Jump to content
vin2install

What is the correct way of measuring video voltage

Recommended Posts


If I was going checking the voltage of a camera's out, I'd put one multimeter probe on the outside of the BNC connector, and the other - very carefully - on the inner core of BNC connector.

 

But, I have a Camera Master:

 

http://www.securityideas.com/fmsycmcamaii.html

 

which measures composite signal IRE (140IRE being 1v pk-pk).

Share this post


Link to post
Share on other sites

...except your average multimeter reads RMS voltage, not P-P. Fortunately the math is easy: Vrms * 1.414 = Vp-p.

 

Or get a multimeter that actually reads p-p.

Share this post


Link to post
Share on other sites
...except your average multimeter reads RMS voltage, not P-P. Fortunately the math is easy: Vrms * 1.414 = Vp-p.

 

Or get a multimeter that actually reads p-p.

-------------------------------------------------------

 

Or get Oscilloscope and learn how to do the right way

using multimeter to measure P-P kinda useless

Share this post


Link to post
Share on other sites
...except your average multimeter reads RMS voltage, not P-P. Fortunately the math is easy: Vrms * 1.414 = Vp-p.

 

Or get a multimeter that actually reads p-p.

-------------------------------------------------------

 

Or get Oscilloscope and learn how to do the right way

using multimeter to measure P-P kinda useless

 

I'd second the fact that the camera master is probably the easiest way, the oscilloscope is the absolute best way to do it, (you could get a Velleman HPS10 for about $175.00 or so that would do fine for that purpose).

 

The multimeter would be a very limited approach, because no basic multimeter is designed to display peak-to-peak voltages. Cheaper ones display an average, better ones display true RMS, but none of them will be able to take a waveform as complex as a video signal and come up with anything close to the correct reading. Some high end ones (Fluke, etc) list peak values as a feature, but they would cost more than a basic oscilloscope that would do it better, and the oscilloscope is valuable for other purposes, as well.

 

Soundy, you are correct with the RMS to Peak to Peak conversion factor.... But, that is only valid for a sinusoidal waveform.

 

A video waveform is very much NOT sinusoidal, and varies depending on Luma (mostly), and Chroma values (and others), in a way that make a fixed RMS-peak multiple pretty much impossible to determine.

Share this post


Link to post
Share on other sites
Soundy, you are correct with the RMS to Peak to Peak conversion factor.... But, that is only valid for a sinusoidal waveform.

 

This is true - I thought of that AFTER I'd left for work so I couldn't edit my post

 

But I agree, the absolute best way to get the most accurate picture (pardon the pun) of what's going on with the waveform is with an oscilloscope.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×