RTFM

Please Read the Specification of Your Scope

Many DIYer like myself, focused on the bandwidth of the oscilloscope itself.
However, when measuring the signal, the bandwidth of the probe will be another important variable needs to be taken into consideration.

The Probe Spec Example




If we take a look at the specification of the probe in the example above, we might notice that the probe only supports up to 6MHz at 1X position.

The Difference between 1X and 10X

Here's SPDIF signale measured with Probe at 1X



The following is the SPDIF measured with probe at 10X



As we can see, if we measure the signal with probe at 10X, the result gives us more clue for the noise.

Well, the old saying is right, RTFM.........