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A High-Performance Open Source Oscilloscope: development log & future ideas

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tom66:
The trigger prototype here is intending to demonstrate the concept of a trigger based on data around the digital trigger - and it is not necessarily the final implementation.  In the best cases the trigger jitter is <20psrms but there is presently an unresolved dependency on the trigger level.

You are not wrong that 300ps would not be ideal for a 'real scope'. The initial goal of the prototype is to replicate the performance of a 1GSa/s oscilloscope,  at a ~$500 price point, so 100ps or less is a fair goal, and "High Performance" in this regard refers to the *state-of-the-art* for existing open-source oscilloscope projects, many of which are based around PC oscilloscope platforms or sample at 10 MSA/s, not 1GSa/s. 

If I am to aim for something around the 2.5GSa/s oscilloscope benchmark, then I need to make the jitter better, of course.

31ps is the level at which the jitter becomes indistinguishable on the display surface, assuming a 1080p display so there is little point (at a minimum timebase of 5ns/div) in achieving anything better, for a 1GSa/s oscilloscope.  If a 2.5GSa/s oscilloscope has a 2ns/div or 1ns/div setting, then the requirements drop to around 5-10ps.

nctnico:

--- Quote from: tom66 on November 24, 2020, 08:23:47 am ---The trigger prototype here is intending to demonstrate the concept of a trigger based on data around the digital trigger - and it is not necessarily the final implementation.  In the best cases the trigger jitter is <20psrms but there is presently an unresolved dependency on the trigger level.

You are not wrong that 300ps would not be ideal for a 'real scope'. The initial goal of the prototype is to replicate the performance of a 1GSa/s oscilloscope,  at a ~$500 price point, so 100ps or less is a fair goal, and "High Performance" in this regard refers to the *state-of-the-art* for existing open-source oscilloscope projects, many of which are based around PC oscilloscope platforms or sample at 10 MSA/s, not 1GSa/s. 

--- End quote ---
I agree. AFAIK the R&S RM3000 doesn't even specify trigger jitter and from judging how fat a trace gets around the trigger point it isn't very good. But then again this oscilloscope isn't made for jitter analysis.

asmi:

--- Quote from: tom66 on November 24, 2020, 08:23:47 am --- "High Performance" in this regard refers to the *state-of-the-art* for existing open-source oscilloscope projects, many of which are based around PC oscilloscope platforms or sample at 10 MSA/s, not 1GSa/s. 
--- End quote ---
Oh, so that explains some things. I also had a question in my mind of what exactly is "high performance" about 1 GSa scope. Initially I thought that it was ETS with very high analog bandwidth, but now it appears that it simply means "less of a crap compared to what's already out there in the open source sphere".

tom66:
Perhaps you should read the opening post?    :-//

rhb:

--- Quote from: asmi on November 24, 2020, 07:07:03 pm ---
--- Quote from: tom66 on November 24, 2020, 08:23:47 am --- "High Performance" in this regard refers to the *state-of-the-art* for existing open-source oscilloscope projects, many of which are based around PC oscilloscope platforms or sample at 10 MSA/s, not 1GSa/s. 
--- End quote ---
Oh, so that explains some things. I also had a question in my mind of what exactly is "high performance" about 1 GSa scope. Initially I thought that it was ETS with very high analog bandwidth, but now it appears that it simply means "less of a crap compared to what's already out there in the open source sphere".

--- End quote ---

This started as an open source version of a product that Micsig now has on the market at a price point a bit higher than Tom's initial goal.  We certainly won't try to undercut the Chinese.   My aborted "Scope Wars" thread was an attempt at documenting the results of my market research of what we viewed as competitive product:  Rigol, Instek, Siglent.  At the time Micsig was not on the radar.

Once I got involved it morphed into a "beat the crap out of HPAK, Tek & R&S" project for me. And I *think* I have almost sold Tom on that.

The current goal is under active discussion.  A lot has changed in the last 18 months.

The canonical response to "I want "high performance" is, "How much money would you spend?"

Have Fun!
Reg

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