New Scope Choice - Memory Questions

[Gandalf_Sr]

Looking for a new scope, considering the Agilent Keysight DSOX2024 or the Rigol DS4024 or the Tek DPO2024B.  A sales guy was telling me that the Agilent has a much lower memory capability than the Rigol but Dave's review says that the Agilent has 50,000 samples per second (which can be upgraded).  The sales guy (seeming to push Rigol) is telling me that Agilent can only store 1 M points and the Rigol can store 140 M points.

http://www.tequipment.net/product-comparison/?Items=428751,367045,430330 compares the 3 scopes

Is the Agilent really that bad, is the Rigol really that good?  What is the real world experience? Can someone help me make sense of this?

Thanks in advance.

[cyr]

The Agilents with 1M max on the 2000X and 4M max on the 3000X is on the low end today, but IMHO it's still more than enough for the wast majority of uses. It basically means that you can capture a screen full of data and then zoom in by a factor of 1000 or more and have a detailed waveform on the screen. Unless you know that you have a real need for the 140M memory I wouldn't get the Rigol.

My real-world experience with the Rigol DS4000 is that it's annoyingly slow to use, and has too many bugs to be trusted.
Rigol offers great value at the low end (DS2000 series etc), but I would not recommend the DS4000 series.

[Gandalf_Sr]

The Agilents with 1M max on the 2000X and 4M max on the 3000X is on the low end today, but IMHO it's still more than enough for the wast majority of uses. It basically means that you can capture a screen full of data and then zoom in by a factor of 1000 or more and have a detailed waveform on the screen. Unless you know that you have a real need for the 140M memory I wouldn't get the Rigol.

My real-world experience with the Rigol DS4000 is that it's annoyingly slow to use, and has too many bugs to be trusted.
Rigol offers great value at the low end (DS2000 series etc), but I would not recommend the DS4000 series.

Thanks, that's exactly the real world kind of advice I was looking for.  I have a DSOX2024A on order from Fry's at $2,399 but it's back-ordered.  I could also buy the DSOX2APPBNDL option to upgrade all software features for $500 (actually been quoted $475) until Sep 9th on the Agilent too.  There are some worrying videos out there that show the Rigol not working properly on I2C/SPI decoding.

Another option might be the Rigol DS2072A - only 2 channels but only $839, I could then buy a separate Logic Analyzer for <$500.  I think all these scopes have 8/8½ inch screens.

[AndyC_772]

Having personally used the Rigol DS4000, I completely agree what what's been said here. Its UI is really quite sluggish, especially cursor movement and serial decoding (which does indeed also have bugs in it).

The huge memory on the Rigol is a definite benefit if you need it, though, and it's well implemented and easy to use.

The smaller memory on the Agilent is a limitation, though not one I've found to be a show stopper, just slightly disappointing on an otherwise exceptionally capable scope.

The software feature bundle is an absolute no-brainer IMHO. I bought it for my 3000X even though I already had most of the options I wanted, because I figured I only ever needed one job to come along that really needed, say, CAN bus decoding or power supply analysis to make it worthwhile. If you're buying a new scope, you'd be daft not to get the options bundle with it too.

[EEVblog]

The smaller memory on the Agilent is a limitation, though not one I've found to be a show stopper, just slightly disappointing on an otherwise exceptionally capable scope.

People have to remember that the Agilent X-Series is now around 3 1/2 years old.
When it was released it was ground breaking, and the 4M of sample memory built into the ASIC was plenty (the 2000X is software limited to less)
Now on paper it doesn't look that great compared to other offerings in the memory depth department. But it's still the leader in terms of update speed and system responsiveness.

[EEVblog]

The huge memory on the Rigol is a definite benefit if you need it, though, and it's well implemented and easy to use.

If you think you might need deep memory you can always buy a Rigol as a 2nd scope and have it for just that use 
Bonus is you have two scopes 

[AndyC_772]

Hey, why not? I've got five power supplies...

[Gandalf_Sr]

The huge memory on the Rigol is a definite benefit if you need it, though, and it's well implemented and easy to use.

If you think you might need deep memory you can always buy a Rigol as a 2nd scope and have it for just that use 
Bonus is you have two scopes 

Good one Dave!  If my auntie had a set of wedding tackle, she'd be my Uncle  O0

I'd really like the MSOX3024 with the APPBNDL option pack but that would be over $6,000 list, I'm more comfortable in the $3,000 range

[Berni]

More memory becomes less of a big deal once you get past a few Meg. Also in the rigol you might end up never using the deep memory as the scope becomes really really slow with it enabled.

With the Agilent scopes you will always be using the full memory available as they don't even have an option for how much memory to use. They don't lose any speed when using it all so no point in having such an option.

I personally have a Agilent MSO6000 with 8M of sample memory and have never needed anything more while loving the lightning quick responsiveness of these scopes( these old pre X scopes even boot in a few seconds)

[georges80]

The agilent ebay store (certiprime refurbished) is a great way to get one of their pieces of equipment well under list. Bought my msox2024 a few months ago for about $2400 delivered. Has the full 5yr warranty and is essentially brand new. Comes with new probes for all the analog and digital inputs and calibration certs etc.

I've used it quite a bit (home office) and it's a great scope for the $$. I have not seen a need for more memory capacity - at some point more memory is essentially a marketing sales pitch versus something you really need (e.g. spending an extra minute improving your trigger setting versus spending 20 minutes scrolling through 140megasamples to find what you're looking for...). I think some of us fixate on gimmick features versus the 99.9% of time needed features

I sold two of my old tek dso's and that covered 2/3 of the price of the agilent scope I purchased, so I'm quite pleased. I have some tek accessories (503b/6302 current probe system and an 1103 supply for my differential probe and my active probe) and they all of course work fine with the agilent since their 'output' is a plain bnc.

I spent a month or two trying to decide between a rigol or agilent scope and during that time visited a few local conventions/shows. Rigol is a decent way to go if on a budget and you're looking at their budget level scopes. Once you get into the $2k+ level I just didn't get a comfortable feeling in terms of software/firmware stability and longer term support (as the unit ages). Tek is out of the picture with their current offerings in the $2k - $4k range.

cheers,
george.

[David Hess]

With the exception of being able to capture a long single shot acquisition or pretrigger record and then zoom in, I have never found long acquisition memories to be much use because in most or all cases they slow down the acquisition or processing rate or both and sometimes to unusable levels.  This is one area where I think marketing specmanship has taken over.  Of course if you do need this capability, then they are mandatory.

Long acquisition records should be helpful if the graded intensity display is generated from the acquisition record and not during decimation but I have never seen an example that I would consider good.

[nctnico]

I wouldn't even consider the Tektronix DPO2000 series (I have used one several times). The display resolution is way too low for any real work.

I think I'll give myself a Siglent SDS2000 series scope for Christmas.

[Gandalf_Sr]

So how good is Siglent?  Have you reviewed one Dave?  The Siglent SDS2304 is $2,558, has 300 MHz BW on 4 channels, and appears to do I2C/SPI/UART/CAN/LIN out of the box.

[tautech]

So how good is Siglent?  Have you reviewed one Dave?  The Siglent SDS2304 is $2,558, has 300 MHz BW on 4 channels, and appears to do I2C/SPI/UART/CAN/LIN out of the box.

There is a large thread for the Siglent SDS2000 series starting with pre release development on through to recent full product release.
https://www.eevblog.com/forum/testgear/siglent's-new-product-msosds2000-series/

The Serial trigger suite is standard and Decoding is 1 of the available options.

Siglent have indicated Dave would get one to test and now development is complete , I would expect him to get one soon.

[Gandalf_Sr]

Thanks for all the input and advice.  I've decided not to buy the DSOX2024, it was backordered and I cancelled. It's a 3½ year old design and they still want $2,500.

I've just ordered a new Rigol DS2072 for $800.  Although it's only 2 channels, in reality it can do all the I2C/SPI decodes I need for the next year or 2, can be upgraded, has better memory, an 8" screen, and is a third of the price of the DSOX2024A.

[Mark_O]

...at some point more memory is essentially a marketing sales pitch versus something you really need (e.g. spending an extra minute improving your trigger setting versus spending 20 minutes scrolling through 140megasamples to find what you're looking for...). I think some of us fixate on gimmick features versus the 99.9% of time needed features

I'd agree with this assessment.  If the Rigols had some method to search and locate points of interest in that vast space (as their competitors do), the super deep captures would be vastly more useful.  As they are, requiring manually scrolling through megasamples, they can often be more of a PITA than they're worth.  So they go unused.  One place they are very useful is in segmented acquisitions, since the trigger conditions allow focusing on desired events, many events can be captured, and then each segment still has excellent temporal resolution.  They can also highlight and identify specific segments that deviate... a very useful capability.

This is just another example of Chinese manufacturers focusing on a feature, rather than a capability.  In the case of Rigol, it's a lost opportunity, since the type of selective post-acquisition search and identify capability requires NO additional hardware, and is purely a software function.  It's a gaping hole in their functionality, that they don't seem to be aware of.  It's certainly been brought to their attention more than once.

[Mark_O]

I've just ordered a new Rigol DS2072 for $800.  Although it's only 2 channels, in reality it can do all the I2C/SPI decodes I need for the next year or 2...

Are you sure?  I'm not knocking the DS2072, and I suspect it will work well for (most of) your needs.  However, focusing specifically on SPI decodes, in my experience, only 2 channels are rarely adequate.  At the very least, it's inconvenient, since there's no way you can see both sides of the master/slave communications at the same time.  Worst case, you can't even separate out the traffic from the device you're interested in from others sharing the same SPI bus.  You have to have the Clock, which uses one channel, leaving you with one channel to view your choice of MOSI, MISO, or DeviceEnable.  Pick one.  Not a good scenario.

[David Hess]

It is too bad that the external trigger input cannot be used for the SPI clock but without care that would defeat being able to see the clock timing.

My ancient 2440 supports combining the external triggers, it has two of them, with the 16 bit word recognizer trigger which itself has a 17th "qualification" bit.  This handily avoids that problem of not having enough channels to include the chip select.

I hope I remember this discussion if I ever go searching a DSO with SPI decoding capability.

[Gandalf_Sr]

Mark, David, thanks for your input.  All points are valid, 2 channels is at best a compromise for SPI sniffing and big memory just gives you a load more data to go digging through.  I've read elsewhere in this forum that serial decoding on a scope - 2 or 4 channel - is a gimmick in itself and that what you really need is a logic analyzer (LA).  I've been looking at LAs to fill that gap and there are several such as the Saleae series that offer excellent performance at around $300.

So, purely from a scope perspective, the DS2072A offers awesome bang for the buck.  I really tried to get an Aglient DSOX2024A, I had one on order but it became back-ordered and then I got an email saying Fry's no longer offered that model.   I tried to get quotes for used stuff, even made phone calls to Agilent's tech support and sales departments, but all I got were offers of new Tek and Agilent scopes at a 5% discount.

Am I cheaping out? Definitely.  But I'd rather cheap out and get pretty good performance than pay top dollar and end up buying something that's already behind the technology curve.  If the right deal was there for awesome technology, I'd pay a lot more than I have laid out.  For under $2,000, I can end up with a DS2072A, a DG4062, and a Salaea LA.

I feel pretty comfortable with my decisions.

[MarcelM]

Mark, David, thanks for your input.  All points are valid, 2 channels is at best a compromise for SPI sniffing and big memory just gives you a load more data to go digging through.  I've read elsewhere in this forum that serial decoding on a scope - 2 or 4 channel - is a gimmick in itself and that what you really need is a logic analyzer (LA).  I've been looking at LAs to fill that gap and there are several such as the Saleae series that offer excellent performance at around $300.

Hi Gandalf,

as long as you're looking at the DSO2072, why not consider the MSO2072A ?
It comes with a 16-channel logic analyzer. I am currently using one and couldn't be happier (for that price point), especially after unlocking the extra features...

YMMV, best of luck with your choices.

Regards,
Marcel

[EEVblog]

So how good is Siglent?  Have you reviewed one Dave?out of the box.

I'm supposed to be getting a Siglent loaner for little bit in a few weeks. Problem is finding time for a full review.

[EEVblog]

For under $2,000, I can end up with a DS2072A, a DG4062, and a Salaea LA.

And that's the trick isn't it.
If it was my money equipping a new lab then I'd be buying the same thing. Rigol just offer such compelling bang-per-buck it's hard to ignore.
I do like the better usability of the Agilent X series as a daily use scope though, but probably wouldn't be enough to sway me.
Couldn't have said that 3 1/2 years when the Agilent was released, they were in a class of their own. But other caught up within a few years.

[Gandalf_Sr]

I've taken Marcel's advice and opted for the Rigol MSO2072A, he's confirmed for me that you can use any of the inputs (2 x analog / 16 x digital) for the serial decode inputs - Thanks Marcel

This provides the neat ability to trigger off a digital channel, say for chip-enable, then capture analog signals to see how the actual waveforms look on CLK and TXDATA lines with another digital line for the RXDATA, all time-aligned and with DEEEEP memory.  It also means I don't need to buy a logic analyzer.