Help with scope purchase decision

[WaveyDipole]

For some time now I have been considering the purchase of a DSO. Having seen many favourable (and some unfavourable) comments about the Rigol DS1054Z, I was considering a purchase based on price only. I’m a hobbyist and although I would like a useful instrument, I can’t justify spending several hundreds or even thousands on one.

I have also looked at PicoScopes, but anything with a comparable spec to Rigol and Sigilent was way higher in price by comparison, especially considering that the latter are complete standalone scopes.

One thing that holds me back from the DS1054Z are the negative comments and the fact that there is no external trigger port. I have a Thandar LA160 logic analyser device that connects to a scope using a vertical channel and an external trigger input. It is an old device operating at only 20MHz, but it has 16 channels and it works nicely on my analogue scope, but it might be useful to use it on the new DSO. However, the absence of the external trigger is an issue and led me to think about other instruments from Rigol, Hantek and Sigilent.

Hantek do not seem to compete on features. Sigilent do not seem quite up there on features vs price point but come close. So what about one of the better Rigol scopes?

Well rather than around 350 pounds I would be looking at twice that much, difficult to justify, but maybe worth considering if it was a good long term investment. An MSO1074Z with built in logic analyser sounds appealing, but AFAIKT the only difference, except for a slight increase in default bandwidth is the logic analyser. It does not have an external trigger input, but with the LA built in this might not be necessary anymore – although it has been usefull on a couple of occasions on the analogue scope. On the other hand, I am sure one could find a standalone or PC connected logic analyser for less than the 350 pound difference. Just briefly looking at Amazon reveals a few USB connected devices for less than half of that.

Then there is the DS1074B. It has 4 inputs and an external trigger and 2Gsa/s vs 1Gsa/s, but no logic analyser. I had to smile at the description ‘High definition 5.7" display (320 x 240)’. Do they not realise that even in the late 1980’s 320x240 would have been low resolution – EGA (640x480) being the default standard resolution at the time. It is perhaps a reasonable resolution for the size of display but by no stretch of the imagination ‘high definition’. Even screenshots of the higher resolution (800x480) DS1054Z look a bit rough sometimes. I can’t believe manufacturers are still sales pitching this kind of nonsense! That aside, the price point is another 50 pounds higher but given the 2GSa/s sample rate, perhaps worthwhile.

So I guess I am looking for advice on whether either of these more expensive scopes is worth buying over the DS1054Z. Can one of the input channels be used as an external trigger perhaps? If so, this would solve my dilemma with the external trigger and it would then be a more straightforward shootout on features.

[Fungus]

One thing that holds me back from the DS1054Z are the negative comments

Well done, all you Rigol haters!

...and the fact that there is no external trigger port.

Not many 4-channel 'scopes do.

The trick is to use one of the channels as a trigger input.

So I guess I am looking for advice on whether either of these more expensive scopes is worth buying over the DS1054Z.

If you're a hobbyist having trouble justifying the purchase then I say "no". You can buy a lot of other stuff with the difference in price between a DS1054Z and the next 'scope that's significantly better than it.

[WaveyDipole]

The trick is to use one of the channels as a trigger input.

Aha, yes tried that with my old analogue scope displaying CH1 and and setting trigger to CH2 and it works perfectly fine, so perhaps using CH4 on the Rigol for the trigger would work as well. Thanks for that. I guess I just assumed it had to be connected to the socket marked Ext. Trigg. without really thinking about it!

If you're a hobbyist having trouble justifying the purchase then I say "no". You can buy a lot of other stuff with the difference in price between a DS1054Z and the next 'scope that's significantly better than it.

Yes, agreed and its quite a jump from that to the next level so I would prefer to avoid if possible.

[nctnico]

One thing that holds me back from the DS1054Z are the negative comments

Well done, all you Rigol haters!

The only one to blame is Rigol because they release their products with non-working firmware! If it is good from the start there is no need to complain about it. Rigol fixed a lot of issues in the end (a few years after release!) because of the comments so you should THANK the people who put the hammer down for getting your scope fixed!

[janoc]

One word of caution, when DS1054 runs in more than 2 channel mode, its sample rate quarters to 250Msps, which is barely above Nyquist frequency of its rated 100MHz frequency (hacked), so if you are observing 2 channels while using another channel as trigger, you will get only 250Msps.
If you are observing digital signal or whatever analog signal with higher than 125MHz components, you may run into aliasing issues.
Though Rigol does have analog LPF in their front end, but I don't think that will work well because rated 100MHz is too close to its Nyquist frequency, 125MHz.

Which happens to be the case for most cheap scopes - they share the ADC between channels, so the sample rate is halved (or worse) with additional channels enabled. So important thing to keep in mind, but hardly something why not to buy the scope - the competitors are not any better.

On the other hand, how often do you need to use 100MHz of bandwidth on all 4 channels simultaneously? If you need that, then this isn't the scope for you, but an average hobbyist is very unlikely to hit this limitation. In the 1% of cases when I need all four channels on mine it is mostly because I am dealing with some signal sequencing or trying to decode some SPI. And for that 250Msps is more than enough. For the 99% of other cases where I need a scope 2 channels are enough already and there I have 500Msps which is plenty.

What bothers me more is the long boot after upgrading the firmware and the sluggish UI. It is certainly usable, but more responsive controls would be definitelly preferred. Also the ability to actually hide the softbutton menus like on the 2000 series - like this I have a large screen, but a large part of it is permanently covered by stupid menu bars that cannot be hidden.

[janoc]

@WaveyDipole Re MSO1074Z

The logic analyzer is useful, because it actually allows to correlate the analog and digital signals in time - e.g. looking at the inputs and the output of a DAC simultaneously.

Whether it is worth it the extra price is something you need to decide. If you aren't going to use that feature every day where the convenience of pushing a button matters, I would say that no, it isn't, rather buy a cheap USB logic analyzer. You can always synchronize it with the scope by triggering it from the scope's trigger output at the back or to trigger the scope from one of the analyzer channels. You won't get the data on the same screen and it is a bit more mess to wire up, but it will allow you to do most of the measurements for a fraction of the price of the MSO scope.

The same for the -Z version (the included signal gen). I have bought my Rigol without the sig gen, because I don't like the impractical user interface. Even as is the Rigol panel is cluttered enough already. I have rather got a separate function generator from eBay for some 50 euro or so. It probably isn't as good as the one in the Rigol, but it is good enough for my needs, much cheaper and has actual knobs and buttons instead of the maze of the menus on the scope.

There is no point in spending a ton of money on a scope you only think you may need sometime in the future, especially if you are a hobbyist. Buy something you know you can use now, you can always sell it and upgrade later if you figure out you need a better instrument.

[David Hess]

One thing that holds me back from the DS1054Z are the negative comments and the fact that there is no external trigger port.

...

However, the absence of the external trigger is an issue and led me to think about other instruments from Rigol, Hantek and Sigilent.

It is common for 4 channel oscilloscopes to lack a dedicated external trigger input because any of the 4 vertical inputs can be used as the trigger source.  Before 4 channel portable oscilloscopes became common, later 2 channel oscilloscopes commonly had "trigger view" capability which would show the external trigger input as a 3rd vertical channel.  Then later this was extended to a 2+2 configuration where two external trigger inputs also served as limited vertical inputs for 4 channels.  Finally 4 channel oscilloscopes became common.

On some mixed signal DSOs, the logic analyser inputs can be used as external trigger inputs for the 2 or 4 vertical analog inputs.  The 1000Z series can do this but I do not know how well it works.

Then there is the DS1074B. It has 4 inputs and an external trigger and 2Gsa/s vs 1Gsa/s, but no logic analyser. I had to smile at the description ‘High definition 5.7" display (320 x 240)’. Do they not realise that even in the late 1980’s 320x240 would have been low resolution – EGA (640x480) being the default standard resolution at the time. It is perhaps a reasonable resolution for the size of display but by no stretch of the imagination ‘high definition’. Even screenshots of the higher resolution (800x480) DS1054Z look a bit rough sometimes. I can’t believe manufacturers are still sales pitching this kind of nonsense! That aside, the price point is another 50 pounds higher but given the 2GSa/s sample rate, perhaps worthwhile.

I would avoid the 1000B series because unlike the 1000Z series, they lack peak detection.

As far as screen resolution, from my perspective they are still catching up to my ancient DSOs which display 1024x1024 on a vector CRT screen.   Unlike the 1000B series, the 1000Z series has an index graded display which further improves the look of its 800x480 display.