Do I smell here a Rigol-Agilent debate?
This is not my intention. I am not a Rigol advocate, even if I use one and I consider it good for my type of measurements.
You understood me wrong. I have said: Rigol D4034 is a higher class than Agilent DSO-X 2002A, which is true. And then my focus was on memory size compared with overall price of the instrument. It still makes no sense for me to put so small RAM memory in DSO today, when you look at the price of memory on the market and compare it with overall price of the instrument and particularly how much each DSO company asks for memory upgrade; it is ridiculous. Besides that, the price of the instrument is totally unreal.
I will answer to each of you individually, but only once, because I am not going to change this thread about Agilent in a Rigol analysis, even if deviation with jokes seems that are allowed as long as are about Agilent/Keisight…
@ Someone
Hello Someone, I am someone that can answer to your question:
“We've had a flood of users all saying how deep memory is the essential feature and they want Mpts in their low end scopes but almost complete silence on what they want to use it for”
I need it and I used it for non-repetitive asymmetrical “long” time signals/events. More or less a DAQ with high speed digitizers would definitely fit better to such analysis, but they were too expensive and I need it once in a while, maybe couple up to several times per year, so occasionally and for the rest of time a simple DSO is just fine. In a previous job I had in my hands for 2 weeks a Yokogawa DL850E scopecorder which was quite good for what I needed, but was around 25K €, quite expensive, but 16 channels with continuous recording at 100MSa/s was good. We were almost ready to buy it together with other instruments, but some things changed in the company and the project of improving the lab stopped and later I left that company. In fact I wanted initially to transform a high end PC into s signal recorder by adding high speed digitizers and dedicated software. A second option was to use frame for digitizers from National Instruments, but the price with software and setup time came close to a ready-made system as the one from Yokogawa.
I will not provide here full details of the application(s), but I will provide below setup examples.
@Neganur
I never said that overall Rigol is a better instrument than Agilent at the same class/band width.
My point was strictly realted to the memory.
My scope is not MSO, so I cannot say if it is terrible slowly. At math functions is still all right for what I need and I do not use them often. For such situations I prefer to export the waveform and analyze it external on PC with dedicated software. In the past I have worked several years with Lecroy Waverunner 6030a oscilloscope and I did the same even if the math functions were there and complex and not slowly.
“I also believe that has something to do with how the memory is accessed in the scope”.
You may be right, but perhaps Bud can help us more here.
“What's the waveform update rate of the Rigol at that memory depth anyway?”
That is not fair and not a good comparison to decide over the acquisition of the signal. Here it is why.
When you click compare Rigol on the next link:
https://www.rigolna.com/products/digital-oscilloscopes/4000/ and you look at the >110K waveforms/s for Rigol (6.5K $) and then >1M waveforms/s for Agilent (11.7K $) then you conclude that is 9 times slower. How about Tektronix in the middle with the >280K waveforms/s (11.5K $)? Who is cheating here? Has Tektronix a slow memory, it is bad scope with high price? You cannot say that.
First of all, this parameter is not important for me at all.
Let’s picture it: you start the acquisition of the signal, lets’ say based on triggering event and not continuous roll mode: we suppose is continuous run and not on single. Then, when one screen is captured, or a segment of memory in case the memory is segmented, that signal is considered a waveform and then the next waveform is captured and we have many waveforms until the memory is full. This is more or less similar with frames in a video. What you show with the parameters above is the “frame rate” of the video, which I agree it may be very important in situations when in a repetitive signals comes once in a while a glitch, a noise, something abnormal and you want to detect it. But this is not my case. This refers refresh rate of the waveforms, how fast are recorded and placed in memory the waveforms, but is not so important (at least not for me) as sampling rate for acquisition of one single waveform, especially when I set the oscilloscope on single acquisition mode. Just follow me few more sentences.
I do not know about your signals, but I work in the range 40Hz-100KHz with repetitive and non-repetitive signals, at which, sometimes/occasionally I detect signal event superimpose noise/pulses of max, 100MHz and even narrower pulses. The problem is that I need to see if these non-repetitive abnormalities of high frequency are maintained for longer period of time.
Here is the example: the time base is 10ms; Agilent DSO-X 2002A can have the sampling rate of 5Msa/s on normal run and 10Msa/s on single; Rigol can have 1Gsa/s sampling rate at 10ms time base.
The point is that there is a direct relation between sampling rate, the time base and the length of the memory of the scope.
As you go to longer time base settings, the sampling rate goes down from 2Gas/ or 4Ga/s to very low values only because there is not enough memory to store the sample.
How stupid is that when the memory is not so expensive today?
I know what you will say as the 1st thought, because I have heard it several times up to now: with the proper triggering setting, you can reduce the time base, increase the sampling rate and you will capture that event, which is true, because I have done that, but that does not show you how long time the non-repetitive abnormalities are maintained. It gives you only info about the signal/pulses in terms of peak, width and when are superimposed over the normal signal, like you know the volts or amperes with whatever values you need, but does not tell you how long time, because you cannot capture long time. And time means energy, which is an important parameter to evaluate how certain device behave or fail.
As you see, I need it on single, long time base, high sampling rate – from here deep memory, more or less as DAQ. For me this is an important feature for a DSO and just few months ago I had a debate over failures of certain devices from which we won 15K € compensations. They used this Agilent DSO-X 2002A and another LeCroy low end, low memory and I used Rigol. The 3rd party, manufacturer of the semiconductor used in the devices voted on our side as customer of the device with a written paper. Of course, the manufacturer of the device detected the abnormalities, not with Agilent, but with LeCroy in their R&D lab, but could not say too much about energy, duration of the pulses.
I am not saying a moment that Rigol is a better instrument than Agilent or LeCroy when we speak about overall design of the instrument and the components used inside, but deep memory is very good many times ( at least in my case) and should be implemented cheap.
@ Bud
I am really impressed about your work and your findings. I have only bravo and applause. It is a Master work.
https://www.eevblog.com/forum/projects/project-yaigol-fixing-rigol-scope-design-problems/ Since I have read your discoveries I have a nail in my stomach and thoughts flies trough my head: is my scope also with open PLL? How can rely on any signal acquisition/measurement? How bad is it?...
That is an R&D “crime”, “suicide” and should be addressed adequately with a market recall as Toyota did with their cars few years ago.
I bought our Rigol online few years ago from next website:
http://www.batronix.com/shop/oscilloscopes/Rigol-DS4034.html My panic increased when I have seen these days next offer:
“
Bandwidth upgrade for free!
Bandwidth upgrade for Rigol DS/MSO403X from 350 MHz up to 500 MHz, with a total value of € 2487.10 (incl. VAT)
All Options for free!
Get all options with a total value of € 3429,58 (incl. VAT) for free with the purchase of a new device. Offer valid until June 30th, 2017!
“
Suddenly came into my mind: do Rigol and/or distributors know about your PLL discovery and they try to get rid of the existing oscilloscope stock or is just because they found out that Rigol Option Key Codes are published free on different websites, including on this forum and nobody buys them anymore?
After adrenaline came to normal levels, my mind started asking questions, which I realize are for you:
1) You mentioned DS1000 was initially fund with problems and later based on your analysis DS2000, particularly DS2072A.
Do you know if DS4000, particularly DS4034 has the same PLL, the ADC clock and power supplies/regulator problems?
2) Can you publish the serial number of your DS2072A oscilloscope and maybe the manufacture date?
3) Did you try to speak/inform Rigol about your findings? If yes, did you get any answer?
4) How do we know if the problems are not related only with a certain oscilloscope series or production series/batch or maybe they have been just corrected in mean time?
I would like to know that and I would like to know if Rigol have made any official statement or they try to cover up everything.
I would like to contact them.
5) Could you tell us what RAM memory is inside to DS2072A?
Does anyone else found similar critical problems with their Rigol?
If yes, could you provide the model and serial number?
I almost forgot, we are on Agilent discussion, but I was caught by the fever of PLL open loop.
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