Rigol DS1054Z vs Siglent SDS1202X-E

[Gandalf_Sr]

Triggering 'Issue'
Tried up to 200 MHz from my arbitrary waveform generator with various signals, I can't get the trigger to fail.  If the timebase is too long you get confused looking waveforms but zooming on on the X-axis produces a well-locked waveform.  The [Auto] button also finds and displays a locked waveform at 100 MHz and 200 MHz.

50 Ohm Input Selection
Put a meter across the Channel 1 input and selected the 50 Ohm setting from the channel soft menu but the input impedance stays at around 1 M Ohm - it looks like it's as @exe says, it's for use with external 50 Ohm feed thrus - at least the ones I bought are not unnecessary.

[boggis the cat]

Triggering 'Issue'

I haven't been able to replicate this problem as described, either.  It may be that exe was unfortunate enough to get a faulty unit, or perhaps there were other factors involved.

50 Ohm Input Selection

This is just an error.  There is no 50 Ohm termination setting, so that menu shouldn't be there.  (Selecting the option does nothing, obviously.)

[boggis the cat]

Only expensive scopes have this option (so far). So, no, it does not have it. You would hear a relay click if it had it. Still, this option is useful for correct measurements as it tells the type of termination. Like, my signal generator also have option "50Ohm / Hi impedance", but this option does nothing but corrects displayed signal amplitude.

A signal generator may want to know the input impedance it is driving in order to correct the nominal output (what you would expect to see on a measuring device, for that impedance).  A 'scope measures the signal, however.  There is no utility to having a false 50 Ohm indication appear, and in fact this could be a problem if you believe that this really should be a 50 Ohm termination as you may be telling your source -- e.g. your signal generator -- that it is driving a 50 Ohm input when it is in fact 1 MOhm.

This is just a mistake on the part of Siglent, leaving in an option that should have been removed.

[tautech]

50 Ohm Input Selection
This is just an error.  There is no 50 Ohm termination setting, so that menu shouldn't be there.  (Selecting the option does nothing, obviously.)

We're not so sure, I can't imagine why it would be left in the menu for no good reason

rf-loop might be onto something:

About FFT. Tiny example.




(there is 455kHz (Radio receiver IF) signal first with 100Hz and after then 120Hz modulation. (Carrier level 1Vrms (0dBVrms) and in both cases modualtion 20%. (with 20% AM mod both sidebands are -20dBc)

Of course 100Hz from carrier can see, and as can see resolution is well enough for separate 20Hz (100Hz and 120Hz peaks) with this frequency. Of course if we rise f Nyquist also resolution change - this is FFT.

Pity there is not 50ohm inputs so it can not show dBm (power) scale.


Please Siglent:

Add function that if user use external 50ohm termination then user can tell it to scope (select External 50 ohm) and after then dBm is available as example in SDS1000X(X+ series.
With rf works dBm is normal and very common way to tell levels what everyone knows and use.  Of course every user can calculate but this is waste of time when scope can do it simply for me.

Only expensive scopes have this option (so far).

Incorrect.

The SDS1000X series that the X-E is the economy version of has 50 inputs.
For ~$50 more you get 50 inputs and the bigger 8" display.
List on the 100 MHz model was $499 and they've been on special for a while for $425.
The MSO (Plus) versions are a bit dearer and have inbuilt AWG.
There is no mention of 50 inputs in the product page but it's stated in the datasheet.
http://siglentamerica.com/pdxx.aspx?id=4688&T=2&tid=1

[exe]

Tried up to 200 MHz from my arbitrary waveform generator with various signals, I can't get the trigger to fail.  If the timebase is too long you get confused looking waveforms but zooming on on the X-axis produces a well-locked waveform.  The [Auto] button also finds and displays a locked waveform at 100 MHz and 200 MHz.

Could you please set sine amplitude at around 100mV p-p and try to trigger at the bottom peak? My unit couldn't do that, it lost triggering half division before the bottom of the waveform. However, it worked perfectly well when triggering level was positive.

I also had "jerking" like here: https://goo.gl/photos/zm3KWYmatkPySThK6 (sorry if I posted this before). Might it happen because of, e.g., faulty clock source? That would explain a lot.

Anyway, good to know it's only my unit. Or a software bug that I triggered somehow.

[boggis the cat]

50 Ohm Input Selection
This is just an error.  There is no 50 Ohm termination setting, so that menu shouldn't be there.  (Selecting the option does nothing, obviously.)

We're not so sure, I can't imagine why it would be left in the menu for no good reason

rf-loop might be onto something:

It would be simpler, and far more useful, to just allow an assigning of dBm (or any other required transformation) than having to set a dummy '50 Ohm' input setting, so I don't believe this to be probable.  Consider what you are suggesting: you want a dBm scaling for the FFT, so rather than select it from a menu related to the FFT functions you go to the channel configuration and set a fake 50 Ohm impedance.  Really? 

Far more likely that it was just overlooked when they shifted the code across to the new platform.

(This seems to be a case of trying to find a 'reason' for a rather obvious error.  There is no utility at all that I can think of, for a measuring instrument, in having a 50 Ohm setting when there is none physically present.  The only thing you can achieve is confusion and additional errors.)

[Gandalf_Sr]

Could you please set sine amplitude at around 100mV p-p and try to trigger at the bottom peak? My unit couldn't do that, it lost triggering half division before the bottom of the waveform. However, it worked perfectly well when triggering level was positive.

I tried this and found that I could get the trigger pretty close to the bottom of the sine wave but not as close as to the top - see first picture - I could get all the way to the top.  However, this is clearly caused by the rising edge trigger because, when I changed to falling edge, I could get all the way to the bottom but only within a few mV of the top (the observed behavior switched polarity).  One thing I noticed was that, when triggering close to the edge, the frequency was wrong, when the trigger was set to zero volts, it was spot on.

[Edit] Also, when I pulled the USB drive from the scope and plugged it into my Windows 10 PC, it complained that the drive needed repair, I repaired it and the files were OK but I can't find any safe eject system on the scope - is there one?

[karkoon]

Could you please set sine amplitude at around 100mV p-p and try to trigger at the bottom peak? My unit couldn't do that, it lost triggering half division before the bottom of the waveform. However, it worked perfectly well when triggering level was positive.

I tried this and found that I could get the trigger pretty close to the bottom of the sine wave but not as close as to the top - see first picture - I could get all the way to the top.  However, this is clearly caused by the rising edge trigger because, when I changed to falling edge, I could get all the way to the bottom but only within a few mV of the top (the observed behavior switched polarity).  One thing I noticed was that, when triggering close to the edge, the frequency was wrong, when the trigger was set to zero volts, it wa

Yes. I could reproduce exactly same behaviour. With falling edge I could go all the to the bottom as well. My signal was 200mv peak to peak due to my signal generator limitation.

Thank you Gandalf!


Typed with thumbs.

[exe]

I tried this and found that I could get the trigger pretty close to the bottom of the sine wave but not as close as to the top - see first picture - I could get all the way to the top.

Can you please do the same, but at a higher frequency? Say, 20MHz. Will this affect triggering anyhow?

[karkoon]

Can you please do the same, but at a higher frequency? Say, 20MHz. Will this affect triggering anyhow?


Yes. I tried with the 20Mhz signal and the triggering worked with the falling edge all the way to the bottom.

I have taken screenshots which I can upload as well.




Typed with thumbs.

[tautech]

Also, when I pulled the USB drive from the scope and plugged it into my Windows 10 PC, it complained that the drive needed repair, I repaired it and the files were OK but I can't find any safe eject system on the scope - is there one?

Yes.....................YOU. 
Just be sure to wait after Print/saves for the USB stick LED to finish flashing before removal.

To others that seem to not be able to let the lower triggering level go......It has been seen and documented and we must wait for the new FW to see the remedy.

[Gandalf_Sr]

I saved a file to the USB drive, waited 5 minutes, and then removed the drive.  When I plug it into my Windows 10 PC, it still reports that there is a problem with the drive which it offers to repair; after the repair, it is fine and the saved files are all there - it seems that the scope doesn't close out the file session after a save.  This isn't a whine, it's an observation.

I don't see the triggering issue (or the USB drive observation above) as a big deal, it's sort of quirky and I could live with it as-is but if they tuned it up to fix both I'd be happier.

[Fungus]

What file system does the stick use?

I think it's just a Windows thing. Windows does it to itself, too.

[stj]

this is a windows problem, i'v seen it before with cards formatted by games consoles etc.
even xp did it sometimes - m$ never properly supports standards - even when they create them!!

[Fungus]

I can definitely unmount a pendrive from Windows and the next time I stick it in the machine it says it needs 'repairs'.

[Gandalf_Sr]

What file system does the stick use?

FAT 32

[rf-loop]

I can't seem to recreate the triggering issue.

Of course . By the nature of the problem I have no doubts it works well on square waves. The problem is much more complex than this.

Long tale short, try using a sine wave 10+Mhz, set low V/div (high sensitivity) and play with triggering coupling and level.

I have now done several test in my lab using many kind of signals with more than just one single scope, including also signals mixed with noise, using my all experience and knowledge from over 50 year hobby and over 40 year profession. I can not see this kind of trigger "issue" what you are talking about. Just nothing but normally working trigger including normal hysteresis (of course it can talk if this amount is best compromise or not)  for edge detection (depending OF COURSE also about selected direction). It need also know how triggers works normally in practice and in theory before start claim issues.  Of course my tests do not proof your individual unit works ok. My test only show how  factory new scope is normally working.

[Gandalf_Sr]

I'm with rf-loop, I don't think there is a trigger issue unless exe has a bad unit.

[Mr. Scram]

I made my choice and went for... siglent. Not because I don't need four channels (I do!), I just want a better 4 channel scope than 1054z. So I decided to buy a decent 2ch scope and wait for a 1054z successor to come. Or for a 4ch equivalent of SDS1202X-E. It looks like scopes evolve quite fast and I'd rather change my scope every few years, than invest a lot of money now.

What is the update cycle on the Rigols? I am leaning towards the DS1054Z at the moment, but fear a newer model might pop up months after purchase. Even though my scope will be just as good as before, it would be nice if a new scope could improve upon some of the shortcomings of the current model. Having a more reponsive UI and better FFT would both be improvements that I would appreciate and those would inevitably be part of a new model.

[ebastler]

What is the update cycle on the Rigols? I am leaning towards the DS1054Z at the moment, but fear a newer model might pop up months after purchase. Even though my scope will be just as good as before, it would be nice if a new scope could improve upon some of the shortcomings of the current model. Having a more reponsive UI and better FFT would both be improvements that I would appreciate and those would inevitably be part of a new model.

Stay tuned for tautech to chime in with some subtle hints about an upcoming new and enhanced Siglent... Must happen any minute now...   

Seriously -- I don't think it makes sense to try and time your purchase based on guesses about future releases. If you need a scope now, buy one now. (And it might be an entry level Rigol or a Siglent, depending on whether 4 channels or better UI response and bandwidth are more important.)

[tautech]

but fear a newer model might pop up months after purchase. Even though my scope will be just as good as before, it would be nice if a new scope could improve upon some of the shortcomings of the current model. Having a more reponsive UI and better FFT would both be improvements that I would appreciate and those would inevitably be part of a new model.

There's always something better and brighter just around the corner in one brand or another.

Want a scope that's current and is the best on offer for a few years......those days are gone, such is the pace of change. Do your homework well, take note of comments from those that have been in the industry a long time, watch countless reviews, but be aware many are rapidly outdated by new firmware and then pick your brand/model.

[borjam]

Want a scope that's current and is the best on offer for a few years......those days are gone, such is the pace of change. Do your homework well, take note of comments from those that have been in the industry a long time, watch countless reviews, but be aware many are rapidly outdated by new firmware and then pick your brand/model.

Indeed. When there is some competition and it's fierce the crown goes from one competitor to the next. This month maybe Siglent has the most exciting offer. Next month it might be Rigol with a newly released product. I remember the old times of the Unix workstations when there was a really heavy competition among Sun (SPARC), MIPS, IBM (Power RISC), HP (PA-RISC) and DEC (Alpha). Usually, the most recently released processor was the fastest and it kept the prize until the next one by another competitor was released.

And in the case of oscilloscopes probably Xilinx has quite shaken the market with the release of the Zynq SoC

[Mr. Scram]

Indeed. When there is some competition and it's fierce the crown goes from one competitor to the next. This month maybe Siglent has the most exciting offer. Next month it might be Rigol with a newly released product.

That does not appear to be the case here. The four channels of the Rigol still make me lean towards it. However, there are some well discussed shortcomings, like the slow UI and FFT. If a new model appears on the horizon, it would inevitably mitigate those issues, so it pays to be aware of the market landscape. I do not absolutely have to buy a DSO right now.

If that new model is unlikely to appear any time soon, the advice to just go with the best choice of the moment goes into effect. There is always the possibility of a competitor coming up with a killer four channel model, but that is, as you mention, just how it is.

[Fungus]

What is the update cycle on the Rigols? I am leaning towards the DS1054Z at the moment, but fear a newer model might pop up months after purchase.

That line of thinking never works.

If it did, nobody would ever buy a car (for example).

[borjam]

What is the update cycle on the Rigols? I am leaning towards the DS1054Z at the moment, but fear a newer model might pop up months after purchase. Even though my scope will be just as good as before, it would be nice if a new scope could improve upon some of the shortcomings of the current model. Having a more reponsive UI and better FFT would both be improvements that I would appreciate and those would inevitably be part of a new model.

If you want better responsiveness, better vertical resolution and better FFT the Siglent SDS1202X-E is what you're looking for. But limited to two channels. Also, the Siglent is not yet supported by software such as Sigrok. If you want the best bang for the buck with four channels, then get the Rigol. Both have shortcomings but both are useful tools as long as you are aware of their limitations.

I'm not sure they will release anything in the low end soon. Maybe they'll jump on the Zynq 7000 bandwagon following Siglent and GW Instek? No idea. They recently made a vague announcement of some new electronics for oscilloscopes but it seems to be targetted to a higher cathegory.

At the end of the day you will have to decide wether one of the alternatives in the market suit you and it does at an acceptable price. In the future of course there will be a new release. That is true especially with cut throat competition between the newcomers to the instrumentation market.