Measuring signals buried in noise with an Oscilloscope

Using an external reference, all the noise gets averaged out leaving only the signal in phase with the reference. Similar to how a lock in amplifier works.

[roelandriemens]

You can also turn on bandwidth filter to eliminate a lot of the noise

[optroncordian]

How we can detemine the frequency of the signal? Would the fft function help ... ?

[tarunarya]

Thanks for the video. I am new to oscilloscopes. I have a Hantek DSO2c15 which sat on the shelf for more than 1 year. The ch1 and ch2 get 200-300mv noise on low voltage settings (20-100mv/div) when attached to only the bnc alligator probe. This is regardless of whether the earth and signal are joined. Is this normal? Is the alligator clip bnc probe acting a radio antenna or sis it a faulty oscilloscope?

[ruhnet]

Very useful info!! Thanks for sharing!

[laurentiusmichaelgeorge]

What a cool poor man's lock in amplifier.
Mathematically, does this have something have to do with sine orthogonality while integrating them (in order to acquire the average)? Is that why the noise just went to zero when we multiplying it?
And another question, if lock in amplifier's concept is this well known, what's so special about the really expensive lock in amplifiers out there?

[WilianMarangoni]

Great video, how could you know there is a 1khz sine wave in channel 1?

[ciprianpopa]

How come they are completely out of phase?