Problem on Normalized Frequency to original analog frequency

I'm having a problem regarding normalized frequency.
The Sine wave .vi, says that the input to the frequency must be a normalized frequency. What I did is tha I divide my frequency to the number of samples.
However, when I attached Tone Measurements to output signal of the sine wave, I'm not having a frequency of what i set.
In my example my input frequency is 60 Hz however what was detected by the tone measurement was the normalized frequency which is 0.06.
How do I modify this VI, in order that i will have a frequency in 60 hZ,

The problem with trying to calculate a frequency is that you need a time element. You don't have a time element. So I'm thinking 1 sample/second is used.
Try using the Sine Wave.vi (it is in the Signal Processing->Waveform Generation palette). With that function, you need to supply the sample rate and the actual frequecy that you want.
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Problem with normalized frequency on fft

Greetings
I have a problem when working with vi fft Spectral measurements, when acquiring an analog signal , the frequency of this switch to a digital frequency affected by the sampling rate, and hence the frequency axis ( of a waveform graph) gives incorrect, how can I multiply the digital frequency by the sampling frequency to obtain the original analog frequency?
how can I save as a text file in 2 columns (frequency and magnitude in db)? I tried to write with 'WRITE measurement FILE' but shows a header file and the columns are time and value, there is another way to store this data?
thanks

greetings and thanks for answering
attached the vi I'm using, the questions are 2
1. How can I multiply the frequency of the signal by the sample rate to get the right analog frequency for example (if the sample rate is 1000 for a frequency of 60 Hz , i got 0.06 Hz observed on the waveform graph)
2. How can I get a flat file without a statement at the top with 2 columns frequency and magnitude db
thanks
Im using labview 7.1
Attachments:
channel.vi ‏211 KB

How can I measure the frequency of an analog signal?

Hi, I am trying to measure the frequency of VAC signal coming from a gas turbine engine at my university. If I can get the values of frequency, I can determine the speed (RPM) of the engine. I am fairly new to LabVIEW and I have been looking through manuals like crazy in order to find out how to obtain the frequency. I have measured the signal with an oscilliscope and the highest frequecy will be about 1.5kHz. I am currently using a USB-6218 and it can collect the voltage signal with ease, but it won't give be analog frequency so simply. Can anyone explain a way for me to obtain the frequency values? And if you could show or tell me in a very simple way (because I am not very fluent in LabVIEW yet), that would be amazing! Thanks!

Check this out:
Attachments:
RPM.vi ‏17 KB

Very low frequency caused by sample frequency in FFT analog input?

I'm measuring a very low frequency on my analog input, this frequency is in connection with the sample frequency of the Analog Input. At a sample frequency of 1000Hz I see a frequency of 0,05Hz in my FFT, at a sample frequency of 500Hz I see a frequency of 0,02Hz.
Attached is a screenshot of an example how I see this very low frequency.
My hardware: NI USB 6008 --> measuring on AI-0 (in this example the input is unwired). But in my real measurement I see the same FFT + signals I want to see (about 2 Hz).
In my real measurement I windowed the FFT (1-3Hz) so I see only the FFT I want to see. But I suspect that my complete signal moves along with this very low frequency of 0,05Hz. I saw this in my measerement.
What did I do wrong?
Attachments:
screenshot.JPG ‏66 KB

First, do you live in Europe? If so, that 50Hz could be power-line pick up.
Antialias filtering must be done in hardware before the DAQ. Because of the way aliasing works if you have sampled the signal it's already too late, you're hosed and no amount of digital filtering can remove the aliased signal. In terms of filter specifications, the filter cutoff needs to be at twice the highest frequency you are interested in seeing. For example, if you are looking for signals in the 2- to 5-Hz range, your antialiasing filter should cutoff at around 10Hz.
Obviously good signal management is also needed: shielding, appropriate signal termination, proper lead dress and spacing from known noise sources, etc...
Mike...
PS: There were no attachments to your last post.
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Problems with Photoshop CS2 I originally purchased this software several years ago. At time I was running Microsoft Windows XP. This computer recently was replaced with a Dell running Windows 8.I reloaded my CS2 on this computer & it ran fine with a few

Problems with Photoshop CS2
I originally purchased this software several years ago. At time I was running Microsoft Windows XP.
This computer recently was replaced with a Dell running Windows 8.I reloaded my CS2 on this computer & it ran fine with a few exceptions as follows;
when the software comes up initially I get a message that says “could not complete your request because of program error”. Hitting OK allows me to continue using the software .
When I try to activate a function using CTLR or ALT keys I get this message “required application failed to load and the product cannot continue. Please reinstall the application”. This causes the application to abort.
Reloading my CS2 continues to generate the same messages when I depress the CTLR or ALT keys.

Your original copy is obsolete and Adobe is offering a free replacement you are entitled to. Download and use that and that should clear it up for you.
https://helpx.adobe.com/x-productkb/policy-pricing/creative-suite-2-activation-end-life.ht ml
Download this copy of CS2 and use the serial number provided next to the download link.

Frequency response at low frequency

I'm working on a bandpass filter, and I'd like to get the frequency response showing that the frequencies outside the lower and higher cutoff frequencies are being cut off. However, the correct plot is shown only when my cutoff frequencies are high (roughly from 1000-8000 hertz). When I use low cutoff frequences(roughly 4-5 hertz), the plot is incorrect. So how can I get the frequency response to my low cutoff frequencies? Thanks.
P.S. In the code, some parts are irrelevent. In the front panel, the only relevent part is the frequency response plot at the lower right corner, and the specs above it; in the block diagram, only the upper half(with IIR and FRF) is relevent. Thanks.
Attachments:
BME_Pressure_Sensor_V1.00.vi ‏591 KB

Hi Manson
There is a bug in your diagram since you connected the number of samples where you should have connected the sampling frequency.
The sampling frequency is related to the pace at which you take the measurement.
Usually, Fs = 1 / dT
where Fs is the sampling frequency and dT is the time interval.
It should work better.
In any case, to have a better resolution in the low frequency range of your spectrum computations, you have to increase the number of points of your data because there exist the following relationship between dF (space between 2 points in you spectrum), dT, and N (number of data points) :
dF = 1 / (2 x dT x N)
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Table name with feild Duration of Task/Frequency , Change in Duration/Frequency for maintenance plan

hi experts,
i need a table for maintenance plan which has field
1) Duration of Task/Frequency
2) Change in Duration/Frequency
below i have elaborated my requirements.
among those fields i have got the table name mpos,mpla,plpo except the above listed two feilds.
i have to create a report with these requirements.
anyone tell me in which table can i get that 6 and 7th fields.
Requirement1:
Maintenance Plan Number
Operation Code
Standard Teode(assigned to Plan)
Standard Text Key description
Cost Center
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Change in Duration/Frequency
Created Date
Created By
Changed On
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Requirement 2: layout of the report should be modifiable with the existing fields.
Requirement 3: A transaction will be created to access the report.
Requirement 4: In the report, Maintenance Plan number will be hyperlinked which will divert to AMP screen (display view of maintenance Plan) once clicked on it.
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regards,
priya

can anyone answer for my above question?
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How do I use a counter to measure frequency and multiple analog signals in the same VI?

I have a PCI-6071E, an SC-2345 with multiple modules, and a PXI-8184 (with a PXI-1002 Chassis).
My goal is to monitor pressures, flows, temperatures, and speed in one VI.
I am using Measurement and Automation Explorer version 3.1.1.3004 to manage my channels.
My speed is a PWM signal which I recently rewired through the counter 0 of my board.
I was hoping to configure this to read frequency directly in measurment
and automation, have this scale the value to RPM, and then feed it
directly in to my labView program.
In labView, it will not except this signal though.
I get error -200300 from the DAQmx Start Task.vi
Possible reasons(s):
Invalid timing type for this channel.
Property: SampTimingType
You Have Requested: Sample Clock
You Can Select: Implicit, On Demand
After doing some research, it seems that the counter wants "Implicit"
selected for the DAQmx Start Task.vi, but then I cannot use my other
channels. Also, counter is included in the "Sample Clock" option
description, so I do not understand why it is not working.
Does anyone know how to work around this problem or a way to configure the counter so that it will work in this way?
All my other channels are Analog.
Thank you.

I am working on getting just the counter working by using
the program posted previously, and I am running into issues. Periodically I get
the error:
Error -200141
occurred at DAQmx Read (Counter DBL 1Chan 1Samp).vi
Possible reason(s):
Data was overwritten
before it could be read by the system.
If Data Transfer
Mechanism is Interrupts, try using DMA. Otherwise, divide the input signal
before taking the measurement.
It seems to work better if I use cascaded counters, but I need timer 0 for
analog channels when I run this code along with the program for the other
measurements.
I have tried averaging, and selecting different values for the millisecond
timer, and these did not seem to have an effect.
I tried different DAQms configurations and "Counter DBL 1Samp" seemed
to work the best.
The program will work for a while and then it will give me the above error
message.
If I use counter 0 as a cascaded counter input, the program runs fine. If I run
this with other analog channels, it errors out because the analog channels use
counter 0.
If I use counter 1 as a cascaded counter input, it seems to work better than a
single channel, but it will still error out with the above error.
If I use only counter 1, I get the error above even faster.
Also, none of the
configurations give measurements outside the While Loop.
The only place I can add a speed dial for the front panel is within the While
Loop.
Is there someway to get the signal to continuously send out of the while loop?
I thought if I could get the signal out of the while loop, I could condition it
anyway I wanted without the program erroring out.
Any suggestions would be much appreciated.
Thank you.
Attachments:
Counter_error.jpg ‏45 KB

Phase shift, frequency of 2 analog signals, Diadem 9.0 or 9.1

I have to acquire 2 signals: FORCE (N) and VELOCITY (m/s) for many frequencies parameter in Diadem 9.0 (5 to 150 Hz). This frequency parameter is a analog voltage output signal which is converted in frequency by a frequency vibrator instrument. The measured signals on the vibrator (force and velocity) are considered as SINE Functions. – 1) How do I measure the output frequency of the two signals and how can I save this data ? – 2) How can I estimate the phase shift between FORCE and VELOCITY ? – 3) How can I automate the estimation of the phase shift by the 145 measurement (150-5Hz) ? – 4) Is a continue measurement of Phase Shift depending on the frequency possible ? – Best Regards from Germany and from France.
Jean-Pierre, Junior Engineer Germany

Hello KenT. I have test your DIAdem exemple. Your idea with a stop-time was not bad for measuring the phase shift beetween 2 generators by 1Hz. I have used this formula by many phase shift and it works. I had change the 2 generators frequency by 2Hz, and the formula works not anymore and that is normaly because of the reduce of the periode lenght (this problem have I show on Picture 3 of the PDF Data). On the picture 6 and 7 have I try to make another solution. My new solution works only for frequency from 1Hz to 5Hz. What about frequency like 150Hz ? I don't know if you have understood what I realy want to do, but if you have any idea to resolve my problems, please write to me. '[email protected]'
Jean-Pierre, Junior Engineer Germany
Attachments:
DIAdemTexte.pdf ‏435 KB

Analog Frequency measurement

Hi,
I have this VI to calculate the frequency and I need to use the frequency to calculate my scan rate...But the value of the frequency is required to calculate the scan rate....How do I take the value of the frequency here?Example I need 10000 Hz as the value of the frequency for my further mathematical calculations.Please help
Attachments:
Simple Analog In Freq Meas.vi ‏222 KB

Maybe I'm not understanding your question but I don't see where your problem is. You HAVE the frequency data in an indicator called "Frequency (Hz)". If you need to use it in your code then connect the indicator to the connector pane, drop the subVI into your main VI and wire the subVI's "Frequency (Hz)" output terminal to the rest of your code.*
* If you have no idea what I'm talking about, then look at some basic LabVIEW tutorials and learn how to make subVIs. You can't get far in LabVIEW without understanding that.
Using LabVIEW: 7.1.1, 8.5.1 & 2013

Detect frequency of an analog signal coming in through myRIo AudioIn analog port

I am working on a fire-fighting robot that runs using myRio. I have a small mic plugged into the 'AudioIn' port of the myRIO and the robot has to detect a certain frequency(2.8 or 3.5 KHz) to start navigation. The AnalogIn express VI gives me raw voltage amplitudes of type 'Double' but the 'Tone Measurment' vi I wanted to use takes in a 'Signal' data type. I tried converting the raw data to dynamic data and feeding it in but did not work. One problem is that I cannot control the sample rate of the AnalogIn express VI (LabView 2013), I appreciate any suggestions on how to go about doing it.
Solved!
Go to Solution.
Attachments:
Capture.PNG ‏16 KB

Thank you all for your feedback.
@Bob_Schor the robot competition is tomorrow. Thanks for the suggestions but the High Throughput Add-on turned out to be what I was looking for.
@MilanR thank you so much. I installed LabView 2014 and the myRIO 2014 High Throughput Add-on and I now have access to low level VIs that will let me control sampling frequency and number of samples.
I am now using 'Tone measurments' to measure the frequency of the sound. But the frequency measured is not accurate, but it is atleast consistent. I am sampling at 7 KHz and taking 5000 samples at once. The two frequencies I want to detect are 2.8 KHz and 3.5 KHz. However, the mesaured frequecies I get from Tone Measurment VI are 0.400 Hz and 0.499 Hz, which are always consistent. Picture is attached below.
Attachments:
Capture3.PNG ‏10 KB

How can I measure the frequencies of two analog input signals simultaneously?

Hi
I have two AI signals, and I need to determine the frequencies of those signals. The frequencies range from 1-125Hz. I currently have a VI where I can sample one of the signals for 1 second (sampling at 300 Hz for 300 samples) and determine the frequency.
I need to read two signals at the same time and get both of the frequencies at the same time, but I can only figure out how to read them individually, so I can read one signal, then one second later I read the second one, then I read the first one again, then the sceond one, etc.. How can I read two signals simultaneously?
Thanks
Attachments:
FreqMeas11.vi ‏41 KB
FreqMeas11.PNG ‏18 KB

"at same time", this depends on the hardware, you can do as has been previously stated just set up a 2 channel acquisition and you will get 2 sampled waveforms back. Most hardware A/D as multiplexed and true simultaneous sampling is not done. At 125Hz this is not an issue unless you are interested in very small phase changes between the samples. just keep this in mind if you are expecting samples to be completly synchronized.
Paul
Paul Falkenstein
Coleman Technologies Inc.
CLA, CPI, AIA-Vision
Labview 4.0- 2013, RT, Vision, FPGA

Problem when combinning PWM signal and Analog signal TOGETHER!

Hello everybody,
first of all i have DAQmx 6212, and i need to run a small water pump (9V-16V) which needs to be driven by a PWM signal; also i have a motor (5V-13V) for a water valve that needs to be driven by a analog signal and it has a built in a force feedback potentiometer, i connected on the extremeties of this potentiometer +5V from the DAQmx and used the output voltage from the third extremety as a diagnose value for knowing the position of the motor.
my VI shows:
1. is a normal Counter output to create my PWMout signal.
2. is an analog input i use it as a PWMin to the LabVIEW to diagnose what is happenning in my water pump through the duty cycle and the frequency.
3. is an analog input from the third extremety of the potentiometer.
4. is an analog output which i have used as a power supply for the motor valve and i have used an AC/DC amplifier to aplify the signal from the DAQmx and drive the motor, between (3. and 4.) i have made a feedback with some calculations i had a P-controller to know the actual position of the motor valve.
My Problem:
when putting 1. and 2. in the same VI alone, i am getting a clean PWM in/out with no problems mentioned;
also when putting 3. and 4. in the same VI alone i can control the motor valve without any problems;
but when i put all these 4 together as found in the attached VI, i have a problem that the motor valve is running continously without stopping even if i change the valve position between 0 and 100 %, i should mention that i am seeing a normal PWM out/in signal on my oscilloscope, one other thing that if i delete one of (1. or 2.) and run the VI the motor valve is working fine without any problems.
so this my problem, if you can think of any solution please let me know.
thanks in advance for your help.
Regards,
Alosh
Solved!
Go to Solution.
Attachments:
pwm.out.in.analog.out.in.vi ‏45 KB

Dear nathand thanks for your reply,
i have ran the vi again and i am have error no 50103 from the (AI, number 3. ) but it is not displaying the error message, the VI keeps running without any error notification.
adding to that, i have tested the VI again today by placing (1. and 2.for the PWM inout) together in one VI and (3. and 4.for the motor valve) in another VI and ran them one after the other, i had another problem. if i turn the motor valve vi, the motor will run smoothly but in the pwm vi i will have a problem in which the AI did not read any value. also doing this vice versa by running the pwm vi first it will work perfect but the motor vi will have problem in reading the measured voltage in AI during this the motor will keep on running without stopping.
so i think now the problem is in AI (2. and 3.) readings they are interfering on each other but i am not discovering where is my problem...
Q: does the AI's seems well build or i can do it in an another way so to get over the interfering?
Regards,
Alosh

Frequency sweep with peak frequency

Hi guys, I need some help here. I´m using a NI 9215 to do a frequency sweep from 30 to 90 Hz.
So far so good. Now I need a resulting resonance frequency at highest voltage.
I tried a max peak frequency VI but couldn´t get it to work.
Any idea what to do?
mfg, Andi
ok, here is my sweep.vi for better understanding
Message Edited by andinew on 08-11-2009 04:14 AM
Attachments:
sweep.vi ‏216 KB
create_log_frequencies.vi ‏15 KB

Hi Andi,
one thought first off: looking at your "create_log_frequencies.vi", I realized that it generates linear frequency hops, not logarithmic ones...
But on to your question: to find the frequency with the highest amplitude (this will be your resonace, I guess), you will have to look at the entire signal - your "sweep.vi" code iterates the measurement and interpretation five times per second, independantly of the speed of the sine sweep.
My advice would be to generate one waveform containing the whole sweep run, and writing this sweep block for block with a constant sample rate onto the output. You could then read back the response with blocks of the same size as your output, do the single tone measurement on this block and store the resulting frequency and amplitude in an array preserved trough a shift register or simply into two auto-indexing tunnels. The latter is okay as you don't need a "while loop" in the measurement loop (you know how long the analog output loop runs - why not use this information to configure a "for loop").
After your analog input "for loop" has finished, search your amplitude array for the maximum - then use the found element's index to index the frequencies array and return the corresponding resonance frequency.
A good starting point could be the example I wrote a couple of month ago: it runs continuously the same "sweep" (you'd have to adjust the waveform, I know) and reads back the stimulus and the response (wire the output to your probe and parallely to ai0, your response signal will be connected to ai1). You can then insert tone measurements etc. at the marked section...
When trying to open the example, you will be prompted to find a VI called "_Get Terminal Name....vi" - you can find this VI at the following location: C:\Programme\National Instruments\LabVIEW 8.5\examples\DAQmx\_Utility\_Utility.llb
As an afterthought: the "phase difference" you are calculating between every other sample of the analog measurement array is a bit confusing: if oyu need the phase difference between the original signal and the stimulus response, you will need to wire the stimulus to a second input and compare the phases of the two separate signals...
Best regards,
Sebastian
Message Edited by SFK on 08-12-2009 04:12 PM
Attachments:
Multi-Function-Synch AI-AO mit Signalgeneration.vi ‏91 KB

After 300 cycles, is the battery problem considered normal?

I now have the dreaded "Macbook won't work unless plugged in" problem. Mine does recognize the battery at various percentages up to 100% and will charge it if it runs down (which it slowly will in sleep mode as I can unplug it then). Purchased the computer on June 6, 2006 (very out of warranty), and just started with this "can't unplug" issue last week.
After trolling this and other sites I have reset the SMU and the PRAM several times. Removed battery looks normal, no warping, and I am always updated on the software updates, so the battery update has been installed for a while now. I run maintenance scripts regularly as well.
I have calibrated the battery several times in the past but cannot now as it will take several days on sleep to run it completely down, and I need the computer daily for work as I am self-employed. I have always let it run down in the past to sleep mode, then plugged it in. I never used it plugged in while at 100%, until now since I have to.
Coconut Battery (which I just started using) says I'm at 3526 mAh of the original 5200, 67% capacity on a 100% charge. Is this typical at this age and usage of battery?
So battery cycles are at 307, plus I'm out of warranty. Is this behavior (can't run unplugged though battery is at 100% or will charge if lower) typical after 300 cycles? In other words, do I have to buy a new battery every year to avoid this sudden shut off if the magsafe cord is yanked accidentally during my work?
And I have read of others who get their battery with the same issue changed out under warranty--only to have the issue recur shortly later. Am I going to drop serious cash on a battery that will leave me in this same predicament in just a few weeks into the future? I really need advice on this one.

redalicat wrote:
Thought I was preventing battery memory issues by running it off the battery so much, definitely won't make that mistake again.
The memory thing has been going around since the Ni-Cad days. Li-Ion doesn't have that problem thank goodness. Here is some info that may also help you with your next battery.
It is OK to leave your battery hooked to the charger most of the time. The only time I unhook mine from the charger is when I calibrate. You should calibrate your battery once a month.
The following links have good information about the MacBook and the care of it's battery.
MacBook reduces processor speed when battery is removed while operating from an A/C adaptor
Apple portable computer's battery does not show a full charge in Mac OS X
Apple Notebook Batteries
Lithium-ion Batteries
MacBook: How to remove or install the battery
Determining Battery Cycle Count
Use and cleaning of MagSafe power connector
Look here for some good tips about battery care.

Problem on Normalized Frequency to original analog frequency

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