Pulse Measurement without a digitizer-Is this doable ?

[Rick B.]

I have the need to measure a pulse in the 100ns range.

I can control the voltage level that I feed into the circuit.

I would like not to have to use a digitizer card (scope).

Would this be possible with a simple voltage divider into a comparator
circuit and the PCI MIO E-1 data aquisition card ?

My concern is with the slowness of the card and whether I will be able
to accurately capture the pulse measurement.

I am using Labview 6 as the software environment.

Thank you for any suggestions.


Rick Barry
Manufacturing & Test Engineering
Warner Power LLc

[Labviewguru]

Rick,

I think you are trying to measure the voltage (please let me know if not). As the time resolution of the PIC MIO 16E-1 is 50ns at best, you obviously can't measure the voltage of this pulse very accurately.

What I believe you need to do is to use some (I think) simple electronic circuitry to condition this pulse peak (is that what you are trying to measure?) to a constant voltage. The exact nature of the circuitry is highly dependent upon the exact measurement that you want to make.

There is of course another option. If you think outside the box, literally (outside of the computer case), you can consider using other hardware for your measurement. If you have a high speed scope that can make the measurement (I assume you have that equipment,
as you described the signal fairly well), then all you need to do is capture the measurement with the scope, and bring it into LabVIEW for analysis and processing. There are a number of ways to do this, including GPIB.

Please clarify the measurement you are trying to make, and the equipment you have and its communication capabilities.

[Rick B.]

On Sun, 30 Jun 2002 10:06:36 -0700 (PDT), Labviewguru
wrote:

>Rick,
>
>I think you are trying to measure the voltage (please let me know if
>not). As the time resolution of the PIC MIO 16E-1 is 50ns at best,
>you obviously can't measure the voltage of this pulse very accurately.
>
>What I believe you need to do is to use some (I think) simple
>electronic circuitry to condition this pulse peak (is that what you
>are trying to measure?) to a constant voltage. The exact nature of
>the circuitry is highly dependent upon the exact measurement that you
>want to make.
>
>There is of course another option. If you think outside the box,
>literally (outside of the computer case), you can consider using other
>hardware for your measurement. If you have a high speed scope that
>can make the measurement (I assume you have that equipment, as you
>described the signal fairly well), then all you need to do is capture
>the measurement with the scope, and bring it into LabVIEW for analysis
>and processing. There are a number of ways to do this, including
>GPIB.
>
>Please clarify the measurement you are trying to make, and the
>equipment you have and its communication capabilities.

Thanks so much for your answer.

Yes, voltage is the key here, but not just a peak, frequency is also a
needed parameter.

Currently, measurements are taken with a scope and a high voltage
probe. The circuitry you describe has not turned out to be all that
simple, at least I have not found a simple way to do it. I have tried
voltage dividers and comparators, but of course, I then sacrifice
resolution to the point of the readings being meaningless.
I am trying to take the scope out of the picture for both cost and
simplification reasons. I have found a way to eliminate the high
voltage probe from the picture but was hoping to also find a way to
remove the need for the scope and/or digitizing card.

The actual pulse is between 24 & 30 KV @ a frequency of 20 mHz.
With a custom designed pick up coil, I have managed to get an
excellent "picture" of this in the 60 volt range @ 50ns. Much more
workable than the high voltage. No sacrifice in resolution either.

Can you recommend anything that would capture this into Labview for me
?

Thanks again.

Rick Barry
Manufacturing & Test Engineering
Warner Power LLc
Rick Barry
Manufacturing & Test Engineering
Warner Power LLc