Measuring with oscilloscope!

[vvcepheus7]

Hi everyone,

This is my first post so take the opportunity to greet everyone.

I do an engineering and I have a question about a practice related with the oscilloscope.

The question:

We use an Agilent oscilloscope. A student wants to determine the value peak-to-peak of a signal during to pass through an attenuator, and the noise voltage will be around 10mVpp. What settings should I use?

Anyone can help me please?!

Thank you!

PS sorry for my english, i'm spanish speaker!

 

[klystron]

Use a 10:1 probe and the channel sensitivity on the 10 V/div. Then reduce the channel sensitivity until the signal fills the screen.

 

[js]

maybe google can help you:
https://www.google.si/search?num=50...2031.3-1j8-1.2.0.les;..0.0...1c.1.U2iht2kH0nU

 

[chuckey]

You can not measure noise with an oscilloscope. Noise is aperiodic so every now and then a pulse will flash across the screen that you can't see. If you could see it you cannot measure its amplitude. The only way to measure real noise is via a noise filter (to limit the bandwidth) and a RMS sensing voltmeter.
Frank

 

[vvcepheus7]

Hi, thanks for your replys!

is it posible?:
use the input signal for trigger the oscilloscope using the chanel 2. After use the median function for reduce the noise before of messure the signal in chanell 1.

??

 

[FvM]

You can not measure noise with an oscilloscope.

It's often done though. Assumed, the noise bandwidth is either set by the oscilloscope, the measured system, or an explicitely connected filter, you can determine statiscal parameters with reasonable accuracy, A popular noise parameter is e.g. Vpp through a 0.1 to 10 Hz bandpass filter, a quantity describing low frequency noise of amplifiers.

In addition, modern oscilloscopes with digital signal processing capability can calculate statistical parameters rather precise.

I presume, that the original poster doesn't want to measure noise, however.

 

[E-design]

You can make a very good estimate of noise level using this very old but, very clever trick published by Tektronix around 1969.
Used it quite a few times myself.
https://www.youtube.com/watch?v=zHU9xdU51FY

 

[zorro]

Hi vvcepheus7,

It is not clear to me what is the relevance of the attenuator.
Can you assume that the signal is much stronger than the noise?
What type of signal is it? What type of noise is it?


Hi Chuckey,

In the determination of tangential sensitivity, noise is measured with an oscilloscope. Of course, there is some uncertainty and a subjective factor, but it is still a noise measure.


Regards

Z

 

[chuckey]

I am sorry, the scope is calculating the RMS noise voltage. i had forgotten that.
Frank

 

[vvcepheus7]

Hi! thank you for your replys!

It was a test question but I don't write all the possible answers because my english is to much poor!

Finally I mark this option:
"use the input signal for trigger the oscilloscope using the chanel 2. After use the median function for reduce the noise before of messure the signal in chanell 1."

I hope that its ok but I don't know! haha
Thanks!