Frequency of signal from anemometer

hello,
I 've to the output of an anemometer, an AC voltage whose frequency is related to the wind speed. unfortunately I did not get my signal frequency. I'm using the CompactRIO 9074 with NI9221 module. I see my good signal but I can not seem to extract its frequency. Have you any idea of VI? This is urgent.
Thank you.

Hi,
I put a screen capture of the code as an attachment. I read my signal from the anemometer on the AI2 port NI 9221. For my range-measuring sensor, I have to measure frequencies from 0 Hz to 125 Hz. Documentation of the anemometer is attached too.
Thanks
Attachments:
code.jpg ‏65 KB
NRG40C.pdf ‏121 KB

Similar Messages

Measure Frequency of Digital Signal from DAQ-Board

I'm using a National Instruments DAQ board and I need to measure the
frequency of a digital signal from my data acquisition board.
I know the measure frequency.vi (In diagram - data acquisition -
counter), but i don´t understand yours implementation mainly in input
"counter". Because i don't understand the relationship of board channel (for
signal acquiring ) and the measure frequency.vi.
Thanks in advance,
[email protected]

Hi,
Attached is a vi which models your signal, and provides a way to measure the average frequency over a window of time. It converts the signal to a sequence of periods. I usually start with this approach because you can save the data in a much more compact form if your sampling rate is high. Obviously over a specified period of time, if there are no zero crossings the frequency is zero, so I was a little incoherent before. The real issue is the latency caused by averaging. Your frequency measurement is most accurate half your window size before the current time, so smaller windows give you more up to date measurements, but also more noisy. If you need the most up to date measurement, then you have to use the time since the last crossing which is the case where the frequency never goes to zero. That's probably not a realistic situation. If you needed less latency, you could use a prediction algorithm.
Also, there are a number of signal measuring and processing vi's that LV gives you, for instance pulse measurements that could be used to partially implement this or other approaches, but I normally steer clear of them unless they fit exactly due to having to convert back and forth to the waveform data type.
Have fun!
Attachments:
DigRandFreq.png ‏62 KB
DigitalRandomFreq.vi ‏34 KB

Is it possible to use "Delay Values" to create a frequency signal from digital "Count Edges" -task? (= are the results I'm getting correct?)

Hello.
I have a digital encoder from which I need freaquency information (to ultimately get rpm -infromation). The problem is that this task is inside a loop with 2 other DAQmx -tasks that are using "one sample on demand"-aquisition mode and if I configure this new counter task to be a freaquency task, it only updates once in ~ second which makes the whole loop lag.
I thus created an "artificial" freaquency signal by using "Count Edges" -aquicition mode and the "Delay Values" -block so that I substract the delayed signal from original "Count Edges" -signal. There is a 0,01s delay in the loop and I figured out that if the history of the "Delay Values" -block is 100 samples I would thus get the real edge-freaquency.
I tested this configuration and the results seem to be at least really close to correct but I have no idea if this idea is in any way correct...
This explanation was probably quite confusing so please see the picture attached.
Thanks a lot in advance!
Attachments:
are_the_results_correct.jpg ‏200 KB

First of all, thank you for quick reply. Unfortunately I don't have the acces to the vi. until tomorrow.
And yes, I think you understood correctly: essentially this arragement measures how many edges have been counted during one iteration. This is how I figured out that this could then be used as a frequency measurement:
1. From the "Edges - Delayed Edges" I get the information on how many edges have been counted during last iteration.
2. I "know" (really I don't?) that one iteration lasts ~0,01s because of the delay in the loop.
3. There is 2048 edges in one round of the encoder so I get the rpm as follows: rpm = (edges - delayed edges)/204,8*60(s)
(If I was using history size of one as you suggested it would be: rpm = (edges-delayed edges)/2048 * 60) However using history size of 10 and taking it account in the multiplication smoothens the response nicely.
But doesn't this arragement count on the fact that the vi runs smoothly and there is no additional lag?
I quess using another loop and notifiers for a dedicated freaquency measurement as you suggested could be worth trying. I just have to first learn how to use them.
If I do use them will the main loop run smoothly and not wait for every update of the notifier? This would be essential since the freaquency output refresses only about once in a second if I use the continious aquisition mode.
Attachments:
are_the_results_correct.jpg ‏198 KB

Transfer 20MHz signal from FPGA to RT

Hi all,
I am a newbie to Labview and FPGA programming... I am using NI PXIe-8133 Controller card and NI-5781 FlexRio card. My task is to take input of 20 MHz external signal and then process it further... I have to transfer that signal from FPGA to RT with the use of FIFO (that is what I understand). I referred the following example and succeeded in transferring a low frequency signal (range of KHz) from FPGA to RT as the sampling rate is in micro seconds.
http://www.ni.com/white-paper/11198/en
But I want to have sampling rate in nanoseconds if I want to take a signal of 20 MHz. How can I achieve that? Is there any alternate method apart from FIFO to achieve that task?
I am a starter in Labview, your help will be appreciated...
Thank you....

Hello Jimmie_A
Thank you very much for your help. The example really helped me to understand the input/out operation.
My application is to take a 20 MHz 'Phase Modulated' signal to FPGA and demodulate it. As a first step i want to take any arbitary signal of Mhz range and examine it if i am getting any phase noise or any other change in attributes.
I tried to give input signal to FPGA transferred it to RT and plotted it. Also from RT i sent the signal again on FPGA out pin to check on Oscilloscope and compare with the given input signal. Now my problem is I can see the signal on the RT signal plotter but I am not getting any signal back on FPGA pin. I have used Two different FIFOs for Target to Host and Host to Target communication.
It will be helpfull for me if you comment on my designed program for the said purpose. Here I have attached the screenshot of RT front panel. Also attached my FPGA and HOST vi files.
Thanks alot....
Attachments:
Host.jpg ‏141 KB
FPGA.vi ‏58 KB
Host.vi ‏400 KB

Converting audio signals from mydaq into discrete values

Hi guys!
I am currently building a project that accepts audio signals from mydaq. I wanted to make the analog signals have it descrete peak values. Is this possible? I plan to use the discrete peak values and sum them up using a shift register instead of doing peak detection. I think it is more easy.
Any suggestions would help. Thank you very much!
.."in the end we all have false hopes"..
Solved!
Go to Solution.

FalseHope wrote:
Well actually, i wanted to make the acquired signal have its discrete values because i will use the number of peaks of the sound to determine which sound is louder (my assumption is that, the louder the sound or the nearer the sound to the microphone. The more sound peaks can be acquired. While lesser peaks are acquired the least louder the sound).
That is wrong (unless you are dealing with Doppler Shifts, but they implies the object is moving). Closer peaks mean that you are dealing with a higher frequency (or pitch). Louder sounds just have higher amplitudes (larger peaks).
FalseHope wrote:
I will acquire sound signal from the mydaq, then detect the peaks and add those peaks while it is entering the acquisition. I wanted to make it discrete so that i will be able to add the numbers and the addition will stop once the sound is no longer present. The sound im talking about is a sound burst. Or a single instant sound and is not continuous.
Just use the peak detection function. You can then add whatever peaks it finds from the current acquisition.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines

Generating frequency hopping signal

I'm working with 5661 + 5671.
I want to generate frequency hopping signal with 5671. The frequency band is 2400-2500MHz, and the hopping rate is one hop per frame (1.024ms) or 976 hop per second.
I also need to be able to test the hopping signal with 5661 RFSA.
Does it possible to run such hopping test with the 5661+5671?
Thanks,
Chen
Solved!
Go to Solution.

HI
I want to generate a hopping signal with PXI-5671 RFSG and want to analys with PXI-5660 RFSA. While seaching for the related posts i came across ur post, The frequency range in my case is between 200-300Mhz but i will use 200-220Mhz due to BW of 20Mhz...the hopping rate i wil use is very slow as compared to urs..i m trying to do this with 10-20 hops per second..
I m new with the hardware i have used it to generate and analyz the signals but stil unable to generate the hopping signal with predefined hopping sequence and hopping rate...
can you guide me that how to do this????or can u give me a copy of ur VI so that i can learn it from ur program and regenrate with my specs to chk weather it works or not...??
I wil b realy thankful if u can help me in anyway....
REGARDZ

Generate and acquire signals from Walkie Talkies

Hello, i am a Portuguese Student and i have some problems in a Academic Project.
The following project consists in two Walkie Talkies that are link to a USB 6009.
One of the Walkie talkies are attached do AO0 and ground with the objective of generate a signal to the 6009 then the other Walkie talkie connected to Ai0 and GND have to acquire the same signal that i generate in the other one, this two signals have the main problem that needs to be represented in the same Chart or Graf.
Please can anyone help me in this question and send me a (vi), i would greatly appreciate.
something send me a post or email for [email protected]

Hello Lynn,
Sorry about the late response, but only today i have access again to the USB 6009 in the LAB.
In below are the graph from the input signal, the first is the graph from the Walkie Talkie (receiver) when the button from the Walkie Talkie that send the signal are not press. What we see is only noise and others frequency's.
In the other graph we can see a different graph this graph is from the Walkie Talkie (receiver) but when the button from the Walkie Talkie that send the signal are press where we can see that is a different kind of signal and the receiver are ready to receive the signal and are receiving some signal from the other walkie talkie.
First I need some help for this first steps
1- But how can I generate a signal wave and send it from the other Walkie Talkie (transmitter), I used a Basic Function Generator
2-How can I see in the Walkie Talkie (receiver) if he receive the Signal that I generate in the transmitter, The graph changes of frequency and amplitude always that I press the button of the transmitter Walkie Talkie.
3-How can I put the two signals in the same chart or graph, The main problem is like you said the USB 6009 is too low sending signals.
Sorry my English, I appreciate any help
Thanks
BTP
Attachments:
input data.png ‏33 KB
input receber.png ‏37 KB

Glitches on digital signal from 5751

I am driving four LMH6574MA multiplexers with digital signals from NI-5751 digitizer (running on NI PXI 7953R FlexRIO). There are glithches on all the digital signals (signal frequency is 40 MHz). Is there a way to clean these signals up in software?

Did you place the AI node in the IO Mod Clock 0 clock domain?
If you don't have those analog input nodes inside of the correct clock domain you'll be performing an unsafe clock crossing that will result in glitching.
The user manual walks you through how to add the IO Module Clock 0 to a project. Or you could start from the getting started example.
National Instruments
FlexRIO Product Support Engineer
Attachments:
CLIP help.PNG ‏32 KB

Integrating a frequency domain signal

Hi
I am trying to extract the response of a frequency dependent signal :
1. First, I use the SignalFFT vi to get into the frequency domain.
2. Then I plan to integrate the FFT signal around a certain frequency and take a ratio of that wrt to the integral over the entire frequency spectrum to get a measure of how strong the signal is around that frequency.
I am choosing a range of frequencies above because the physical phenomenon producing the time domain signal produces a certain lifetime width. I need a numerical integration VI that can do step 2 above. The numerical integration VI that I found in Labview (using ver. 7.1) integrates the whole signal, and there is no way to define limits between which the numerical integration should be carried out.
Any ideas ?
Thanks.

That a cool question!
This has to do with the sample rate, when you adquire the signal, you get set of samples, that hava a sample rate, and when you do an FFT on those samples, every sample corresponds to frecuency bin (kinda of frecuency samples). Example:
If you get 100 samples at 1kHz, you will get a 100 windows, this is 100 samples to represent 1kHz, however, only the half of the spectrum is valid, because of the Nyquist teorem, so this mean that from 0 to 49, you have a correct representation, from 50 to 99 you have a reflection of the spectrum. So in the first 50 "frequency samples" you have 0-500Hz
Tania Lozoya

Wireless signal from iMac to TV?

I have a new 20" iMac G5 isight on the way and have a question. Has anyone tried to hook up the iMac (or other mac) wireless to your TV. There is products like this www.amazon.co.uk/exec/obidos/ASIN/B000068TYR
ref=erra_acc_dp1/026-6032989-4654855 that will send a signal from your antenna to your TV wirelessly. I thought mabye in combination with a TV tuner like EZ there would be a way to get the signal from the mac to the TV. That way I dont have to drill a cabel-hole in my livingroom floor down to my office to enjoy FrontRow on my TV. Or is there any other solutions/suggestions?
(And i dont think there will be an Airport Express A/V launched next week... though I wish!)

You should be able to connect your ATV directly to your iMac using Internet sharing, but you can't use the same NIC that the iMac is using for its connection. If your iMac is connected to your router by wi-fi, you can share the Ethernet port with the ATV. If your iMac is connected to your router by Ethernet cable, you can share your iMac's AirPort with the ATV.

How to read and display a signal from my a miccrontroller (MCB1700) onto labview connected via a CAN port on a PXI machine

How do you read and display a signal from my a miccrontroller (MCB1700) onto labview connected via a CAN port on a PXI machine?
I tried using a DAQ Assistant but the CAN port is not included as one of the supported physical channels even though all its drivers are upto date.
Please help..
Thanks.
Solved!
Go to Solution.

Attached herewith is a print screen of what is showing on MAX
The CAN ports are on NI PXI-8461
Hopefully that clarrifies something.
Attachments:
Untitled.png ‏212 KB
Untitled.png ‏212 KB

How to read and display a signal from my PIC Microcontroller onto Labview?

Hi,
I am doing a project on a Pulse Oximeter and i am trying to read and display the signal from my PIC Microcontroller on Labview? How do i go about doing it? I am using the PIC16F877 and also making use of the USART?
How do i implement and initialise the USART in PIC16? What are the steps to be taken, please guide me through the process? The link provides information regarding the USART connection, initialisting and stuff? Is it correct to use these codes in my program?Link: http://ww1.microchip.com/downloads/en/AppNotes/00774a.pdf
Also, i am using the RS232 serial interface to connect to the PC? The connector i am using is the DB9 Connector. Which template and VI can i use? Am i supposed to use the NI-DAQmx and VISA? Also, for my USART connection, i am using the MAX232 Driver which is applicable for my application as i am working with +5V. So far, i have been reading and trying out on Labview and the steps i have taken are:
1) Open a New VI and used the Instrument I/O(Read & Display) template?
2) How do i configure the Instrument I/O Assistant Express VI to read the info from my device connected to COM1?
3) I was reading the Labview Manual, 'Getting Started with Labview' and i was following the steps under Page 55, Communicating with an Instrument. Am i on the right track?
4) How do i check and make sure that the port settings of the I/O Assistant and my PIC Micro Match
Please help me out and guide me through the process. I am student at a polytechnic and i am very new to Labview and the software is used as a development tool for the project. I have a deadline to meet and i hope i can get a response as fast as possible. Your help will be kindly and greatly appreciated. I hope to hear from you guys soon.You can e-mail me all your answers at [email protected]
Thank You
Best regards,
Ashwin
Ashwin Kumar Mansukhani
Attachments:
Getting Started with Labview.pdf ‏901 KB

Hi Ashwin,
It is a good idea to first be able to communicate with the microcontroller using some sort of serial communication software such as "HyperTerminal" or "Procomm", etc. Refer to MicroChip's recommendations on this.
Once that works, then you are ready to use LabView.
Here is a link which covers many aspects of serial communication. Link - click here
You probably received a development kit. They usually have a readily available interface. It's been a long time since I played with the PIC, but I seem to remember that you need to program the serial communication driver (as well as at least a bootloader) to get the serial communication going. The driver contains the necessary protocols so that you PC can have a machine conversation with the target (PIC).
It sounds like a fun & interesting project. Please avoid to have replies to your personal email. By having the answers posted to this thread, you will get much more support and advice.
Have fun,
JLV

How to read and display a signal from my PIC Microcontroller onto Labview

Hi,
I am doing a project on a Pulse Oximeter and i am trying to read and display the signal from my PIC Microcontroller on Labview? How do i go about doing it? I am using the PIC16F877 and also making use of the USART?
How do i implement and initialise the USART in PIC16? What are the steps to be taken, please guide me through the process? The link provides information regarding the USART connection, initialisting and stuff? Is it correct to use these codes in my program?Link: http://ww1.microchip.com/downloads/en/AppNotes/00774a.pdf
Also, i am using the RS232 serial interface to connect to the PC? The connector i am using is the DB9 Connector. Which template and VI can i use? Am i supposed to use the NI-DAQmx and VISA? Also, for my USART connection, i am using the MAX232 Driver which is applicable for my application as i am working with +5V. So far, i have been reading and trying out on Labview and the steps i have taken are:
1) Open a New VI and used the Instrument I/O(Read & Display) template?
2) How do i configure the Instrument I/O Assistant Express VI to read the info from my device connected to COM1?
3) I was reading the Labview Manual, 'Getting Started with Labview' and i was following the steps under Page 55, Communicating with an Instrument. Am i on the right track?
4) How do i check and make sure that the port settings of the I/O Assistant and my PIC Micro Match
Please help me out and guide me through the process. I am student at a polytechnic and i am very new to Labview and the software is used as a development tool for the project. I have a deadline to meet and i hope i can get a response as fast as possible. Your help will be kindly and greatly appreciated. I hope to hear from you guys soon.You can e-mail me all your answers at [email protected]
Thank You
Best regards,
Ashwin
Ashwin Kumar Mansukhani
Attachments:
Getting Started with Labview.pdf ‏901 KB

Hi Ashwin,
I am not familiar with the PIC Microcontrollers, but I am assuming you mean that you have the microcontroller sending out serial data that you want to read on another computer with LabVIEW. Please let me know if this is incorrect.
What type of data is coming out of the serial port? Is it ASCII, or binary? The reason I ask this is that the serial communication in LabVIEW is done through a protocol called VISA, which uses ASCII data to send and receive. You can later convert this data into whatever form you need, but this is what it is designed to read and write.
You can check the settings such as baud rate and data bits in a configuration utility called Measurement and Automation Explorer, or MAX. When you open up the MAX interface, you can expand the Devices and Interfaces entry on the left, and then expand the Ports entry to see your serial port. When you highlight this port, select the Port Settings tab at the bottom of the window, and you can see what the current settings are, and change them if you need to. You can also set these parameters in LabVIEW using the VISA Configure Serial Port VI.
You can also test communication in MAX by right clicking on the correct port and choosing Open VISA Session. Then choose the Basic I/O light blue tab, and then go to the Read tab. When you click execute, it should read in what is coming from the serial port. This will allow you to verify that the correct information is coming in before even trying to acquire the data in the LabVIEW environment.
In LabVIEW, the best resource to use the Basic Serial Write and Read example program that ships with LabVIEW. By examining the block diagram of this program, you will be able to see the basic programming flow of serial communication in LabVIEW.
I hope this information was helpful! Please let us know if there's anything else we can help with.
john
Applications Engineer

How to compare signals from two different .tdms files?

i'm developing a lie detection system in labview.so inorder for that i need to compare the threshold physiological signals from the .tdms file with the signals i acquire continuelsy from the subject for each question asked.i use respiration monitor and heart beat monitor together with the sensorDAQ to acuire the physiological signals.so which are the function i should make use of?i have the following toolkits
1. advanced signal processing toolkit
2. adaptive filter toolkit
3. digital filter design toolkit
4. biomedical toolkit
please give me advise on this.
thank you.
Solved!
Go to Solution.

Lie detector systems (polygraphs) generally work by looking at the physiological responses to the own subjects baseline, and do this in real-time. You could use a file that represents the stored "baseline" for the subject, but the overall environment, circumstances, general state of the subject, etc. may not be similar enough to easily see subtle changes.
From the stored file, you might determine a set of parameters or thresholds that indicate "normal, relaxed" for each signal. You could read the file into your LabVIEW program, process each channel, and save these parameters. Then when you have the new data, you can read the new data file in and process it in a similar way and then determine whether the parameters are outside the limits that you established for a "lie".
You may get more responses to this question if posted in the Biomedical User Group
Visit the NI Biomedical User Group at:
www.ni.com/biomedusers

How can I tell if signals from two devices are truly synchronised?

Hi there,
How does one check that signals from two devices (two separate devices in a single X-series chassis) that should be synchronised actually are? I am using a PXIe6361 and PXIe4331 on a PXIe-1073, with Labview 2001 SP1 64-bit. All devices are using the Sample Clock from the 4331 device, and an AI Start Trigger, so they should be synchronised.
I thought that writing the signal data to file and checking the time stamp for each column of data would be the most accurate, but I have been told that timestamps are software created and therefore don't reflect the actual time that the signals were acquired by the hardware. When I do this, the timestamps vary by up to 150ms which is larger than I expected.
If I set the x-axis of the waveform graphs (on the GUI) to "Time" then it appears that the first data sample is taken at different times for the two plots (one plot per device).
If I set the x-axis of the waveform graphs (on the GUI) to "Ignore time stamp" (so that the x-axis just starts from 0 rather than a date-time) then the first data point occurs at "0" for both graphs. However, I'm not sure that this reflects the actual alignment of the signal.
What is the best way to check if signals collected on different devices in the same chassis are actually synchronised?
Thanks,
Claire.

Hi Lynn,
Thanks for your help and for sending the demo.
I understand the concept of how the signals will look if they're not synchronised and your demo shows that nicely. I guess I have been perplexed by someone else telling me that the timestamps in the output file (and following from that I assume timestamps on a waveform graph) do not give an indication of whether signals are synchronised. The reason they gave for this was that the timestamps are manufactured by the software, not the DAQ hardware. They suggested that I put the setting "ignore waveform timestamps" on my waveform graphs, and then check that both signals come in at the same time (i.e. both start at zero), but I'm not convinced about this.
When I use an analog trigger, neither the timestamps in my output file or on the two waveform graphs are synchronised. If I don't use the trigger, then there is far less disparity in the timestamps in the output file. I've attached two output files here, and my VI.
This is my first attempt to synchronise a voltage module and a strain gauge module on an X-series chassis, so I want to make sure that I'm achieving the best synchronisation that I can, and the difference in behaviour with and without the trigger worries me.
Thanks,
Claire.
Attachments:
without trigger.txt ‏5 KB
with trigger.txt ‏6 KB
Multi-Device Synch-Analog Input-Finite Acq-Analog Start_Claire_wDigitalin_12June2012 PTbridge.vi ‏196 KB

Frequency of signal from anemometer

Similar Messages

Maybe you are looking for