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VRF - Objects or DLL for threshold detection

Question asked by VRFuser on Mar 12, 1996
You did not mention how accurately you need to measure this.

Typically, one would use an electronic counter for this.
Accuracy is dependent upon the slew rate and noise in
your signal, but is usually in the nanosecond region.
The HP 53131A is a good basic counter (and has a VEE driver).

If you're using a PC, you'd be lucky to get 20mS of resolution.

However, if you're digitizing the signal with time-correlated
samples, you can push the data (once you get it into VEE)
through the comparator and look for the first failure.
Then your resolution is equal to your sample rate, accuracy
is somewhat less (and rather hard to determine).
HP has a good app note on counter accuracy if you're interested.

Mark Ahrens
Hewlett Packard T&M AEO         Email:
"Ask me about Custom Test Solutions"

>From: John Sletten <>
>Subject: VRF - Objects or DLL for threshold detection
>Date: Wed, 13 Mar 96 10:44:30 PST
>I need to detect at what times a given signal crosses a specific
>threshold. I have tried doing this in HP-VEE but it takes far too
>long time.
>I would like to know if a set of VEE objects exist for this type of
>application. Will this be added to VEE 3.2 ?
>If not I will probably have to write a DLL in C. That leads me to my
>next question, can I pass a waveform to C ?
>I would be thankful for any advice
>John Sletten
>Independent consultant
>Oslo, Norway