Anyone who is confused display yourself 
I hear what Dave is saying and I would expect that newer expensive digital scopes would be much better than older expensive (at the time) Analog scopes. My first thought when I watched video 1 was why have the inputs not been terminated. Ok Dave in video 2 states that he did terminate them and it made no difference.
My confusion is this.
If God made me a perfect 10mhz signal Generator with probes and I feed a 100mv sine wave from it into both types of scope, the Analog one is going to show me a nice clean sine wave while the Digital one is going to show me a whole bunch of crap riding on the sine wave. So where did this noise come from?
It's very logical to assume that Dave is right and I am not saying that he's not right but my own logic tells me something else is at play here. I think that all those clock circuits in the fancy digital scopes bleed into the front end OR that the A/D converters are somehow creating the noise that does not exist or does not exist to the level we are seeing.
At the end of the day it's very confusing because I have this high end scope that no matter what I do shows several mv of signal and I don't think Dave has properly clarified where this noise is coming from other than to say "I am seeing something that is really there!" There from where?
I would love to see this test redone with the scope in a shielded RF free cage and have the inputs terminated and see if the noise is still there. If it is then it's got to be coming from the scope itself. If it's not then my question is where exactly is it coming from in his original tests, the lights, other equipment, stray RF! And all of this leaked in through terminated inputs? Also if it is gone then it comes back to another issue, it's like having a 7 1/2 digit DMM and shorting out the leads and getting a 20mv reading. If that the case every time I use the DMM I have to subtract 20mv from my readings. With a Digital scope am I going to have to always ignore that noise? If so what's the point unless you work in a shielded room and everything else in that room is perfectly emission clean.
BTW I am a Ham Operator and it's not uncommon in Ham Radio equipment world for a very expensive $10,000 radio to be inferior to a $2000 radio in the Receiver section. Sometimes the need to design in as many bells and whistles also makes it difficult to make a Rx section that can match a much simpler straight forward design.
BTW this is no critique of Dave, I loved those episodes, I am just not convinced because of the above reasons.
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Topic: Do you believe in the myth of noiser digital oscilloscopes (Read 6399 times)
