How to obtain a sine wave polar representation?
i need some hint
LabVIEW has a polar plot. I do not know if the Base Version has the featur though. Goto functions >> graph >> ctls >> polar plot indicator. This places a combination VI and picture control on the diagram and front panel. The data terminal for the VI is an array of clusters of mag and phase in degrees. You can easily construct the data for a sine wave in a For Loop by bundling 1 with the i and building an array of 360 elements.
Similar Messages
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How to get the sine wave sample of the input and output in the same time?
I discovered that the samples were acquired did not in the same time in my vi.Could you tell me how to get the sine wave sample of the input and output in the same time?
Output:9263;
Input:9201
Attachments:
singal requency.vi 104 KBHello Yun_Zhu,
Your VI looks like you started from an example, and you are on the right track.
To clarify are you trying to synchronize the input and the output waveforms? If you you will need to share a time base and a start trigger. Check out the synchronization examples from LabVIEW
Anthony F.
Product Marketing Engineer
National Instruments
Attachments:
HIODAQmxSyncMultiDev.png 70 KB -
How to view different sine waves in an array and make an fft of these and display it in one graph
How can i cannect the output of my mathscript in the Spectral Measurements VI SIgnal Input. I'm having a problem since the output of the mathscript file "D" is DBL 2D. I dont know how to convert this data type in order to be connected to the signal input of the Spectral Measurements VI. I also want that the waveform graph connected to output of the Spectral Measurements VI, will display the FFT of the three sine waves in one graph.
Attachments:
1.JPG 32 KBDuplicate
LabVIEW Champion . Do more with less code and in less time . -
How do I simulate sine waves up and down several triangular waveforms?
I need to simulate a number of sine waves at about 10 or 20 Hz and run these up and down a number of triangular waves. I am using the "Simulate Signal" box which generates the sine waves but am not sure what or how to connect to this to "ramp" the sinusoidal waves up and down triangular waves. The triangular waves would run at about 1 Hz.
thanks
MartinMartin,
It seems as if you could use a second "Simulate Signal" VI, set it for a triangle pattern at your desired frequency, and then add the resulting waveform to the sine waveform. If I run that in a loop, I get a nice ramping sine wave (see attached image).
Hope it helps,
John
Attachments:
triangle_sine.png 8 KB -
How to create sine wave and step input using cwgraph in VB 6.0
hello..
i'm doing my master's project now. i'm stuck on how to create a sine wave and a step input using the cwgraph using VB 6.0. please help. thanks.hello..thank for the reply.
i'm having problem with my coding using cwgraph. can anyone help. everytime i do the full compile, there's error.but it can still can run, but can't convert to application form.for your info, i'm using RTscope and cwgraph to plot graph.the error is in the cwgraph coding.below are part of the coding with error. and can somebody tell me how to add cwgraph component in the VB? i try adding component, but it's not in the list of component,and i've browse for it already too.i'm doing the software at home, but i'can run it at my lab cause cwgraph component is not listed.please help.
Dim countTime As Integer, count1 As Integer, countFreq As Integer, countVolt As Integer
Private Sub cmdRun_Click()
If cmdRun.CausesValidation = True Then
cmdPause.CausesValidation = False
tmrOsc2.Enabled = True
tmrOsc3.Enabled = True
Else
cmdPause.CausesValidation = False
tmrOsc2.Enabled = False
tmrOsc3.Enabled = False
For count1 = 0 To 100
Data1(count1) = 0
Data2(count1) = 0
RT1.Value(1, count1) = 0
RT1.Value(2, count1) = 0
RT1.Refresh
CWGraph2.Plots(1).PlotY count1 ' THIS CODING HAS AN ERROR ...
CWGraph2.Plots(2).PlotY count1 ' THIS CODING HAS AN ERROR ...
Next count1
End If
End Sub -
Acquiring a sine wave of 1KHz riding on a DC and Detecting its peak value through compact rio
Dear LabView Programmers,
We are trying to acquire a sine wave input through cRIO-9004 using I/O module cRIO-9215 which is a 16-bit ADC.
We are able to acquire sine wave below 100Hz faithfully but not higher frequencies, the higher frequencies(1Khz) get distorted. How to acquire this sine wave of 1Khz faithfully through the above mentioned hardware.
Regards
LabView LoversUsing LabVIEW 8.0, you will need to place the data from the 9215 into a dmaFIFO buffer, such that you do not need to poll the 9215. It is the polled or the interrupt process that reduces the sample rate.
Hope this helps.
Preston Johnson
Principal Sales Engineer
Condition Monitoring Systems
Vibration Analyst III - www.vibinst.org, www.mobiusinstitute.com
National Instruments
[email protected]
www.ni.com/mcm
www.ni.com/soundandvibration
www.ni.com/biganalogdata
512-683-5444 -
PXI-5406: unable to generate 10 mV p-p sine wave with 1.5 V dc offset
I'm using the PXI-5406 and FGEN Soft Front Panel to output a low amplitude sine wave. It works fine when I have the amplitude set to 10 mV and the DC offset set to 1V but when I increase the dc offset (I want it to be set to 1.5V) the FGEN front panel reports an error and stops outputting the wave. It starts working when I have the DC offset set to 1.5V and the amplitude increased to 50 mV. Any ideas on how to output a sine wave with 10mV amplitude (p-p) and 1.5V dc offset with the PXI-5406?
Thanks,
RachelI also wanted to mention that while using the FGEN Soft Front Panel, some of the settings are coerced to set values (particularly Digital Gain). Is it possible for you to use the driver API through LabVIEW or another program? This would allow greater control and a potential workaround.(set Gain to a value less than one (0.25) and the Amplitude to a value to 40mV).
Evan S.
National Instruments -
Generating a sine wave using PXI 5441
How to generate a sine wave using PXI 5441 (Arbitrary Waveform Generator)?
Can anybody post a vi that generates a sine wave with frequency at a user defined frequencies.
Thanks in advance.Hi Venki,
When using an arbitrary waveform or user-defined
waveform, you provide the actual waveform you want to generate to
the device, so it is easy to also just connect a graph to the waveform
and see what it looks like. Unfortunately, when using standard function generation (which is the method used in this example), you are not providing a signal that is created in software. Because the standard function
generation is happening on the FGEN and not in software, there is
really no way to display the exact signal without measuring
it on a scope or some device. You can, however, simulate the signal in
software such that the parameters which are given to the FGEN functions
are the same parameters that you use to generate a simulated wave. This
would be somewhat complex since you can change parameters such as
frequency and amplitude on-the-fly, and also you would need separate
functions for each of the different signal types available for the
FGEN. You would need to place the software waveform generator in your
inner loop and have a waveform graph connected to it in the loop as
well to display the signal. The main thing to keep in mind is that this
will only be a simulated signal and so it may not exactly match what is
being generated (this also depends on how you program the simulation to
work). Hope this helps,
Daniel S.
National Instruments -
Simultaneous updation of sine wave using 2 PXI-6711 cards using RTSI Trigger
Hi ,
How to generate continuous sine wave using two pxi-6711 cards at same time without any phase shift using traditional nidaq functions.
Regards,
satyaIn LabVIEW, go to Help>>Find Examples. Navigate to Hardware Input and Output>>Traditional DAQ>>Multiple Device. There is an example there called "Two E Series Shared Scan Clock". That example is for analog input, but you should be able to modify it to be for analog output. Basically you will just have to share the scan clock from one board(master) and use it as an 'external' clock for the other board(slave).
-Alan A. -
How can I get stable Sin wave through NI 9264 ?
Dear all,
I would like to generate 64 analog sin wave with frequency up to 20K Hz.
Then I bought 4 NI9264:
25 kS/s/ch simultaneous output
Hot-swappable operation
Spring terminal or D-SUB connectivity options
250 Vrms isolation (spring terminal version)
60 VDC isolation (D-SUB version)
.The attached is my file for the generation. when I used Osciloscope to monitor the output, I could not get any stable output.
Could I have the reasons and suggestions for my objective please?
Thanks!
Zhu_nuo
Attachments:
64 Channel Programmatic v2.vi 22 KBHi Zhuming,
The VI above only provides waveform information for a single channel. In order to output data across all 64 channels in the task, we can make use of a For Loop to build an array of waveform information for each channel. In the example below, I've made use of an Auto-Indexing For Loop in order to build up a waveform output array of 64 elements. I've wired this to an NI-DAQmx Analog 1D Wfm Write VI; the 1D array's elements represents each channel in the group of selected channels for generation.
An important thing to note is that the NI 9264 16 channel analogue output modules have a maximum sample rate of 25 kS/s/ch. This means that each channel is capable of writing 25kS/s simultaneously.
To reliably generate a signal, we generally need to have it comprised of around 5 to 10 points of data. This allows us to represent the signal to a good degree of accuracy. For example, if I wanted to reliably output a 1Hz Sine Wave, I would need to break the 1Hz wave into ten separate points and then output them at a rate of 10Hz. In terms of the NI 9264, the maximum frequency content (Two points of information) that can be generated is 25kHz/2 = 12.5kHz wave. The maximum clear wave frequency that we could produce with the 9264 (A wave built up of ten points) is 2.5kHz simultaneously across each channel. This is all to do with Nyquist's Theorem. This should explain why the frequency appeared to drop.
Out of interest, how are you measuring these output frequencies?
Kind Regards,
Alex Thomas, University of Manchester School of EEE LabVIEW Ambassador (CLAD) -
I am trying to convince my company to send me to purchase labview and send me to classes for labview.
I am trying to put together a small demo for them using the Labview 7 express evaluatin copy that I recieved.
What I am wondering is how can filter out everything besides the valley peaks on a sine wave.
What I am trying to accomplish, is create an example showing that Labview can sameple from a sine wave, read about 5 "valley" points of the wave, evaluate these based on a value that i can define, and signal pass or fail.
attached is a picture of what i have so far
Ryan
LV 7.1
Attachments:
progress.bmp 3841 KBHi,
I built a VI using LabVIEW 7.0 that detects the valleys in a sine wave. It uses the 'Peak detector' VI that I believe is available in the evaluation version.
(Functions palette >> All Functions >> Analyze >> Signal Processing >> Time Domain >> Peak Detector)
I have attached a VI as well as the screen shots its front panel and block diagram.
I hope this helps.
Sincerely,
Feroz
Attachments:
valley_detector_bd.jpg 36 KB
valley_detector_fp.jpg 72 KB
valley_detector.vi 29 KB -
How can I Write a sine wave in an Access-fil​e?
I measure a sine wave in LabView 6i. How can I write the datas automatically to an Acces-file, at the same time?
In my program, I managed it with Execute SQL.vi, I change a number in a SQL statement(String) -> after this I push start and then it writes the statement in the Access-file.
The problem is, it writes only one data per measurement in the file. How can I write all datas in the Access-file and measure the wave at the same time?
Thanks for help!
Attachments:
getwave.vi 49 KBOn the waveform palette, you will find a "to components" vi that you can break out the array of the waveform. You can then, using a for loop write all of the values from the waveform.
Better yet, there are examples in the database toolkit manual on pages 3-13 to 3-15 that deal with reading arrays (and even has a waveform example).
Good luck! -
How can I calculate the frequency of a 2-4Hz three phase sine wave in 50msec?
I want to calculate the frequency of a sine wave using either all three phases or just one, but I want to know the frequency after 50 msec, I don't want to have to wait for a full period.
I have a mathematically sound suggestion but I do not know how well it will work in application. Most period measurements measure the time between a full period or several periods to eliminate the error introduced by the measuring device. Essentially the device error is made insignificant.
Mathematically you can do much more but there is a tradeoff between recording less information and knowing (or assuming) some values. For instance, if one knew the amplitude and could calculate the derivative of the signal, one could calculate the frequency. A sine wave can be represented by the function: A sin (BX)=C , where A is the amplitude, B is the frequency, C is the present measured value. If the equation is solved for X, we get: X=(sin^(-1)(C/A))/B. The d
erivative of the first equation is AB cos(BX)=C. If the equation for X is now substituted into the second equation, we get, AB cos(B (sin^(-1)(C/A))/B)=C. Solving for B we get B=C/(A cos(sin^(-1)(C/A))). Remember, we already know A and C, so we are done.
Practically every step and assumption in the above argument introduces possible error which will affect the accuracy of the frequency. Unfortunately it is a trade off and that is why at least a whole period needs to be measured to get an accurate frequency.
Jeremy Braden
National Instruments -
How to change the phase by 90 deg of a sine wave
Hi
Does any one know how to change the phase of a sine wave by 90 degrees.
MalHi Malkoba,
Thank you for your post.
Having looked at your VI I can say that you have created the correct inputs to the 'Sine Waveform.vi'.
However the dial you had created had no affect as it was not wired into it the 'Sine Waveform.vi' on the block diagram.To fix the problem I have wired the 'Phase' dial into the 'phase' terminal of the waveform generator. This now changes the phase of the sine wave during runtime.
The dial also now has a digital display (numeric box below it)- this can be used to read the dial's value, or feed in specific values into the control.
Please find a modified version of your VI below.
Regards,
Field Sales Engineer | National Instruments | UK & Ireland
Attachments:
NI_phase shift sine.vi 31 KB -
How to count the number of cycles in sine wave
Hi,
I am new to Labview. I have labview 8.2 version and my dataacquisition is NIDAQPAD6015. I could write a program to generate a sine wave of desired frequency through simulate signal. My question is how do i measure the number of cycles for this sine wave as soon as I run the program. Hope my question is clear.
Ravi MokiralaTo find the offset (which in this case is the Y value midpoint around which the sine wave is symetrical):
Capture more than one cycle. Find the min and max values. Subtract Min from Max and divide by 2. Then subtract this result from the Max value (or add the result to the Min value). This is the offset.
To count the number of cycles where the offset is unknown, just use the first data point value as a reference. If the next data point is more positive, then count the number of times that the first data point is repeated and the next data point is more positive. Of course with DBL data type, you probably would not get the exact same value as the first data point, so you need to use In Range with a very tiny limit. It all depends on your signal amplitude, frequency, and sampling rate.
Example: Lets say your first data point value is 0.5 and the 2nd point is 0.55. You need to look for another value that is between 0.48 and 0.52. Then read the very next data point value. If it is greater than the previous value, add one to the cycle count. If it is less than, you are at half a cycle, do not add to the count.
- tbob
Inventor of the WORM Global
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