Display frequency measurement of ECG signals

hello there....i m feeling very stress right now...
its seems tat i could not display my frequency measurement when i use timing & transition measurement....
plz help me
i tried so many method but nothing seems 2 work
i attached my program
anyone plzzzzzzz help me
thx...
Attachments:
read_mod2(new)[3].vi ‏407 KB

I have this program which I used to compute heart rate. See if
this is helpful. It uses an algorithm from a paper to get a nice
peak and then to perform peak detection to determine the time between
the peaks.
Randall Pursley
Attachments:
EKG Processor.vi ‏84 KB

Similar Messages

NI9411 wrong frequency measurement of flow sensors / 24 impulse signals

Hello Ni Forum,
I already searched for similar problems, but haven't found anything helpful. So I'm posting our problem here. I'm apologizing in advance for bad english, it's not my mother tongue
We're encountering some strange behaviour of our NI9411 Module. We're using it in a Compact Rio with some other modules (2x Analog In).
Our goal is to measure the frequency of three flow sensors (impulse high = 24V, 0-22kHz) among with a torque sensor (TTL 5V, 30-60kHz) and a speed sensor (TTL 5V, 0-51,2kHz).
They are wired as follows:
DI0a = torque sensor
DI1a = flow sensor 1
DI2a = speed sensor channel A
DI3a = speed sensor channel B
DI4a = flow sensor 2
DI5a = flow sensor 3
Correspondig ports b are left unconnected, as it is said in the data sheet. All ground ports of sensors are connected to COM port of 9411. The module was connected to a 24V power supply.
Now the torque and speed sensor measurement works fine. But measuring the signals of the flow sensors seems to be difficult.
If an external frequency generator (impulse high about 9V, f=1,000kHz) is connected to port DI1a instead of the sensor signal, LabView shows exactly 1,000kHz. DI5a showed an avarage of 10 Hz, with a range from 10 to 60 Hz. DI4a equaled constant zero. The flickering up to 60Hz of DI5a was gone after disconnecting the 24V supply of the module. This changed nothing on the phenomenon described below.
If the signal high impulse voltage is raised, the measured signal frequency goes up to 1300 Hz @ 24V signal high impulse voltage. The signal additionally raises, if an oscilloscope is connected to DI1a, to 2180 Hz (range 2110 to 2240Hz). However, there is no change of frequency if the osci is connected to DI5a. With the 24V supply connected, DI5a showed a frequency up to 600Hz @ 24V signal high impulse voltage on DI1a, also rising when connecting the osci on DI1a. As mentioned, there was no frequency measured on DI5a after disconnecting the 24V power supply.
The signals of the generator showed some peaks on each edge (rising and falling) with values for example of 11V above high impuls voltage of 9V (20V together). That may causes that wrong frequency measurement.
The signals of the flow sensors do not have such peaks, the LabView-frequency nevertheless does not match the real frequency, as shown below (all values in Hz):
LabView
ideal values
Flow Sensor 1
Flow Sensor 2
Flow Sensor 1
Flow Sensor 2
4600
12200
740,6
6760,0
6400
13500
1481,3
7500,7
9700
16400
2962,6
8982,0
12900
19500
4443,8
10463,2
We're kind of helpless now. How can we get the signals of the flow sensors measured the right way? Are we doing something essentially wrong? Thanks in advance for offered help. I hope, I've given any necessary information. Any missing details will of course be delivered.
Puls-Measure-VI is attached beneath.
Regards,
Johannes Rost
Attachments:
vi.png ‏20 KB

Dear Lynn,
thank you for your reply. The impedance was an issue that our local technical distributor already suggested to check. According to the datasheet of the flow sensor (see attachement) it can drive a current of 25mA. The signal generator we used is a test generator that can be used instead of the flow sensors to check the any evaluation unit the sensor is connected with. So it should generate signals that are equal to those the sensor would have generated. And even with this the frequencies measured with LabVIEW are not as expected.
We are in contact with the sensor manufacturer to exclude mistakes in connection on the sensor side. But the behavior with the signal generator makes us think that is has to do something with the characteristics of the NI9411 that we don't know yet.
Attachments:
block diagram signal amplifier and signal description.png ‏151 KB
technical data.png ‏124 KB

NI-5122 measure trigger frequency of TTL trigger signal

I have two signal channels and a TTL trigger signal on my NI-5122. The frequency of the tigger signal is between 5 and 30 Hz. Before I want to sample the two signal channels I need to know the actual trigger frequency to calculate and set sampling rate and number of sampling points. I use LabView 7.1
What's the best way to measure the frequency (5-30 Hz) of the TTL signal connected to the 5122 trigger input?
many thanks for your help.
Markus

Jason V,
thanks for your help. So there is no programable counter on the 5122...
My freuqency is constant and I need an accuracy of <1%.
What I did meanwhile:
I make a loop of e.g. 10 triggerevents.
I record the times when the trigger events occur.
After the loop I fit a line to the time vs. iteration number.
This gives a pretty good value for the period, hence I get the inverse frequency.
I need 10-30 trigger events to be accurate.
For 10 Hz this makes 1-3 seconds init at the start of each measurement.
I can reach a relative error as low as 1e-4. That's o.k.
I did some more tweaking to allow for missed trigger events.
The whole VI works fine to retrieve frequencies up to 100 Hz.
For higher frequencies I am limited due to the millisecond resolution of LabViews 'Tick' vi.
====
For higher frequencies I would program a counter:
Start a measurement for 1000 scans and measure the time for that.
However, this is not accurate enough for low frequencies and short recording times (10-30 trigger events).
====
I also thought about Fourier transforming the signal itself and locating the peak frequency.
Same as above: This is only accurate when I record many periods.
====
The fastest and most accurate solution would be to sample the trigger signal itself.
Then I would need only one period and could detect the trigger slopes with microsecond resolution.
However, I need both input channels for recording simultaneous signals.
Conclusion:
(1) The NI-5122 does not has a programable counter on board
(2) For my application I found a solution tht works.
MarkusMessage Edited by Nepu on 03-09-2005 02:04 AM
Message Edited by Nepu on 03-09-2005 02:07 AM

DAQ frequency measurement using anolog input channel

Hello,
I try to develop a DAQ application which run on a real time target.
I want to measure frequency using anolo inpur channel of my DAQ card. I have a problem.
Let me first try to explain what i trying to do. In the first loop i do sampling and show the result as double array.
I need to show samples as double array so i can not read sample as waveform. With a shared variable i sent these samples to second loop.
First loop reriod is msec and second loops period is 20 msec.So when the second loop run, 20 samples were alraady ready, frequency measurement is done.
The problem is that i need to show frequency measurement as far as possible. Say frequency of my signal is about 100 hz, then this
configuration gives correct frequency measurement. But if frequency of the signal is about 10 hz, this configuration fails since period of second loop is 10 msec and it is not enough time to measure a 10 hz signal. But if i adjust period of the second loop as 100msec,
then i can measure 10 hz signal but then i can give measurement of a 100 hz signal +90msec late. What can i do so i can measure frequency af signals ranges 0-100hz and give measurement result as far as possible?
Attachments:
measure_amp_freq.GIF ‏35 KB

eesen,
What you are doing doesn't make any sense to me. First of all, you should take multiple samples with the DAQmx Read and not one sample at time with the timed loop. Your frequency measurement will then actually be more accurate. You also should return a waveform. That includes timing information that the Freq & Amp function needs to determine the frequency. It cannot do it with a dbl array. If you have to display a dbl, then just use the Get Waveform Components to extract the y array. You can get rid of the second timed loop and use a regular loop for the DAQmx Read. If you just set the rate to be twice the highest input frequency and acquire enough samples for a couple of cycles, you should have a pretty accurate reading.

Why does my AI acquisition slow down to my frequency measurement rate?

I'm using Labview/Daqmx to program my SCXI 1520 and TC modules while at the same time using the multifunction capabilities of the E-card controlling the SCXI. This has been fairly easy until I wanted to use the frequency and counter measurements (outputs/DIO works great). I'm using a waveform with buffered acquisition for the read on the AI channels and obviously there is no waveform for the frequency measurement so I'm just combining the signals using the dynamic data. This works great when my input frequency is higher than my acquisition frequency. When my input frequency is lower than my acquisition frequency the acquisition slows down to that frequency and the AI read falls behind (buffer fills while waiting for another frequency measurement). I'm assuming the frequency read is not keeping up with AI read. I understand that as the frequency is reduced it takes more time to calculate the frequency. So how do I "read" the frequency measurement at the same rate as the AI data? I'm fine with using the last frequency measurement until a new frequency measurement is available but I can't even seem to be able to do that.
An example of the problem is measurement of vehicle pedal force (AI channel) with pulse input for vehicle speed. Assuming 100 Hz acquisition and the vehicle stopped or going slow (very slow pulse train) I should be able to acquire data at 100 Hz even if I just use the last data point for the frequency channel until another point is available.
Please help, thanks.

Basically, the very fact that you're *doing* a frequency read suggests that you don't know the expected freq ahead of time, and probably suggests that it can vary. The waveform datatype assumes a constant interval between samples which wouldn't generally be true for frequency measurement, and that's why you can't use it. Since the actual timestamps of the frequency measurements are NOT the same as those in the analog waveform, it's likely a mistake to pretend they are.
My method is to create my own array of "timestamps" for the frequency data. Create a For loop with a shift register initialized to 0 from outside the loop. Let your freq array auto-index the loop. On each element, perform (1/x). Add result to the left-hand shift register value and write it to both the right-hand shift register and to an auto-indexing output. When the loop completes, the output array will hold timestamps that correlate to your freq measurements. From there you can choose whether to display on an X-Y Graph, or whether to perform some interpolations to calculate freqs at the analog sample times or vice versa.
-Kevin P.

Low-Frequency measurements using counter/timer

I am trying to measure speed, and am using the FP-502 counter timer module to count the pulses from my sensor. The field point example that uses a fixed width gate pulse will not work for my appliation because I need a gate pulse so big that it updates way to slow.
Does anybody have any sugestions on how to measure a low frequency signal using a counter/timer?
Thanks
Dan

Hello guys
Thanks for all your sugestions I have the final results. I got it to work but I would like to add some comments for anybody who is trying to attempt this.
Triggeing on the gate is a must for low frequency measurements. I used the divide by sugestion however using a factor of 3 only gets you about 60 Hz after that you can't sample fast enough. My application required me to measure from 0 to 150 Hz. I added a "gear shifter" routine where the terminal count was set to 3 on frequencies lower then 45 Hz and 15 for frequiencies greater than 45 Hz. Using a terminal count of 15 for all measurements made the udate rate on really low frequencies way to slow i.e. .5 seconds for 20Hz (check the math on this).
I a
lso needed to cascade the counters. At low frequencies the count went higher than 6550. Using the previos channel function of the fieldpoint module enable me to get 32 bit worth of terminal count data.
Finally I needed to add a timeout condition for 0 Hz. If there are no pulses coming from the senser the program displays the last value read. That won't be 0. So I added a time out routine that if I didn't see a pule in a certian amout of time, output 0 and reset the gate count.
Thank you for you help you relly saved me. I hope my comments made sense.
Dan

Frequency measurement question

hi,
i'm trying to get a graph/table of the frequency of a signal as it varies with time using LabVIEW 8.2. the frequency of the signal i'm analyzing is constantly changing, so i would like to, ideally, find the frequency of each pulse so that i would be able to graph that frequency as a function of time. the signal is generated by a fiber optic system which is hooked up to a standard NI DAQ card.
right now i'm trying to use the Spectral Measurement VI wired to a graph, however it doesn't seem to be producing the desired results.
thanks

Hi Ben,
Ah, I get it now, thank you for the pictures.
"Just
to clarify, does the Counter I/O -> Frequency task work with
non-digital signals?" No, the input to a counter task must conform to
the 5V TTL logic standard. Here
is a document that talks about how to use non-TTL signals with counter
tasks. Since you are interested in the length of time between two
adjacent peaks or troughs, it would be nice to use a digital frequency
task, but this analog signal needs a lot of help before you can use it
as a TTL counter input.
"Also,
it would seem that the Analog I/O ->
Frequency would be the ideal task for my application, however it
doesn't seem as though it is supported by my card..." You are correct,
you cannot directly take an analog frequency measurement with your
hardware. Different hardware is required.
What's coming to mind is a direct measurement between two adjacent peaks and troughs. LabVIEW ships with some very nice examples for this type of measurement. From LabVIEW's Help Menu >> Find Examples... >> Analyzing and Processing Signals >> Time Domain Analysis >> Peak Detection and Display. Please note that some of the VIs required by this example are not included in the LabVIEW Base Package. Below is a screen shot of the front panel. Computing the frequency of each pulse is then a matter of calculating the time between two adjacent peak or trough values. I hope this gives you some ideas.
Message Edited by Pie56694 on 07-09-2008 11:34 AM
Message Edited by Pie56694 on 07-09-2008 11:35 AM
Attachments:
2008-07-09_101048.jpg ‏94 KB

Compact daq frequency measurement

hello,
I am considering using the compact DAQ NI cDAQ-9172 for my measurement and I want it to acquire frequency measurement. I have some analogue input, they are signal with noise. (A example is a measurement of a magnetic pick up)
I want to have a counter, I wuold use the internal counter (5 / 6 slot) of the chassis ) NI cDAQ-917.
I am considering using the NI 9201, but I can utilize the internal counter with a analogue input module?
THANKS!!!!!!!!!!!!
chiara.

thanks for your reply. maybe i explained my situation incorrectly.
From the that sample freq program you showed me, i'm just using the numberic indicator for frequency only and not the other graphical displays (like the voltage and frequency spectrum).
In my original program, i already have a bunch of graphical displays measuring physical channel ai8 to ai12.
I wanted to see what frequency my ai12 channel as well as measure/display the voltage graphically. I believe your saying that i can't measure both frequency and graphing at the same time on 1 channel?
What i did was I connect ai12 channel to ai13 and basically copied the the sample freq measure vi program to my original program to indicate frequency.
my orignal program has set the DAQmx reading ai8:ai12 to a analog 2D DBL multiple sampling.
but i noticed that the sample frequency measure program requires the DAXmx read.vi set to 1D waveform to measure frequency not 2D DBL like the rest of my program. I think it is where this part i'm having problems with sampling all my inputs ai8 to ai13.
so when i copied the sample frequency measure program into my original program, it only runs one physical channel. Only the sample frequency program (ai13) or my other ai8 to ai12 graphs will work but not both at the same time. It can't do all ai8:ai12 2D including the ai13 1D measurement continuously.
i dont think its possible to read in analog 1D and 2D measurements at the same time?
Thanks again.
Message Edited by immortalc on 01-04-2008 10:02 AM

Continuous frequency measurement~

Dear sir,
    How are you today?
    I tried to program the "Measure Frequency.vi" in LabView 5.1 . I've the simplified version
from "LabView Measurements Manual" in page 10-26. Basically, we want to measure the
frequency change within 20 ms (chirp). So I just naively added the "for loop" enclosing everything,
as the attached VI. But the testing result (please see the attached document) showed that
sometimes the counter/timer (AM9513) lost count. Could you please troubleshoot my VI and
tell me how I should improve?
    In addition, I tried to use the oscilloscope to see the gate signal from counter-1 (counter 5)
OUT pin, but it showed 0.14V. The signal from GATE pin of counter (counter 1) showed 5V.
I was expecting what I would see is something like TTL signals with different pulse widths and
delay widths. Can you tell me what I was doing wrong?
    Thank you for your previous answers!
Best regards,
Margaret
Attachments:
Continuous Measure Frequency1.1.vi ‏122 KB
continuous frequency measurement.doc ‏168 KB

Hi Margaret,
I think that there is one way to obtain a count every 20ms. What you will need to do is:
1. Generate a 50 Hz pulse train
2. Connect your signal to the a counter source
3. Connect the 50 Hz pulse train to the counter gate
4. You will obtain a series of counts over a 20ms period and you will be able to determine the frequency of the signal using post processing by dividing the count # by 0.02.
I noticed that you are using LabVIEW 5.1. This version of LabVIEW is no longer supported. I highly recommend upgrading to a newer version of LabVIEW. This will allow you to program with the DAQmx driver and creating your application with this driver would be significantly simpler and take a lot less time.
If you do not want to try this method, then I am attaching the screenshot for measuring the time the while loop takes to execute. I want you to know that the overall time will not have an effect measuring the signal's frequency. There really isn't anything you can do to decrease the execution time for the counter. I hope that you find this information helpful.
Regards,
Hal L.
Attachments:
While Loop Timing.gif ‏12 KB

How can we substitute the invalid option "reset after read" in FP-CTR-500 + FP-1600 frequency measurement application?

We nned to incorpore the values of 2 frequency signals (0-10 Khz)into a process controlled by a VisualBasic application running on 1 PC with W'95. Because the FP-CTR-500 working with FP-1600 hasn't the option "reset after read", the process of reading is a bit complicate, and sometimes, we receive wrong values of frequency from those devices. Could you help me? Is there any extremely reliable method of reading? Best regards,
Puho

For frequency measurement information on the FP-CTR-500/502 modules. Please see KnowledgeBase Article #1TB63SUS
http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/d8db42f9fdc3607e862568640047f144?OpenDocument
Ultimately, the FP-CTR-500/502 modules are not designed for frequency measurement, although it is possible to use them to measure frequency. The one thing is that it works best to do the measurements over relatively long integration periods (1/4 second or more).
Regards,
Aaron

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 i enter the ECG signal to the lab view through the sound card

first i open the help and find example the display the signal of the mic
and i enter the ECG signal through the mic and displaied
but when displaied the ECG appearied only one period on the chart so on if the chart with full screen you can see only one period
and when i change the x scale the signal compressed in a part of chart and the remain part of the chart empity
so how i display at least three periods of ECG
Attachments:
ECG with sound card.vi ‏20 KB
Untitled.jpg ‏37 KB

I do not have LabVIEW version 9, only 8.6
Without looking at your program can take a guess. Have you set the property "chart history length" of the graph? If you consider that an individual has a heart rate of up to 50Hz, or period of 20ms. Soon the number of points required is (3 * 20ms) / (sample time).
If this is not the problem, you could send the converted code to version 8.6 of LabVIEW?

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

New M Series DDK Example: High Frequency Measurement with 2 Counters

This example demonstrates how to configure two counters on an M Series device to measure a high digital frequency. One counter generates a continuous pulse train of a set frequency while the other counts the external signal using the pulse train to latch values. Data is transferred via DMA.
Use this example to add high digital frequency measurements or DMA data transfer for counter input to your driver.
Please let me know if you have questions or problems. Thanks :-)
Joe Friedchicken
NI VirtualBench Application Software
Get with your fellow hardware users :: [ NI's VirtualBench User Group ]
Get with your fellow OS users :: [ NI's Linux User Group ] [ NI's OS X User Group ]
Get with your fellow developers :: [ NI's DAQmx Base User Group ] [ NI's DDK User Group ]
Senior Software Engineer :: Multifunction Instruments Applications Group
Software Engineer :: Measurements RLP Group (until Mar 2014)
Applications Engineer :: High Speed Product Group (until Sep 2008)
Attachments:
gpctex5.cpp.gz ‏4 KB

You should connect the signal (whose frequency needs to be measured) to Ctr-1, and there gonna be an internal connection between the output of the first counter and the gate of the second counter (as described here).
You may want to check this link as well.
I am not allergic to Kudos, in fact I love Kudos.
Make your LabVIEW experience more CONVENIENT.

Frequency measurement using Labview 8 and Fieldpoint FP-CTR-502 - wind speed measure

All the information regarding this kind of application seems to be outdated, I did not find no solution or example to construct frequency measurement VIs using Labview 8
The examples at "NI Discussion Forums :
Most Active Hardware Boards :
FieldPoint Family :
Low-Frequency measurements using counter/timer" is very strange and so far the steps given seems to be usefull only do old Fieldpoint Explorer.
I was trying to find a way to learn how to make an anemometer send its signal to a FP-CTR-502 but I have no sucess.
I am realy very new on this Labview stuff, any help would be welcome.

(similar thread here)
Message Edité par Mathieu R. le 12-23-2005 02:28 PM
.mrLeft{float:left} .mrInfo{border-left:solid 1px #989898;font-size:x-small;color:#989898}
Mathieu R.
  CTD - Certified TestStand Developer / Développeur TestStand Certifié
  CLAD - Certified LabVIEW Associate Developer

Display frequency measurement of ECG signals

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