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Owon SDS7102 or Tektronix TBS1062 or TDS1002

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luca1000:
I'am not an expert (I understand only about audio D/A converter that is different).

But for my opion the REAL limit of these digital scope is resolution (8 bit 256 point are not enough).

When I see a sine signal on the analog like 2445 I see a VERY perfections , no any defects about the scope, only the defect of the signal (if there are).

When I see on digital scope (expecially on cheap scope, but not only) I see only some points and the result is not accurate.

Ex: on a screen of 800x600 (256 points are not suffcient to fill 600 points and interpolations or other is a compromise). And apart this, 1 G sample is another compromise that cause inperefect result.

In short if you want Quality and accurate result (>10 Hz, periodic signal) I think no way better then analogue you can find.

when I see  a periodic signal (>10 Hz and < 50 Mhz) the result of a analogue 2445 is a REAL result, but with a digital scope < 700 Euro the result can be false and in all case is a compromise (some points no perfect reconstructions like analogue) and when you compare the result, you can be sure that analogue tell the true.

Wuerstchenhund:

--- Quote from: rf-loop on May 15, 2013, 10:48:37 am ---What I'm some amount worry is entry level hobbyists who do not know enough and then he can not understand why and what this digital scope show.
--- End quote ---

I agree, but the way around that is for them to learn and understand their DSO and how it works.


--- Quote ---Shortly, for many peoples. Know your equipment, know basic fundamentals. It need learning work but is is only way to get other than just false measurements. With analog scope it is more "safe" and these traps which can drop is less.
--- End quote ---

Yes, but the proper way for a beginner is to try to understand these limits in the first place and not try to avoid them, especially if EE is supposed to one day become more than an aoocasional hobby.


--- Quote ---(about Siglent, yes, in its price class ok for many use and many nice features and building quality very good in its price class and acceptable if do not take price to count...and even protective real glass front of TFT hehe... wait a moment after I get SDG5000 for tests)

--- End quote ---

As I said in another thread, I really didn't expect much when I ordered my SDS1102CNL scope, but I was really positively surprised (build quality is good, as you say the LCD is protected). My only critics would be the low display resolution (not a real problem, but could be a bit better), the lack of 50 Ohms switchable inputs, and the very simplistic persistance mode (no grading). But again, considering the price, this thing is really good.

And I'm probably well known for not being a great fan of Chinese scopes or entry level scopes in general  ;)

Wuerstchenhund:

--- Quote from: luca1000 on May 15, 2013, 10:56:48 am ---I'am not an expert (I understand only about audio D/A converter that is different).

But for my opion the REAL limit of these digital scope is resolution (8 bit 256 point are not enough).

When I see a sine signal on the analog like 2445 I see a VERY perfections , no any defects about the scope, only the defect of the signal (if there are).

When I see on digital scope (expecially on cheap scope, but not only) I see only some points and the result is not accurate.
--- End quote ---

Be careful, this is not the same as listening to audio! And yes, for scopes 8bit is generally more than enough even for very high frequency signals (and for the few cases it isn't there are 12/14bit scopes available as well). And while you may think that the signal you see on an analog scope is free from influence, that is not true as even analog scopes suffer from imperfections like frequency-dependent distortions and non-linearities.


--- Quote ---Ex: on a screen of 800x600 (256 points are not suffcient to fill 600 points and interpolations or other is a compromise). And apart this, 1 G sample is another compromise that cause inperefect result.
--- End quote ---

You ignore that not all of the 800x600 screen is used for displaying data points, it also contains the scale and other data like the settings or measurements.

And 1GSa/s is plenty of data for signals say up to 100MHz.


--- Quote ---In short if you want Quality and accurate result (>10 Hz, periodic signal) I think no way better then analogue you can find.
--- End quote ---

I'm sorry but I'm not sure you really know what you're talking about. Please define what you mean by "quality", as again, this is not the same as listening to music.


--- Quote ---when I see  a periodic signal (>10 Hz and < 50 Mhz) the result of a analogue 2445 is a REAL result, but with a digital scope < 700 Euro the result can be false and in all case is a compromise (some points no perfect reconstructions like analogue) and when you compare the result, you can be sure that analogue tell the true.

--- End quote ---

I get the impression you don't fully understand how a scope is used, and you bang on points that are generally of little relevance in most applications. It doesn't matter much that a DSO builds up the waveform from little points while the analog scope 'plots' the signal as it is. A scope is all about displaying information. However, the additional 'fidelity' on an analog scope does not necessarily give you additional relevant information. But with most analog scopes the waveform you see is all you get. On a DSO, the waveform display is just a small part of the information you get, aside from a bunch of additional parameters that would take quite a lot of effort or are simply impossible to get from an analog scope.

I think the term 'oscilloscope' for a DSO is a bit misleading, as it's much more than that. A DSO is really more of a signal analyzer than a traditional scope, albeit it can also be used in this function.

PA4TIM:
Just make it clear, I'm not against DSOs. I'm agains cheap DSOs operated by people who do not know the limitations. Like I'm against cheap tools in general. Mechanicl snd electrical. If I buy something I wait until I can buy a good tool ( or camara, TV, ect) and I kep using them very long. If they brek I first repir them and exchange them only if they become to old to function. In the long run this is the cheapest way. ( at least for me the last 30 years)
But I become a bit recalcitrant if people talk bad about my precious babys. Analog scopes are history, that is sure.

Not all DSOs are alike. The very high end scopes are in a way more related to analog scopes as to cheap DSOs. And the problem with the hybrids was they were so good you indeed almost never needed the ( whole) analog part. Most times the analog amplified signals were send to the CRT direct or to the ADC nd then to the CRT so you ould add nice functions. i have a hybrid Tek SA who does this.

The difference between high end and cheap scopes is the way they sample. If I would use the output of an anlog sample plugin and send the output of that to an ADC/ uP and LCD display you get the idea. ( btw, using a 132 and 1S1 makes that possible, something like this and will be for me a future project) Much higher resolution and less dead time. The ADC only needs to deal with rather low frequency signals. But in modern high end ( many GHz) sample scopes the sawtooth, stepper ect is made digital intstead of analog. And that is not how a siglent, Owon, Rigol, Agilent 3000 ect work.
( in a very raw nutshell)

I'm a scope collector too so I love to restore and play with analoge scopes.

I know the limitations of both DSO and analog scopes. And like I said in an other topic. If I had to keep 1 scope it would probably be the Hameg DSO ( but I hope I never have to choose, because I'm in love with my 547) if I had to choose between the DS1102E it would be an analog scope for sure, would not have to think more as a second)

This 547 ( and even nicer but I do not have one, the 556) scope including my plugins can do things most DSOs can not even dream of.
- most sharp trace I've ever seen. ( btw the 24XX have , for an analog scope has rather fluffy traces)
- i can measure up to 5 GHz
- measure things with 10 uV/div resolution
- measure very high voltages
- it has several differential plugins, for AC, DC, high voltage, low voltage ect
- high DC offset measurements, the Z plugin can do upto 2000 divisions offset ( max 200V) , no DSO can do this)
- measure transistor timing ( R plugin) ( ok, not very usefull today, but it can do it)
- with the Opamp plugin you can do the wildest things like integration, preamplifiction, measure capacitance ( managed to come down to 1 pF/div), meaure BH curves ect. Just two very good tube opamps in one unit with a buch of in and outputs. Real cool, a build in breadboard in your scope.
- it has a very good delay option and two timebases. Excellent calibrator, 1 mV to 200V
- upto 4 channels, very much trigger options and very good triggering ( you can show two traces and each adjust their own trigger. This I find the biggest downside of a DSO ( but maybe in the high end they have  dual timebase and dual trigger)
- whole lot of input and output connectors
- It does TDR with high resolution using the 1S2
- it can be used as a SA and the 556 can do time domain and frequency domain at the same time ( So a realtime SA and realtime normal trace at the same time, upto 8 traces, Williams used that in appnotes)

The 7000 4 slot can do even more because you can use vertical and horizontal plugins in all slots, so make things like raster displays.

( downside, the 547 works very good as a heater and it gives a new definition to large, including the scopemobile and no cursors, readout ect and that for sure is the best thing of DSOs)
If you do, like most, do only digital then a DSO is first choise. But I'm analog.



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