Oscilloscope SDS1104X-E or DSOX1202G which to buy?

[adam4521]

Hi everyone, a debut post here. I really enjoy the forum and of course, Dave's video postings. I'm at the point where I'm ready to buy a DSO + signal generator (budget < £1000). I'm a hobbyist with some distant electronics engineering from University. I currently have an analogue Tek 2245A (4ch 100MHz) which I find a real joy to use, a beautiful example of late '80s design and engineering.

I made for my son a DCC model railway injector (DCC++ project, Arduino based). This superimposes digital comms on the power to model trains by inverting the power lines at a variable pulse width. The stream of messages from the device while repetitive, is quite long and I really couldn't get the analgoue scope to get me a stable view -- lots of twiddling of trigger filter, long A timebase, short B, hold-off and then hold your breath! So I've became quite eager for a DSO where I can grab a frame of data and just freeze, zoom and pan the image! The other job I did recently was convert the battery power for a little audio generator from 9V batteries to 2xAA, using one of the low cost DC-DC converters you can buy on Ebay. I noticed quite some fuzz on the signal output but it was only when I zoomed right in that I saw alarming oscillations after the 'on' and 'off' switching pulses (c. 900kHz switching). The ringing on the power lines was 140MHz! I know the amplitude of my trace will have been attenuated and maybe accuracy not so important for this example but nonetheless I'm not super enthusiastic about having a new instrument with <100MHz. I'm an electrical engineer and the other maker project I'm planning is a compact and safe device to measure power quality/harmonics. Single phase, Teensy based ADC with bluetooth to send data to a simple phone app. I'm therefore quite keen that the scope I buy has an 'adequate or good' FFT for the tests I will need to do. I can also see myself using an FRA/Bode plot feature if I can get that to optimise the performance of my circuits when using op-amps etc. 

I've done quite some research, reading and shortlisted Siglent and Keysight:

1. Siglent SDS1104X-E (£455) + SDG1032X generator (£277), from Telonic, total cost £732. I could add the Micsig differential probe (DP10007, £162) which I could really use for my power projects and still stay well within budget. This is the sensible, logical option.

2. Keysight DSOX1202G (£921), Mouser. Or the DSOX1202A without generator (£727) and get a separate economy generator from Aliexpress, like the UTG932 (~ £100). (With the second option I’d lose the built in FRA feature of the oscilloscope, but could still use the ‘gain only’ Bode plot technique demonstrated by Dave by just sweeping the signal generator). This oscilloscope has fewer features and channels than option one, but does have Keysight internal engineering and user interface, and will likely do everything I need it to do. I don’t indulge myself very often..

Both will be huge improvements on what I currently have. I’m flipping between these two and can’t decide, and wondering if people on the forum could help weigh this with me. Siglent and Keysight are quite different companies, and I have problems with both of them. It’s great that Siglent are engineering led, and investing in their staff development and R&D, but I have noticed some explicit plagiarism in their oscilloscope manual from - I guess - Keysight. Compare bottom of p75 https://www.siglenteu.com/wp-content/uploads/dlm_uploads/2021/03/SDS1000X-ESDS1000X-U_UserManual_UM0101E-E05A.pdf
 with bottom of p131 https://www.batronix.com/files/Keysight/Oszilloskope/1000X/1000X-Manual.pdf.
Copying a technical explanation word for word just isn’t playing the game fairly. And Keysight, I resent them de-speccing their product via bandwidth filters, and then charging hefty license fees just to restore the natural bandwidth of the hardware. I think that policy really grates in the low end scope market. It is like you have bought a camera with a really good lens but the manufacturer smeared it on the inside with some grease, to deliberately blur the image! The people who don’t pay are hacked off that the hardware they bought has been ‘degraded’ by the manufacturer, and the people who do pay the bandwidth charge are annoyed that they are being tapped to lift the average selling price of the hardware. Why not make everyone happy by just raising the price (a little, to the average sell price) and give everyone 200MHz? Maybe keep the EDUX as a special case.

The others…
3. GW Instek. GDS-1054B often recommended on the forum, but it’s priced rather high in the UK market, about the same as the Siglent but with less bandwidth and only one ADC. But I do like that it can do arbitrary maths functions on the signals and selectable digital filters.

4. Rigol. DS1054Z is getting old but has withstood assaults from above and below for literally years. I hear people grumble about the lack of velocity control or laggy UI, but it does seem to do the job, well made with great maths and trigger options. It deserves its place as a classic of its time that transformed the low end oscilloscope market. The thing that lets it down for me is the constrained FFT. Maybe I should be considering MSO5000 series but was put off by them using Keysight-type software locks for literally everything and the low vertical sensitivity. I don’t need touch screen or MSO.

5. Micsig. I do like the idea of using Android as a modern platform for the software but I’m worried about tying tablet hardware to the oscilloscope. Tablets only last 3-5 years (software updates stop, battery dies). If it was a hardware sampling module that plugged into a bog standard tablet then it would feel more optimised/efficient and I would be quite interested.

6. Rhode & Schwarz. RTC1000 a bit too pricy. For people with more budget there is a good promotional deal at the moment that enables all the bandwidth and options. I didn’t like the low-resolution screen.

7. Tektronix. Sigh. They seem to be lost in the woods. They have version bumped the TBS1000 series and increased the sample memory from 2.5k to just 20k points. What is going on?


Really interested to hear any comments people have to help me jump one way or the other.

[nctnico]

5. Micsig. I do like the idea of using Android as a modern platform for the software but I’m worried about tying tablet hardware to the oscilloscope. Tablets only last 3-5 years (software updates stop, battery dies). If it was a hardware sampling module that plugged into a bog standard tablet then it would feel more optimised/efficient and I would be quite interested.

This reasoning makes no sense. Just like any other oscilloscope MicSig uses their own hardware platform. There is nothing 'tablet hardware' about it and MicSig can supply updates & hardware replacements for as long as they like. Under the hood the MicSig oscilloscopes have the same kind of chips compared to the other scopes on your list (except for the Keysight which uses a special acquisition ASIC).

[rvalente]

I'd go with the #1, SDS1104X-E, best scope in this budget IMHO. I'd drop the SDG1032X and get a DG811 that can be upgraded to a DG992 (check forum threads). You'd loose the bode-plot resource, only matters if you're going to use it anyway

[Doctorandus_P]

Siglent makes quite good scopes, and if you don't have specific needs, I see no reason why to invest twice as much in another scope.
I have an old Rigol DS1952E myself, and it's already more scope than I need, although I am thinking of upgrading it with a Siglent, cause I like 4 channels and a much bigger screen with higher resolution.

I find the Micsig quite intriguing devices. If I remember well they have a quite long boot time though, and I don't like that much. But the combination of both buttons and touch screen looks quite good to me. A Siglent with touch screen costs around EUR1500, and that is more then double, and would be a bit too much for me.

What I dislike of Siglent, is that accessoires seem to be quite expensive. Adding a function generator (just a box with no knobs nor display) cost more tan a complete function generator these days.
I bought a cheap JDS6600 (the 15MHz variant) and I'm quite impressed by it's functionality. And it's just an EUR60 Function generator.

And if you're working with microcontrollers, then also buy an EUR10 Logic Analyser. Any box in that price range will have a Cypress CY7C68013A and is compatible with Sigrok/Pulseview. Even if I'd had a Siglent oscilloscope I would probably still make more use of such a LA, because it's just a small box you can stick on a breadboard and a PC monitor with mouse is a quite good interface for a Logic Analyser. Such a cheap LA is also plenty fast for a whole load of serial protocols. You don't need a 100MHz scope to look at I2C or 115k2 UART. I once decoded some low-speed USB (1.5Mbps) with it, and it is amazing what sort of protocol details appear on your screen. Pulseview also has 100+ protocol decoders for all kind of signals built in for free. (It's an Open Source project
Or even better: Buy two of them boxes! The hardware is cheap enough to not worry, and if you damage one somehow, you've still got another.

[2N3055]

Smart choices for you are.

Siglent, Micsig or Picoscope with a notebook or PC tablet.

Siglent is great inexpensive bench scope, Micisg has portability and Picoscope is more expensive but has other good ( and bad features )..

Good feeling that you "treated yourself with little luxury" with Keysight scope will wear off quickly if you realize that it cannot do some stuff you expected it to do, it being more expensive premium brand.
Yes they are very responsive with "analog feel" and generally are good quality devices, but also have some compromises, some worse that those much less expensive. They are not bad choice, but might not be the right one...
Don't buy technology on feeling. Otherwise, you'll end up buying 10000USD cables for speakers...

For instance, you mentioned DDC, Picoscope can decode the protocol and  show you decoded messages.. Micsig you can carry with you (which, by the way, is not a consumer tablet, but a scope in that form factor, that happens to use Android as an OS. And battery is replaceable module..), Siglent has segmented memory and history, color grading, nice long memory, integration with Siglent AWGs (all of them, not just that USB module) for multichannel FRA etc etc....

It is simple, if it's a hobby, don't spend all money on one thing that you can spend elsewhere. Scope and a multimeter is more useful than just a scope.

Siglent SDS1104X-E (£455) + SDG1032X will give you a powerful combination of good scope and 2ch good, proper standalone AWG, that you can use integrated with scope or by itself.
That one is most bang for the buck.

And, yes buy one of those cheap LA.. They cost nothing and are useful. They are not pro equipment, but if you damage one, it is cheap to replace.

[Fungus]

Micisg has portability

And and awesome, fast UI.

(less features than the Siglent though)

[normi]

If an AWG is nice to have device then the one integrated in the scope is fine, however if you need an AWG then go with a separate unit. So option 1 would be best.
I have a scope with 2 AWGs and use often as a quick convenience but if it is not for a quick check I would use my separate AWG. Also if you are going to carry the scope to do field work an integrated AWG will be good to have.

Scopes are going the way of mobile phones, they are a becoming a one stop for all measurement devices. Before cell phones, we had separate mp3 player, radio, flash light, watch, pedometer, voice recorder and camera, now persons just walk around with one device. An individual device for each of these will perform better but it is more convenient to have it all in a tiny phone.
This is not a bad thing as I can remember many years ago at university, they were lecturing about Lissajous figures and they would setup a scope and signal generator prior to class and you had to get close to see the screen. Not so today, one scope has everything and also has video output so it can connect to projector for everyone to see. No need to lug around with multiple heavy equipment.

[adam4521]

Well thank you all for your insightful responses. Its clear what the direction of the advice is for me: I should buy the SDS1104X-E.

nctnico, I suppose I didn't appreciate how Micsig build their product. I was worrying about the 'tablet part' more than the rest of it. That's not really logical thinking is it.

rvalente, I can see the significant cost/performance advantage of your Rigol generator recommendation, but to be honest in my case I think I will benefit from the Bode plot/NVA integration more.

Doctorandus, you are right if I ever need protocol decoding in earnest I'd be better off with a low cost analyser, so decoding not a major consideration.

2N3055, your point very well made. I was banking on if I needed a missing feature on the Keysight at least I'd be able to download capture frames and crunch it in python or something. But it might not be always possible or convenient to do that. And for 'analogue feel', I can of course just switch on a CRT oscilloscope.

I've been lucky enough with my timing that I found some used isolated/differential probes for sale on Ebay, so hopefully I have that side of things sorted!

Looking forward to putting my order in after the w/e.

Thanks all for helping me to clear up my thinking!

[nctnico]

Doctorandus, you are right if I ever need protocol decoding in earnest I'd be better off with a low cost analyser, so decoding not a major consideration.

Don't be so quick with this conclusion because it isn't right perse. If you are into reverse engineering then a low cost protocol analyser is handy. If you are troubleshooting a design then protocol decoding on a scope is essential. Most of the problems with communication are in the analog domain so you will want to see what the actual signal looks like. A logic analyser will only show something is wrong but not what. Once the physical layer is OK you typically debug communications at a higher level (debug messages / optional formatted data dump in software for example). Being able to capture lots of packet using an oscilloscope is very useful for tracking down elusive problems. In some case you don't know what to trigger on so filtering as much as possible using a trigger condition and then search through the messages can turn out to be the only effective way.