Enlever la composante continue d'un signal dans la FPGA
Bonjours,
Je cherche à enelever la composante continue d'un signal dans ma FPGA, pour cela j'ai essayé d'utiliser un filtre butterworth passe haut d'ordre deux avec fc= 20Hz, celui-ci m'enlève bien la composante continue mais il me laisse un offset à la sortie, certe petit mais un offset quand même et vu qu'après cela j'ai besoin d'intégrer mon signal cette offset est très embêtant. J'ai essayé avec d'autre filtre créer avec le IP core generator mais le problème reste le même.
Avez vous une idée de comment procéder pour enlver la composante continue d'un signal avant de l'intégrer avec Normalized Discret integrator.vi?
Cordialement
Sébastien Kuenlin
Bonjour Skuenlin,
Avez-vous essayé d'augmenter la fréquence de coupure de votre filtre de manière à atténuer plus fortement les basses fréquence?
Quelle est la fréquence minimum du signal que vous souhaitez récupérer?
Si cette fréquence est proche du DC avez-vous pensé à utiliser un autre type de filtre "tchebycheff" ou autre, ou simplement augmenter l'ordre de votre filtre?
Cordialement,
Rémi D.
National Instruments France
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Superposition de trois signaux dans un seul graphe
Bonsoir à tous;
j'ai un problème avec le graphe où j'aimerai bien afficher trois signaux superposés. Alors lorsque j'exécute le programme je remarque qu'un seul signal qui apparait dans le graphe et je ne sais pas pourquoi les deux autres n'apparaissent pas? si vous avez une idée, s'il vous plait n'hésitez pas à la poster? merci bien en avance.
Cordialement;Bonjour à tous;
D'abord je vous remercie beaucoup pour vos réponses et à votre intéret que vous confiez à mon problème. Alors, j'ai essayé vos suggestions, et bain j'ai arrivé à afficher les trois signaux sur le meme graphe, dans l'image ci-joint vous trouverez une impression ecran de la face avant de mon programme où vous verrez les trois signaux superposés dans un meme graphe. En fait, ca c'est la première étape de mon problème, car mon but est de faire en quelque sorte afficher les trois signaux comme si nous avons un seul signal dans le graphe mais en réalité ce sont trois signaux superposés. Mon objectif est de faire une sorte de fenetrage c'est à dire choisir dans le signal qui apparait dans le graphe les deux parties que je vais traiter en utilisant les couleurs pour destinguer entre les trois signaux: le signal dont la couleur est blanche correspond au signal original acquis à l'aide d'une carte d'acquisition NI et dans ce signal je vais choisir deux parties qui me concerne comme si vous dites deux fenetres de couleurs différentes: rouge et vert par exemple. j'espère que j'ai été claire dans la description de mon problème, s'il vous plait si vous avez une idée n'hésitez pas à la poster. Je travail sous windows 95 avec labview 6i. Avant de ne pas oublier, vous trouverez ci-joint deux impressions écran: une concerne la face avant de mon programme et l'autre concerne le diagramme correpondant.
Merci beaucoup;
Cordialement;
Pièces jointes :
impression1.JPG 1407 KB
impression2.JPG 1407 KB -
How to read a continuous temperature signal from a Pyrometer via RS-232
I'm trying to read and graph a continuous signal from a Pyrofiber Lab pyrometer which is coming in through an RS-232 cable. As far as I can tell there are no device drivers for this instrument (or any other pyrometers).
If I have the pyrometer take single measurements I can get those into LabView using the Instrument I/O Assistant, but only as an ABC string reading " 'emmisivity value' 'temperature' 'corrected temperature'" and not as individual numbers or data that I can use/graph. If I have the pyrometer in High Speed Transmit mode (which is the mode I need it in), I can't read the signal at all. How can I get LabView to continuously read (and record or graph) the incoming signal? And is there some way to parse the signal when it comes in as a string with " 'time' 'emissivity' 'temperature' 'corrected temperature'"?
I'm very new to LabView (and programming in general), so any hints on a good starting point would be appreciated.
Solved!
Go to Solution.progers - There is not a specific solution, as there is not a device driver for this device (assuming you are also using a pyrometer).
There are serial communication examples in LabVIEW, by going to Help >> Find Examples >> Hardware Input and Output >> Serial.
You will need the programmer's manual for the device to know what serial commands to use to talk to the device (see Dennis's post above).
Best Regards,
K. Anderson
Applications Engineer
National Instruments -
Décaller un signal dans le temps
Bonjour,
Dans ma programmation, je récupère deux signaux provenant de deux détecteur selfique installé à 180° l'un l'autre avec un rotor ferromagnétique en leur milieu.
Les signaux que je récupère sont en opposition de phase. J'aimerais pour les comparer entre eux, que les signaux soient en phase. Mais je n'arrive pas à faire ce bout de programmation...
J'ai déjà essayé en rajoutant Pi au signal en passant par sa FTT, mais celà ne marche pas car mon signal n'est pas purement sinusoïdale. Sur le programme en pièce jointe il y a le complexe conjugée pour déphasé, celà marche mais a des moments il se désynchronise (cf Essai).
Merci d'avance pour vos réponses et d'avoir pris le temps de lire ceci.
Cordialement Julien.
Pièces jointes :
Programme.docx 67 KB
Essai.docx 43 KBBonjour,
si vous passez par des waveform, il est possible d'utiliser la fonction "aligner des waveforms".
Cordialement
Cordialement
L.MICOU -
UVerse TV continues to lose signal at the exact time everyday
I recently called in with problem with my receiver and they sent me a new one. I have installed the new one and it is worse than the other one. Since 1:01am I have not been able to watch tv. It continually loses signal and about a minute later it regains it only to stay on for another 30 sec to 1 min to lose it again. Several times it has told me that network settings has changed and it needs to restart, so I restart it and it does it again. This happens every night at the exact time and continues for atleast an hour. I have gone thru all the troubleshoot online help where it has restarted my receiver and my gateway but yet again the next night it happens again. Can someone please help! Thanks
It is a wireless receiver and it is only one receiver that is affected.
My internet access still works and it is at 1:01am everyday and does it for about an hour. The lights are still green from what I have seen, but it goes on and off so frequent that it's hard to know. There is one light I saw say go off on the WAP, so I unplugged it for 10 sec and plugged it back in just for it to do it again. I have reset the gateway, receiver and DVR and nothing fixes it. -
My new iMac continually drops wireless signal
Anyone having issues with their imac continually dropping the wireless connection?
Well the solution was short lived and after leaving the laptop in sleep mode for a couple of hours the problem was back. Originally I was told to copy my system configuration folder ontop the desktop and restart my computer. With this only being a short term fix I called back again this afternoon and I was walked through setting up a new location which included adding 2 dns server addresses (208.67.220.220 & 298.67.222.222). Once again this was a short term fix. The next step I was advised was to change the channel of my rotuer. According to the apple advisor they have some reported sucess with users changing the router channel from automatic or 1 to either 6, 9 or 11. I've just changed mine to 9 and after resetting the router and laptop it seems to be working again (longer than it normally lasts). If this fails I guess I will try changing the router to the other channels suggested and if that doesnt work the next piece of advice was to re-install the OS. Interestingly a friend bought the same mac book pro as me and his is working perfectly fine even when sharing the same connection. Very fustrating! Good Luck.
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Pour mon application, je suis obligé de mesurer le temps d'évolution d'un signal acquis (de t1 à t2) par une entrée analogique d' un module NI 9203, et comparer cette valeur avec une valeur connu afin de juger si ce temps d'évolution est correct ou non.
J'espere que vous me donner un exemple qui figure la situation citée ci-dessus.Hello.
To get an answer on this part of forum you should post in English. Another possibility is to post on the french forum here.
Could you explain us more which problems you have? Could you attach your code and explain to us where are you bloked? It should be helpfull.
Thanks in advance.
Best Regards.
Message Edité par R_Duval le 04-23-2008 12:14 PM
Romain D.
National Instruments France
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NIDays 2010 : Conférence mondiale de l'instrumentation virtuelle
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Continuous square wave signal with time high pulses between 1 and 2 ms
Hi,
I need to generate a wave signal with time high pulses between 1 and 2 ms. I am trying to use the pwm on a digital output (Inhibit) but nothing happens.
I am using a PCI7330 and UMI 7764.
My labview version is 8.2.
Does someone have an example how to generate it?
Best regardsHi,
I need to generate a wave signal with time high pulses between 1 and 2 ms. I am trying to use the pwm on a digital output (Inhibit) but nothing happens.
I am using a PCI7330 and UMI 7764.
My labview version is 8.2.
Does someone have an example how to generate it?
Best regards -
3gs reception issues. Continuously searching for signal- WHEREVER I GO
I have been having an issue with my 3GS. Last week it suddenly started showing me NO SERVICE or showing some bars, but the circle would be spinning non-stop in the corner next to the ATT 3G symbol. Can't make or receive any calls. Tried restoring phone to factory settings which worked for about 4 hours, but now its doing it again. Any ideas on how to fix?
Have you tried reseating your SIM card? Clearning your sim card? If that fails, replace your SIM card.
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Problems Scaling a Signal with a FPGA!!!
Hi!!! I am working with this system:
1) NI 5761 The ADC Module:
Sample rate: 250 Ms/s
14 bits of resolution
4 channels simultaneously sampled
2) NI PXI-795xR:
FPGA Xilinx Virtex-5 SXT
Recomended for high-speed digital signal processing
Continuous filtering is a typical application
3) NI PXIe-1073
Chassis with 5 slots for the NI Cards.
MXI-Express controller integrated to link with the host computer at least at 208 MB/s
And I am trying to sacale a signal but I get something extrange. Anyone know what is happening?It is hard to tell from the picture you have shown. It appears like you are trying to scale by half, but that perhaps every other sample being returned is zero. Without knowing more about how you are trying to scale the data it is hard to guess as to why you are seeing this behavior.
The NI 5761 adapter module has a few different CLIPs: Single Sample, Multi-Sample and Low Speed. Which one are you using? Did you start with an example program such as "NI 5761 Getting Started"?
The Getting Started example uses the Multi-Sample CLIP, and packs two samples per cycle into a FIFO to pass back to the host.
The raw binary data is unpacked and scaled to volts in the host VI. Are you attempting additional scaling inside of the FPGA code or at the host? Are you working on two samples in parallel to scale both samples from the Multi-Sample CLIP? Check for the data types within your scaling algorithm (U16, U32, I16, I32 ?) to make sure you aren't inadvertently coercing the data to cause the problem. If you are still having difficulty, perhaps you could post the VI or a picture showing what you are doing, and also provide details on how you need to scale the data ( simple multiply/divide by power of 2, linear etc).
Attachments:
GettingStarted.jpg 205 KB -
Why is the Analog signal from the FPGA is distorted?
Hi,
I am using the PXI-7831R board with LabView 2010. I'm trying to transmit TDMS files from the computer hard drive via the analog output of the 7831R. I've used the "Basic DMA output - R series" example and replaced the generated signal with a TDMS file. When I tried it on a synthesized pure sine file, it transmitted the positive part of the sine wave (which was a little distorted) but instead of the negative part I saw 0V DC. When I tried to use a "real" TDMS file (that I sampled earlier) the signal came out completely distorted. In both cases I used a graphic output in the host VI and checked that the data coming from the file is ok. Can anyone help me with that?
I would also appreciate some explanations on the "Update Rate" block (I suspect that he's the one causing all my trouble) - how am I supposed to use it and is it mandatory?
Thanks in advance.It sounds like when you are using the sine wave, you are clipping the data. I am assuming that this is because you are sending it negative values. R-Series cards can not handle fixed point values, so try to offset the signal so that the lowest point of the signal is at 0. See how that works for you. As far as the Update Rate goes that controls the speed of your loop. If you do not set it high enough, the loop will simply run as fast as it can. I hope you find this helpful.
Brandon Treece
Applications Engineer
National Instruments -
High Speed Clock Signal Generation Using FPGA Ouput
Hi,
This a screen shot of a LabVIEW FPGA program. Here I am trying to generate 5MHz Clock signal at Connector 0 DIO12. But I get around 2MHz when I measure the signal using an oscilloscope. Would some tell me what’s wrong ?
LabVIEW 2011
FPGA Target : PXI 7841
I set DIO 12 to Nerver Arbitrate in the property setting.
Solved!
Go to Solution.I'm not certain but maybe some of the delay is happening because you are changing the mode of the pin. According to the specs on the card it is capable of having a Maximum Clock Rate of 40MHz under the DIO section. So if you are purely doing digital reads, or digital writes you should be able to update/read 40,000,000 times a second. If you perform a read, which can take up to 1/40M of a second, then invert which takes some time but practically none, then another write which can take up to 1/40M of a second, your loop rate should still be faster than the 10MHz you showed. That's why I suspect there is time involved in changing over the pin from a read mode to a write.
If you try to do something similar with the analog you'll notice the maximum update rate is only 1MHz. So while your logic and code can run at 40MHz you can only update the analog value at 1MHz. Because of this in the past I have had two loops. One running a at the maximum clock rate doing the logic calculations, and then sending the result to another loop that updates the output at the maximum rate which in the case of an analog out is only 1MHz.
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If 10 out of 10 experts in any field say something is bad, you should probably take their opinion seriously. -
Calculer période signal avec labview FPGA
Bonjour,
je cherche à calculer la période/la fréquence d'un signal d'un couplemètre avec sortie fréquentielle < 5-10>kHz, en utilisant le labview FPGA.Bonjour Addoula,
Merci d'avoir posté sur le forum National instruments.
Pour réaliser une mesure de fréquence ou de période, il est courant d'utiliser un ou plusieurs compteurs.
Au lien ci-dessous, vous trouvez un document expliquant les techniques pour effectuer ce genre de mesure:
http://www.ni.com/white-paper/7111/fr/
Pour réaliser un compteur avec labview FPGA, le document suivant vous montre un petit exemple:
http://www.ni.com/white-paper/2993/fr/
Bonne journée.
Cordialement
Aurélien Corbin
National Instruments France
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Cahiers de vacances de NI
Présentations en ligne : 12 fondamentaux à réviser, du 9 juillet au 29 aoû... -
Generate analog signal using samples fpga
Hi,
I have 20 samples of (time,data). using these samples i need to write data to AO channel in FPGA card. Here the data should be written to a channel w.r.t time. i need to generate signal(ramp) based on time and data available.
for example -
time( in seconds) - 0 0.01 0.04 0.05 0.07 ...
data - 0 1.0 3.2 2.5 1.3 ...
Please suggest me best way to achive this.
Thank you,
RanjithKeep all ur samples in a array and auto index the array to a for loop, Inside the for loop put a wait timer and give the dt as input(t2-t1) to the timer. Inside the loop connect the auto indexed output to the A0 Channel.
Balaji PK (CLA)
Ever tried. Ever failed. No matter. Try again. Fail again. Fail better
Don't forget Kudos for Good Answers, and Mark a solution if your problem is solved. -
How to take a derivative of a signal in Labview Fpga
How to make derivative of a position signal acquiring using AI module of cRIO to get the velocity signal.
I got one example in forum and i m attaching that, bt i need to implement this in FPGA.
Note : The position is varying at 30Hz to 80Hz Freq.
Attachments:
derivative.jpg 48 KB
derivative.jpg 48 KBI forgot to mention that one problem with numerical differentiation is that if you have a noisy signal, the noise is amplified!
You can try implementing a moving average or median filter in the FPGA code. There are a number of previous threads and Community posts on these, ranging from simple implementations to more complex ones. Try using the search function at the top of the page to look for them.
Of course, it's easier to acquire the raw data, send it to the RT host and do your processing there, depending on resources.
Regarding the sampling time, you have hopefully set this via the tick delay you set in the FPGA acquisition loop.
CLD
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