# How to capture the period of a rising signal

Discussion in 'General Electronics Chat' started by Engr, Jul 20, 2011.

1. ### Engr Thread Starter Member

Mar 17, 2010
114
5
Hi All,

I have a signal from 0V to 10V and I need to capture the period of this signal from 0V - 4V, 4V - 7V and 7V - 10V. This is a one shot signal so I need to measure the period all at once. Is their an existing IC or circuit that can make me do this?

2. ### debjit625 Well-Known Member

Apr 17, 2010
790
186
Use an ADC to sample the signal.

3. ### RiJoRI Well-Known Member

Aug 15, 2007
536
26
We use 3 window comparators for a similar situation here at work. But then, we need to repeatedly sample the signal. If it's a one-time-only deal, I'd go for a digital o'scope with a one-shot feature. Trap the signal and measure it.

--Rich

4. ### Engr Thread Starter Member

Mar 17, 2010
114
5
We are using an ATE to measure the period of the signal. Using the scope we can capture the signal but using the ATE we have to repeatedly fire the signal 3 times so that we can measure the 3 period. We are looking for a circuit or a component/ IC in which we can measure the 3 period with just a single fire of the signal. Our ATE can only measure the period one at a time so we have to fire the signal 3 times and measure also 3 times.

5. ### ErnieM AAC Fanatic!

Apr 24, 2011
7,334
1,573
So you already HAVE the scope, but it has limited measurement features, one measurement per capture?

Can you get at the signal information itself? Our ancient (1980) HP scopes allowed you to get the signal measurement reading samples. TI's in the 90's has something similar.

Get the sample data and do your own analysis of it. You've got 1 sample per unit time, count samples till the limit, multiply by sample rate, and there is your interval time.

Hey, post # 500!

6. ### Engr Thread Starter Member

Mar 17, 2010
114
5
We have a scope but our scope is only for verification if the measurement of our ATE matches the scope plot. We are not measuring the signal using the scope, we are measuring the signal using our ATE.

7. ### someonesdad Senior Member

Jul 7, 2009
1,585
141
If you're willing to buy an instrument, a modern \$500-\$1000 digital scope can capture the signal and you can download it to a computer for further analysis. I recently used one that captured about a million points in the waveform (8 bit vertical resolution) and downloaded the data to the computer over the USB interface. It worked great and was trivial to use. Then it shouldn't be difficult to analyze the waveform in software and pick off the numbers you want.

8. ### Engr Thread Starter Member

Mar 17, 2010
114
5
You're correct on that, using a scope and downloading the data to a computer will not be difficult, but right now we are looking for a way in which we will not be using an external instrument. Our goal for this is to make it an on-board circuit so that we will not be using any external instrument to do the gathering of data.