Year 2013 Oscilloscope Choices...

[Hydrawerk]

Choose an eshop with good reputation.

[hgg]

I've already did, but do you mean? 
That he is lying and that the 200Mhz Hantek does not have a fan???

[Wytnucls]

Here is a small review for the UNI-T scope:

I work in the maintenance - service business. I had a small budget to put together a basic repair lab, that would qualify to do the job. I had no choice, so I started with products that have "Made In China" stickers. Following other peoples opinion on the Net, and after trying out almost all "cheap" oscilloscopes, I found that all brands had some good, and many bad features. I got an opportunity to "play" with the UTD2102CM, from UNI-T. The first thing I noticed is the weight. It is heavier than the rest with the same specs. The quality of workmanship deserves a thumbs up. You should expect the fan noise. The Large screen is crisp, and clear. The second thing that got my attention, is the capture rate. I saw my waveforms in more detail than any other oscilloscope in the category I mentioned. The GUI is so/so, due to the fact, that the color of the cursor is the same as the wave, (they kind of blend together) and the fact, that currently the captured wave I save to memory, can't be transferred to memory stick. I heard they are working this problem to fix it. The filter is working excellent. My overall impression is, that this is the first scope I have used that deserves the thumbs up, and that I should keep. I'm not trying to compare this scope to other brand names, but it is "worth the money ".

Date Added: 07/31/2012 by Gyula Lami

[Wytnucls]

Here is a comparison between the UNI-T UTD2102CM and the Siglent SDS1102CML scope:
https://www.mortoncontrols.com/blog/files/archive-01-july-2012.html

[hgg]

Wytnucls I just finished reading the exact same article!   
I think that the UNI-T is going up the list.  Everything looks good on it except maybe the firmware
that is somewhat work in progress.  Double Faraday shielding in the scope and power supply.
Vertical knobs though do not double as push buttons.

So we have at least one report that the waveform per second is high on the UNI-T.
Not sure if its 150.000 but its faster then all the others.

[marmad]

Here is a comparison between the UNI-T UTD2102CM and the Siglent SDS1102CML scope:
https://www.mortoncontrols.com/blog/files/archive-01-july-2012.html

People have posted this link on the forum before, and honestly, what does a 'comparison' of two DSOs sold by the writer of the article exactly illustrate? It's as irrelevant as just reading the datasheet.

Also, as discussed before in the forum, some previous Uni-T scopes had misleading specs for memory depth, so I would be wary of trusting their datasheet - or their claim of 150k wfrm/s rate (supposedly faster than Rigol DS2000/DS4000; Agilent X2000; GW-Instek GDS-2000A?) unless it's verified with instruments by someone who isn't selling it.

[nctnico]

nctnico, a nice point if you are using a lot both inputs.
Owon and Hantek and UNI-T, have the highest vertical resolution.

Even if you use one input the more vertical pixels the better. Don't forget that a display with twice the resolution has four times more pixels so text takes 4 times less space!

[marmad]

So we have at least one report that the waveform per second is high on the UNI-T.
Not sure if its 150.000 but its faster then all the others.

One thing to note: I personally find UNI-T's wfrm/s claims difficult to believe - but even if they are true, the best reason for having a high wfrm/s rate is to have intensity-grading - which allows the DSO to move more captured waveform information to the display with each screen refresh - and gives your DSO the feel of an analog scope. But the UNI-T has no intensity-grading - so it obviates one of the great reasons for having a high refresh rate.

[Wytnucls]

I don't know if the high acquisition rate of the UNI-T is correct, but it is not a misprint in the catalogue datasheet, as it is also mentioned in the scope user manual.

There are two major benefits to a high acquisition rate:
1) the ability to find and measure infrequently occurring events
2) faster and more reliable results during compliance and characterization testing.

http://www.ecnmag.com/articles/2010/12/importance-oscilloscope-acquisition-rate

 

[marmad]

I don't know if the high acquisition rate of the UNI-T is correct, but it is not a misprint in the catalogue datasheet, as it is also mentioned in the scope user manual.

That's all well and good, but since the UNI-T does not have a Trigger Out signal to easily verify their claim, they could print anything. The only way to test it is to open it up and check it internally or run tests involving delayed pulses or glitch-capturing; either way, it takes some effort to verify.

Also, since the advertised wfrm/s rate on all DSOs is a best case scenario (single channel, one certain timebase, etc), serious DSOs with high rates specify what settings are required to achieve the fastest rate. The UNI-T does not. That means their 150k wfrm/s rate might mean ONLY for the split-second when you turn the dial from 20ns to 10ns - or any other nonsense - since there's no easy way to verify.

[hgg]

I thought that the Uni-T had an external trigger out...?
Please have a look at the picture:
http://www.reichelt.de/?ACTION=3;ARTICLE=123970;GROUPID=4044;PROVID=2382;&utm_source=Preisvergleich&utm_medium=CPC&utm_campaign=Preisvergleich_shopping.com/

They actually state that its equal or greater than 150.000 wfrm/s...

[marmad]

I thought that the Uni-T had an external trigger out...?

That's an input; all DSO's have them.

They actually state that its equal or greater than 150.000 wfrm/s...

Sure   One more reason to believe their specifications: that's the minimum speed of their DSO 

[Wytnucls]

I don't think they would deceive their clients purposefully. It could just be a snafu in their publishing department.
The company specifies a lower acquisition rate of 20k waveforms/sec on their new top of the range 1GHz machine.
The new scopes in the 4000 range, with a sample rate of 2GS/s, also have an alleged acquisition rate of 150Kwfms/s.

[marmad]

I don't think they would deceive their clients purposefully. It could just be a snafu in their publishing department.
The company specifies a lower acquisition rate of 20k waveforms/sec on their new top of the range 1Ghz machine.

Um... err... ah... yes, a snafu in the publishing department. Funny, I've run into these 'snafu's before in the specification department of Chinese-made test equipment - and even when you confront them with the 'snafu' (which, BTW, always helps increase their sales - it's never a 'snafu' which lowers the DSO's capabilities), and they admit that it's a mistake - they don't manage to correct the 'snafu' for many many months (especially odd since most documents are just online in electronic form these days).

[hgg]

That's an input; all DSO's have them.

Yes, sorry... 

[Wytnucls]

Also, since the advertised wfrm/s rate on all DSOs is a best case scenario (single channel, one certain timebase, etc), serious DSOs with high rates specify what settings are required to achieve the fastest rate. The UNI-T does not. That means their 150k wfrm/s rate might mean ONLY for the split-second when you turn the dial from 20ns to 10ns - or any other nonsense - since there's no easy way to verify.

Not true, R&S datasheet only mentions an acquisition rate of more than 1 million waveforms per second.

[marmad]

Not true, R&S datasheet only mentions an acquisition rate of more than 1 million waveforms per second.

Really? As a counter-example you're going to use one of the companies which publish the MOST literature about their DSOs? It took me about 5 minutes to find this:

"The R&S RTO oscilloscopes acquire, process and display 1 million waveforms per second while capturing a 1000 sample record length at the maximum sample rate of 10 Gsample/s."

I'm guessing I can find even more detail with a few more minutes. While I do, would you care to dig up and post some more detail on the UNI-T's capture rate?

[Wuerstchenhund]

Not true, R&S datasheet only mentions an acquisition rate of more than 1 million waveforms per second.

Yes, because R&S claims that the 1M wfms/sec will be reached at most settings. Not sure if that's the case (apparently not, as marmad's table below suggests).

LeCroy also claims 1M wfms/sec for their WaveRunner Zi Series on any (sequential) setting, even when running on all 4 channels.

On the other side both the R&S RTO scopes and the LeCroy WaveRunner Zi cost a bit more than 360€. Quite a bit more.

[marmad]

Here are two charts from R&S which show both the acquisition rate for a constant resolution - and the acquisition rate for a constant record length. This is more info than you get from virtually any manufacturer:

[Wuerstchenhund]

The things that are more important to me are the following:  (with that order)
Price Range around 360 euros / $470.   Maximum 400 euros if its a must.

  1) Accurate measurements & signal quality.  (for the price range)
  2) Stable firmware.
  3) High quality internal power supply.  (very important for any device)
  4) Crisp display with decent viewing angles.
  5) Bandwidth >= 50Mhz.
  6) Usable probes for the given bandwidth.

I know you have narrowed down your selection already but have you considered buying 2nd hand?

[Wytnucls]

We are comparing datasheets here, nothing else. So the UNI-T information provided on the datasheet is not necessarily misleading, like you implied. 
I will contact UNI-T tomorrow for more information on that strange high acquisition rate and report back soon.

[Hydrawerk]

All high speed waveform update rate scopes must have intensity grading and Trig Out. If not, then the scope is weird and not suitable for buying.

[marmad]

We are comparing datasheets here, nothing else. So the UNI-T information provided on the datasheet is not necessarily misleading, like you implied.

That's not what I wrote - I never mentioned datasheets - you did; I already tried looking through the UNI-T User Manual and other docs.

And I didn't imply anything - I specifically stated: "...serious DSOs with high rates specify what settings are required to achieve the fastest rate. " - and they do: sometimes in the owner's manual, sometimes in supplemental literature.  I can find it for Rigol, for GW-Instek, for Agilent, for R&S, etc. - but NOT for UNI-T.  And strangely, no one has been able to find this information in the months the DSO has been available.

Listing a maximum wfrm/s rate without specifying how/when it's achievable is like specifying the frequency response of something without the decibel deviation - it's rather meaningless.

I will contact UNI-T tomorrow for more information on that strange high acquisition rate and report back soon.

Fine. And while you're asking them questions, ask them why they don't use intensity grading with such a fast rate - and how someone can measure their claimed wfrm/s rate to verify it?

[Hydrawerk]

and how someone can measure their claimed wfrm/s rate to verify it (without Trig Out)

I saw a method somewhere, but i cannot find the website now. You need a special signal generator or something...

[marmad]

and how someone can measure their claimed wfrm/s rate to verify it (without Trig Out)

I saw a method somewhere, but i cannot find the website now. You need a special signal generator or something...

I know how to do it - I just wanted to hear the response from UNI-T.