Rigol DHO900s series vs function generator + DHO800 - Page 1
Forum section: electronics / testgear

author: nodshuffle
author_rank: Newbie
timestamp: December 11, 2024, 04:54:03 am
content: Hi. I apologise if all of the information I am seeking already exists in posts. I had a look through existing threads and couldn't find exactly what I was after...Specifically, I am looking at buying the DHO914S. I primarily do audio work, so the inbuilt function generator is quite appealing. The bode plot function is quite novel as well.From what I can tell, the 914S was very buggy and just generally disappointing at release. I just watched a video on an alarming amount of coupling between the function generator and input channels... A year on, is this still the case or has it been patched/improved substantially?I am quite interested in applying all of the nice hacks (wifi, bandwidth upgrades, record length, etc.)Is the 914S a worthwhile buy, or am I better off with the 804 and a separate function generator? (DG series)? Both options are roughly the same price.The logic analyser is somewhat appealing, although I have generally heard that I'd be better off with a cheap logic analyser that can be used with the Saelae software.Thanks!

author: LEER333
author_rank: Contributor
timestamp: December 11, 2024, 05:36:57 am
content: I personally think the best solution is 914S and free upgrade to 924S, logic probe with a simple version of the solution

author: nodshuffle
author_rank: Newbie
timestamp: December 11, 2024, 06:14:54 am
content: Is the 914S still buggy or has it improved over the last year? My general impression is that the 800 series bugs are being squashed more rapidly due to its popularity.

author: TurboTom
author_rank: Super Contributor
timestamp: December 11, 2024, 07:19:51 am
content: The 800 and 900 DHO's share the same hardware platform, the AWG is just a piggyback plug-in board that has been added to the 900 (plus a handfull of unpopulated components on the '800's main board, mainly connectors, OpAmps and PSU silicon that are populated on the 900 model). The two models also share the same software, configured accordingly. Hence, the bugfixes for the 800 also affect the 900. As yet, Rigol doesn't seem to have addressed/improved their poor Bode plot implementation. If / when they will approach this, noone can tell. Over the time, I came to the conclusion to consider any instrument to stay the way it is at the time of purchase, don't take anything for granted or expect any "could be's". You will almost certainly get disappointed...Regarding the AWG of the 900 model, I'm not aware of a hardware change, so the coupling in the higher output voltage swing ranges via the power rail is probably still present, but it's not so severe that it would make the AWG unusable for general jobs. When comparing it to a stand-alone AWG, you should rather have the (almost always available) second, identical signal channel in mind as well as the connectivity (reference input, sync/mark output, external modulation input etc.) that are available to more or less extent on the stand-alone models. Moreover, software support may be better (but check that before placing an order, depending on the make/model, you may be up to a surprise...).If you haven't got any particular use case in mind and just want a "minimum footprint" solution, the 900S may still be a good choice, especially since the integration of the AWG into the user interface is much improved vs. the older models due to the touch screen. Be aware that the probe set for the digital channels comes at a steep additional price or may require considerable effort to make if you favor the DIY solution. Price-wise, I'ld consider the two options on-par.

author: ataradov
author_rank: Super Contributor
timestamp: December 11, 2024, 03:03:36 pm
content: Signal generator on DHO924 is a joke. Same goes for the logic analyzer. I'd go as far as call them unusable. Signal generator has so few options and limited settings that a random no-name generator from AliExpress will run circles around it. And logic analyzer is just too frustrating to control. Plus it needs special probes and they cost a ton of money. There are projects out there to build custom ones, but really, it is just a lot of trouble for not much benefit.You need internal generator if you want Bode plots, but that seems like a very niche use case.

author: iMo
author_rank: Super Contributor
timestamp: December 11, 2024, 03:49:53 pm
content: Guys and girls, could you answer me these simple questions, plz?1. could you write an C app for android (let us called it "myBode"), specifically for DHO800/900?2. could you talk to scope via scpi off myBode?2. could you read the ch1 and ch2 data with myBode?3. could you talk to the internal AWG via scpi off myBode4. could myBode talk to any external generator, over the network or over the front/rear USB?If the answer would be yes for the above points you may create a pretty good FRA/Bode, whatever you call it..That means to stop lamenting and start doing something, of course..

author: ataradov
author_rank: Super Contributor
timestamp: December 11, 2024, 04:04:00 pm
content: C app is not happening, it would be Java/Kotlin.You can in theory talk SCPI over the localhost with the scope app, I don't think it will know the difference. Talking to the external devices over USB may be trickier, but the network should be doable.But the internal Bode is fine. The issue with internal AWG is that it is useless beyond very basic things. And this is not going to be fixed by external software.

author: nodshuffle
author_rank: Newbie
timestamp: December 11, 2024, 11:05:20 pm
content: Thanks for all of the detailed replies. I suppose I use pretty simple signal injection functionality for fault tracing for the most part, but it sounds like the AWG isn't very good value for money and with the price of probes the logic analyser is pretty much a non-feature. It's a shame that the pricing is the way that it is, where the 900 series is almost double the cost of the 800 series.The bode plot generator seems more like a novelty than anything. I mean it could be nice to use it to characterise crossovers, but admittedly I can live without it.So it really comes down to the increased bandwidth + integrated AWG being worth it, where one could obtain an 800 series and a decent separate AWG for the same price.

author: nodshuffle
author_rank: Newbie
timestamp: December 11, 2024, 11:07:10 pm
content: Does anyone know if you can truly get 250Mhz bandwidth out of a hacked 914s? I have one project in mind that deals with a clock running up to 165Mhz.

author: ebastler
author_rank: Super Contributor
timestamp: December 11, 2024, 11:13:04 pm
content: Quote from: nodshuffle on December 11, 2024, 11:07:10 pmYes, you can. But the scope's sampling rate -- 1.25 GSa/s, divided over the channels -- will only support that bandwidth in single-channel and dual-channel mode. If you activate the logic analyser's digital channels, they will consume half of the sampling rate, so only a single analog channel is sampled adequately for the bandwidth.In my opinion you are better off with a DHO800 series scope and an external signal generator. Or consider a Siglent SDS800X HD instead, which has better sampling rate, better FFT, and can control external Siglent signal generators to acquire Bode plots automatically.

author: Fungus
author_rank: Super Contributor
timestamp: December 12, 2024, 02:18:49 am
content: Quote from: nodshuffle on December 11, 2024, 11:07:10 pmYes.(Actually about 280Mhz measured, and even the DHO804 can do it...)