cro noise calculation.

hi,

i am using GDS 1102 U dso from GW-INSTEK. i am connecting probe with photodiode. DSO displays output with 40mV noise. I want to calculate noise generated by photodiode. I am confused that in 40mV how much noise is generated by DSO ? and how much by photodiode?

Connect the DSO to ground and measure its noise voltage. Then subtract that value from the total noise (using the square root of the sum of the squares calculation) to determine the signal noise.

hi..

thanks man for your reply. while connecting cro probe with ground output gives more noise than before its 80 to 100 mV.

hiren.dave@bhuved.com said:

hi..

thanks man for your reply. while connecting cro probe with ground output gives more noise than before its 80 to 100 mV.

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That shouldn't happen. Where are you connecting the cro probe ground? It should be tied to the signal ground when you do the measurement.