How to measure frequency

hi i have made FM Jamer circuit in multisim 13 , my circuit image you can see below , now i want to measure the Measure Frequency which is Generated it L1 Inductor , so i do not know how to measure frequency in multsim , please help me , or also it would be good to use Antena instead of inductor or not , i have not see any Antena component in multsim 13

Hi Zahis,
The measuring probe measures frequency, this video shows how you can use a probe in Multisim:
http://www.youtube.com/watch?v=xKEQ3EXEaP8
Tien P.
National Instruments

Similar Messages

How to Measure Frequency to RPM NI-DAQmx Tasks

Hello,
I am trying to measure frequency using NI DAQmx task and then convert this to an RPM if at all possible.
I have the following hardware options at my disposal.
I have SCXI 1126 Module along with a SCXI 1327 terminal, as well as a PXI 6289 Multifunction DAQ.
I have wired in a mag sensor to ai7 on my 1126 and when I pass a metallic object I get a amplitude of 6 - 8 so I am able to read the mag sensor.
What I am trying to do is to somehow convert this analog measurement into a RPM while only utilizing the NI DAQmx task.
Any help would be appreciated.
Tim
Solved!
Go to Solution.
Attachments:
Freq Set Up.jpg ‏2993 KB

So I would select new in "Custom Scaling"
Then would I select linear?
Your calculations are simple but I am unsure if this would give me the desired result. From my attachment I am seeing an input amplitude of 6 Hz for each pulse. What I mean by this is that every time I bring a ferrous object near my mag pick up I get a pulse, this is what I was trying to illustrate in the attachment. The analog pulse comes in a 6 Hz so I would simply multiple this pulse by 60 (assuming I get one pulse per rotation) to get RPM?
How would this make sense if I only input one pulse for a long duration of time?
I have notice the amplitude of the pulse input increases with increased pulse frequency. Does this mean the lowest RPM I can record is 360 RPM?
Tim

How to Measure frequency of less than 300 Hz

Is it possible to measure frequency without a counter module? All I have is a cDAQ with 9205, 9221 and 9263 modules.

Hello,
I am assuming that you want to measure analog frequency, since you have analog input and output hardware. There is a useful LabView Help file titled Measuring Analog Frequency. You will be able to measure analog frequency using just software and no counters. However, this involves using Fast Fourier Transform (FFT) functions that are only available in LabView Full and Professional versions. Please also take a look at the examples in the Example Finder. Some helpful ones are titled … Signal Generation and Processing.vi, Spectrum Measurements.vi, and Simple Spectrum Analyzer (sim).vi. These example’s block diagrams are a little busy, however you can see how they are using simulated signals with the FFT Power Spectrum.vi. Note that the example titled Spectrum Measurements.vi uses express functions. These functions are going to involve less programming, but offer lower program efficiency.
Samantha
National Instruments
Applications Engineer

How to measure frequency when no static line

Hi. I think to directly measure frequency using DAXmx function my input signal should be connceted to DAQ PFI Lines but in my application the clock frequency is outputted on P0.0 line . Is there any way to directky measure frequency uding DAQmx function or I should do it manually?
Thanks

Hi tintin,
you really should have learned to post good ( read as: meaningful, with sufficient explanations and background information) questions after more than 200 posts in this forum…
What frequency do you want to measure?
What is the relation to outputting your own "clock frequency" on some DO pin?
Which hardware do you use?
Why do you need to measure a signal frequency when you know that frequency as you output that signal?
How do you measure frequencies "manually"?
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

How to measure frequencies of two sources simultaneously using 6602?

I am using pci-6602 & LabView to measure frequencies of two sources. I wired Measure Frequency (NI-TIO).vi to do it, but it seems the counter only works at one channel at a time. Can anybody send me an example vi?
Many thanks in advance
ZYuan

Hi ZYuan,
To measure the frequencies simultaneously, you would need to duplicate the code for the single counter example twice and link the error cluster from one set to the next. I don't have a specific example but the following example can be used as a guide.
Simultaneous Buffered-Event Counting on All Eight Counters of the 6602 or 6608 Devices
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3DC9F56A4E034080020E74861&p_node=DZ52325&p_source=External
Hope that helps. Have a good day.
Ron

How to measure frequency with PCI-4474 card

Hi,
I'm trying to measure frequency with PCI-4474 card.
Any sample code available?
Thanks.

Hi,
Thank you for posting the the NI forums. There aren’t any example programs that ship with the DSA drivers. Will you be using this with the Sound and Vibration Toolkit? If so, there are numerous examples that install with this software package. Check out the LabVIEW Example Finder >> Toolkits and Modules >> Sound and Vibration Toolkit.
In addition to this, you could also use the signal processing VIs that ship with LabVIEW. There are also examples that ship with LabVIEW that use these VI in Example Finder >> Analyzing and Processing Signals FFT and Frequency Analysis. There is an entire Signal Processing palette that should contain the functionality that you need.
I hope this helps. Post back if you have further questions.
Ed W.
Applications Engineer
National Instruments

How to measure frequency by USB 6211?

Dear all,
I'm using USB 6211 to measure the input analog voltage signal, then use a counter to yield the frequency. Please find the VI figure in the attachement.
The problem is the insteal of measure the right frequency, which is from 300Hz to 1000Hz. There is a lot of high frequency noise from thousand to milliion Hz. I think it pick up the high frequency harmonics. How to avoid it or use a more effective way to achieve the measurements.
Regards,
Alan
Attachments:
flow rate frequency measurement.JPG ‏43 KB

You have to suppress high frequencies on the analog side of your signal. You must set it to a frequency which is not higher than half of your aquisition rate. If you sample with 10 kHz your filter must have a cutoff frequency of max. 5 kHz. Otherwise you will see the signal mirrored at the half of the sample rate. A 6kHz signal will lead to a 4 kHz signal after the sampling.
Waldemar
Using 7.1.1, 8.5.1, 8.6.1, 2009 on XP and RT
Don't forget to give Kudos to good answers and/or questions

How to measure frequency using daq 6009

HAI..
Im using PFIO line to measure the frequency..i have attached my vi along with this..output is read approximately to the given input when i highlight the execution,but when i use run and run continuosly alone,am getting incorrect values..im totally confused..suggest some ideas..
another doubt, may i use analog port to measure the frequency of an oscillator?if so kindly help me to create a vi for this also..
Attachments:
counter.vi ‏19 KB

From your VI, one thing is clear, you are creating a task, but you are not clearing it. Please take a look at this example:http://decibel.ni.com/content/docs/DOC-8172

How to measure and log frequency with fieldpoint CTR

Hi,
I am developing a data acquistion and control system for an engine dynamometer using the fieldpoint modules and Labview. One of the most important signals is the engine speed, measured in RPM. The RPM signal is a 0-12V pulse where one pulse equals one revolution of the engine. As well as being an important piece of data for later analysis, engine RPM will also be in the input into a PID controller, so the signal must be both accurate and have a high measurement frequency.
Currently I am using the FP-CTR500 modules to measure the frequency of the signal. I am already aware of the included frequency measurement VI example, as well as the one posted before for low frequency measurements, and I have gotten both to work with my setup. I would be using the low frequency VI becuase the max frequency measurement would be in the 200Hz range.
The first problem I am having is with the structure of the VI and how the data is output. The case structure in the VI activates when the counter is read and resets the counter, then switches to the next case. I would like the RPM number to output out of the case structure into a write_to_file VI and PID controller input. The problem is that when the case switches, the counter is reset to 0, which will be recorded in the written file.
This is some example output data (RPM):
1232
0
2321
0
2400
0
2521
0
The data is being written correctly, but of course I can't have 0 readings when the case structure changes. This would be especially problematic when input into a controller VI.
The next problem I am having is with sampling rate. If I were to use the low frequency measurement VI, the sampling rate of RPM would be variable based upon the the speed of the signal. Or, the original frequency measurement VI has an adjustable sampling rate. Of course, in my system there are a number of other signals that need to be recorded at the same time. I have found that as I am collecting data, the "write to file frequency" is entirely dependent on the read frequency of the frequency measurement. Therefore, if I had set the read frequency VI to read at 1 Hz, data will be recorded only every 2Hz. Ideally I would like an overall measurement frequency of all channels (mix of analog and digital) to read between 20-50Hz, but if I am limited by the frequency measurement.
Any ideas on how to solve this problem, either through Fieldpoint or Labview?
I can post my VI if this help.
Thanks,
Huang

Thanks for your reply.
I should probably describe my current setup before I go into anymore details with the problem. As for my specific setup, I am using an FP-1000 connected with an AIO600, AI110, CTR500, and TC120 all running through the RS232 line to a desktop running labview 8. The actual counter module is reading a tachometer signal output from a separate engine controller. THe output is a 0-12V ON 50% duty cycle signal. As for data logging, i am simply using a "write to measurement file" Express VI. I have a while structure which holds all of the express VIs which access the fieldpoint IO, and these are all routed to the "write to" VI.
As for the specifics of the data logging problem, as I said, when I set the count frequency of the "Fieldpoint Frequency Measurement" VI to 1Hz, (which means the VI calls the case structure at 2Hz), the "write to measurment file" VI is called at the same rate (2Hz). Which means that the overall logging rate of the VI is only 2Hz. Is there someway to decouple this?
I was able to solve the problem of calling the frequency variable from the case structure by using a local variable which is called outside the case structure.
And now I have been having a lot of problems with reading the actual frequency from my engine controller. THe actual signal will only range from 0 to around 200Hz. I noticed, by comparing the actual signal to what was being read in my labview program, that after around 80Hz the signal increases by around 1.5times more than the actual signal. ie. Actual signal = 100hz, Read Signal = 150Hz. After trying to figure out what was the problem, I decided to change the Noise Filter settings to 200Hz. It actually worked for all the frequency ranges up to around 150Hz but after that the filter attenuates the signal to the point where the actual signal is 160Hz, but is being read at 100Hz. My question is if there is a way to change the actual filter setting outside of the 2 given setpoints (200hz and 40khz) or if you have any other suggestions on how to fix this problem? I was thinking of creating a noise filter input in MAX so that i could play with the values in Labview, but am i only limited to those two filters?
Thanks again for your help,
Huang

How do you measure frequency using the onboard counter on PCMCIA 6024-E

I am using LABView 6.1 and NI-DAQ 7.2 with a SCXI-1000 chassis and a PCMCIA 6024-E on a laptop. I need to measure a frequency of about 3KHz and would like to do that using an 1180 direct through connector.
Firstly, should I see this 1180 in MAX like any other module?
And secondly, how do I use this 6024-E card to measure frequency? Which pins are supposed to be used on it to measure, and will I see the counter run in the test window in MAX according to the frequency measured?
I know NI also have a frequency module for the SCXI chassis. So lastly, will it be better to use that, rather than measure directly off the 6024-E?
Any help, advise or comments will be greatly appreciated!
Thanks!

Hello,
I think I can help out with some of your questions. First, the 1180 module won�t show up in MAX since it is really just a feedthrough cable which allows you access to your unused signals from the DAQ card.
You definitely can measure frequency using your 6024E. An example installs with NI-DAQ 7.2 which shows how to accomplish this. To access this example go to the LabVIEW start up screen and hit the Find Example button. When the Example Finder opens up browse to the following location: Hardware Input and Output -> DAQ -> Counters -> DAQ-STC -> Measure Frequency (DAQ-STC).vi
This example measures frequency and has a connection diagram on the front panel. The documentation for the example can be accessed by going to File -> VI properties -> Document
ation, after you have opened the VI.
You are correct that we offer a frequency input module for SCXI (SCXI-1126). This module would be useful if your input voltages are non-TTL, or if you need to measure more than one channel of frequency signals. This module has an input range of +/- 250Vrms and 8 input channels.
I hope this helps! Let me know if there is anything I can help with or clarify.
Ken S.
Applications Engineering
National Instruments

Can you tell me how to measure audio signal frequency in measurement studio with visual basic 6.0?

I'd like to measure two differential input signal(I.e. A+ and A-),below is two test projects,
1.connect A+/A- to PCI 6052E card's ACH0/ACH8 ,and refer to GND for testing
2.connect respectively A+/A- to PCI 6052E card's ACH0/ACH8 for testing
Could you tell me the details of the second project?and give me a illustration in measurement studio with visual basic 6. 0 about the second?
In addition,I would like to measure the audio signal frequency,could you give me a illustration in measurement studio with visual basic 6.0?
Wait for your reply!

Dear kelven,
Thank you for contacting National Instruments.
To address your question, there are Analog Input shipping examples that demonstrate how to measure an analog input differentially, as you specify in (2).
As for measuring the audio signal frequency, you may want to check out the following KnowledgeBase. The link is:
http://digital.ni.com/public.nsf/websearch/4b08380530d72d3b86256340004c3005
Let me know if you have any further questions or if this does not resolve your issue.
Thanks again and have a great day!
Chad AE
Applications Engineer - National Instruments

How to measure the frequency of a pulse being generated by a counter

Hi,
I am using labview 8.6 to generate 5 evenly spaced pulses for every 1 revolution of my shaft. However, I would also want to know the frequency of these pulses so I can determine the shaft speed. Since I am already generating the pulses using one of my counters, can I still tap into that or task another counter to measure the pulse frequency? If so, how? I have attached my code for generating the pulses and I am using an Ni 9401 module and an NI 9172 chassis. If someone can helo me modify the code to measure and tell me the pulse frequency as well, that would be really appreciated
Attachments:
autotrain2.vi ‏19 KB

You'd probably get a more coherent answer if you didn't bounce around from thread to thread so much...
How can I generate a pulse train from shaft encoder? (5/13)
pulse train from encoder (5/15)
how to measure rpm (5/20)
How to measure rpm using shaft encoder and labview (5/23)
This thread (also 5/23)
I see you ignored my suggestion from the other thread--Kevin's solution is good too but using an encoder task offers more noise immunity (I think this is probably the cause of the problem you reported on the other thread). You can fix it with digital filtering if you want to keep using a counter output instead of an encoder task. Noise during transitions is pretty common for a quadrature encoder.
A finite counter output task uses 2 counters on the 9172 (although you said 9174 earlier at one point--this wouldn't be the case on a 9174) so you wouldn't have one left to make your frequency measurement. With the solution you have now, you can change to continuous to free up a counter if you don't care about outputing an exact number of rotation's worth of pulses (I'm not sure if you do or not--I didn't read through all of the various threads relating to this application to find out).
For your actual question in this thread... Have you tried running one of the frequency measurement examples? From the code here I can't tell what you have tried (it just looks like a mangled version of the code Kevin gave to you in your other thread).
Best Regards,
John Passiak

How I can measure frequency of TTL signal without external clock?

Hello,
I want to measure frequency of TTL signal using PXI-6254 or PXI-6713, without using external clock.
Frequency will be up to 100kHz. How I can use internal counter of 20MHz or 80MHz?

Hi Yuta K,
You have not stated what software you want to use for this measurement, but in case you're using LabVIEW, please go to the Example Finder (in LabVIEW go to "Help >> Find Examples").
In the Example Finder, you make sure the "Browse" tab is stil selected, and than you go to:
Hardware Input and Output >> DAQmx >> Counter Measurements >> Digital Frequency
Here you will find some good examples of measuring a digital frequency with 1 or 2 onboard counters.
If you need additional information, please let us know!
Best regards,
Peter S

How to measure two frequency simultaniously in a PCI 6014

Hi I am measuring RPM of two gear drives by measuring the pulse/second(Measure frequency.vi). I have interlinked the gate of counter1 to the output of counter2. Similarly I have connected the gate of counter2 to output of counter1. to measure frequency.
This way in a cycle one counter acts as gate counter while the other counter counts and later the counters changes their role.But my problem is that I have to measure the two counters frequencies simultaniously.
I cannot do period measurement becasue I have several irregular pulse widths generated in each cycle.
I am currrently experimenting with mesure period(DAQ-STC).vi. I have the following doubts in this VI.
1)Can I replaced source configuration fr
om internal timebase to external PFI source signal.
2)If I replace my source signal from internal timebase to the pulse generated from my gear drive then would at the end of 1 sec (when the counter is disarmed due to change of trigger signal state and hence end of while loop) will the count attribute contain the count of my ttl edges?
3) Would this be a accurate method for measuring frequency simultanuiously without using two counters?
Thanks.

Hi balajkasthuri,
The best way to perform this is to use the frequency generator (freqout) of your 601x board. Your board only has 2 counters but it also has a frequency generator that doesn't use the counters. It is an output found on the freqout pin. You can choose to have a frequency of 10 MHz or 100 kHz divided by any integer between 1 and 16. This means you can create a pulse train of known frequency and known period and use that into the source or gate of your two counters depending on the frequency measurement method you are using.
For example, assuming your two signals are much faster than the freqout signal, you can apply the freqout signal to the gate of a counter and have your signal feed the source. The number of counts you get in 1 pulse
width of the gate (which is known since it is the frequency you generated) will determine the frequency of your signal.
Otherwise, if your signal is much slower than 20 MHz, you can simply use the 20 MHz as the source of the counters and perform a simple period measurement on your signal. You would then take the inverse of your period measurement.
Anyway, using the onboard frequency generator will give you the flexibility you need. I have linked below a useful tutorial describing the 3 typical frequency measurements. Hope that helps. Have a good day.
Making Accurate Frequency Measurements
http://zone.ni.com/devzone/conceptd.nsf/webmain/CD2C8AAED8FA59A486256C230078FE75?opendocument
Ron

How do i measure frequency?

lets say theres this signal in volts. if you plot the signal it forms a sine graph. is there any way to use labview to determine the frequency of the signal? i've tried to use the "measure frequency vi" but my device is connected to a virtual channel, and i dont think that VI supports that...

Hi Polly,
There are several ways to measure frequency in LabVIEW. You can measure the frequency of a pulse train using DAQ hardware (counters). You can also just take a buffer of data and simply use LabVIEW functions to read the frequency of the buffer. An example function would be Extract Single Tone Information.vi. There are many other functions as well. Hope that helps.
Ron

How to measure frequency

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