I'm trying to figure out if my cheapo 150Mhz probes will keep me below Nyquist if I enable all 4 channels with 250Mhz bandwidth enabled. I just poked the probe into the BNC of my SigGen to see what I got.
This is my rise time with the crocodile clip:
This is my rise time with the little spring accessory:
There's quite a big difference between the two!
Conclusions...
Crocodile clip... yes.
Spring... not so much.
First of all thank you for recent info. I did not find all of that in manual, thank you for that.
Also I like the probe test. When in doubt, measure.
Also if you remember previous topics about probes, by Perfoma01 and others, similar results to that.
If you have low enough source impedance, probe will have much higher BW than specced.
As I said, in order to be
sure it won't alias with all 4ch , scope should be run in 100 MHz configuration.
With 1 or 2 ch it should not alias much (2ch) or at all (1ch).
Aliasing will be most visible as unstable edges or large overshoots on square wave , but you will generally see it more as spurious tones in FFT. They fold back, like in the mirror..
By using manual control of sampling on a scope we can simulate effects of aliasing so we can see how they look like.
Let me explain with images: same 20 MHz squarewave with 1ns edges (I deliberately stayed from faster edges, this should be similar to Arduino UNO I/O pins ).
It was sampled at 1.25 GS/s, then at 500MS/s and 250 MS/s. Sorry my scope cannot do 625 and 312.5 and this not supposed to be exactly the same, but to illustrate the effect so people can recognize it.. To simulate BW, I enable 200 MHz BW limit but on your scope it will be more like 250 Mhz so aliasing might be easier to show.
On 1.25 GS/s it looks pretty much perfect. on two lower sampling rates it goes down the hill. Make note that repetition rate is only 20MHz and that edges are no very fast. 1ns edges or faster are pretty much guaranteed today in anything digital., unless you are working only on legacy TTL logic and retro computing...
Use this as baseline for comparison. Hope it helps with your evaluation.