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REVIEW - Rigol MSO5000. Tests, bugs, questions

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Fungus:

--- Quote from: 2N3055 on September 05, 2022, 08:21:17 pm ---
--- Quote from: Fungus on September 05, 2022, 12:56:16 pm ---you have multiple samples within each 350MHz time period. Averaging them won't make the bandwidth less then 350Mhz, it simply reduces the noise inherent in the ADC process.

--- End quote ---
Hires is not averaging.

--- End quote ---

It's a calculation done on adjacent samples. It might be the mathematical average, it might be a FIR filter, we don't know.

We do know it's done in an FPGA with steps of 2x, 4x, 8x, 16x so I'm leaning towards "averaging".


--- Quote from: 2N3055 on September 05, 2022, 08:21:17 pm ---Averaging is useful only for repetitive, low phase noise (low jitter) signals.

--- End quote ---

That usage of the word "averaging" isn't what was meant here, and you know it.


--- Quote from: 2N3055 on September 05, 2022, 08:21:17 pm ---So you could say that 1 bit improvement would be transparent , like you say. But not more

--- End quote ---

That's the worst case scenario.


--- Quote from: 2N3055 on September 05, 2022, 08:21:17 pm ---For 2 bit improvement BW is 0,0625 (1/16) of original Nyquist (8GS sample rate, 4GHz Nyquist  effective 250MHz).

2 bit improvement is roughly what MSO5000 need to show similar RMS of noise to RTB2000 or SDS2000X+.

--- End quote ---

So with 1 channel enabled you can get as good as a Siglent (16x oversample, 500Mhz NYquist). Even with two channels enabled you can still get very close (8x oversample, 500Mhz Nyquist).


--- Quote from: 2N3055 on September 05, 2022, 08:21:17 pm ---Or I could just say your are right. It doesn't matter, and we should all just stop using any scopes with more than 20 MHz BW because it is all just some unwanted interference we don't care about anyways.

--- End quote ---

Or we can be grownups and admit that most signals in daily life simply aren't so small that we need to do any of this. This makes for a nice bullet point on the sales brochure but it's mostly an edge case.

2N3055:

--- Quote from: Fungus on September 05, 2022, 11:55:18 pm ---
--- Quote from: 2N3055 on September 05, 2022, 08:21:17 pm ---
--- Quote from: Fungus on September 05, 2022, 12:56:16 pm ---you have multiple samples within each 350MHz time period. Averaging them won't make the bandwidth less then 350Mhz, it simply reduces the noise inherent in the ADC process.

--- End quote ---
Hires is not averaging.

--- End quote ---

It's a calculation done on adjacent samples. It might be the mathematical average, it might be a FIR filter, we don't know.

We do know it's done in an FPGA with steps of 2x, 4x, 8x, 16x so I'm leaning towards "averaging".


--- Quote from: 2N3055 on September 05, 2022, 08:21:17 pm ---Averaging is useful only for repetitive, low phase noise (low jitter) signals.

--- End quote ---

That usage of the word "averaging" isn't what was meant here, and you know it.


--- Quote from: 2N3055 on September 05, 2022, 08:21:17 pm ---So you could say that 1 bit improvement would be transparent , like you say. But not more

--- End quote ---

That's the worst case scenario.


--- Quote from: 2N3055 on September 05, 2022, 08:21:17 pm ---For 2 bit improvement BW is 0,0625 (1/16) of original Nyquist (8GS sample rate, 4GHz Nyquist  effective 250MHz).

2 bit improvement is roughly what MSO5000 need to show similar RMS of noise to RTB2000 or SDS2000X+.

--- End quote ---

So with 1 channel enabled you can get as good as a Siglent (16x oversample, 500Mhz NYquist). Even with two channels enabled you can still get very close (8x oversample, 500Mhz Nyquist).


--- Quote from: 2N3055 on September 05, 2022, 08:21:17 pm ---Or I could just say your are right. It doesn't matter, and we should all just stop using any scopes with more than 20 MHz BW because it is all just some unwanted interference we don't care about anyways.

--- End quote ---

Or we can be grownups and admit that most signals in daily life simply aren't so small that we need to do any of this. This makes for a nice bullet point on the sales brochure but it's mostly an edge case.

--- End quote ---

Hires can be implemented only one way.  As a filter, of whatever implementation you chose. But result is same, lowpass filtering of current sample buffer.
If it is not implemented that way then it is not Hires, but something else. Simple. So we know exactly how it's made.
And it creates BW limiting.

Also averaging is averaging. That is also term that is well defined in this context. In this context it means repetitive triggers and combining (averaging) multiple buffers on top of each other. It does not create BW limiting and can be used to extract signals that are autocorrelated and in a fixed timing to trigger from noise. Signals have to be stable and repetitive.

I calculated whole table to show how rapidly BW drops and how it drops to very low bandwidth if you try to use Hires to actually have some usefulness from it. From it you took one data point and proclaimed victory.. Numbers are if you run at fastest sample rate. If you go with slower timebases and scope decides to drop sample rate BW will drop too.

Problem with Hires that is annoying that BW changes all the time in seemingly unpredictable ways. Every time you change timebase sample rate might change. You enable or disable a channel it changes. You change how much Hires, it changes. You change  memory size it might change. You end up with a scope that has "random" BW. What it does is that signal on the screen changes all the time. Looking at I/O pin on Arduino, signal risetime will vary from 1ns to 5 ns depending on Hires. You go slower timebase, it will drop slower than that.
That is confusing as hell.
Expectation from the scope is that BW won't change with you twiddling knobs and signal won't look different at different setting of timebase.

Hires is a special acquisition mode. Like peak detect mode it is there for special occasions.

Yes we could behave like adults. And admit that you are wrong. You are pushing that worse specification of a specific device are not important to all and everybody, because you are of the opinion that it doesn't matter because everybody out there is doing same thing as you, apparently.
Signals in real life are absolutely small and large and all in between. All together on a same scope screen.
What are you saying, that we don't need vertical sensitivities better than 100mV/DIV, and scopes faster than 50Mhz?

I said many times, if you are doing only digital level signals, on low speed digital, MSO5000 is going to do good job for you. In it's price class it is a decent device for that kind of work. It has few quirks, but it will do that work.
If you want to look at analog domain properly, on mV level signals, any number of devices (including cheaper ones like Micsigs, SDS1104X-E, hires Picos etc) are going to be better for that. Tool for the job.

Stretching that to a statement that it makes it same as a devices with much better specs is what is wrong in your efforts. These workarounds might work for you, for the stuff you do. Good for you and enjoy. That doesn't make it universal truth. Just workarounds that happen to be good enough for you.

Fungus:

--- Quote from: 2N3055 on September 06, 2022, 07:12:08 am ---Stretching that to a statement that it makes it same as a devices with much better specs is what is wrong in your efforts. These workarounds might work for you, for the stuff you do. Good for you and enjoy. That doesn't make it universal truth. Just workarounds that happen to be good enough for you.

--- End quote ---

I've said many times that it isn't the same.

What I'm saying is that prices aren't equivalent (70% more) and that those "workarounds" will do the job for many people.

To use a car analogy: Asking for oscilloscope buying advice on EEVBLOG is like asking for car buying advice at a drag strip or a BMW-owners club. The answers you get will be skewed.

Yes, you'll have to fiddle around to get to see a really low level signal on a Rigol. If it's only occasionally though, where's the problem?


--- Quote from: 2N3055 on September 06, 2022, 07:12:08 am ---Hires is a special acquisition mode. Like peak detect mode it is there for special occasions.

--- End quote ---

Looking at mV signals is a special occasion for many people. Don't pretend it isn't.

(bites tongue to not go down the "Siglents seem to think that zooming out is a 'special occasion' " path)


--- Quote from: 2N3055 on September 06, 2022, 07:12:08 am ---admit that you are wrong. You are pushing that worse specification of a specific device are not important to all and everybody, because you are of the opinion that it doesn't matter because everybody out there is doing same thing as you, apparently.

--- End quote ---

Pot, kettle.

The person asking the question a person who is buying a "very first oscilloscope for casual / hobby use". With the money saved they could buy a multimeter+soldering iron+hot air gun+power supply. Which is a better investment right now?

A Rigol can always be sold later on if OP discovers they're really into mV signals. They keep their value very well.

PS: What do Siglent owners do when they need to see a 0.1mV signal?

tv84:

--- Quote from: Fungus on September 06, 2022, 12:03:33 pm ---To use a car analogy: Asking for oscilloscope buying advice on EEVBLOG is like asking for car buying advice at a drag strip or a BMW-owners club. The answers you get will be skewed.

--- End quote ---

 :-DD

OTOH, should it be guests only? That's the responsibility of the searcher to distinguish. I could ask for car advice in a pharmacy but is it the pharmacists fault that the advice was biased?

Fungus:

--- Quote from: tv84 on September 06, 2022, 03:01:29 pm ---
--- Quote from: Fungus on September 06, 2022, 12:03:33 pm ---To use a car analogy: Asking for oscilloscope buying advice on EEVBLOG is like asking for car buying advice at a drag strip or a BMW-owners club. The answers you get will be skewed.

--- End quote ---

OTOH, should it be guests only?

--- End quote ---

Of course not. You can go there to see what it's all about and discover the pros/cons but you don't have to come away owning one.

Toyotas are perfectly driveable and can get to your destination for a lot less money. The need to get down a 1/4 mile in 10 seconds is a specialist need. The massaging seats and little robot arm that hands you your seatbelt when you sit down are nice but they aren't a necessity.


--- Quote from: tv84 on September 06, 2022, 03:01:29 pm ---That's the responsibility of the searcher to distinguish.

--- End quote ---

To do that:
a) They need to hear both sides.
b) They probably need to have some oscilloscope experience under their belt to pick features based on how they used one in the past.

Edit: Suggestion: Go to a Rigol MSO5000 owners club and listen to them talk for a while.

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