RMS noise measurements using an oscilloscope

[R_G_B_]

 Heres a practical example of RMS noise  measurements using an oscilloscope.

https://youtu.be/5Rk8I5BT2KU

R_G_B

[G0HZU]

I've seen this video linked to on here before and it's an interesting technique

Back then I did try it with my old Tek 465 and got very good results. However, I didn't use quite the same test setup.

This is because my main comment on the video would be that his scope 'tee' connection is going to load the 50 ohm output at frequencies above a few MHz so I'm assuming he used a noise source of limited bandwidth to prevent this issue being significant.

In my case, my noise source extends well into the HF/VHF region so I made one direct connection to the scope via a thru terminator and used short connections to the other channel. This will give a much better broadband termination if the noise source bandwidth extends well up into the HF region.

I guess a decent DSO would measure the noise voltage directly nowadays.