Should I get a Keysight DSOX6004A ?

[bdunham7]

Would you be willing to quickly summarize your biggest showstoppers where Tek would be vastly superior to SDS2000X+, please?

I can quickly summarize a few and then when I have time I'll post more photos and detailed explanations if anyone wants.  I don't want to do a hit job on Siglent either, and some of these things may merit further investigation, others are just known characteristics from design choices.  I just compared the SDS1104X-E with an old TDS340A and the TDS340A is the worst performing Tek DSO I can get my hands on. It still wins, more or less, in these areas.

1.  My SDS1104X-E has a consistent issue with a spurious 2nd harmonic when using the FFT function.  There's something with the input amp that I think causes this, and it can vary over time and whether or not I do a self-cal.  This has actually caused me some issues recently trying to measure and adjust the THD of an AC voltage calibrator, since I do not have a THD analyzer nor an SA that goes to very low frequencies.  Or, actually I do have an SA that goes to 10Hz, but it is a disassembled junker that is never going to work again.  An 8-bit scope FFT isn't actually quite good enough, but I was hoping I could at least spot a gross error (and I guess I did...).  The TDS340A, in addition to being way easier to set up the FFT, displayed it cleanly and without the second harmonic. 



2.  When trying to look at a small signal immediately following a large falling edge, you may want to expand the vertical scale so that the part prior to the falling edge is many divisions off the screen, overdriving the input amplifier which is designed to survive such abuse, presumably clamped and well protected.  Every scope has a recovery time from the overdriven condition, they're almost never explicitly specified.  The actual signal I was trying to read when I ran into this would be too hard to reproduce, so I'm using a 0-5V 1kHz square wave with 10mV pulses riding on it.  The TDS340A has about 100uS recovery time when overdrive 500 divisions, which is terrible compared to everything except the Siglent, which is over 40ms and is totally useless for this measurement.



3.  Aliasing.  We all know about it, so no big deal, right?  If I were a Tek salesman, I'd make it a big deal.  Set up one channel with a 300MHz input and you get a nice clear signal with a readout of 300.000 MHz.  Turn on the other channel and you get a very similar screen--about the same amplitude--but now it is 200.000 MHz with no other indication that something is wrong.  This is simply a result of overselling the sample rate.  It doesn't bother me too much, but it could easily cause a major error and it isn't pro.

4.  The whole memory management thing that has been discussed before.  Even the ancient TDS340A will allow you to view a half of screens worth of extra signal from either end of a stopped acquisition.  Again, a  design choice, but not a good one IMO. 

Anyway, that's just 4 off the top of my head.  Only the first two are worth discussing further, the last two have been beat to death already and I doubt anything is going to change.

[nctnico]

You should have skipped a few posts back. That isn't a bug but a limitation all AWGs have. In the end there is a limited number of point to form a waveform. Tektronix also specifies this in the datasheet. Shariar probably overlooked it in the heat of the moment.

Yeah, I just now noticed that and corrected my message appropriately.

But here, the carrier frequency is an integer multiple of the deviation.  A fully upgraded instrument has 128 million points per channel.  The frequency range that it needs to generate is from 99 MHz to 101 MHz.  For special cases like this, it might be possible for a digital signal synthesizer to properly generate the needed waveforms, but the effort needed to do that might not be worth it.

And even so, a modulated carrier frequency of 100 MHz that is less than 1/10 Hz off from its unmodulated form doesn't seem terrible at all.

EDIT: By the way, this is the bug in the Siglent you're referring to, right?   https://www.eevblog.com/forum/testgear/the-siglent-sdg2042x-thread/msg2893004/#msg2893004

How does that differ from the carrier frequency drift issue we're talking about here?

My assumption is that the Siglent generator accumulates a rounding error somewhere. For really slow modulations there is no reason for the carrier to drift.

[bdunham7]

No. Frequency stability is a different thing.

I'm going to think about the whole thing, but I'm not convinced an AWG must have this error even with limited math precision, at least not when every parameter is a power of 10.  And if the spec you quote is due to intrinsic AWG design issues, why do they list the temperatures at which it applies?

I'm thinking that if an AWG is asked to output the same frequency on two channels but modulate one of them, for the modulated one it could always start with the base signal and then calculate the deviation from there.  There may well be limited precision issues (but in two dimensions) with regards to the placement of any one point, but I see no necessity for those errors to become cumulative.  Perhaps I haven't thought it through far enough or there is some worse consequence for doing it that way.

[kcbrown]

My assumption is that the Siglent generator accumulates a rounding error somewhere. For really slow modulations there is no reason for the carrier to drift.

I'm not sure I follow.  Was the carrier actually drifting, as in changing its apparent frequency over time (so if you were showing it alongside a wave of the base frequency, you'd see the relative movement change over time), or was it simply slightly incorrect, but otherwise consistent?

And how were you measuring it?

[jmw]

If I had a year to wait, I wouldn't be buying any Keysight DSOX series scope (except maybe the 1000-X if that fit my needs). Reason: MegaZoom IV is getting very long in the tooth; notice how the 1000-X and most other Keysight equipment now comes with black furniture, while the 2000-6000 are still wearing white? That's a tell that they're likely getting a refresh soon. With a year to go, time is on your side to wait and see what's new later on. Worst case they dump WinCE for Linux and nothing else changes, best case some of that UXR/MXR tech walks its way down the value chain and shows up in lower end scopes.

[2N3055]

Thank you for the time and effort to write it up. I appreciate it.
But you misunderstood me. I said compared to to SDS2350X+ scope that cost the same.
Nevertheless since you did take time let me reply a bit.

1. That second harmonic seems to be valid point, provided amplitude was correct. In cases like this playing with vertical sensitivity is recommended to see if there are changes that would point to distortions. But a valid question.

2. Overdriving input amplifiers was discussed to death. You cannot do that, and it's not a guaranteed spec, not even on 150000 USD scope. On SDS2350X+ you could use vertical zoom. But not at factor of 1000x magnification. Great late Jim Williams  had several application notes where he had to create custom circuitry for that type of measurement. Only scope that can do that is sampling type ( analog repetitive or random with sample bridge ).
EDIT: went and tested, my MSOX3104T craps up at 100 mV/div, with a 5V P-P signal....

3. I have been repetitively  saying that SDS1104X-E is a great 100Mhz scope.  I advise against hacking it to 200 MHz, because people are not disciplined (or knowledgable) enough to be trusted to use it only with two channels. Or sometimes signal is tricky and there is a choice of : A. not seeing anything because front end simply cut it of with a lowpass filter. B: seeing aliasing. Pick your poison. I prefer A.
But, also not important, because I said against SDS2350X+. Which has 2GS converters and has no aliasing problems.

4. Spend too much time on that allread for the rest of my life.  But NOT a SHOWSTOPPER. You have full right not to like it. Some people are vegan, I eat meat. Power to us all!!

Please keep them coming...

Regards,
Sinisa

[2N3055]

If I had a year to wait, I wouldn't be buying any Keysight DSOX series scope (except maybe the 1000-X if that fit my needs). Reason: MegaZoom IV is getting very long in the tooth; notice how the 1000-X and most other Keysight equipment now comes with black furniture, while the 2000-6000 are still wearing white? That's a tell that they're likely getting a refresh soon. With a year to go, time is on your side to wait and see what's new later on. Worst case they dump WinCE for Linux and nothing else changes, best case some of that UXR/MXR tech walks its way down the value chain and shows up in lower end scopes.

As I mentioned some time ago, I stumbled upon a model number MSOX-3104G mentioned...
They are surely preparing new models, but don't expect earth shattering changes. They have to preserve the structure... It could be only a color change, or some minor upgrades.
They could come out with MegaZoom V, but if they do, it will be carefully tailored not to be TOO powerful.. Pricing structure is the king...
Maybe a bit more memory and that's it. Which might not be a bad thing, no changes. I keeps familiarity, and minimum changes on both their and customer side.

But mind you, that means new 2000, 3000, 4000 and 6000... That is a lot of scopes at the same time...

[nctnico]

My assumption is that the Siglent generator accumulates a rounding error somewhere. For really slow modulations there is no reason for the carrier to drift.

I'm not sure I follow.  Was the carrier actually drifting, as in changing its apparent frequency over time (so if you were showing it alongside a wave of the base frequency, you'd see the relative movement change over time), or was it simply slightly incorrect, but otherwise consistent?

And how were you measuring it?

The drift rate was constant. I compared the 10MHz reference input to the output signal using an oscilloscope triggered to the 10MHz reference clock. On the oscilloscope you get a band which goes from left to right. Over time that band moved indicating that there is a phase drift. Note that phase drift and frequency drift go hand in hand. In hindsight it is possible that it is a limitation of the SDG2000X series. In that case the effect Shariar shows in his video on the AFG31000 should be much worse on the SDG2000X.

No. Frequency stability is a different thing.

I'm going to think about the whole thing, but I'm not convinced an AWG must have this error even with limited math precision, at least not when every parameter is a power of 10. 

As soon as you start modulating the frequencies no longer have a relationship that is an integer number.

And if the spec you quote is due to intrinsic AWG design issues, why do they list the temperatures at which it applies?

That is a good habbit when writing a specification.

[bdunham7]

But you misunderstood me. I said compared to to SDS2350X+ scope that cost the same.

Oh, well I don't have one and I don't have the TBS2204B here with me.  Someday! 

Overdriving input amplifiers was discussed to death. You cannot do that, and it's not a guaranteed spec, not even on 150000 USD scope. On SDS2350X+ you could use vertical zoom. But not at factor of 1000x magnification. Great late Jim Williams  had several application notes where he had to create custom circuitry for that type of measurement. Only scope that can do that is sampling type ( analog repetitive or random with sample bridge ).
EDIT: went and tested, my MSOX3104T craps up at 100 mV/div, with a 5V P-P signal....

Well, every Tek scope I have, DSO, hybrid or otherwise, will do this type of thing even though you're right in that it isn't a guaranteed spec.  It is interesting that your MSOX3104T loses it at the same point as my Siglent.  I suppose it is possible that modern input amplifiers have made design compromises that result in improvements in other areas at the cost of this ability.  My newest Tek, a TPS series, also recovers quickly--although that is an old design that Tek sells for an exorbitant amount.  So I can't even guarantee that the TBS won't fail the test--but I'll report in as soon as I try it out.

I have been repetitively  saying that SDS1104X-E is a great 100Mhz scope....
But, also not important, because I said against SDS2350X+. Which has 2GS converters and has no aliasing problems.

I thought that was my line.  But the SDS1104X-E uses a digital filter after the ADC for the 100MHz cutoff, so its ability to suppress a 300MHz signal is determined by that filter's attenuation at 200MHz.  The aliasing is still happening. 
I would assume the SDS2000X+ works the same way, so you might call it a great 200Mhz scope.  And Tek would agree, since the TBS2204B uses the same 2GSa/s per two channel setup.  It would be interesting to see how either of them responds to mild overdriving with over bandwidth signals.

[2N3055]

Well, every Tek scope I have, DSO, hybrid or otherwise, will do this type of thing even though you're right in that it isn't a guaranteed spec.  It is interesting that your MSOX3104T loses it at the same point as my Siglent.  I suppose it is possible that modern input amplifiers have made design compromises that result in improvements in other areas at the cost of this ability.  My newest Tek, a TPS series, also recovers quickly--although that is an old design that Tek sells for an exorbitant amount.  So I can't even guarantee that the TBS won't fail the test--but I'll report in as soon as I try it out.

TPS2000B ? Well that one is a bit unusual, that one has floating insulated channels. I can see that those input channels might have a bit different design, that would (could?) make it recover better. Whether that is deliberate or just happenstance of the design , who knows ....  But all single ended modern scopes will have low voltage amplifier design and they will all have pretty much same problems.

[grg183]

Thanks for all the responses, I still need to go through the posts but I wanted to share my opinion on the discussion of A-brand vs B-brand tools...


It is true that at the end of the day it is the end result that matters, an oscilloscope is just a tool to get a job done. It is like a car, you could buy the cheapest car or the most expensive one, as long as you get to destination it doesn't matter which car you drive. If you drive a lot you'll appreciate the comfort of the luxury one, if you have an accident you'll appreciate the better safety features, better infotainment might make your life in traffic a bit more pleasant but at the end of the ride no matter which car you drove you can get out and do the same great things. For many years I used a $40 Atten hot air station and an equally cheap Hakko knock-off soldering iron. I was able to solder virtually anything from 0201 parts to fairly big BGA parts and get the job done successfully. Did I like these tools? No. Did I waste more time than necessary de-soldering some parts? Yes definitely. Did I damage a couple of boards due to unintentional overheating? Yes. Did they sometimes fail on me? Yes. However these annoyances didn't stop me from starting and being successful in my business. In more recent years I bought professional JBC soldering iron and hot air station, in total costing at least 50 times more than the cheap stations I had earlier. Are these JBC units 50 times better? Absolutely not but I bless every dollar that I spent on them every time that I use them. They are easier to handle and control, quicker to reach temperature, the operate in a more predictable manner, I no longer have to worry about damaging boards, I de-solder parts in a breeze, etc... What I'm getting to is that the difference between an A-brand and a B-brand tool is not so much about the 'getting the job done' part as much as it about making life easier and also ensuring that you can get the job done every time in the most efficient and repeatable way possible. When you are building and growing a business there is a point reached where these 'annoyances' related to cheap tools become more important than the 'getting the job done' part.

As to being able to 'show off' A-brand equipment to clients, this is not so much a matter of 'showing off' in an attempt to win clients (although it could get you the edge in certain cases). Clients that are not knowledgeable in test equipment can be impressed with the cheapest of brands, while big companies will probably have better equipment themselves anyway. Having A-brand equipment also doesn't imply that you know how to use them properly or that you are keeping them calibrated or well maintained. If I demonstrate a result using either the cheapest of oscilloscopes or the most expensive one it really doesn't matter so much, a research paper that demonstrates a result using the cheapest of scopes doesn't make it less reputable. The main difference with A-brands still has to do with those annoyances that I mentioned above. Going back to the cheap soldering station example, if I am expecting a client to pay abundantly for my service, do you think it is acceptable that I send them a discolored PCB just because my $40 hot air station is unable to control temperature correctly? or that I delay everything by 2 weeks just because my $60 soldering iron broke down? It is the same thing with all equipment including oscilloscopes. If I quote for a job that should take a few hours but I waste a day trying to figure out and searching online as to why something doesn't add up, I'd simply be making a loss. As you grow a business you eventually reach a point where neither you nor your clients will tolerate having to deal with annoyances like that, having tools that 'get the job done' is not enough anymore. Having A-brand tools also helps to build a sort of 'trust chain'. It is true that if a client trusts you they will also trust that you are able to choose your equipment wisely as someone said above. With bigger projects and bigger clients there are often multiple parties involved, clients will have their own clients, so there are a lot of people to convince and in my experience having A-brand equipment often gets you a long way at that. Whether having A-brand equipment ultimately translates to a better end result is a totally different matter, there will be always those who can do incredible things with a bunch of cheap rusty tools while others whom with an entire workshop of top quality tools wouldn't be able to screw a light bulb even if their life depended on it.

[tv84]

Regarding KS position on customer service for hobbyists, I advise all to read this latest post (and KS answer to the OP). 

[grg183]

Regarding KS position on customer service for hobbyists, I advise all to read this latest post (and KS answer to the OP). 

"Keysight products are designed, manufactured, and tested for professional and industrial use. They are not designed or tested for personal, domestic, or household use. While we thank you for your interest in our products and/or services, we are unable to provide you with technical support without a VAT ID or equivalent proof of business license.

Wow that is the lamest excuse I've ever seen, it would have been better had they not replied at all! I must say that whenever I needed support for my Keysight equipment I've never had any problem and support was prompt even though I am a small business.

I have however seen this kind of attitude by parts manufacturers including big ones like Texas Instruments and Bosh that openly ignored my requests for basic support simply because in their view I'm not big enough of a business to be worth their attention, even though my client's volume production forecasts were rather high. Texas Instruments support (on the ticket system) even told me directly that they only forward requests from "serious customers" to their sales team, how they got the impression that I'm not serious I don't know. This is absolutely ridiculous, especially in this day and age when small businesses is where a lot of innovation is happening.

[tautech]

I have been repetitively  saying that SDS1104X-E is a great 100Mhz scope....
But, also not important, because I said against SDS2350X+. Which has 2GS converters and has no aliasing problems.

I thought that was my line.  But the SDS1104X-E uses a digital filter after the ADC for the 100MHz cutoff, so its ability to suppress a 300MHz signal is determined by that filter's attenuation at 200MHz.  The aliasing is still happening. 
I would assume the SDS2000X+ works the same way, so you might call it a great 200Mhz scope.  And Tek would agree, since the TBS2204B uses the same 2GSa/s per two channel setup.  It would be interesting to see how either of them responds to mild overdriving with over bandwidth signals.

You're forgetting another factor which is the analogue input design yet certainly the digital filter predominately determines max BW but that's only relevant to the model in a series whereas input design is the overriding factor.

The 350 MHz SDS2354X+ with it's 500 MHz option is some example of this however its 500 MHz rating only applies to 2 channels (one on each ADC) so to comply with Nyquist and SW limits its total BW by reducing it if more than 2 channels are active back to 350 MHz and displaying such in each channel tab.

[grg183]

The Rigol 8000 has genuinelly been absolutely rock steady and no issues have I found when using it which is almost daily. Now when I am conducting our critcal measurments then yes I will use the Wavepro no question or one of the othe Lecroy's. Though on occasions; I have out of curiousity fired up the Rigol just to see how good in REAL terms it compares against a a quality reference. It does stand up very well indeed in a few areas no question. I would suggest this Rigol model is more than a hobbist scope, maybe a semi pro range but with some really nice features. Its also been robost and stable.

@Sighound36 thank you for your valuable input as someone who actually has a Rigol 8000.
From your input and some other comments that I've seen around it appears that the Rigol 8000 is not to be underestimated and as a second high bandwidth scope it is definitely a good choice. However if you were to hypothetically have the Rigol 8000 as your only scope without any of your Lecroy scopes to cross-check with, would the Rigol give you enough confidence in your measurements? Would it limit you in any way and if so what would be the main limitations in your opinion?

[kcbrown]

The drift rate was constant. I compared the 10MHz reference input to the output signal using an oscilloscope triggered to the 10MHz reference clock. On the oscilloscope you get a band which goes from left to right. Over time that band moved indicating that there is a phase drift.

OK, so it sounds like you were viewing the modulated 10 MHz carrier signal against a 10 MHz reference signal.  With an FM signal, you'd expect to see the modulated waveform change its drift rate over time as it is modulated back and forth around the carrier frequency, with the drift rate boundaries being defined by the frequency deviation value you selected.  For your test to work, you'd have to use a pretty small frequency deviation value (1 Hz would get you a maximum drift rate of 1 peak to peak change per second).

What was the frequency deviation value you used for your test?

Now, in your case you were using a tiny modulation frequency, 10 millihertz, i.e. one complete modulation cycle every 100 seconds.   So you wouldn't see a band on your scope, but rather a waveform that drifts back and forth around the carrier frequency, with the maximum rate of drift depending on the frequency deviation you selected.

What was the actual average drift rate that you noticed from that?  Which is to say, how long did it take, on average, for a peak of your modulated waveform to move from one peak of the reference waveform to the next peak (it has to be an average because the actual drift rate of the modulated waveform relative to the reference changes over time due to modulation)?  That'll tell you the amount of error in the generator's carrier frequency.

In the case of Shahriar's Tektronix, the error was less than 0.1 Hz for a carrier of 100 MHz, which is rather good.

Note that phase drift and frequency drift go hand in hand. In hindsight it is possible that it is a limitation of the SDG2000X series. In that case the effect Shariar shows in his video on the AFG31000 should be much worse on the SDG2000X.

That's possible.  When you had yours, did you compare the average drift rate of the 10 mHz modulated carrier against the drift rate of the same carrier modulated by a much higher frequency signal (like, say, 1 kHz)?   If so, what was the end result?

[nctnico]

Note that phase drift and frequency drift go hand in hand. In hindsight it is possible that it is a limitation of the SDG2000X series. In that case the effect Shariar shows in his video on the AFG31000 should be much worse on the SDG2000X.

That's possible.  When you had yours, did you compare the average drift rate of the 10 mHz modulated carrier against the drift rate of the same carrier modulated by a much higher frequency signal (like, say, 1 kHz)?   If so, what was the end result?

I have not done any further tests; using the SDG2000X is no longer relevant. Maybe someone with an SDG2000X generator can chime in and do some tests. There is a thread about this issue but I don't know if anyone has bothered to test various function generators.

[kcbrown]

I have not done any further tests; using the SDG2000X is no longer relevant. Maybe someone with an SDG2000X generator can chime in and do some tests. There is a thread about this issue but I don't know if anyone has bothered to test various function generators.

Which generator do you use now, and how does it perform with respect to something that's reasonably close to what Shahriar was doing?

[Sighound36]

The Rigol 8000 has genuinelly been absolutely rock steady and no issues have I found when using it which is almost daily. Now when I am conducting our critcal measurments then yes I will use the Wavepro no question or one of the othe Lecroy's. Though on occasions; I have out of curiousity fired up the Rigol just to see how good in REAL terms it compares against a a quality reference. It does stand up very well indeed in a few areas no question. I would suggest this Rigol model is more than a hobbist scope, maybe a semi pro range but with some really nice features. Its also been robost and stable.

@Sighound36 thank you for your valuable input as someone who actually has a Rigol 8000.
From your input and some other comments that I've seen around it appears that the Rigol 8000 is not to be underestimated and as a second high bandwidth scope it is definitely a good choice. However if you were to hypothetically have the Rigol 8000 as your only scope without any of your Lecroy scopes to cross-check with, would the Rigol give you enough confidence in your measurements? Would it limit you in any way and if so what would be the main limitations in your opinion?

Hello grg183

Sorry but the pc swallowed the last reply:

Th reason I use Lecroys is for the work we do I require really tight accuracy that the 12 bit scopes really do give, the app toolbox is just amazing and they really do work very well and have many decent features but at a cost.

We have a narrow focus of products, audio digital, high speed data transfer, PDN, ultra quiet linear power supplies, fpga coding and green energy projects. The Rigol 8000 is a very capable scope is far and away any toy. It has features that a lot of the big four scopes will not be able to access until you reach a basic scope price of £18Kish. the apps from R&S and KS are not in the 'its only a bit more category' IMHO if you spend £20K on a scope then with the basic quality robes current/HVDP and qaulity 1Ghz active probe then that can be up to half the cost of the scope again, this is without any toolbox apps, Tek jitter app is £6K alone.

To have the Wavepro HD to have the same features as the Rigol 8000 this is going to be £54K plus the logic probe is quite a bit and the 500Mpts of memory they have another of you buy model 'x' then you will receive either a BW upgrade or Mem upgrade to 1GPTs to 2, but that’s costly.

The HDO8000 is not far behind and limited to 2Ghz bw. but again its a class act only with 10G/s instead of 20G/s compared to the wavepro HD

the EXR & RTO6 are the same money as basic 600mhz units, add in the basic eye and jitter apps plus probes and you are well over £30+K

The 8000 has a great long memory which is useful for diagnosing serial data faults, clock lane noise, signal glitches that are infrequent, serial data glitches etc.

Its noise floor the lowest I managed with an open port 50 ohms, High rez on and bw to 20 Mhz with precision mode engaged on a 2.3Ghz model was around 85uv (after warm up) which is not bad for a 2.3Ghz scope, the Lecroy (8Ghz) manages around 1/3of that. Buts its more than four times the cost!

The eye app is a good basic starting point that will help you with signal integrity and data lane noise and checking board connectors and for looking at ISI by way of eye-opening patterns and widths. Te persistence is rather good to plus it has big waveform rates as ell.
The jitter app is also very nice and well thought out with C2C/TI/ -W2<>-W/ +W<> +W, plus you can change the cornerstone frequencies as well as a couple of PLL as well. plus three clock recovery options. Standard measurement parameters are all there and work well you can move the whole meas panel around the screen no probs either.

With jitter you can add a track & trend graphs as well are a histogram and throw in a spectrum analyser plot as well, It is all on the same screen though so do not expect multiple windows on this scope.

It is pretty accurate when you get into the large VTB numbers but it is very stable and never locked up on me at all, the digital ports and harness is pretty fair as well (this came with the scope as part of the bundle).

This is like a third generation Rigol product at this level and I feel they are really getting the acts together. Would it be my primary scope if we didn't need the fancy low noise and speed plus monster apps. It may well be.

This is just about using your tools to work for you in the best way possible imho.

If you went down this route you could also purchase a great Keithley 6.5 or 7.5 digit DMM as well plus a a couple of misig new current probes as well.

Each has it place on my bench, for different reasons.

Here some images of the 8000 and the Wavepro going head to head last year and you can see the 8000 is not bad at all.

Its still on my bench 18 months down the line and sitting with some big hitters but it feels safe and secure 

Sighound36

[bdunham7]

You're forgetting another factor which is the analogue input design yet certainly the digital filter predominately determines max BW but that's only relevant to the model in a series whereas input design is the overriding factor.

The 350 MHz SDS2354X+ with it's 500 MHz option is some example of this however its 500 MHz rating only applies to 2 channels (one on each ADC) so to comply with Nyquist and SW limits its total BW by reducing it if more than 2 channels are active back to 350 MHz and displaying such in each channel tab.

Even in 350MHz mode, a 600MHz signal will alias back down to 400MHz, which will not be efficiently suppressed, or at least I'm guessing it won't since I don't have one to try.  Give it a whirl if you have the stuff handy--I'd be interested to see how it does.  If you had a fixed hardware single-pole input filter at 200MHz followed by digital anti-aliasing, that would be suppressed pretty far down.  If you take the 2GSa/s - 1GSa/s split channel architecture as a given, it then boils down to a design and marketing choice, including upgradeability hackability. 

[tautech]

You're forgetting another factor which is the analogue input design yet certainly the digital filter predominately determines max BW but that's only relevant to the model in a series whereas input design is the overriding factor.

The 350 MHz SDS2354X+ with it's 500 MHz option is some example of this however its 500 MHz rating only applies to 2 channels (one on each ADC) so to comply with Nyquist and SW limits its total BW by reducing it if more than 2 channels are active back to 350 MHz and displaying such in each channel tab.

Even in 350MHz mode, a 600MHz signal will alias back down to 400MHz, which will not be efficiently suppressed, or at least I'm guessing it won't since I don't have one to try.  Give it a whirl if you have the stuff handy--I'd be interested to see how it does.  If you had a fixed hardware single-pole input filter at 200MHz followed by digital anti-aliasing, that would be suppressed pretty far down.  If you take the 2GSa/s - 1GSa/s split channel architecture as a given, it then boils down to a design and marketing choice, including upgradeability hackability.

Don't overlook this is also a manufacturing choice in which one HW design covers models from 100-500 MHz.

Only have SDS2104X Plus in stock ATM so no playing today however I do know the top models have Full,350, 200, and 20 MHz filter settings and experienced operators can immediately identify if they're entering aliasing territory from the OSD indicators of frequency, sampling rate, timebase setting and mem depth.

As an advanced novice I overlooked such visible things until posting some screenshots pushing SDS2202X-E way way above rated BW where it still triggered perfectly and waveforms looked perfect but the HW frequency counter was miles off ! rf-loop rightly picked me up on that and such a simple lesson is not forgotten. 

[2N3055]

If you take the 2GSa/s - 1GSa/s split channel architecture as a given, it then boils down to a design and marketing choice, including upgradeability hackability.

Would please, you , and everybody else, please,stop repeating this nonsense. License unlocking of bandwidth is not there "because of hackability".. All manufacturers do it because they want to physically produce only one motherboard, and to give option of field upgrades. Nobody wants to send scope back to factory to install other motherboard to get new options. All the scopes on today's market are done this same way.
As for "hackability", it is also same as different manufacturers of software take piracy protection differently. Some software will have hardware dongle, computer locked licenses etc, and some have only a string you type in and it unlocks it.

Very strong security is a burden to manufacturer. It makes many steps in production more complicated. So if you take R&S effort to make their scopes less prone to "hacking", that practice not only resulted in not many of those hacked, but also, and you believe this, it is one of the reasons that contribute to higher prices. It makes it more expensive without benefit to customers.

So Siglent is simply pragmatic here, i believe. You cannot unlock just like that, and if you do take effort to unlock it, at any moment it can be proven it is not legal license, if need be. Fact that they are not being harsh and cracking down on people is because they want to be friendly to their customers. Hacking is hurting them financially, don't doubt that. But not as much as a mad customer.

It is just they don't want to behave like Keysight is doing right now, as evidenced in few new topics that appeared on the forum last few days.

Also, SDS2000X+ HAS analog anti aliasing filters (software switchable ones). It is only when you unlock it to 500MHz that what you're saying is true. That is why I said: If you're are so concerned with aliasing, you get 2204X+ (200 MHz is max on that Tek we spoke about) and you will not have aliasing problem. In which case you made deliberate, conscious  tradeoff between maximum bandwidth and minimum aliasing because that is your priority. Somebody else that wants to look at 400MHz sine signal might want to buy 500MHz version because that is their priority. And they will have to make sure to keep it in 2 ch mode.

Of course, none of that will save you from what some people are doing to "prove something is wrong" : You cannot input 5V RMS 600 MHZ signal at input set at 500uV/div and expect some of that signal NOT to shoot through all the way to the A/D and alias.. Filter will suppress it 30-40-50 dB but some of it will still go through if you shoot bolt of lightning in the input BNC...
But in that case if you switch to 2 Ch mode, you will still get even nice 800MHz sine signal without aliasing...

[bdunham7]

Hacking is hurting them financially, don't doubt that.

I'm not convinced that is true, anymore than I think piracy hurt Microsoft in its early days.  The incremental cost to them of a hack is zero if they wouldn't have been able to sell the upgrade to that customer in any case.  Any rational analysis would not count losses from sales that would not have happened in the alternative.  And I'm guessing they have done that analysis and sold a lot of equipment in the process. 

Also, SDS2000X+ HAS analog anti aliasing filters (software switchable ones).

I wasn't aware of that.  Are you sure?  And at what BW are they?  Is it just at the 350MHz point?

[armandine2]

The Lecroy WavePro 254HD would probably be the best choice from a technical and feature standpoint. Budget-wise I can afford it and probably even justify it but for the current size of my business it is still a lot of money. I am not very familiar with Lecroy gear but it seems to be a better bang per buck compared to the Keysight DSOX6004A.

Be sure to make a youtube video if you do plum for it - It seems the others are too embarrassed to show theirs.

[Caliaxy]

So Siglent is simply pragmatic here, i believe. [...] Hacking is hurting them financially, don't doubt that. But not as much as a mad customer.

That’s one way of looking at things.

Another way is that Siglent (or Rigol, for what it matters) are deliberately selling their equipment at dumping prices in an effort to take over the market. In theory, they are not selling dirt-cheap equipment per se (that would be too obvious and could trigger legal procedures in many markets). They are only selling reasonably priced equipment that can be hacked (i.e. upgraded) at no cost.

Hard to prove, but the hackings (which appeared out of nowhere and don’t seem to bother them) might have “leaked” from their own marketing departments. In practice, this would allow them to effectively sell at dumping prices while keeping the dumping pricing policy under the radar.

I’m not complaining (I recently cheerfully “upgraded” some of my own Riglent equipment), I’m just noticing.