Frequency counter

sir,
our project is about designing an "eddy current based sensor for contactless measurement of breathing".we had so far designed an colpitts oscillator with 12MHZ of output,this frequency is converted to square pulse using a schmitt trigger.Now we want to know whether it is possible to count this frequency of 12MHZ in lab view?.what is the maximum and minimum frequency counted by lab view?
Solved!
Go to Solution.

Not until you tell me exactly which DAQ hardware you are using (model number) and what you mean by "feeding 12MHz to LabVIEW". Are you trying to measure the frequency, pulses, edges, what?
“A child of five could understand this. Send someone to fetch a child of five.”
― Groucho Marx

Similar Messages

Frequency counter unreliable using rotary vane anemometer

I have set up an anemometer to measure air flow speed, with the signal being acquired by a 9402 module in a cDAQ-9174 chassis (4 slot). I am using Signal Express 2011 to program the instrument.
I have set up a frequency counter task, using a maximum frequency of 1.8 kHz a minimum frequency of 250 mHz, rising edge and 1-counter (low frequency). The output is scaled using y = 0.0111x + 0. This gives 20 m/s when the frequency is 1.8 kHz.
The readings given by Signal Express give a very noisy signal, at a frequency much higher than the bandwidth of the anemometer. The range is in the order of 20% of the mean. I have attached a PDF of the signal, for two different air flow sources, the seproj file and the tdms file for one of the runs. I have also observed that the counter output is rounded to the nearest multiple of 10, e.g. 490, 470, 480, 480, 470, etc.
Is this consistent with a digital bounce issue? Is this consistent with an earthing issue? Is this consistent with a sample rate issue? Any other ideas for investigating this issue?
thanks
Attachments:
EXPT 20 - ANEMOMETER NOISE.pdf ‏49 KB
EXPT 20 Anemometer Noise.seproj ‏637 KB

I have logged the voltage signal coming from the anemometer, using our 9239, a report of a few cycles is attached as a PDF. The graph clearly shows a small digital bounce. The noise is small compared to the signal, is there any way it can be filtered when acquired by the 9402?
Other tests that I ran showed a background noise in the order of 50 microVolts and a frequency of 50 Hz, this is very likely a background noise from a power supply (we run at 50 Hz in Aus) but is many orders of magnitude smaller than the signal, I assume it would be ignoredby the 9402.
Attachments:
EXPT 20 Anemometer Noise Voltage.seproj ‏261 KB
EXPT 20 Anemometer Noise Voltage.pdf ‏19 KB

Frequency counter with E-Series DAQ Card

I am trying to measure the frequency of a signal at 0.1 sec increments using a DAQCard-6062E and an AT-MIO-16E-10. I am using a VI from the examples (frequency counter.vi, in a while loop) which works well with the DAQCard, but it's giving wrong measurements with the AT-MIO card. Why is that?

Hello Waw,
Take a look at this KnowledgeBase to see if it fixes the problem.
http://digital.ni.com/public.nsf/websearch/862567530005F09E8625681C0074935E?OpenDocument
If not, what version of NI-DAQ do you have? Are you getting incorrect measurements with different ranges of frequencies? Is LabVIEW giving you any errors? Do any examples provide correct results with the AT-MIO-16E-10? Please let me know if you have any questions. Have a great day!
Marni S.
National Instruments

Best way to implement a word frequency counter (input = textfile)?

i had this for an interview question and basically came up with the solution where you use a hash table...
//create hash table
//bufferedreader
//read file in,
//for each word encountered, create an object that has (String word, int count) and push into hash table
//then loop and read out all the hash table entries
===skip this stuff if you dont feel like reading too much
then the interviewer proceeded to grill me on why i shouldn't use a tree or any other data structure for that matter... i was kidna stumped on that.
also he asked me what happens if the number of words exceed the capacity of the hash table? i said you can increase the capacity of the hash table, but it doesn't sound too efficient and im not sure how much you know how to increase it by. i had some ok solutions:
1. read the file thru once, and get the number of words in the file, set the hashtable capacity to that number
2. do #1, but run anotehr alogrithm that will figure out distinct # of words
3. separate chaining
===
anyhow what kind of answeres/algorithms would you guys have come up with? thanks in advance.

i had this for an interview question and basically
came up with the solution where you use a hash
table...
//create hash table
//bufferedreader
//read file in,
//for each word encountered, create an object thatWell, first you need to check to make sure the word is not already in the hashtable, right? And if it is there, you need to increment the count.
has (String word, int count) and push into hash
table
//then loop and read out all the hash table entries
===skip this stuff if you dont feel like reading too
much
then the interviewer proceeded to grill me on why i
shouldn't use a tree or any other data structure for
that matter... i was kidna stumped on that.A hashtable has ammortized O(1) time for insert and search. A balanced binary search tree has O(log n) complexity for the same operations. So, a hashtable will be faster for large number of words. The other option is a so-called "trie" (google for more), which has O(log m) complexity, where m is the length of the longest word. So if your words aren't too long, a trie may be just as fast as a hashtable. The trie may also use less memory than the hashtable.
also he asked me what happens if the number of words
exceed the capacity of the hash table? i said you can
increase the capacity of the hash table, but it
doesn't sound too efficient and im not sure how much
you know how to increase it by. i had some ok
solutions:The hashmap implementation that comes with Java grows automatically, you don't need to worry about it. It may not "sound" efficient to have to copy the entire datastructure, the copy happens quickly, and occurs relatively infrequently compared with the number of words you'll be inserting.
1. read the file thru once, and get the number of
words in the file, set the hashtable capacity to that
number
2. do #1, but run anotehr alogrithm that will figure
out distinct # of words
3. separate chaining
===
anyhow what kind of answeres/algorithms would you
guys have come up with? thanks in advance.I would do anything to avoid making two passes over the data. Assuming you're reading it from disk, most of the time will be spent reading from disk, not inserting to the hashtable. If you really want to size the hashtable a priori, you can make it so its big enough to hold all the words in the english language, which IIRC is about 20,000.
And relax, you had the right answer. I used to work in this field and this is exactly how we implemented our frequency counter and it worked perfectly well. Don't let these interveiewers push you around, just tell them why you thought hashtable was the best choice; show off your analytical skills!

Frequency counter with start and stop - Need help

When No load, 200VA Unity , 400VA Unity, 600VA Unity, 400VA LAG, 400VA LEAD or Short is active Frequency Counter starts.
When OFF and BENCH PWR is active Frequency Counter stops and is grayed out.
Frequency Counter is grayed out when BENCH PWR is inactive
Any one know ho to do this?
Attachments:
Buttons.vi ‏77 KB

In order to enable or disable a control you need to write a U8 value to the Disabled property of the property node for that control.
The values are:
0 = Enabled
1 = Disabled
2 = Disabled and Grayed Out
Kelly Bersch
Certified LabVIEW Developer
Kudos are always welcome

JTables and frequency count report

Is it possible to use jTable and make the cells un-editable and have it set up where if you click on a cell it could perform a specific action? I�m working on a program that calculates a frequency count report and I want to be able to click on the cell and have it display in another window the observations that contributed to that cells count. Is this possible using jTable or is there a better way to get what I want? Thanks for any suggestions.

Yes, it looks to me as if it should be possible.

No reading on the frequency counter

I'm not getting a reading on the frequency counter when I wired the clock signal onto it. There's just one input to the counter, so I wired a clock and try to get a reading. All I see are the dashes. Is there something else I need to do? thank you.

Hi,
You can configure some parameters in the pop-up window of the instrument. Trigger Level, sensitivity and AC or DC Coupling. You can try to set these based on your circuit.
If you want us to take a look at it, please post the circuit.
As an alternate, you can also see the freq in the measurement probe. Go to Simulate -> Instruments -> Measurement Probe and click on the net (wire) where you want to check the frequency.
Hope this helps.
Regards,
Tayyab R,
National Instruments.

Variable frequency counter output

I found this example of how to vary the frequency of a counter output, but it appears this is not supported and i receive the following error. Can anyone tell me if there is an alternative method at all? my device is a usb6341 which has 4 COs
thanks
Attachments:
Capture.JPG ‏118 KB

If you found that code in an NI-provided example, it's probably more likely that the operation is not supported by your specific hardware.
What is the range of frequencies you want to create?
How accurate does the clock need to be?
How often will the frequency be changing?
Can the hardware receiving the clock tolerate and "discontinuities" in the pulse train?
You could momentarily stop the clock, change the setting and then restart it.
MIke...
Certified Professional Instructor
Certified LabVIEW Architect
LabVIEW Champion
"... after all, He's not a tame lion..."
Be thinking ahead and mark your dance card for NI Week 2015 now: TS 6139 - Object Oriented First Steps

Counter 1 - Measure Frequency & Counter 0 - Generate PWM POSSIBLE?

Is this POSSIBLE with a NI-6025E DAQ card? Can I use the two counters to generate % control a TTL PWM signal and at the same time measure frequency from a circuit? This is my connection.
GPCTR1_SOURCE - connected to find frequency circuit
GPCTR1_OUT - connected to GPCTR0_GATE
GPCTR1-GATE - not in use
GPCTR0_SOURCE - not in use
GPCTR0_OUT - connected to DC motor circuit
GPCTR0-GATE - connected to GPCTR1_OUT
My concern is that changing or controlling the TTL PWM might change the frequency reading. This is because COUNTER O is connected to COUNTER 1.

I understand to measure frequency of a signal there are TWO methods. A ONE counter method and a TWO counter method. I need to measure a frequency between 1 Hz to 200 Hz. Is the ONE counter method possible? What is the ONE counter method?

Frequency Count

I was given the task to create a line of code that would count the frequency of each number, boldarray[counter]*bold*. I'm stuck because the numbers are randomized and I am suppose to find the count for each of the random numbers, seeing as only 10 of 100 numbers are being printed I am confused. I am also aware of the lines in there that aren't being printed. Please help.
public class InitArrayy {
     public static void main ( String args[] )
          int array[];
          int fCount=0;
          int count = 0;
          array = new int[ 11 ];
           for(int counter = 1; counter < array. length; counter++ )
                array[counter] = (int) (Math.random()*100);
                count = counter;
                System.out.printf("\t Frequency=%5d",array[counter]);
                if(array[counter]==5) fCount++;
                if(counter%2==0)
                System.out.printf("\t array(%3d)=%3d\n", counter,array[counter]);
                else
                System.out.printf("\t array(%3d)=%3d\n", counter,array[counter]);
     }

Please explain what in your mind was each line of the below to do?
                        if(array[counter]==5) fCount++;
                if(counter%2==0)
                System.out.printf("\t array(%3d)=%3d\n", counter,array[counter]);
                else
                System.out.printf("\t array(%3d)=%3d\n", counter,array[counter]);

I need a 2-channel 100MHx frequency counter

What can I use? I need to measure the change in resonant frequency on a SAW device.

How often do you have to make your measurements?
What kind of signal?
What kind of range?
How much delay between measurement and display of same?
Answers range from DSA hardware doing JTFA through freq counter read via GPIB to Freq to voltage converter monitored by sandard analog in device.
More info would be helpfull.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

I need a 2 channel 100MHz frequency counter

I need this counter to measure the resonant frequency of the delay lines on a SAW sensor. I am hoping I can come up with a device and a software package that can measure the change in frequency at a high rate of speed (no specific speed, just needs to work). As mentioed above, I am working on ST cut quartz, so the resonance is close to 100MHz. There will be sinusoidal signals entering the counter.

Hi ,
Please take a look at our PCI-6602 counter/timer card. I am providing a link below.
PCI-6602
Please let me know if you have further questions.
Sincerely,
Sastry V.
Applications Engineer
National Instruments.

Synchronize sampling of rpm using frequency counter with force (voltage) signals

I have a VI attached which converts the voltage values measured from the ATI force/torque senosr to force values. I would like to integrate the measuring of TTL pulses from an RPM senosr. There is a bug with my current program, as the RPM value only updates once. If I put the read VI in a while loop, the program returns an error. How should I modify my code to solve this, and as well as to synchronize the recording of data from both sensors?
I have no prior labview experience, and really appreciate any help.
Attachments:
atidaqft-mx.llb ‏93 KB

Dear Jochen,
(1) Principally, I'd like to use PCI-6602 to be a motion encoder also be a counter (Is it possible? Due to the manual, it is possible). I expect to have all information, such as position, time, velocity, etc. from that motion encoder (or at least the position and time). It is also expected of using PCI-6602 to do all measurements that I mentioned before . My meaning is, after having a signal from the counter, that 'count' will be converted to desire units under other programs. So, in this case, PCI-6602 is only used to get the 'count'.
Simplified, the voltage command will send to the system (linear motor) through PCI-6052E (-10V to 10V). The actual position or other actual information will be catched (read) by using PCI-6602 (as a motion encoder, also as a counter). Then, this actual position will be used as a feedback, that will be compared to desired position.
Is that also possible to use PCI-6602 be a motion controller + a counter + a frequency measurement in a same time parallely?
I don't decide yet (I don't know) which acquisition rate will be needed/required, higher is better.
(2) I'd like to apply an adaptive robust controller (yes, it is a closed loop system) under matlab with their feature called Real-Time-Workshop instead of using LV.
(3) Power drive for the linear system will be driven by AC servo drive.
Thanks for your help before,
Warmly regards,
hendro

Word Frequency Counter...

Hello all, I am working on a project that is supposed to read in a text file from a command prompt, and then break all the words up. As the words are read in by the Scanner, I need to have a counter that counts the number of times the word has occured already that I can access and display in the output. I have come up with this so far as my driver/main class, and also the Count class that I'm trying to use to keep track of the number of times a word has occured in the text, and then so I can add it to a HashMap and display later... The problem is, whenever I try to run the program with a text file, it just ends up displaying all the words in a line and then a number 1 next to it. What I need is the output to look similar to this... For example,
hello 1
world 1
Any help would be appreciated! Thanks.
   import java.io.*;
   import java.util.*;
    public class Driver{
       public static void main(String[] args){
         HashMap words = new HashMap();
         String nameOfFile = args[0];
         File file = new File(nameOfFile);
         String wordd;
         Count count;
         try{
            Scanner scanner = new Scanner(file).useDelimiter(" \t\n\r\f.,<>\"\'=/");
            while(scanner.hasNext())
               String word = scanner.next();
               count = (Count) words.get(word);
               if(count==null){
                  words.put(word, new Count(word, 1));
               else {
                  count.i++;
               System.out.println(word);
             catch(FileNotFoundException e){
         Set set = words.entrySet();
         Iterator iter = set.iterator();
         while(iter.hasNext()) {
            Map.Entry entry = (Map.Entry) iter.next();
            wordd = (String) entry.getKey();
            count = (Count) entry.getValue();
            System.out.println(wordd +
               (wordd.length() < 8 ? "\t\t" : "\t") +
               count.i);
{code}
{code}
public class Count
     String word;
     int i;
     public Count(String inputWord, int increment)
          word = inputWord;
          i = increment;
{code}
Edited by: VisualAssassin on Apr 22, 2009 2:45 PM

VisualAssassin wrote:
Scanner scanner = new Scanner(file).useDelimiter(" \t\n\r\f.,<>\"\'=/");
{code}According to the documentation for Scanner.useDelimiter(), the String supplied is used as a regular expression. Therefore, for the scanner to tokenize into two separate tokens, your input stream would have to contain all of those listed characters in order!
Instead, use this (untested):
{code}
Scanner scanner = new Scanner(file).useDelimiter("[" + Pattern.quote(" \t\n\r\f.,<>\"\'=/") + "]+");
The beginning and end square braces tell the regular expression engine to match +any+ of those characters, and the plus means one or more times. The Pattern.quote is used to escape some of the characters that would get you into trouble because they have a special meaning in regexes, notably "."
Edited by: endasil on 22-Apr-2009 11:43 PM

Simple in line frequency counter? Need to measure 48hz variable resistor

Confused.
Been searching all day. Is there a simple way to measure if I've correctly adjusted a variable resistor from 50hz to 48hz?
Below is the email to me from Russia, explaining how to adjust the variable resistor.
This is variable resistor adjust a speed of motor.
But, you need frequency measuring device for check a value of speed.
You can connect measuring device to Pilot signal socket .
50 hz signal = 25 fps.
48 Hz signal = 24 fps.
Other idea, you can take frequency from resistor R6 on PCb.
25 fps = 500 Hz
24 fps = 480 Hz.
Attachments:
image005.jpg ‏23 KB

Hi Djwerk,
This question might be better answered in the specific hardware forums if you are using an NI Data Acquisition Device or in the LabVIEW forums if this is strictly a software question. Could you give me some more information about the harware you are using/want to use to make this measurement?
As a general solution, you could use a multimeter to simply measure the resistance as you change it. If you are applying a known current, you could measure the voltage across the resistor and calculate the resistance. If you want to directly measure the frequency, you could input an analog voltage signal into a DAQ card and use a Fast Fourier Transform in software to calculate the frequency of the signal.
Zach P.
Product Support Engineer | LabVIEW R&D | National Instruments

Frequency counter

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