In DHO series only ASIC is analog front end ASIC. Their ADC is not ASIC as much as local ADC source. That ADC can be replaced with any other ADC, and if you get good one at a good price, you can match them.
Actually believe the Rigol 12 bit ADC is more of an Application Specific ADC than not. Reasoning is that Analog Devices and TI ADC design targets a much broader range of applications than just the DSO, whereas Rigol may have reduced the initial design requirements, efforts, and cost with just the DSO product target. This allows relaxed specifications for the ADC in many areas and thus reduces the initial design task and costs. Of course we don't know for sure, and don't generally like to speculate, but do have some background here and some "hints". Would be very interesting to find the actual "wafer yield", but that's usually a highly regarded parameter and not going to be disclosed by Rigol or the IC fab.
Rigol still needs to utilize a boatload of these ADCs to recover the NRE, and likely the DSOs under discussion are the recipients of the lower grade ADCs from the chip testing fallout, where the higher grade ADC chips go the higher class DSOs.
Sure one could replace the Rigol ADC with a TI or AD 12 bit ADC and be done, but this would have a higher Recurring Cost and not achieve this attractive price point IMO.
ENOB, Linearity and so on will revel just how good these ADCs are. However, without a better FFT as R&S and Siglent have implemented, some of this might be difficult to properly access.
All this might not matter to the audience these lower cost DSOs are targeting and just having a 12 bit ADC with low noise front end, good screen resolution, and HDMI is enough. Being able to "see" finer waveform details and a nice Hi-Rez display may be all that matters to many whether they are "real" or accurate isn't important!!
A good set of tests would be in order. The classic 2-Tone IMD and another interesting test would be to utilize the math functions to evaluate precision waveforms and view the numerical results. Things like waveform average, RMS(SD), DC Levels and so on might hint at just how good the input channels behave over the ranges. We did such when we got our 1st SDS2000X+, and were pleasantly surprised how well it performed.
Anyway, fun discussions going on.
Best,
One of these FFTs isn't like the others...can you see which one?
Rigol still needs to utilize a boatload of these ADCs to recover the NRE
and likely the DSOs under discussion are the recipients of the lower grade ADCs from the chip testing fallout, where the higher grade ADC chips go the higher class DSOs.
Yeah, I have no idea what Dave did there... It is obvious that scopes are not set the same... Which is not surprise because Rigol decided to implement "FFT dummy mode" transformation with no control of FFT parameters.
..Yeah, but nicer to just have the results displayed directly on the DSO. ..
Yeah, I have no idea what Dave did there... It is obvious that scopes are not set the same... Which is not surprise because Rigol decided to implement "FFT dummy mode" transformation with no control of FFT parameters.
Uhuh, but there's a third 'scope there which does allow you to control all the parameters ... and it's agreeing with the Rigol.
Yeah, I have no idea what Dave did there... It is obvious that scopes are not set the same... Which is not surprise because Rigol decided to implement "FFT dummy mode" transformation with no control of FFT parameters. I keep repeating that you need to either implement full RT Spectrum analyser (that does ALL of the necessary transformations from FFT to spectrum display) or a proper FFT mode where you have control over mathematical FFT parameters.
Are you really that thick or you are paid to spew bullshit?
What is wrong with that FFT? It is slower because device has slower CPU. That is not a bug.
A 8 bit converter dynamic range is bug??
Muppet.
Rigol decided to implement "FFT dummy mode" transformation with no control of FFT parameters. I keep repeating that you need to either implement full RT Spectrum analyser (that does ALL of the necessary transformations from FFT to spectrum display) or a proper FFT mode where you have control over mathematical FFT parameters.
Which ones are missing?
No DOTS display?? only vectors? I wonder why?
So what you think which scope was not set up the same as the others ??
Thank you for summarizing it much better than what I ever could.
As for my "not really ASIC" comment for Rigol ADC I thank Asmi and you for education. I'm not in ASIC business so my use of terminology will not be correct. What I wanted to say is that while Rigol's ADC obviously is ASIC as a type of product because it is custom made IC that was made by company for their specific use, ASICs are usually made for a very specific function: a switching matrix for a high speed interconnect, a complete integrated sound engine for a synthesizer, or something like that.
In this case, Rigol made "just another ADC", a chip for which there is alternative. Of course that assessment is based on my limited knowledge from what Rigol has published. Maybe they did combine ADC and some sort of DSP to linearize response or something like that.. In which case it would be really single use application specific chip for scopes that could not be replaced easily. And would allow them to have simpler BOM and maybe make significant saving in FPGA resources and such...
But from what I see they still have same architecture as before with ADC-FPGA-App processor. So it seems any saving would be just in price of chip. I personally think it is more about control of sourcing the chip than good price (which is just a bonus).
Where is the size setting ?
Thank you for summarizing it much better than what I ever could.
As for my "not really ASIC" comment for Rigol ADC I thank Asmi and you for education. I'm not in ASIC business so my use of terminology will not be correct. What I wanted to say is that while Rigol's ADC obviously is ASIC as a type of product because it is custom made IC that was made by company for their specific use, ASICs are usually made for a very specific function: a switching matrix for a high speed interconnect, a complete integrated sound engine for a synthesizer, or something like that.
In this case, Rigol made "just another ADC", a chip for which there is alternative. Of course that assessment is based on my limited knowledge from what Rigol has published. Maybe they did combine ADC and some sort of DSP to linearize response or something like that.. In which case it would be really single use application specific chip for scopes that could not be replaced easily. And would allow them to have simpler BOM and maybe make significant saving in FPGA resources and such...
But from what I see they still have same architecture as before with ADC-FPGA-App processor. So it seems any saving would be just in price of chip. I personally think it is more about control of sourcing the chip than good price (which is just a bonus).
You are welcome!!
The ADC, or FPGA, is likely the single most expensive IC component in the DSO, and at this price point every $ in BOM matters. Without a custom in-house ADC, one is restricted to available chips from AD, TI and maybe some others, and don't think that anyone can get these ADCs at a price that would fit this price point.
We must remember that TI, AD and others have developed and produced high end performing ADC chips that satisfy many market segments, these incurred much higher development costs, and likely occupy more precious silicon area, involve extensive testing and so on. Whereas Rigol was able to isolate the important parameters that are more meaningful to the DSO market, trim the architecture to reduce the up front development costs, reduce the Si area, and so on.
Would wager that if we got ahold of one of these ADCs where we could do detailed isolated standalone chip testing, the overall performance would be mediocre in general compared to TI and AD. Things like no missing codes, monotonicity, differential & integral linearity, ENOB, aging, drift, temp, PSRR, and so on would not compare well with the TI and AD counterparts. Many of these parameters aren't that important in a DSO application, I mean who really cares if the ADC has a stuck lower bit, or non-monotonic around the LSBs, and so on. Now consider using this ADC as feedback in a complex high speed control system, stuck bits and non-monotonic behavior would be a disaster indeed!!
Yeah, I have no idea what Dave did there... It is obvious that scopes are not set the same... Which is not surprise because Rigol decided to implement "FFT dummy mode" transformation with no control of FFT parameters. I keep repeating that you need to either implement full RT Spectrum analyser (that does ALL of the necessary transformations from FFT to spectrum display) or a proper FFT mode where you have control over mathematical FFT parameters.
Hmm. That sounds quite different than your outburst half an hour earlier:Are you really that thick or you are paid to spew bullshit?
What is wrong with that FFT? It is slower because device has slower CPU. That is not a bug.
A 8 bit converter dynamic range is bug??
Muppet.
Did you actually watch Dave's video before you lashed out at Fungus? Care for an apology?
And speaking of Rigol's "FFT dummy mode": Maybe Siglent's "FFT expert mode" is not all that great, if Dave supposedly can't use it properly?
I appreciate your T&M expertise and the fact that you share it freely on this forum. But your continuous undercurrent of Siglent vs. Rigol bias does taint its value.
...........
- they are bringing to market 12 bit scopes with good analog performance to low cost market.
Where is the size setting ?
One less parameter to juggle.
What really counts is the resolution.
Guys, to be more constructive in comparing your DSOs - let you design a measurement, which may show some tangible data when running on the DSOs of your choice. .....
Looks nicer..QuoteWhich ones are missing?
Wait until you have it in your own hands.
Before one example:
Where is the size setting ?
I also wonder why some of you are so obsessed with FFT. What is it good for (in this category)? Many old scopes have it too. Practically useless. At least to what I've seen.
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- they are bringing to market 12 bit scopes with good analog performance to low cost market.Are you sure ?
Go back a few pages and look at the disturbing display from a Bodnar pulser where fast edge artifacts seem to be hidden.
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- they are bringing to market 12 bit scopes with good analog performance to low cost market.Are you sure ?
Go back a few pages and look at the disturbing display from a Bodnar pulser where fast edge artifacts seem to be hidden.
For low frequency stuff FFT can be quite usefull to get an idea where noise is coming from. A spectrum analyser doesn't work well at 50Hz or even less. A good FFT implementation on a DSO will. But it does take a bit more effort ....