC signal, and it is often sufficient to measure the internal resistance of a battery. If you need a more flexible control for the measurement, you probably get a card like the function generator and then set a multimeter to measure the voltage and another DMM to measure the current and calculate the impedance of these values.

    I hope this helps!

    Kind regards

    -Natalia

  • Frequency of measurement with cDAQ NI 9402 chopper

    Hello world

    I'm new in the world of the cDAQ and try now just get a frequency of a TTL signal output chopper.  I confirmed 23 Hz frequency on an oscilloscope.  It's a nice clean 5V square wave, but when I try to measure the frequency in labview using a VI (dig frequency of continuous measurement) example, it comes to expire.  Trying to look at the entrance of the signal in express shows signal an incompatible digital signal that is around 3 Hz and clearly the result of the port being interviewed for entry too rarely.  The final objective is to get this work with the labview vi PLL is a detector lock in the amplifier, but first of all, I have to be able to measure and to read correctly this frequency.

    My hardware is a cDAQ-9174 with a 9402 OR for use with the digital input.  I don't know it's important, but the 9402 module is in slot 3 and I'm on channel 0.  The software is labview 8.2 with DAQmx 9.1.  Is there some timing issue material or the definition of I'm missing here?  Any help is greatly appreciated, thank you!

    Hi Skaboss,

    Counters have multiple terminals (source, the door in and out), which map to separate on your NI 9402 PFI lines. For the measurement of the frequency, the default input terminal depends on the method of measurement (low frequency, high frequency, wide range). Here's the relevant section of the NOR-DAQmx help (which is on the Start Menu):

    Connections of signals C series for counters

    The following table lists the default input for various measures of meter terminals. You can use a different line of the PFI for one of the input terminals. To edit the entry PFI for a measurement, use channel NOR-DAQmx attributes/properties.

    NEITHER 9402 and NI 9435 (4 channels)

    Measure Ctr0 Ctr1 Ctr2 Ctr3
    Number of edges Edges: PFI 0
    County Executive: PFI 2
    Edges: PFI 3
    Branch Count: PFI 1
    Edges: PFI 1
    Branch Count: PFI 0
    Edges: PFI 2
    County Executive: PFI 3
    Pulse width measurement PFI 1 PFI 2 PFI 3 PFI 0
    Duration/frequency measurement (low frequencies with a meter) PFI 1 PFI 2 PFI 3 PFI 0
    Measure of duration/frequency (frequency with two counters) PFI 0 PFI 3 PFI 1 PFI 2
    Duration/frequency measurement (wide range with two counters) PFI 0 PFI 3 PFI 1 PFI 2
    Measure semiperiod PFI 1 PFI 2 PFI 3 PFI 0
    Measurement of two-Edge separation Departure: PFI 2
    Stop: PFI 1
    Departure: PFI 1
    Stop: PFI 2
    Departure: PFI 0
    Stop: PFI 3
    Departure: PFI 3
    Stop: PFI 0
    Measure of position A: PFI 0
    B: PFI 2
    Z: PFI 1
    A: PFI 3
    B: PFI 1
    Z: PFI 2
    A: PFI 1
    B: PFI 0
    Z: PFI 3
    A: PFI 2
    B: PFI 3
    Z: PFI 0

    Alternatively, you can override the default with the CI. Freq.Term channel property.

    Brad

  • frequency corresponding problem with myrio!

    Currently, I am working with myRIO and Labview 2013 to generate sinusoidal PWM signals.
    When I created 'analogue output' tab myRio and connected to the Oscilloscope, oscilloscope waveform could not show me the appropriate frequency combined with a frequency that I gave in labiew. Is there a relationship between the frequency of "the"(myRio tap) of analog input between real-time rate? ". Otherwise, is it certainly possible to calibrate the frequency in labview? Please help me!


  • Synchronization of several high at different frequencies of sampling DAQ cards.

    I'm having sync problems 3 high DAQ cards with different sampling frequencies. I use 2 cards PXI-6259 nec 10,000s samples and 1 PXI-6221 Board to interface for my SCXI modules in 10 samples/second. The problem that I discovered is the time related with the waveforms of the NI PXI-6221. When I run the code on a development computer using virtual devices in MAX, it works as expected. When I run the same code on real hardware, the stopwatch turns approximately 25 X faster than normal. I enclose the code and the config that I use.

    Any ideas?

    Hi NGNN CAD.

    First of all, let me say that your code is very nice!

    The problem is that you are using the fast sample for the device that is supposed to be slow clock:

    Even if you specify the rate as 10 Hz, the clock itself is still at 10 kHz (by specifying the right rate allows the DAQmx driver determine the size of buffer etc and don't actually change your external sample clock speed - however, it changes the rate of the simulated device).

    My recommendation to synchronize devices would use the built-in PLL and lock to the reference clock 10 MHz of your PXI chassis.  Your devices would always share a trigger to start, but each would generate its own sample clock based on its time base that is locked to 10 MHz reference.

    The code should look like this:

    I hope this helps, let me know if you have any questions!

    Best regards

  • I use a simple low-pass, but the output of the filter outputs at a different frequency, even if the input frequency is the bandwidth

    I'm simulating a sine wave at approximately 1000 Hz (I'm variable according to the frequency with a slider), I would like to pass this signal by a lowpass filter (butterworth) with a high frequency of 2200 Hz cuttoff and a low pass to 2900 Hz frequency. However, the output after the filter frequency seems to be lower in the order of a thousand. the output frequency is about 0.1 Hz.

    Y at - it someone who can guide me please to solve this problem, I tried different filters and I'm still having this problem, it would be incorrect sampling?

    I enclose the block diagram and the front panel

    Because you use express screws and the type of dynamic data...

    You convert the signal of DDT (which contains the clock information) in a table DBL to perform filtering. Take it a DBL array (which contains no data of timing) and converted it into a DDT (which now contains no data timing). That's why when you try to view and analyze it you have lost all the data timing (frequency).

    If you were to exit table DBL of your filter and build a wave form and provide the dt to the waveform of the sampling frequency control, then it will work.

    Better yet, ditch the DDT and use waveforms from the beginning

Maybe you are looking for

  • Satellite M40x-183 - memory upgrade

    Hello I'm looking forward to upgrade the RAM in my Satellite M40x-183. The laptop came with 512 MB of RAM. Of the record, I learned that it can be expanded to 2 GB. I don't know what type of RAM (DDR1/2) and how often rely on m40x-183. Please help me

  • Video installation MASTER

    I returned to an old thread and installed the VideoMASTER after installation of scope. Also, I installed LabVIEW before installation of TestStand. Now the videoMASTER is installed as a stand-alone not as the TestStand module option. The new thread sa

  • Duplexer C9058A-002 - looking for another model of the printer to use on

    Now that my OfficeJet J6450 is no longer operational, I was wondering if anyone knows of any other current models of printers all-in-one type that the duplexer C9058A-002 (which came with the J6450) could be used on. I tried it searching unsuccessful

  • Redundant recovery in Windows 10 partition?

    Hi, I have an Acer V3-371 and I just upgraded to 10 Windows and everything works fine. I have created a recovery drive on a 32 GB USB and I have also regularly copy the complete c:\drive on a USB WD elements HARD drive backup.I would now like to dele

  • Cannot remove display languages (Windows 7)

    I tried (unsuccessfully) to upgrade to Service Packet 1 and found this support site to help with the error that I get: https://support.microsoft.com/en-us/kb/2700530 I tried method 1, but still got the same error. Now I try Method 2 ("uninstall unnec