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?
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
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.
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.
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
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.
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."