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Building my own scope

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David Hess:

--- Quote from: rob77 on October 24, 2022, 05:47:36 pm ---your sampling scope would not even catch the runt pulse, and your 1GHz bandwidth 40MS/s scope you love so much would not even notice half of the data... so what to use ? Mr. Tggzzz with a sharp pencil and a paper roll will do the trick i guess... while everyone else is happily using the 1GS/s scopes which are in fact not usable because the almighty omnipresent and omnipotent Mr. Tggzzz said so  :-DD
--- End quote ---

Both a sampling oscilloscope and a 40 MS/s digital storage oscilloscope would capture a runt pulse eventually, but neither could decode the data.  Actually that is not quite accurate; some older DSOs supported synchronous sampling so a 40 MS/s DSO could decode 40 MHz SPI if provided with the clock.

But it does come down to using the right tool for the job.  The subject of sampling oscilloscopes came up in connection with what could be done with Arduino class hardware.  Such would be useful to very accurately characterize the communications channel of an SPI interface, but not for decoding it.  Most often I use my sampling oscilloscope to verify the transient response of other oscilloscopes.

rob77:

--- Quote from: David Hess on October 24, 2022, 06:19:17 pm ---
--- Quote from: rob77 on October 24, 2022, 05:47:36 pm ---your sampling scope would not even catch the runt pulse, and your 1GHz bandwidth 40MS/s scope you love so much would not even notice half of the data... so what to use ? Mr. Tggzzz with a sharp pencil and a paper roll will do the trick i guess... while everyone else is happily using the 1GS/s scopes which are in fact not usable because the almighty omnipresent and omnipotent Mr. Tggzzz said so  :-DD
--- End quote ---

Both a sampling oscilloscope and a 40 MS/s digital storage oscilloscope would capture a runt pulse eventually, but neither could decode the data.  Actually that is not quite accurate; some older DSOs supported synchronous sampling so a 40 MS/s DSO could decode 40 MHz SPI if provided with the clock.

But it does come down to using the right tool for the job.  The subject of sampling oscilloscopes came up in connection with what could be done with Arduino class hardware.  Such would be useful to very accurately characterize the communications channel of an SPI interface, but not for decoding it.  Most often I use my sampling oscilloscope to verify the transient response of other oscilloscopes.

--- End quote ---

synchronous sampling ... isn't that called logic analyzer ?  ;)

but anyways... sampling scope or a 40MS/s scope (be it whatever GHz bandwidth) is not the right tool in that case, we can agree on that.

and if we steer back to the topic of the thread , then neither of those is a good candidate for a DIY build as as learning experience.

Mechatrommer:

--- Quote from: David Hess on October 24, 2022, 06:19:17 pm ---The subject of sampling oscilloscopes came up in connection with what could be done with Arduino class hardware.

--- End quote ---
no, it came up much earlier when someone broke the box proposing that we dont need nyquist minimum sampling criterion (for real-time sampling) to build an dso. since there is no objection from OP so far, so lets discuss and expand it with current reinvention into tiny and cheaper unit linked earlier. known guy using sampling (equivalent) scope here is Leo Bodnar to verify his 40ps rise time pulser device which i bought one.

tggzzz:

--- Quote from: Mechatrommer on October 24, 2022, 08:55:03 pm ---
--- Quote from: David Hess on October 24, 2022, 06:19:17 pm ---The subject of sampling oscilloscopes came up in connection with what could be done with Arduino class hardware.

--- End quote ---
no, it came up much earlier when someone broke the box proposing that we dont need nyquist minimum sampling criterion (for real-time sampling) to build an dso.

--- End quote ---

I haven't seen any claim to the effect that Nyquist can be circumvented.

I have seen some people fail to understand the definition of bandwidth of a signal in the context of the Nyquist criterion. And then either go on to either deny certain types of equipment work successfully, or change their statement without acknowledging the change.

Mechatrommer:
because generally when a person want to build a diy dso implicitly means the real-time one. a person will come with building a "sampling" scope in the topic when he knows what he is talking about. and nobody will recommend newbies asking about buying a new scope to buy a "sampling" scope.

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