OwenDuffy.net 

This calculator estimates the uncertainty to a given confidence level of measurement of noise of a given bandwidth for a given integration time.
... be warned it is slow for large integration times and bandwidths unless you use the "Fast" option.
The calculator is based on the method given at Noise measurement uncertainty.
The "Faster approximation" uses an inverse square law extrapolation for cases where Bandwidth*IntegrationTime*2 is greater than 1000.
Normal probability distribution  Confidence level 
1σ  68.27% 
2σ  95.45% 
3σ  99.73% 
Confidence level is often expressed as an equivalence to the Normal probability distribution, in multiples of the standard deviation σ. Noise measurements are not a normally distributed variable, but Table 1 shows common Normal probability distribution limits and the associated confidence level. So if the requirement was for Confidence Level equivalent to 2σ, the Confidence level is 95.45%.
If you're clever, you will have worked out you can download this page to your hard disk. If you're smart, you won't, you will run it from the web site and automatically take advantage of any updates.
Other VK1OD tools.
© Copyright: Owen Duffy 1995, 2021. All rights reserved. Disclaimer.