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1V p-2-p

R

Roger Tegard

Jan 1, 1970
0
Hi All,

Trying to bring a new Pelco cam online. Part of the setup procedure
detailed under "Direct Drive Auto Iris Lens" is as follows:

"Slowly adjust the pot counterclockwise until the optimum picture in
obtained (video output level of 1V peak-to-peak)."

The only way I know how to read peak-to-peak voltages is with a 'scope.
Any of you old timers know how to accurately read peak-to-peak voltages
with something other than a scope?


Roger
 
R

Roger Tegard

Jan 1, 1970
0
Robert said:
Have you tried using a monitor? :^)
Click to expand...


Naw.... too obvious! :)

The goal was to keep all system adjustments to objective, repeatable
standards wherever possible.

Roger
 
R

Roger Tegard

Jan 1, 1970
0
Aegis said:
Lots of these around at various prices... This is just one non-scope
option: http://www.securityideas.com/fmsyscm1camm.html

Personally, I now use a Fluke ScopeMeter
http://www.tucker.com/java/jsp/controller?event=CUST_PROD_DETAIL_SEARCH&partNo=FLU123&invID=28642
Click to expand...


Both of those are very sweet. After reading this, I did a search on
Ebay (portable oscilloscope) and found this:


http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=45014&
item=3809183802&rd=1&ssPageName=WDVW


Anybody used one of these or heard any reviews??


Roger
 
R

rory

Jan 1, 1970
0
you can use a regular meter to test video signal also.
 
A

Aegis

Jan 1, 1970
0
Explain that.

rory said:
you can use a regular meter to test video signal also.





Have you tried using a monitor? :^)

Alarm and Home Automation System FAQ
http://www.bass-home.com/faq/masterfaq/faq.htm

Regards,
Robert

=============================>
Bass Home Electronics
2291 Pine View Circle
Sarasota · Florida · 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
941-232-0791 Wireless
Nextel Private ID - 161*21755*1
http://www.bass-home.com
http://www.bassburglaralarms.com
=============================>
Click to expand...
[/QUOTE]
 
A

Aegis

Jan 1, 1970
0
Still waiting to see how you get a peak-to-peak measurement from a meter.
 
G

G. Morgan

Jan 1, 1970
0
Someone named "Aegis" <[email protected]> Proclaimed on Tue, 20 Apr
2004 21:15:01 GMT,

Huh? So if the RMS voltage is 2v, then 2 x 1.414 x 2 ?
Click to expand...

yes
If RMS= 2V then PP~5.656V

1.414 is rounded sqrt of 2

you multiply by 2 because RMS times 1.414 is Peak
 
A

Aegis

Jan 1, 1970
0
G. Morgan said:
Someone named "Aegis" <[email protected]> Proclaimed on Tue, 20 Apr
2004 21:15:01 GMT,



yes
If RMS= 2V then PP~5.656V

1.414 is rounded sqrt of 2

you multiply by 2 because RMS times 1.414 is Peak
Click to expand...

..707 is the inverse of 1.414... I know the formula, but yours didn't have an
equal sign and didn't make sense at the time.

Vrms = Vpeak (or Vp-p/2) x .707 and Vp-p = Vrms x 1.414 x 2

However, that's all fine and dandy if your meter is sensitive enough... A
Fluke 72, for instance, is not... It puts a load on the circuit and will
throw off your adjustments (at least at the 1Vp-p level). Most techs don't
have an RMS meter that won't augment the readings with its own built-in load
assuming they have an RMS meter at all. Have you actually tried this in
practice?

Then again, most techs don't have o-scopes either (or would know what to do
with one if they did).
 
G

G. Morgan

Jan 1, 1970
0
.707 is the inverse of 1.414... I know the formula, but yours didn't have an
equal sign and didn't make sense at the time.
Click to expand...

Sorry about that.. :)
Vrms = Vpeak (or Vp-p/2) x .707 and Vp-p = Vrms x 1.414 x 2
yep.

However, that's all fine and dandy if your meter is sensitive enough... A
Fluke 72, for instance, is not... It puts a load on the circuit and will
throw off your adjustments (at least at the 1Vp-p level). Most techs don't
have an RMS meter that won't augment the readings with its own built-in load
assuming they have an RMS meter at all. Have you actually tried this in
practice?
Click to expand...

Nope.. Never had to. I have installed many auto-iris lenses and never
heard of measuring 1Vp-p !!

Also I wouldn't rely on a RMS meter and that formula to calculate a
p-p voltage in the 1V level at all! :0

I know what you were really saying to the guy who wanted to use his
meter for "measuring video signal" :) I concur - can't be done. It's
just the way you worded your second reply about "how can you measure
p-p voltage with a meter " when I chimed in.
Then again, most techs don't have o-scopes either (or would know what to do
with one if they did).
Click to expand...

It's been 10 years since I used a scope - I wouldn't know how to use
it now either! :)

-Graham

P.S.
(ironically it's been over 10 years since Bass used Scope or any other
brand mouthwash)
 
R

rory

Jan 1, 1970
0
you wont get peak to peak, but you can tell if it is getting a good signal.
 
A

Aegis

Jan 1, 1970
0
Tell me what exactly you are looking for... Are you measuring AC voltage
with an RMS meter?
I really am curious to see how this is done... seriously.
 
D

David

Jan 1, 1970
0
For very-low-frequencies, if you're looking for 1Vp-p, in a pinch you
*could* use a really good, accurate RMS AC meter and adjust it for a reading
of .353 volts.
That's cause: Vrms = Vpp x .353 (and Vpp = Vrms x 2.83)

But then you have to wonder, if that RMS AC meter will give an accurate
reading at whatever *frequency* it's reading.
Most Rms meters are real accurate at 60 hz, I think. Forget about accuracy
at video frequencies...

For an accurate reading, I think you're hosed without a scope. :)

-Dave
 
A

Aegis

Jan 1, 1970
0
I agree, but he insisted... If he is correct, I must know his technique...
Frankly, I don't see it happening.
 
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