FFT of Sine Wave-FPGA

Also tried generating a sine wave of 50 Hz and an amplitude of 100 and then do an FFT. But the FFT does not give magnitude at 50 Hz..
Attachments:
FFT-2_Sine Wave Generator.PNG ‏52 KB

Your problem is that the output of the FFT is an array of complex numbers. Take the magnitude and you will be able to plot it.

Similar Messages

Problems graphing FFT of sine wave with Waveform Graph

I know that this type of question has been posted
many times, so I apologize for posting a similar one. Unfortunately,
after reading quite a few threads I still have a question or two.
Basically, I need to use a Waveform Graph (not an XY graph) to graph
the magnitude of an FFT of a sine wave. I can't figure out which VI I
should be using to obtain the magnitude of the FFT. I think I'm using
the proper FFT vi (just the regular FFT.vi), but I can't find a VI
dedicated to magnitude. Of course, I could be misinterpreting the
pseudocode which I am following.
If you
wouldn't mind taking a gander at my VI, I'd appreciate any input you
might have. The pseudocode is contained in the block diagram. You
can see that I have another graph for just the sine wave, and I think
that works as it should. I'm primarily concered about the waveform
graph which isn't currently connected to anything, but should
eventually be hooked up to the FFT.
Thanks!
Attachments:
Labview5.vi ‏199 KB

Your problem is that the output of the FFT is an array of complex numbers. Take the magnitude and you will be able to plot it.

LabVIEW FPGA Sine Wave Generator Reset Input Behavior

I would like to know what the output from the Sine Wave Generator express VI is while the reset input is true, and what happens to the output immediately after the reset input is set false.
I need to generate a regular sequence of positive half-cycles of a sine wave, with an arbitrary delay between them that is not related to the actual frequency of the sine wave. So my plan is basically to periodically fire a trigger in the fpga software that resets a sine wave generator and directs its output to an analog output until the sine wave goes negative, at which point the analog output is set to 0 until the next trigger.
Thanks

Muchas gracias por responder steve.bm
El problema que tengo es el siguiente, estoy desarrollando un proyecto en el cual uso los conversores DAC y ADC de la tarjeta FPGA Spartan 3E para lo cual use como base el proyecto que esta subido por la NI que se encuentra en uno de los enlaces que me dejaste,( Lesson 8 - Linking Existing VHDL Code from WebPACK into LabVIEW FPGA) del mismo solo modifique para usar el ADC y el DAC mediante el cual adquiero una señal senosoidal y la tengo que reconstruir, el problema es que como uso un generador de señal de laboratorio al ingresar la frecuencia de muestreo para obtener una buena reconstruccion, la frecuencia se baja lo cual en el proyecto real no podra pasar ya que la frecuencia ya en proyecto final la adquiero de la red electrica publica pero ahora para pruebas estoy con un generador, la verdad no se que pasa porque tiene un retrazo la señal.....
Te parece si te puedo dejar mi proyecto subido en enlace para que lo revices ??

FPGA sine wave generator

NI工程師你好
我在FPGA端使用sine wave generator
可是出來的波形卻不是一個完整的Sin波圖形
可以請工程師幫我解答一下嗎??
已解決！
轉到解決方案。
附件:
sin.png ‏10 KB
sin-1.png ‏13 KB

好吧，我認為問題可能是您使用的圖表上的FPGA。不幸的是，LabVIEW的通信方式，有時會導致與 FPGA圖表更新不當，因為他們目前沒有時間同步的時間在芯片上。我組建了一個簡單的應用程序，而不是傳輸分回的主機和波形似乎是正確的。讓我知道這是否有助於。
附件:
Sine.zip ‏317 KB

How can i do a sine wave with High Throughput Sine for fpga?

I try to do a sine wave looking the examples but i can't. I have a sbRio 9606.
I need to do a sine wave with high throughput block. In my exercise i have 2 inputs (amplitude and frecuency) and i have to look the output (sinewave)
I need help!!

Hi pablosan,
If I understood correctly, you want to generate a sine wave with a high throughput block in Labview FPGA.
I'm afraid you won't e able to do this, as these blocks are specifically designed for other FPGA targets with better features for high performance. So instead of using the example named "Sine and Cosine.lvproj" under High Throughput examples, you can use the "Sine Wave.lvproj" under Signal Generation and Processing examples, which is more adequate to your Single-Board RIO.
Regards.

Sin wave generation for R series FPGA

Dear All,
I am generating sin Wave with (FPGA Sin Wave Generation Express vi) from Rseries FPGA Target.Frequency range is from 1500Hz to 3000Hz.Frequency and Amplitude parameters are coming from Host .Wave is going to an AO.The wave is not displaying in my Host with the set parameters as required.
What am I doing wrong??
Certified LabVIEW Architect
Certified TestStand Developer

Hi,
I am using NI 9263 4x AO.the problem was with the FPGA Express vi Parameters used the example sin wave Generation from the FPGA fundamental folder and modified the Host parameters to meet our requirement and it worked fine.
Thanks
Certified LabVIEW Architect
Certified TestStand Developer

How can I get 'sync' signals for sine wave out? [FPGA USB 7856R]

Hello,
I'm Sean Ahn using NI 7856R, USB FPGA with LabVIEW 2014.
I'm trying to make 'sync' signals for sine wave of adjustable frequency, like general function generator's sync out.
I use sine waves whose frequency is feedback-congtrolled between 25~30 kHz and need sync signals of square wave.
Like [1] below, when I try resettng two wavefom-generators, sine and sync signals are not perfectly synchronized.
And everytime I adjust sine's frequency, the phase difference between sine and sync changes arbitrarily
In case of [2] using 'zero-crossing detector', I have severe jitter of sync signals not suitable as 'sync' signals for other parts.
Please, give me some help.
Thanks in advance
Sean Ahn
[1] Reseting two waveform generators
[2] Zero-crossing detect

Here’s my issue. When I try to move any data between my PC and the iPad2 I receive an error message that states that “the [sync] session could not be started with the ipad, Please disconnect and reconnect the iPad and try again”
I have tried again and again by various methods etc . and all I get is the same message when I attempt to sync, backup or update the iPad.
I have tried the following AND FAILED:
Deselect all Apps, Music etc in iTunes, then attempt to sync
Disable and enable the iPad in device manager and restart itunes and try to sync again
Disable and enable Apple Mobile Device Services and sync/backup/update
Run iTunes as Administrator
Reboot all devices (iPad buy pressing two buttons at once)
Turn off all security and reboot and sync
Connect directly to internet without a router
Tried to sync with all wireless turned off and in airplane mode
Running iTunes Diagnostics...... nothing all test passes
Changing USB ports and cables
Removing my SIM card and rebooting and trying to syc
Trying to sync via wifi only
Turning off all icloud services
Uninstalling all Apple Software and reinstalling again
I am syncing to a 64bit PC running Win 7 Premium with all the latest updates, all firewalls off. WiFi and direct connect ethernet to Internet service with and without router.
I am trying to Sync an iPAD 2 running iOS version 5.1.1 (9B206)
I am trying to update from iOS 5.11 to 6.01 by using Itunes 11.0.0.16.3 in a USB or directly through the iPad via wifi.
Please help as everything I have tried has failed.

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 KB

Duplicate
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Générer une implusion avec "Sine Wave Generator" en FPGA

Bonjour,
Content de vous rejoindre sur ce forum. Tout nouveau en Labview (pas très à l'aise avec certaines notions), je voudrai soliciter votre aide. En fait, je veux créer une impulsion de 100Hz avec la fonction " Sine Wave Generator" de FPGA. En simulation j'ai réussi mais dès que je compile en target il m'affiche ce message : "Top-level clock rate does not match rate for which the Sine Wave Generator VI was configured. Reconfigure the Sine Wave Generator or the top-level clock so that their rates match. You also might need to modify computed values for the frequency (cycles/tick) input."
Je change donc FPGA clock rate et je choisis 40MHz (la seule qu'il me propose). Mais dans ce cas, je me perds pour retouver mon impulsion (qui doit durer une période 0.01sec). J'ai essayé de jouer sur le nombre d'échantillons en changeant le nombre d'itérations de la boucle For afin de générer toujours une période ( pièces jointes) mais ça marche pas!!!
Pourriez vous m'aider à déchiffrer ce problème?
Merci d'avance
Pièces jointes :
burst sine.png ‏372 KB
burst sine_40MHz.png ‏336 KB

Bonjour M2IM,
En mode simulation, on utilise une fonctionnalité appelée "Interactive Execution" car l'exeuction/affichage ne peut être géré à une fréquence élévé (40 MHz dans le cas de la Top Level Clock par défaut).
En mode FPGA target, la vitesse est plus élevé et donc uniquement certains points du sinus seront afficher mais le signal electrique lui sera bien un sinus.
Je t'invite à regarder le lien ci-dessous qui reprend quasiment la problématique que tu rencontres:
Generate a sine with LabView FPGA and connect it to an AOModule
Bonne journée,
Valentin
Certified TestStand Architect
Certified LabVIEW Developer
National Instruments France
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Unable to generate sine wave

Hello everyone!
I am currently working on my Bachelor project at a company. i am stuck with a problem.
I have designed a labview program for vibration test system. I have used cRIO 9076 as the controller with NI 9263(as D/A) and NI 9234(as A/D).
The loop works as follows. the input is given from the labview program. it is then sent to the cRIO. the output of CRIO(that is output from NI 9263) is given to the amplifier. the vibration shaker vibrates based on the input from aamplifier. then the accelerometer detects the vibration and sends it to the NI 9234 and loop repeats iteratively. since i have designed a sweep sine vibration system, the output of cRIO is a square wave. it should be sine wave.
the probelm is i am getting a square wave as output from my NI 9263 which should be a sine wave output. I have two subVI where i use nominal to binary convertor(for NI 9234) and binary to nominal (for NI 9263) as calibration mechanism.
the question is where have i went wrong? what should I do to get a sine wave?
PS: on searching NI i found out some formulas (to generate sine wave) and designed a FPGA and LabVIEW program to generate a simple sine wave and got a sine wave. if that formulas is to be included where should i include that?
Thanks in advance.
Regards,
Vishal.

Without seeing your current code, there is no way we can even uess as to why you are creating a square wave instead of a sine wave.

Question on the result of using Wavelet transform on sine wave

Dear all,
I have apply the Wavelet transform on a 50Hz sine wave. The result is shown below. But I don't understand the result of Wavelet transform. Anyone can help me? Thanks.
Victor

You seem to have something against the FFT, yet continually compare other transforms to the "sweet spot" for the FFT, ie. sinusoidal and periodic functions. Without trying to write a treatise on the subject (there are many fine books), a few observations.
The primary purpose of any transform pair is to perform a rotation in function space, for the FFT we are familiar with the time domain and frequency domain. The wavelet domain is not so simple. The FFT is very effective for sinusoidal and periodic functions, ie. those that have no localization in the time domain. If you have a sinusoidal input, the infinite signal in the time domain can be reduced to a pair of numbers (one if you take the power spectrum). That is very efficient, other periodic signals can usually be approximated by a small number of terms.
Wavelets on the other hand are chosen to be localized in both the time domain and the wavelet domain. If you look at a periodic signal like your sine wave, you see a mess, and to recreate the input signal you will need to keep an awful lot of the points around for the inverse transform. You may be able to set the last 1/3 to zero, but that's it. To see an effective application, you should be looking at localized functions, like an impulse. Put an impulse into the wavelet transform and you get something that is still a bit complex, but pretty simple. The FFT of an impulse contains components at all frequencies and the wavelet clearly wins in this case.
On paper, there is usually a clear choice, and the FFT almost always wins for spectral estimation. On the other hand, if you are trying to compress "real world" data, for instance an image, then there is a choice to be made. Standard JPEGs are FFT based, you take the FFT and try to keep just the largest frequency components. As you probably notice, edge contrast usually suffers, especially at higher compression. With wavelets, it is typical to have slightly better contrast leading to better preservation of details for a given compression.
In short, my opinion is that transforms are useful when they simplify the problem. Wavelets do not simplify the representation of a sine wave.

Generating a 6X Sine Wave using an absolute encoder

How do I get an Analog Signal Generation Synchronized to six times the frequency of an absolute nine bit parallel encoders output with adjustable phase relation. I am using a PXI-6533, a PXI-6711 and have available a PXI-6070E.
Now the long version of the problem. I have a 9-bit absolute encoder connected to a motor shaft (up to 420Hz). From the encoders 9-bit (0-511) parallel signal I need to create a synchronized 6X sine wave (up to 2500Hzwith an adjustable phase relation. Picture an electronic timing chain. For every cycle of the encoder, I need to produce six full sine wave cycles with a variable tuned phase shift. I have LabView 7 w/RT.
I have tried to use the Update Clock (PFI5) to step through a buf
fer but it seems to drop an update every so often. I also have tried to monitor the bit-0 line to determine freq. and scaled the update rate accordingly but the phase shifts all over the place. Does anyone have any ideas on the matter ? I would really appreciate it! Thanx….Phil

Phil,
Another different option to solve your application would be to use the new LabVIEW FPGA module and the 7831R reconfigurable I/O hardware. Using these tools you can configure the FPGA on the board to generate the sine wave based on the 9-bit parallel input. The most simple setup would be to have a lookup table in the FPGA that has a corresponding output value to each of the 512 possible input values. This 512 sample table would contain 6 cycles of a sine wave. Every time the parallel input changes the analog output value would be updated accordingly from the lookup table. This setup would also allow to easily add a phas
e shift of the output by shifting the point in the lookup table you are reading by a known constant.
Christian L
NICS
Christian Loew, CLA
Principal Systems Engineer, National Instruments
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How do I Fix DDS Generated Sine Wave That Produces a Periodic Square Wave?

Hello,
I'm an undergraduate researcher with almost no experience dealing with FPGA semantics and other National Instruments hardware in general. Part of my project revolves around creating a sine wave signal via the FPGA on an sbRIO-9632 that is output via the board's analog I/O pins, and I found it convenient to adapt the code provided by the National Instruments tutorials (http://zone.ni.com/devzone/cda/epd/p/id/6066) to have it run on an sbRIO FPGA. The problem I'm encountering right now is that the actual output I'm seeing is a square wave as opposed to the smooth sine wave that was expected, and I've exhausted all my ideas on possible ways to debug this issue. Can anyone please give me feedback if they've seen this problem before or offer other suggestions on fixing this?
I'm currently running LabVIEW 2009 with the appropriate real-time and FPGA modules on a 64-bit Windows 7 machine. Again, the hardware is an sbRIO-9632 complete with analog I/O. I appreciate it everyone!

I am also having this issue and have not been able to find a solution in the forums. I am somewhat of a rookie so pardon me if I seem ignorant in any way. I am working on a graduate project where I need to produce some sine waves and I am getting more of a square wave when I output it and measure on the scope. The program I am running is quite simple at the moment to attempt to discover any errors by process of elimination. I have the sine wave generator in a while loop outputting to an AO port. I am using the cRIO 9022 with the 9269 AO module. I will attach screen shots of my code and my oscope image
Attachments:
sine wave.jpg ‏76 KB
code for project.PNG ‏169 KB

How to measure relative phase of several sine wave inputs

I'm using a USB-6229 to acquire 10 sine waves, and I would like to output their rms amplitudes and relative phases. The rms amplitude is not a problem, but I wasn't sure how to go about determining the phase of one signal relative to another. Do I need to use the Frequency Response analysis step? Thanks.

Hi,
There are some functions you can use to measure the relative phase. You can either measure the phase of every signal related to another one using like you said: a frequency response function step. Using one of these to functions might do the job: “Frequency Response, Express VI” or “Frequency Response Function (Mag-Phase).vi, if you are working in LabVIEW. The first one of these functions "Frequency Response" is also found in signal express and is the one I think you are refering to.
Although this functions is use for a stimulus response approach they will give you the relative phase of Y with respect to X, “Typically, time signal X is the stimulus, and time signal Y is the response of the system. in signal express your options is the frequency response step.
I would also like to point you to some references that might serve you as reference when doing spectrum analysis: An Overview of Frequency-Domain Measurements and FFT Analysis.
Message Edited by Jaime F on 02-06-2008 11:42 AM
Jaime Hoffiz
National Instruments
Product Expert
Digital Multimeters and LCR Meters
Attachments:
frf.png ‏37 KB

Help needed with generating a sine wave with NI-5640R card

Hi there,
I have created a simple programe using the 5640R card, and i am attaching the programe to this question. Using a "sine generation" function/block i am generating a sine wave and outputting to one of the o/p ports and then i am connecting that o/p port to one of the i/p ports using a cable. Then i am plotting what ever i have recieved through the i/p port (this has to be same as what is generated using "sine generator" ). The graph shows that i am not receiving aything from the i/p port, but when i plot the o/p of the "sine generator", i see that the sine generator is generating the sine wave. Please refer to the attached figure and please tell me what mistake i have made in this simple programe.
Thanks,
Sandeep.
Message Edited by sandeep palreddy on 07-08-2007 12:46 PM
Sandeep Palreddy, Graduate Research Assistance
The Microwave Remote Sensing Laboratory (MIRSL)
University of Massachusetts
151 Holdsworth Way
Amherst MA 01003-9284
Attachments:
figure.doc ‏27 KB
figure.doc ‏27 KB

Hi sandeep
This small segment of code will not work on the NI PCI-5640R. This module does not support running the FPGA Vis directly. A Host VI must be run that calls to the FPGA Vis.
I suggest that you look at the ni5640R Analog Input and Output example that is installed by the NI PCI-5640R software.
Jerry
PS: Make sure that you are using the NI PCI-5640R software version 1.1.

FFT of Sine Wave-FPGA

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