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markone:

--- Quote from: marmad on January 29, 2016, 05:35:51 am ---Display memory = 1400 bytes on the DS2000 = 1200 bytes on the DS1000Z= 50 pixels * screen divs * 2

--- End quote ---

So actually it's even worst, heck ... i'm embarrassed, we have also a ridiculously slow interface, no sh*t !

Sorry for the french, but on the base of what you report it would be enough to deal with a mere 72 KB/s data exchange to maintain a remote live screen 4 channels @30FPS (600*4*30) and as you guys have proved, the DS1054Z  is actually a loooot slower!

I can understand that those physical interfaces are there mainly for instrument setting, but hell, these are numbers suitable for an Arduino UNO board.

The performance of the CY7C68013A USB controller that we can find in 60USD 20Mhz DSOs here seems an unbridled luxury (and they are transferring the whole acquisition buffer to PC).

Year ago i hacked one external PATA HDD enclosure based on CY7C68013A (that contains a sort of 8251 mcu) and attaching a TI 14bit 80MS/s ADC evaluation board on its original IDE PATA bus i achieved sustained 16 MS/s transfers (32MB/s) at easy.

Once properly programmed such controller requires only to write the 16bit word on its data bus and then put a transition on its bus clock pin (the controller code is upload from PC as soon as the device is attached, of course with proper device driver installed) so the external data source has not to be smart.

Ok, as far as i understood, no remote live screen is possible with mine DSO (DS1074Z), so i'm definitively on the market to buy another one.

I should have a sit in front of a real scope screen to evaluate, but right now i do not know how.
marmad:

--- Quote from: markone on January 29, 2016, 11:02:57 am ---So actually it's even worst, heck ... i'm embarrassed, we have also a ridiculously slow interface, no sh*t !

--- End quote ---

No, it's larger than the 800 bytes you mentioned (I'm assuming you're getting that figure from the old DSOs with 320x200 screen sizes). It's 1400 (or 1200) bytes per channel; display memory contains vectors for each horizontal pixel.


--- Quote ---The performance of the CY7C68013A USB controller that we can find in 60USD 20Mhz DSOs here seems an unbridled luxury (and they are transferring the whole acquisition buffer to PC).
--- End quote ---

You're comparing apples and oranges. Those 60USD 20Mhz DSOs aren't capturing 30k wfrm/s into an intensity buffer - they are a whole different animal. You could argue that the DSO maker should allow you to choose between slower update rates / faster transfers and faster update rates / slower transfers - but that is, if not extra hardware, certainly more programming and development costs - so it would mean more expensive DSOs.


--- Quote ---Ok, as far as i understood, no remote live screen is possible with mine DSO (DS1074Z), so i'm definitively on the market to buy another one.

--- End quote ---

Of course it's possible - you'll just have an update rate of a few waveforms per second.
markone:
Ok, so we have two bytes for a single dot and we have to multiply my numbers by two.

Still i cannot justify few frames per second, it renders this function useless for a lot of  purposes.

I agree with you that those instruments are not natively designed for remote viewing, but if it's only matter to write some more code (and not a system limit) it could be an additional selling point and/or SW option to pay for.

For sure the dirty cheap price must be taken in account, but i'm in a quite different position because i purchased the 70Mhz version.

I was convinced that analog front end was different BW wise...obviously, as now everyone and their dog know (after Dave's great analysis),   i was WRONG !

To summarize, please correct me if i'm wrong, DS2000 series has much faster screen transfer function than DS1000Z, in the order of 10 factor.


marmad:

--- Quote from: markone on January 29, 2016, 01:15:19 pm ---Still i cannot justify few frames per second, it renders this function useless for a lot of  purposes.
--- End quote ---

Well, even 30 FPS would be useless for many purposes when compared to 30,000 FPS; it depends on what you need it for. I've found many uses for the remote viewing - even when it's just doing 5 FPS. Obviously you can scale the display on a PC screen to 4x the size of the DSO screen, so you can see it from across a room. Of course, for very fast changing signals, it's less useful (although you can simulate persistence).


--- Quote ---I agree with you that those instruments are not natively designed for remote viewing, but if it's only matter to write some more code (and not a system limit) it could be an additional selling point and/or SW option to pay for.
--- End quote ---

Well, the hardware needs to be designed correctly to allow unencumbered asynchronous access to display memory, unless you don't care if the acquisition rate of the DSO is occasionally interrupted for transfers.


--- Quote ---To summarize, please correct me if i'm wrong, DS2000 series has much faster screen transfer function than DS1000Z, in the order of 10 factor.

--- End quote ---

I never had the time to test it fully (and it might have been improved in later FW), but I think it was perhaps closer to a factor of 5. The problem with the DS1000Z is that, in order to keep it very cheap, it's rather under-powered. You can see how the GUI slows down when MATH functions are enabled, etc (I believe the DS2000 has at least one extra FPGA for display processing).
markone:
When i provide numbers like 30 or 60 for FPS i'm referring to typical lcd panels max refresh rates, every task for persistence, analog moking, rare event capture and so on are already performed by DSO on its own, where FPGA crunch all the KiloWaveforms/s, so we have to transfer the final result to PC as well the DSO LCD transfers it to your eyes, so your brain.

Both of them have an actual frame BW of some tens per second, otherwise it's like to say that the scope's panel  shows 30000 waveforms per second :-)
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