Is Bandwidth/memory depth a waste of money in oscilloscopes? - Page 1
Forum section: electronics / testgear

author: Pete F
author_rank: Regular Contributor
timestamp: June 30, 2018, 04:56:02 am
content: Hi, my trusty old Tektronix 2215 oscilloscope just blew up and after poking around inside, it was time to admit it's days were over.While electronics is actually my trade, that was sadly a long time ago and things have changed a LOT. After a career change I don't do much in this field now, but do occasionally still dabble and don't want to be without an oscilloscope. It's quite likely I'll do more work in the field in future however. Most of my work would be in the low frequency area, audio, power supplies etc. I'd consider it was relatively easy work by oscilloscope standards.I've been looking at the offerings from Hantek in the 5000 series. I've read mixed reports about the Hantek overall quality but that aside was wondering if the differences in bandwidth and memory depth are worth the extra money for the above applications? The series starts with a DSO5072P (70 MHz/40K mem) @ A$320, through to a DSO5102B (100 MHz/1M mem) in the midrange @ A$455 and extends up to the DSO5202DM (200 MHz/2M mem) @ $550. Other manufacturers have similar models in their own ranges.My question is; given the work I expect to do, is the significant increase in cost between the manufacturers' offerings likely to provide me any real benefits, or should I just spend the difference on cheap wine and hookers?The DSO5072P is a popular model and the overall consensus from buyers seems to be that they're happy with the purchase, it may well do everything I want, and I really don't need to spend more than that.Advice and opinions gratefully received.

author: Rerouter
author_rank: Super Contributor
timestamp: June 30, 2018, 05:12:20 am
content: If your working in the audio and power supplies area, your requirements are not that high, bandwidth comes down to what you intend to measure, and memory down to how many slices of that ting do you want saved to reveiw.at my work we went with a cheap 2 channel siglent and it has more than me our requirements (component level repair of mixed signal boards below 10Mhz)

author: Muttley Snickers
author_rank: Unknown
timestamp: June 30, 2018, 06:35:33 am
content: I'm still in the market myself but haven't even bothered to look at the Hantek stuff because I don't believe there are any local distributors so if there were any problems with the unit you might have to send it back to Asia at huge expense and no guarantee, there may well be a local Hantek distributor in Australia but I haven't found any who carry any substantial stock.Not long ago I was looking at purchasing the Siglent SDS-1072 CML+ which is 70 MHz and has 2 Meg of memory in addition to a 7 inch 800 x 480 screen and 3 year warranty but I hesitated because Siglent have failed to release a new firmware update to address the bugs and issues which member hereStilltryinghas gone to great lengths to document.I spoke to Wavecom Australia and they did have these listed on special at $338AUD for a long time but have recently bumped them up to $468AUD plus tax so that counts me out, if Siglent had of pulled their head out of their arse in regards to updated firmware earlier then I would now be using one of these instead of my TDS-1002 with 60 MHz and 2.5kpts of memory. For my applications I would much rather use a shitty old thing that works than a fancy new thing which doesn't.

author: Pete F
author_rank: Regular Contributor
timestamp: June 30, 2018, 07:07:25 am
content: Some of these intro models of various brands are available in Australia, but at around double the price. My experience with the local interpretation of "warranty" from small distributers hasn't been good I'm afraid, not much better than the Asian interpretation, and I personally wouldn't pay 1 cent extra for it. Maybe the locals will lift their game as more and more people give up and shop online/offshore, but I'm not holding my breath. However that's my experience and opinion, and others' milage may well be different. I do try my best to support our economy, and shopped around locally but I have no intention of paying double. At this price range I'd consider it disposable in any case, a shame, but that's just life and a sign of the times.I did have another look at the 2215, I just can't bear to see her go. I did get excited when I had beat it into life, but one of the channel switched was intermittent and didn't seem to want to clean up, at least one of the probes is dicky, and then it died again. I'll threaten it with screwdrivers and stern words once again, but I think the old girls is telling me it's time to go.

author: tautech
author_rank: Super Contributor
timestamp: June 30, 2018, 07:25:52 am
content: Pete F, just because it's a scope doesn't make it any more special to fix than anything else and there's some way you can go in attempting to fix it with minimal tools and some brain power.First you need probes you can trust and even the $10/pair P6100's on eBay are shit loads better than nothing.Grab a 2215 service manual online and do some serious study.You say it 'blew' up, just what exactly failed ?There's a few threads on these and models from the same series in the Repair board so hunt them out and see if you have similar symptoms.Ideally if you're to upgrade your Tek, 2Mpts is what you should set as a starting point for a DSO in order to utilize its capabilities when Single triggering or examining a Stop'ped waveform. 100 MHz is what many these days consider appropriate for most of the modern things we look at.

author: Pete F
author_rank: Regular Contributor
timestamp: June 30, 2018, 08:10:04 am
content: By "blew up" I mean the magic smoke escaped. No idea where from, there was enough that it should have been obvious, but upon opening it up ... it wasn't obvious! I suspect it's actually from a PCB type arrangement within the power supply. I have no idea why it's designed that way and it's not worth trying to explain as I haven't seen anything like that before.These machines come with a service manual, because that's what they did back then. So I have it, no serious study required, they were pretty simple back then. Pretty much everything can be repaired and I'm sure this oscilloscope is no exception. Indeed it may well be not a particularly difficult repair. However sometimes using that brain power is to realise when it's about not wasting time and resources on flogging a dead horse. Yes I could spend what will inevitably turn out to be a considerable amount of time messing about with the current machine and get it going. I would also need to go out and spend another 20-30 bucks on probes that are crap and no doubt just as unreliable as the ones I have. I'm then left with an unreliable machine, with crap probes that takes up a lot of room and is well over 30 years old. These puppies aren't wine, they don't get better with age! If I had nothing better to do with my time it might be a good exercise, but I do, so it's notI don't feel it's worth pursuing it further, if I can find an obvious fix and if that doesn't work that's it. If anyone else wants to mess about with it they can check the Sydney dumpsters and knock themselves out!Edit: Out of interest here's a thread from this very forum discussing the above machine. It seems many share my opinion on the power supplyhttps://www.eevblog.com/forum/repair/tektronix-2215-problem/Which brings me back to the point of the post. For many years I made my living with a dual channel oscilloscope and never felt the need for more channels. I had many available but my own personal one wasn't particularly high bandwidth and I also rarely, if ever, felt the need for more. Back then I was doing a lot of RF work too. Most of the time I found the faults were reasonably binary; the device is either working or it wasn't. If it wasn't working properly it was normally relatively obvious and there wasn't much need to zoom in on specific parts of waveforms etc. The people designing might need to do that, maybe the people doing a lot of digital, but that's not my experience anyway. I guess I'm just after something that can do what I has, but isn't 35 years old

author: tautech
author_rank: Super Contributor
timestamp: June 30, 2018, 08:27:45 am
content: I get all that, and see you're quite ready to move to something more modern.Don't overlook SDS1202X-E.

author: bd139
author_rank: Super Contributor
timestamp: June 30, 2018, 08:36:31 am
content: If your 2215 actually exploded it’s probably the RIFA caps. Dead simple fix.Don’t buy a Hantek.

author: David Hess
author_rank: Super Contributor
timestamp: June 30, 2018, 09:03:45 am
content: Bandwidth is bandwidth with either an analog oscilloscope or DSO and nothing makes up for lack of bandwidth but if you do not need it, then you do not need it. I am sure your applications can get by with 50MHz.Memory depth in DSOs is important for maintaining high sample rate at slow sweep speeds and acts as a crutch to make up for the lack of a delayed timebase which your 2215 has. It is one of the cheapest things they can add to a DSO for bragging purposes.DSOs are very handy for power supply work because their storage capability prevents flicker at slow sweep speeds and they can capture startup and shutdown events.My go-to oscilloscope is a Tektronix 2230/2232 which is basically a 2215 with more bandwidth and complete digital storage capability. Since it has delayed timebase capability and peak detection, it does not need a large record length as much as a modern DSO which lacks these features.

author: Pete F
author_rank: Regular Contributor
timestamp: June 30, 2018, 09:08:08 am
content: Quote from: bd139 on June 30, 2018, 08:36:31 amI'm not sure how you would come to that conclusion. How many 2215s have you found have that issue? Is it a known issue with that machine?Why would you say "don't buy a Hantek"? From what I can ascertain reading through the people who have bought that brand, the build quality is pretty ordinary. If I was still doing this malarky professionally I would want something decent. My original CRO was a Kenwood (not a brand that comes to mind normally), given to me by my father who was also in the game. It was by far the best oscilloscope I'd ever used and I will always miss that machine (it was stolen). Not high bandwidth and with no bells/whistles, but a rock solid machine that always triggered well and did what it said on the box.In the research I've done so far I didn't see any obvious trend in terms of reliability or otherwise in regard Hantek. People are generally quick to whinge and complain when something goes wrong, and I've seen most brands pretty well represented on the whingometer. Once I narrow down what it is that I actually need I will refine the brands more. I certainly appreciate the reasons why recommendations are being made so I can learn for myself and make up my own mind, as without that the person at the other end of the keyboard could be sitting there with a lucky 8 ball for all I know.

author: nctnico
author_rank: Super Contributor
timestamp: June 30, 2018, 09:14:14 am
content: Quote from: David Hess on June 30, 2018, 09:03:45 amAll modern DSOs have delayed time bases! That has been pointed out before. You can set the trigger point outside the screen and there you have it.To the OP:In general brands like Hantek, Owon, Rigol, Siglent may have hidden problems in their firmware which may take long (or never) to get fixed. Just be aware that you get what you pay for when buying an oscilloscope. For your purpose you may want to look at the GW Instek 1072B or MicSig tBook to1072. The latter is a (thick) tablet sized scope which can be both battery and mains powered. It is very handy to take with you or as a scope you can grab quickly and do some measurements.

author: bd139
author_rank: Super Contributor
timestamp: June 30, 2018, 09:27:10 am
content: Quote from: Pete F on June 30, 2018, 09:08:08 amI’ve repaired numerous scopes (tens of them) including a few 22xx units. The age of the units and the power supply design suggests that as a failure mode. Other failures usually result in power supply ticking. RIFAs are the hot side and the only bit that tends to actually let magic smoke out as they’re the only bit that doesn’t fail safe.Not hantek because you’re paying to have every corner cut. 8 bit sample size. Bad. Low memory depth. Bad. Lowest bidder. Bad. UI and software are just dire. Most of the reviews are from people who haven’t used anything better.Personally I’d go for the Rigol DS1054Z. 4 channels, crack it to 100Mhz and 24M sample depth and 12 bit ADC. Software is a bit laggy in places but it seems to win on value. Software is pretty mature as well and most of the bugs have been worked out. Also why it’s still extremely popular today on here. Siglent are also a perfectly good contender.However one thing to factor in here. Your 2215 has lasted a long time. Nothing you buy today has any guaranteed longevity past 3y really. 5y if you’re lucky. 7y if you’re really lucky. Factor that into the purchase cost. Hantek maybe 1-2y.Edit: nctnico mentioned GW as well. Definitely worth a look there.

author: Fungus
author_rank: Super Contributor
timestamp: June 30, 2018, 10:04:12 am
content: Quote from: Pete F on June 30, 2018, 09:08:08 amFrom what I've heard the problems with the Hantek are the firmware, both in limited functionality and bugs.The favorites at the moment would be:Rigol DS1054Z (4 channels, easily hacked to 100Mhz plus all options)Siglent SDS1202X-E (200MHz, two channels)GW-Instek GDS-1054B (nice to use, more 'analog' than 'digital', eg. good FFT but no serial decoders)The Rigol is an awful lot of bang per buck but there's a lot of irrational Rigol hatred in these forums. There's also a lot of Siglent sellers so opinion isn't unbiased, watch out for that/them.At the end of the day it probably comes down to where/how you can buy one and how much emphasis you place on the warranty. The hardware seems very reliable so long-term warranty is maybe not important.PS: If you're thinking about doing any digital stuff at all then go for 4 channels.

author: Fungus
author_rank: Super Contributor
timestamp: June 30, 2018, 10:12:04 am
content: To answer the real question:Quote from: Pete F on June 30, 2018, 04:56:02 amIf you were happy with a 60Mhz Tek then you'll be very happy with a 100MHz DSO.(once you get past the mind-blowing number of things they can do compared to an analog 'scope)Quote from: Pete F on June 30, 2018, 04:56:02 amIt depends on how much wine and hookers you can get for $150 where you live.

author: Pete F
author_rank: Regular Contributor
timestamp: June 30, 2018, 10:28:42 am
content: Quote from: bd139 on June 30, 2018, 09:27:10 amI didn't intend the post to be about the 2215, so don't want to be drawn too far in to that area. For the record however it's now blowing fuses (didn't do that before). As I said, I believe the source of the smoke was a small PCB type arrangement on one of the semiconductors. It's a weird arrangement and anyone who has actually fixed one of these would know what I'm referring to, but it's a totally crap arrangement in my opinion. I did manage to get a thermal imager on it, and one of the output caps is overheating. It only ran for a few seconds but it was thermally very obvious. That would be in keeping with the age of the machine in my experience, especially one that's not used very often. That was one of the motivations for not pursuing it as it's not unusual to have a whole pile of faulty caps in machines of this age/lack of use. If it was fired up regularly it would likely last much longer. I will reassemble it and put it to one side until I get a replacement. If I find the time/motivation I may throw a new cap in there and see what happens, but it's barely worth the effort in my opinion. These old power supplies can be an absolute PIA to repair sometimes (unless you're into guessing and weegie boards).I did however want to address the comments made about the Hantek brand. I'm definitely not trying to hold myself out as any form of instant expert, which is why I joined to forum and will accept anyone's opinion. However I also know how to read a spec sheet!Most oscilloscopes in the price range I'm looking at are 8 bit, including (I believe, though happy to be corrected) the one you recommended. From what I can determine that isn't considered a limitation for this type of work. As I said in my opening post, the memory depth varies from 40K to 2M in the 5000 series. That's the whole point of my question, to determine what is the most appropriate memory for my application. Hantek is a brand, not a model number. I already said I have no need for a 4 channel oscilloscope, I thought the DS1052Z is very dated and didn't overwhelm me. The DS1054 is 2 more channels I don't need and attracts a significant price premium down here in 'stralia. The Hantek can also be hacked, to 200 MHz in that case, no biggie in my opinion, I would just buy the higher bandwidth oscilloscope if it was important to me. Hacking machines isn't a selling point to me.I was one of the agents for GW when they first came in to Australia. Don't know anything about them now. They were one of the first "affordable" test instrument companies available here, well before the days of the internet of course.Sadly you're right and longevity is just a sign of the times. What I'm finding is that even buying what was previously a very good brand is no guarantee that you're getting any real value. My wife was only 30 minutes ago bemoaning that fact with our relatively new Asko dishwasher. We've used that brand for many years and are prepared to pay a premium. However the past two appliances from them have been very disappointing. My Hilux is the same. So it goes on. I do sense there is a definite brand snobbery when it comes to the test instrument area, and it appears Hantek is the bottom of the pile. When I was in the game it was GW. That's fair enough, but even I can see that many of the assertions are being made based on no personal or even close experience. Many of the reviews I've seen have indeed come from extremely experienced people in the field and they acknowledged the generally low attention to build detail with the Hantek brand. Nevertheless they have been reasonably balanced reviews. I've looked carefully at both Hantek and Rigol, and it appears to me the Hantek functionality is better. I don't hold out much hope for either of unwrapping an HP when I open the box!

author: nctnico
author_rank: Super Contributor
timestamp: June 30, 2018, 10:33:14 am
content: Quote from: Fungus on June 30, 2018, 10:04:12 amThe irrational part is in your brains only. The fact is that Rigol puts oscilloscopes on the market with very buggy firmware and not all people are willing to pay good money for a piece of equipment which doesn't work as specified. Especially with a recently introduced oscilloscopes the bang per buck is only there on paper.

author: Fungus
author_rank: Super Contributor
timestamp: June 30, 2018, 11:13:41 am
content: Quote from: nctnico on June 30, 2018, 10:33:14 amIs Siglent remembering to put all the components on the PCB these days or do they still post little bags of capacitors to people so they can solder them in at home?How's the firmware coming along, it is out of beta yet?

author: tautech
author_rank: Super Contributor
timestamp: June 30, 2018, 11:46:06 am
content: Quote from: BillB on June 30, 2018, 11:41:28 amShould I mention Yaigol.....nah I won't.

author: Pete F
author_rank: Regular Contributor
timestamp: June 30, 2018, 12:00:12 pm
content: Yeah look guys (as it invariably is) I appreciate the passion. I'm very new here, but have been around forums ... well more than one or two! I know how this all works.My trade and background was in electronics but I don't really have a passion for it. Just the same I do have a strong interest in it and was literally bought up on it. But forums, by definition, attract those with a real strong interest and a lot of time invested in the topic. That's great and why I'm grateful to be invited on here. What comes with that passion however is a bias, particularly a gravitation to pro-quality and serious users. For that reason I didn't ask for a recommendation on brands or models, and instead I asked a couple of specific questions about DSOs in general.If anyone is in doubt, pretend this is a sport car forum and I've just come on and asked if I should buy a Kia. My post would likely be torn down by the administrators! But for somebody who isn't a sport car enthusiast and only wants a car to drive to the shops or the train station by themselves, driving a maximum of 2,000 km a year a Kia may be perfectly acceptable and they don't need to go out and buy a Ferrari!So to bring the topic bang to the original question I'm keen to know how a (relatively) high bandwidth oscilloscope (let's say 100 MHz) would help somebody who generally works in the audio range of frequencies. Maybe clock freq, but that's about it at this stage. I personally can't see how 100 MHz has even the vaguest assistance, but that's why I'm here to ask.I think I'm getting the idea of the memory, and from my understanding if I have a slow sweep (as I might with low frequencies) then want to store and zoom in on that waveform, I'm going to need memory to do so. So how much memory is "enough" to do that. Am I going to get a 40K oscilloscope and always be wanting more memory every time I use it? What if it's 1 M/2M/25M. Bragging rights carry no weight with me I'm afraid, see paragraph 2 aboveI appreciate those taking the time to educate me so I can make a rational decision based on facts.

author: nctnico
author_rank: Super Contributor
timestamp: June 30, 2018, 12:05:59 pm
content: It seems 50 to 70MHz is at the low end of the memory bandwidth nowadays and affordable oscilloscopes have between 5Mpoints to 10Mpoints of memory per channel. Aim for that. With a lot of memory you can record a single sweep and zoom in on areas of interest. What I often do is just capture a whole lot of data without triggering on a specific event and just zoom in on the area of interest. That is quicker than setting up specific trigger conditions and re-measuring different parts of the signals over and over. Especially if it takes some effort to generate the signal of interest (an intermittent fault for example).Regarding your sports car remark: I think you got that wrong. Nobody has been suggesting buying a US $10k scope so far. To get back to the car analogy: it is similar to buying a too cheap car which has wobbly wheels, squeeking wind shield wipers, sloppy steering, etc while spending a little bit more buys you a car which drives excellent. Still not a sports car by far but something which will get you from A to B comfortably.

author: Pete F
author_rank: Regular Contributor
timestamp: June 30, 2018, 12:15:42 pm
content: Feel free to substitute "Ford Taurus" for "sport car" and "Mazda MX5" for "Ferrari" if it makes you feel better. It was the analogy I was getting at and not a literal translationThe point was, I wasn't asking for ANY brand recommendation, because I know how that ends up. Which it did!A car with squeaky windshield wipers and sloppy steering will still get me to the train station in precisely the same time, and I didn't ask for a car that was "comfortable"I asked if a car with fuel injection and capable of 160 kph might be important to me in driving to the train station. A "comfortable" car might be important to you, but what makes you think I'm interested in paying more for that?

author: nctnico
author_rank: Super Contributor
timestamp: June 30, 2018, 12:20:34 pm
content: Quote from: Pete F on June 30, 2018, 12:15:42 pmWell, feel free to spend money on anything you want. However: you wouldn't be the first to be dissapointed by buying something cheap first and end up buying a different (more expensive) piece of equipment from a better brand. I've been down that road a couple of times myself (and lost quite a bit of money in the process) so I write from my own experience.

author: tautech
author_rank: Super Contributor
timestamp: June 30, 2018, 12:20:56 pm
content: Stepping from a CRO to a DSO there's a few simple things to understand.Traces won't appear as crisp and at first you think WTF, what's all this noise ? Check for Daves vids on why DSO's appear noisy.Mem depth and sample rate are related in so much as a captured waveform represents a portion of the sample rate related to the timebase setting and therefore the # of data points captured. The more mem you have the more data points at any given timebase setting and the more accurate the reconstruction of the waveform. For ordinary repetitive stuff none of this matters too much if the interpolation is accurate based on the points available.For non-repetitive or complex waveforms is when you want as many as possible so in pro scopes high sampling rates and large mem depth are there to give the best possible reconstruction as to not miss any glitches or spikes.Also the modern DSO has a truly digital trigger with which any data point that meets the trigger conditions will permit you to capture the waveform that created it.All fairly straightforward once you get your head around it.

author: Fungus
author_rank: Super Contributor
timestamp: June 30, 2018, 12:25:27 pm
content: Quote from: Pete F on June 30, 2018, 12:00:12 pmThe "MHz" in the bandwidth rating of an oscilloscope usuallyisn'trelated to the frequency of the signals you're looking at.Any signal other then a perfect sine wave has harmonics. These harmonics can be much higher frequency than the base frequency. eg. Square waves have infinite harmonics, to see a perfect square wave on an oscilloscope screen you needinfinitebandwidth. This is true even if you're only looking at a 1Hz square wave!It's also true of zero Hz square waves. A single transition from low to high voltage may have infinite harmonics. You need alotof bandwidth to see the detailed characteristics ofa single rising edge. You may see discussion of "rise time" in forums like this, that's what it refers to. "Rise time" is a better measure of oscilloscope performance than "MHz" but rise time would confuse sales people (is a 4ns rise time twice as good as a 2ns rise time...?)So .... it doesn't matter if your clock freq has a base frequency in the audible range, you need a lot more than audio range in your oscilloscope if you want to look at it.

author: Fungus
author_rank: Super Contributor
timestamp: June 30, 2018, 12:34:12 pm
content: Quote from: Pete F on June 30, 2018, 12:15:42 pmHe is, of course, exaggerating. None of the oscilloscopes listed so far is anything like a car with "wobbly wheels, squeeking wind shield wipers, sloppy steering, etc". People who drive Mercedes may look down on Ford Fiestas but Ford Fiestas are good little cars (and very well equipped these days).If you know forums then you should have already guessed there's oscilloscope snobs, too...Quote from: tautech on June 30, 2018, 12:20:56 pmYes, the world of beautiful smooth green traces will end but you'll soon realize a DSO is capable of showing a lot more real information than a CRO.Here's the video:

author: tautech
author_rank: Super Contributor
timestamp: June 30, 2018, 12:38:38 pm
content: Quote from: Fungus on June 30, 2018, 12:34:12 pmYou forgot there's two of them !https://www.eevblog.com/2014/04/27/eevblog-610-why-digital-scopes-appear-noisy-part-2/

author: Mr Nutts
author_rank: Regular Contributor
timestamp: June 30, 2018, 12:39:02 pm
content: Quote from: bd139 on June 30, 2018, 09:27:10 amAren't most digital scopes 8 bit?QuoteSince when does the DS1054z have a 12bit ADC?

author: bd139
author_rank: Super Contributor
timestamp: June 30, 2018, 12:53:33 pm
content: You are correct. My bad. Assumed it had HMCAD1520 ADC in it but it's a HMCAD1511. I shall get my coat

author: Muttley Snickers
author_rank: Unknown
timestamp: June 30, 2018, 12:54:23 pm
content: @Pete FThere is a Hantek MSO-5074F for flaky currently listed on ebay.au for $275 and is open to offers, this is a 70 MHz scope with 1Mpts memory depth, 8 channel LA (3 volt max) and a large 800 X 480 screen, the item is described by the seller as fully operational but a bit flaky and frustrating at times to use. Anyway, it appears to be within your budget and at that price you can easily afford to grab it, have a play and then either keep it if found to be suitable or sell it off again at little risk. Certainly worth a closer look if you are set on a Hantek, sorry I cannot post a link to it from this device.

author: nctnico
author_rank: Super Contributor
timestamp: June 30, 2018, 01:00:22 pm
content: Quote from: Fungus on June 30, 2018, 12:34:12 pmHow do you manage to write so much nonsense again?Look at my posts on various pieces of equipment more carefully and you'd know I have a whole range of test equipment. From cheap Ebay stuff to really high end stuff. Whatever gets the job done quickly and without being annoying.

author: Pete F
author_rank: Regular Contributor
timestamp: June 30, 2018, 01:02:49 pm
content: Thanks. I thought Dave's video on "noise" was excellent. I'd seen that before asking here as part of my research. I'd always thought it was part of the ADC process and thought, oh man, that is going to do my head in! I had no idea until that video I'd been looking at it all along and just never knew!Yes I spent something like 7 years in college trying to stay awake while a lecturer tried to do otherwise, so I do have a vague idea of what a square wave isMy point is that I'm probably not going to be designing this stuff, building it maybe, but unlikely to be designing it. I've never once, in my career, had any need to examine the leading edge of a clock frequency! It's either A) there/vaguely on frequency = good B) Not there = bad.To put this in further perspective, I bought that 2215 something like 15 years ago, quite used, because it was something similar to what I mainly trained on (I think they were 2213s if my memory hasn't completely gone). In the past 15 years I have probably used it, maybe, 7 hours use?ie it would be used maybe 30 minutes PER YEAR on average. Now that admittedly fluctuates, and when I move house I will have a dedicated small electronics area so expect that to come up a lot. But that should put things in perspective. That's almost certainly why it now failed; electronics, especially power caps, don't like to sit idle! It's a bit of a PIA to get that 2215 out from storage, set it up on the kitchen table, and try to get organised. One day that will hopefully change.Why did I get it out now you might be wondering, a lucky year? Well I discovered that my main hifi amplifier (mid to higher quality) had a channel not working. A bit of poking around and I could see it's not being biased on. Not exactly a space shuttle launch we're going for in that repair! I also discovered my CD player was playing up (hey I never have time to sit down and listen to any of this these days). Again it's an audio fault and shouldn't be a big deal.The future? Well who knows. I still have an interest and would like to get back in to it more when I get more opportunities. But that's the reality of where I'm at now. If it means spending A$600 on an oscilloscope then that's how much they cost. Pay the fare and hop on the ride. But if I can get something that might only last 500 hrs before it blows up, or isn't the best quality, or can't measure the nearest black hole, etc and only costs A$350, then why would I want to spend $500. That's probably a hundred bucks an hour for its expected life and my use. Even the aforementioned hookers are cheaper than that!!!

author: bd139
author_rank: Super Contributor
timestamp: June 30, 2018, 01:08:01 pm
content: Sounds like you need to spend $20 on caps and save the rest for hookers and beer.

author: Pete F
author_rank: Regular Contributor
timestamp: June 30, 2018, 01:09:04 pm
content: Quote from: Muttley Snickers on June 30, 2018, 12:54:23 pmThanks, yes I saw that. However I already have one oscilloscope that doesn't work and don't want anotherI thought it was a bit overpriced to be quite honest. They're not all that much more than that new from what I've seen and shopping around.My "budget" is what it takes to get the job done. To me this isn't anything to get very excited about and it's just a tool with about as much interest to me as a pair of side cutters. Having said that I do appreciate quality and aren't interested in buying rubbish I will just be disappointed/frustrated with and won't do the job. I'd rather have a lower spec but better quality tool is of much more value to me than a POS that lets me down, or a "brand" name that doesn't do much. A bit of a balancing act I guess.

author: epongenoir
author_rank: Contributor
timestamp: June 30, 2018, 01:11:50 pm
content: I'll just add my 2 cents.I am graduating in electronics engineering but always had a passion for it since I was a kid.I had a really old 4Ch Tektronix 2465 I bought on Ebay, but I needed a DSO (digital electronics, waveform run/stop..), so I sold my old one and bought a Siglent SDS1104X-E.I've been amazed on how capable the little beast is in terms of responsive and nice UI, functions, boot time, few clutter on screen..(BTW it can be hacked to a 200Mhz BW, look in this thread:https://www.eevblog.com/forum/testgear/siglent-sds1204x-e-released-for-domestic-markets-in-china/msg1612639/#msg1612639).I have used a Rigol a couple times before the Siglent but never had the same feel for that instrument.If you plan to use a bit of advanced functions or something a tad more serious, I'd recommend the same one I bought.

author: Fungus
author_rank: Super Contributor
timestamp: June 30, 2018, 01:15:39 pm
content: Quote from: nctnico on June 30, 2018, 01:00:22 pmThen you know you're exaggerating. DSOs in the $400 range are Ford Fiestas, not clown cars.

author: Pete F
author_rank: Regular Contributor
timestamp: June 30, 2018, 01:19:53 pm
content: Quote from: bd139 on June 30, 2018, 01:08:01 pmUnfortunately I think this hooker will give me a dose of something even the strongest penicillin won't help!If it was just the one cap I'd throw one at it and move on. But as I said above, it's time for the old girl to go. I don't have the time to be constantly fiddling with tools. I want to turn them on, they work, I do what I bought them for and then I turn them off again. What shouldn't be overlooked is a modern DSO can do a heck of a lot more than my old 2215 ever could. Something I've been reminded by, as I dropped my multimeter a while back and while ruggedized it still manage to go a bit flaky. Another thing I'll need to replaceIt's been a week of the magic smoke fairy dancing around my place I tell you!!!

author: rf-loop
author_rank: Super Contributor
timestamp: June 30, 2018, 01:24:45 pm
content: Quote from: Fungus on June 30, 2018, 12:25:27 pmOnly theoretical ideal square wave or transition (step) what have 0 rise and/or fall time have infinite harmonic frequencies. And these do not exist in real world.Limited rise time signal do not have infinite harmonics and all signals in practice in real world have limited risetime.-------------------------------Overall:So, depending how accurate measurements need do example for risetime this is key factor what BW (risetime) oscilloscope is needed. If risetime what need measure is 1.75ns and it need measure with no more than around 2% error it need 1GHz oscilloscope. (bit more if it have "brick wall" type frequency response shape)Why I take here just 1.75ns. Because it is typical 200MHz oscilloscope risetime. Common "rule of five" is, you need 5 times faster oscilloscope risetime what is signal risetime if you want "good" accuracy for measure risetime.For pulse/square type of signals (aka "for digital signals") it is best to define needed BW (risetime) using some estimate of fastest rise/fall times what need observe.If fastest risetime is 3.5ns and we can accept 40% error on rise time measurement then 100MHz scope is enough.Now with low frequency pulses and if want look these on the screen and also zoom in to rising / falling edge for observe these edges together with visible whole pulse period there nee be also enough memory what make possible to keep sample speed enough high.It need also note that some older technology entry level scopes may have two kind of memory. Full speed and then reduced speed. Example some scope may have only quite short fast memory and then example 1M "long" memory is only half speed. Many times product brochure do not tell it clearly or not at all.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: June 30, 2018, 02:02:26 pm
content: I have a hantek 5072p and it's pretty good, works well, a pleasure to use, haven't had a single problem yet (+5 years), and was cheap, 180€ IIRC. Buy one of these if you like it, it's not an Agilent but it's fine.

author: rstofer
author_rank: Super Contributor
timestamp: June 30, 2018, 02:30:00 pm
content: Quote from: Pete F on June 30, 2018, 12:00:12 pmFor audio and other low frequency sinusoidal signals, high bandwidth isn't necessary. It is an indication of the quality of the front end but so what? You simply don't need bandwidth - today.Where it comes up is verifying signal integrity of square waves where we NEED high bandwidth to include the various harmonics. With a 100 MHz scope, if we want to include the 9th harmonic of a square wave, its fundamental frequency needs to be around 10 MHz (leaving a little on the table to stay away from the knee).But that 100 MHz number is pretty low when thinking in terms of 50 MHz FPGA signals. For folks involved with digital signals, bandwidth is everything. Except channels...More channels is good in the digital arena - not an area you appear to be interested in. Fair enough! Four channels works great for decoding the SPI bus and that's why I bought the Rigol. It's my go-to scope but I'm keeping my Tek 485 for bandwidth.The DS1054Z is being offered with all the options except 100 MHz bandwidth and it may be one of the low price leaders. I wouldn't have any idea how equipment is priced in Australia. From what I have read, US prices are a good deal lower. The Rigol has been out for quite a while and has gone through several iterations of the firmware. The usability bugs have been worked out. Siglent is taking an aggressive approach to fixing their problems with the new SDS1204X-E (or 1104 or 1202) but I haven't been following along. I am seriously interested in the 200 MHz 4 channel variant (SDS1204X-E) but I just haven't outrun the DS1054Z, yet...I think the only way to make a choice is to create a spreadsheet with features and costs. Sort the data in order of preference and then start reading reviews.The idea of having an interest in only lower frequencies comes up all the time. A lot of folks are interested in audio and not interested in digital.

author: stj
author_rank: Super Contributor
timestamp: June 30, 2018, 04:12:45 pm
content: 2 pages and still arguing?just buy a damned Riglent and be happy!

author: bd139
author_rank: Super Contributor
timestamp: June 30, 2018, 04:14:09 pm
content: Or buy a DSO138, cry for a bit and fix the 2215, nodding approvingly at the money you now have to spend on a new DMM

author: maginnovision
author_rank: Super Contributor
timestamp: June 30, 2018, 04:26:17 pm
content: Another option would be hantek 6022 with openhantek software if you'd rather go cheap for something you basically don't need.

author: Fungus
author_rank: Super Contributor
timestamp: June 30, 2018, 05:01:51 pm
content: Quote from: rstofer on June 30, 2018, 02:30:00 pmQuote from: stj on June 30, 2018, 04:12:45 pm"Audio" people might be better off with the GW-Instek.

author: bd139
author_rank: Super Contributor
timestamp: June 30, 2018, 05:06:54 pm
content: Audio people would be better off with the one with the least shit FFT.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: June 30, 2018, 05:10:46 pm
content: Quote from: stj on June 30, 2018, 04:12:45 pmRiglentek

author: David Hess
author_rank: Super Contributor
timestamp: June 30, 2018, 05:13:02 pm
content: Quote from: nctnico on June 30, 2018, 09:14:14 amIt has nothing to do with the screen or display record. None of the single timebase DSOs I have evaluated allowed the trigger to be moved outside of the waveform record. But if the waveform record is long enough for the application, then this is not a problem except perhaps for performance when processing a long record length.Where this becomes a problem, and this was discussed on these forums more than a year ago, is things like measuring jitter in a 1 pulse per second GPS signal. 20M points over 1 second is only 20MS/s yielding 50 nanosecond resolution which is worse than the jitter of many GPS 1 PPS signals.The thing about this which really annoys me is that manufacturers like Rigol deliberately obscure this in their documentation by confusing delayed sweep, pan, and zoom functions. The only way I have found to reliably know what a DSO can do is look for the B trigger capability; if it is lacking, then the DSO is limited to pan and zoom within the waveform record.Here is another discussion of the same problem:https://www.eevblog.com/forum/testgear/rigol-ds1054z-triggering-question/25/If what you said was true, then magnification (delayed sweep according to Rigol) would allow the fastest time/div and sample rate at any point within the waveform record under all conditions.PeteF, none of this would matter for power supply and audio applications so ignore this limitation. It would be expensive to avoid unless you want to buy a used instrument which I do not recommend unless you would enjoy refurbishing your 2215.Quote from: tautech on June 30, 2018, 12:20:56 pmDave never actually made objective noise measurements. Most DSOs are both subjectively and objectively noisier. The subjective noise in the display is just because they are cheap. The objective noise is due to poor design and additional quantization noise.Quote from: bd139 on June 30, 2018, 12:53:33 pmEven worse in averaging or high resolution mode, it is *still* 8 bits.Instead of thinking in terms of bandwidth, think in terms of rise/fall time. 100MHz is 3.5 nanoseconds. 50MHz is 7 nanoseconds which is still sufficient for even switching power supplies. 20MHz is 17.5 nanoseconds which will be marginal for switching power supplies.

author: nctnico
author_rank: Super Contributor
timestamp: June 30, 2018, 05:38:17 pm
content: Quote from: David Hess on June 30, 2018, 05:13:02 pmI just tried with my GW Instek GDS2204E and it does exactly what you describe is not possible. I could try some of my other scopes as well but I'm pretty sure I get the same result. I get the feeling you have tried a few very limited DSOs and now map that information on all other DSOs. Doing a delayed trigger is pretty easy to implement in a DSO so there is no reason not to have it.

author: iMo
author_rank: Super Contributor
timestamp: June 30, 2018, 05:51:32 pm
content: @PeteF: this topic you have started repeats periodically since very existence of this forumYou may find dozens of similar threads where an OP is asking which oscope to buy.. And you get always the same answers or "recommendations", from usually the same posters..Nobody helps you here with the spoilt for choice. The final decision is up to you. There are several oscopes which may fit your needs, but you have to undergo the risk of the purchase. When you start to dig into very technical details (and analyze or study all the hw/sw bugs/issues) you most probably will not buy a new DSO oscope and you rather repair the old TEK one

author: Pete F
author_rank: Regular Contributor
timestamp: June 30, 2018, 08:57:29 pm
content: Quote from: imo on June 30, 2018, 05:51:32 pmWell once again I didn't ask an opinion on which 'scope to buy, so I don't know why people insist on making specific model recommendations! I don't need anyone ot make up my own mind, I have one of my own.I asked, specifically, whether bandwidth would be of any use to me. Having very specifically described my application, use, and period of use.I also asked how much memory depth would affect that situation and why.If somebody wants to tell me what they use and why it might be good for me, they can knock themselves out, but I won't be taking much notice until I'm very happy with my understanding of the first two questions.

author: rstofer
author_rank: Super Contributor
timestamp: June 30, 2018, 11:14:14 pm
content: Quote from: Pete F on June 30, 2018, 08:57:29 pmThose have pretty much been answered. For audio work, you don't need bandwidth so just about anything will work. 100 kHz is more than enough. I don't know what the slowest current DSO is but probably a lot faster than you need. It may be on the order of 50 MHz for all I know. I can't imagine anyone designing a new DSO with a 2 MHz bandwidth like my old Dumont.Memory depth is a little trickier if you want a large number of samples per second and a very slow sweep rate. A couple of megabytes are probably enough. Usually sample depth is tied to sample rate and you sure won't be sampling a low bandwidth scope at some huge number.Remember 2.5 - that's the magic number for number of channels * maximum bandwidth per channel * 2.5 for Shannon. A 4 channel 100 MHz scope * 2.5 will have a sample rate of 1 GS/s (minimum).A 2 channel 50 MHz scope * 2.5 will have a sample rate of 250 MHz (minimum). Such a rate would fill up a 10 MB memory in 40 ms so you want to have a sweep rate of 40 ms / 10 div or 4 ms/div (slowest). I really hope I did the math right. The scope will simply back off on the sample rate if you run slower sweep speeds. It doesn't matter because there are only so many horizontal pixels anyway.Here's an article on the subject:https://www.testandmeasurementtips.com/memory-depth-and-sampling-rate-in-oscilloscopes/You don't need a high sample rate for audio - 44.1 kHz is adequate to represent 22 kHz audio. Here is an article on the subject:https://www.masteringthemix.com/blogs/learn/113159685-sample-rates-and-bit-depth-in-a-nutshellIt wasn't all that long ago that sample memory was measured in kB. I don't think I would spend much time on this concept. Anything will be good enough for audio.It might be nice if the scope had a decent FFT (and the Rigol doesn't but the Siglent seems to but I don't have one so I really don't know much about it) but if I wanted precision in an FFT, I would be looking at the Analog Discovery 2 with its 14 bit ADC. I also tend to like 27" screens.Don't get concerned about comments re: 8 bit ADC. Even some very high dollar scopes are no better. How many pixels in the vertical direction? The DS1054Z is 800x480. It might be nice to have 1 more bit but memory tends to come in multiples of 8 bits of width. They do some tricks with AD to effectively increase the bit width. In any event, DSOs don't have 1024x768 screens (usually).Limited to audio, there is no point in buying much of anything. A low $ 50 MHz scope will be more than enough.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 30, 2018, 11:52:03 pm
content: Early DSOs &verycheap modern ones have very little memory, even if their fastest sample rateis quite reasonable.Back in the day, the Tek & HP reps would turn up at my old work, touting the latest offering.After looking at some other waveforms, we would ask to look at a PAL video signal at field rate.OK, that's 50Hz, so set the thing at about 2ms/div----- that should give a nice display of 10 divisions.What's this?---- something which looks nothing like a video signal, more like my overgrown back yard.DSOs with poor memory reduce their sample rate at long time/div settings.That's no problem with sine waves, but complex waves like video signals have frequency components well above the sample rate----hence "alias city".The guys from Tek/HP couldn't get their heads around the problem, & suggested all sorts of beaut workarounds, none of which were " worth a pinch of cockatoo's poo ", & went away, convinced we were "dinosaurs" because we didn't welcome the new technology with open arms.Modern reasonably priced DSOs like the Rigol & its direct competitors do not have this problem, as they have sufficient memory.Some "El Cheapos" are even worse than those old mainstream manufacturers & show obvious aliasingon the colour bursts when displaying a line rate PAL signal.One such device was given an enthusiastic write up in "Silicon Chip " some years back, despite their screenshots showing this effect on a video signal.Some will say "analog video is obsolete, so who cares?", but the same problem will raise its head whenever we are looking for Mains hum perturbations of a fast pulse train.(switchmode?)

author: forrestc
author_rank: Unknown
timestamp: July 01, 2018, 07:01:26 am
content: Quote from: Pete F on June 30, 2018, 04:56:02 amI'm going to try to answer your question this way:On my bench I have a Tek MDO3024, Mixed Domain oscilloscope. 200Mhz, 2.5Gs/second, 10Mpoints of memory. Right now it's actually in spectrum analyzer mode since I was doing some EMI compliance work. It replaced a tek TDS2014, and that replaced a TDS1002B before it. The TDS1002B in particular is a 60Mhz scope, with 1GS/s and 2.5K points of memory.So, lets start with Frequency response: If you're only doing audio, and maybe some digital, you probably don't need more than a few tens of Mhz. I don't think you really probably need more than 50Mhz or so. I'm assuming you didn't bump into the 60Mhz response of your old Tek so getting a similar Mhz DSO should be fine.As far as memory depth - If you're using the scope exactly as a replacement for your analog scope, you don't need more memory than you can see on the screen. That TDS1002B would be a good example - I used it for years to measure intermittent one-time events. So any scope would have enough memory depth for that.Where the extended memory depth helps is where you want to capture a period of time and then zoom in and around the data. For instance, I can do a single shot trigger on my MDO3024 and then zoom in and out and look at different portions of the waveform, even those off the screen. Someone else mentioned measuring time between events - for example, if you had two events say a second apart, you could use the deep memory to capture data for that period and then use cursors to measure the time difference. In my MDO3024 I have the protocol decoders enabled, and occasionally use them. For this it's very helpful to have deep memory since you need to capture the entire waveform of the protocol you're decoding, which can be over an extended period if you're talking long messages.However, none of the above applications seems applicable to "low frequency, audio, power supplies, etc."The one area I can think of which a long sample depth might be useful for you is if you are wanting to run a FFT (audo spectrum analysis) or other analysis on a signal. But even then an extreme sample depth might not be all that helpful. Note that even the cheapest DSO's today see to all have at least a few million points, so that really what you're needing to decide between is 'reasonable' and 'extreme' as opposed to 'too small' and 'reasonable'.Maybe someone else can suggest some other areas where you might want a long sample depth - or longer than the cheapest of the scopes provide.I'll add one more note: I recently was in the market for a scope for the automated test system in the manufacturing plant. Just needed something cheap to do some basic signal measurements. Needed a mask test, some way to control the device via LAN or USB, etc. After a side-trip with a siglent that didn't work for the application, I ended up buying a Rigol DS1054Z. I'm impressed enough with the scope that I'm pretty certain that if I was wanting one for hobby work, this is the one I'd get. I'm assuming that many of the other scopes out there will work just as well. But for the type of work you're looking at I'd be more interested in what features you might want and whether there's any gotchas you're likely to encounter with what you will be doing.One more thing I just thought of: If you're interested in FFT, you may want to look at eevblog #845, being mindful that some of this might have changed since it was filmed, and may not include the scopes you're talking about.

author: nctnico
author_rank: Super Contributor
timestamp: July 01, 2018, 09:30:16 am
content: Input filtering is also a useful feature to get rid of unwanted noise.

author: nfmax
author_rank: Super Contributor
timestamp: July 01, 2018, 07:48:18 pm
content: For audio work, you need a frequency response that goes up above the highest likely frequency of oscillation of the power output transistors in a class B amplifier, or enough to let you look at the switching times in a class D amplifier. Say 100 to 200 MHz. A wider bandwidth scopegenerallymeans a faster ADC sample rate, which for audio work means that in 'hi-res' mode (where successive ADC samples are averaged/combined together to give the effect of more bits & less noise at a lower sample rate) you get a wider bandwidth. You should do fine with a 1 GS/s 8-bit ADC for two channels (or two of them for four channels)Memory depth is not particularly important for audio (except if it's so short the FFT resolution is too low to be useful). For audio, 50,000 to 100,000 samples per channel is fine.What does matter, especially if you are used to an analogue scope, is waveform update rate. If you are playing audio (not sinewaves) into a digital scope, too low a waveform update rate produces a 'freeze-frame' effect where what you see on the screen is a series of delayed, momentary snapshots of what you are hearing. Most disconcerting. A waveform update rate of 10,000 updates/secondat the timebase rates you will be usingis about the minimum I'd accept.Of course, more is always betterbut as you are concerned about wasting money you may not want to go there...

author: Fungus
author_rank: Super Contributor
timestamp: July 01, 2018, 09:02:31 pm
content: Quote from: nfmax on July 01, 2018, 07:48:18 pmThat's a point worth mentioning: To look at amplifier outputs, etc. you need to connect apairof probes and look at the difference between them. For stereo that means a four-channel oscilloscope.

author: David Hess
author_rank: Super Contributor
timestamp: July 01, 2018, 09:53:32 pm
content: Quote from: nctnico on June 30, 2018, 05:38:17 pmThe GW Instek GDS2204E fits in the exception I deliberately mentioned in my post which you apparently did not bother to read or did not understand:The only way I have found to reliably know what a DSO can do is look for the B trigger capability; if it is lacking, then the DSO is limited to pan and zoom within the waveform record.Guess what, the GW Instek GDS2204E has B trigger capability although they do not call it that on page 145 ofthe manual. So good for GW Instek and thanks for supporting my point.Are there any less expensive DSOs which have this capability?As far as record length and sample rate, I have been disappointed with the display fidelity of every DSO compared to an analog oscilloscope. (1) I would have expected large record lengths to improve the situation but if there has been improvement, then it has been small for general purpose applications. I do not consider a large record length to be advantageous for display fidelity especially if it slows down the display processing speed.My compromise has been to rely on peak detection or DPO (digital phosphor oscilloscope) operation and just live with it. My 2230/2232 has a terrible display in this respect since it lacks index grading but most DSOs which support index grading handle it poorly and the 2230/2232's very high display resolution compared to modern DSOs somewhat makes up for it.Rohde & Schwarz make some DSOs which apparently address this issue but I have not had a chance to evaluate them. They wrote a great application note on the subject which described what they did not long ago but I read it once and have not been able to find it since.Basically, I would ignore this issue because there is little to be done about it except insofar as the instrument you pick supports peak detection which avoids the worse problems. Then learn to use the DSO to best effect within its display limitations. Ignore marketing's record length wars.For audio work, an old oscilloscope I might consider is the Tektronix 2225 because of its 5MHz bandwidth limit and 500uV/div sensitivity. The Tektronix 2210/2211 is the same oscilloscope but with digital storage capacity. But I do not recommend these because they are old and the DSOs lack peak detection.If there was a modern low cost DSO which supported network analysis, I might recommend it. Keysight has something but it is neither inexpensive nor does it have acceptable performance; it is a toy. The closest I am aware of are from Cleverscope and Syscomp Electronic Design but they are USB based instruments:https://cleverscope.com/products/https://www.syscompdesign.com/products/I would not consider 8-bit DSO FFT capability as useful for audio; at best it is only sufficient for low fidelity.(1) Try doing tangential measurement on a DSO; the ones which support index grading are actually *worse*. This just demonstrates that they are not making a serious effort to duplicate an analog display; they only make a serious effort to say they are.I do not even think DSOs *should* duplicate an analog display as there are better ways but as it is, they are not doing either.

author: nctnico
author_rank: Super Contributor
timestamp: July 01, 2018, 10:05:37 pm
content: Quote from: David Hess on July 01, 2018, 09:53:32 pmEven the Rigol DS1054Z has this feature according to the manual. Sorry but you are reallyhere. I can't imagine why a DSO wouldn't have delayed triggering.Edit: Delayed trigger also works on my MicSig TO1104

author: David Hess
author_rank: Super Contributor
timestamp: July 01, 2018, 10:22:06 pm
content: Quote from: nctnico on July 01, 2018, 10:05:37 pmThe Rigol DS1000Z series is what brought this issue to my attention. It is my prime example of a modern DSO which does not. Check the link I gave earlier which describes the sample rate falling as the time/div decreases.

author: nctnico
author_rank: Super Contributor
timestamp: July 01, 2018, 10:45:33 pm
content: I guess the DS1000Z is an exception then but I find it hard to understand why it can't do it because it is so simple to implement.

author: rf-loop
author_rank: Super Contributor
timestamp: July 02, 2018, 09:30:30 am
content: Quote from: David Hess on June 30, 2018, 05:13:02 pmHere is example with cheap Siglent SDS1104X-EIt allow trigger to be placed outside of the waveform record as can see in attached images.What is difficult here. Just very normal perhaps with most modern oscilloscopes.1pulse/s, pulse width 100ns and around 15ns rise and fall times and around 3V amplitude.Trigger normal and rising edge. Acquisition mode normal. Sinc iterpolation and display mode vectors.Trigger position far out from display and also far out from acquisition lenght.Acquisition length here is 14ms (14M memory) and sample speed 1GSa/sWhole 14M is between screen leaft and right border, no overlapp.image aThen just scope running with this 1s delayselected zoom and zoomed in so that pulse is well visible. It can zoom also more but it do not give any advantage for example pulse to pulse jitter measurements.I can tell that this scope is not suitable for characterize example GPS 1pps jitter. Scope own reference have too much jitter. (just for random readers thinking: 1us in 1s period is 1ppm what is far away what need if want really characterize good GPS 1pps jitter. We need far better. Here in zoomed window one time division is 50ppb from delay and scoppe own short time jitter is roughly around this class...not enough for this purpose. And scope can not use external reference clock)Also even my old ancient Hewlett-Packard boat anchor 545xx series DSO's can do it (even better - least amount of max delay is even more and due to better reference clock also jitter is less ).Note, both images are snap shots from live running scope "on the fly"

author: RoGeorge
author_rank: Super Contributor
timestamp: July 02, 2018, 11:46:07 am
content: Quote from: David Hess on July 01, 2018, 10:22:06 pmNot sure if I properly understood the complaint, but Rigol DS1054Z can do something very similar with delay triggering, and still keep the high sampling rate.Here is a video for a signal made out of 10ns pulses spaced half a second apart, and watched at 1 GSa/s at 1 second or 0.5 seconds after triggering. The video was made to show how phase noise can lead to jitter that accumulates with the distance in time between the triggering point and the observed point. As it can be seen, the sampling rate is kept at 1GSa/s all the time, and the delayed is varied to 0s, 1s and 0.5s (the number in the upper right corner of the display indicates the delay after trigger).

author: nctnico
author_rank: Super Contributor
timestamp: July 02, 2018, 01:49:49 pm
content: So it seems the DS1054Z can do delayed triggering.

author: emece67
author_rank: Frequent Contributor
timestamp: July 02, 2018, 01:50:12 pm
content: .

author: Fungus
author_rank: Super Contributor
timestamp: July 02, 2018, 02:16:48 pm
content: Quote from: nctnico on July 02, 2018, 01:49:49 pmYep. It's not a special thing you need to enable (which is maybe why it's not mentioned in the manual), you simply move the trigger point to the left and keep on going.There's an on-screen box dedicated to it (top-right, labelled 'D' for 'delay'). The farthest I could get it to go was 500s.(Update: It works, too. I left it there and stuff started appearing on screen after 8 minutes or so)The farthest I could get it to go at 1GS/s and full memory was 1 second. That's way outside the 24MSample memory but maybe not a massive delay in real terms. What delays can other 'scopes manage?

author: Fungus
author_rank: Super Contributor
timestamp: July 02, 2018, 03:24:18 pm
content: Quote from: rf-loop on July 02, 2018, 09:30:30 amIs one second the maximum delay on the Siglent, too?

author: nctnico
author_rank: Super Contributor
timestamp: July 02, 2018, 03:36:59 pm
content: I think I start to understand where the confusion is coming from. David Hess is looking for (delayed) B-trigger. This effectively means having 2 different time bases (time/div). On a DSO you can mimic that behaviour by using the zoom mode which will show the same signal using two differen time bases but the amount of time you can move left/right is indeed limited by the record length and sample rate. Another way around it would be using a reference trace at a long time/div setting and then trigger on a specific part of a signal using the delay and a much shorter time/div setting. On my GDS2204E I can use this trick to have traces with different time/div settings on screen at the same time. It allows to do cursor measurements on the reference trace taken at 500ms/s and do the same for the acquired trace at much shorter time/div settings. This however depends on how well the reference traces are implemented. I think this may not work on Keysight oscilloscopes because as far as my experience goes the references traces are just pixels on the screen.

author: Pete F
author_rank: Regular Contributor
timestamp: July 03, 2018, 01:59:53 am
content: Without wanting to OT the OT, thanks for the contributions on the questions I had.The bandwidth I feel I understand pretty well (better than some here it seems; oscilloscopes don't suddenly stop seeing inputs just because they've reached their specced bandwidth limit!), but didn't know if maybe the DSO situation is different to an analogue 'scope. It seems it's just the same so happy days there.It was the memory depth that was very confusing for somebody like myself trying to get my head around the modern DSO and my own particular use. This is an area I've never been exposed to, and while I understand the whole concept of the sampling etc, it's transferring the theory to my practical applications where without practical experience I wasn't sure of the effects of different memory sizes.The FFT could definitely be something that I would find useful if it's actually a serious tool and not just a bit of a gimmick, I suspect the latter. I used to have access to a spectrum analyser, but that was more for RF work anyway, but yes maybe it would be good. From what I have read it's not really suitable to serious audio work where THD is being chased etc, but hey if it's a function that's there, why not!"Where this becomes a problem, and this was discussed on these forums more than a year ago, is things like measuring jitter in a 1 pulse per second GPS signal. 20M points over 1 second is only 20MS/s yielding 50 nanosecond resolution which is worse than the jitter of many GPS 1 PPS signals."Ok I do have to ask, out of curiosity, why would you be measuring the jitter of a GPS signal? Many years ago my apprentice built a master clock oscillator for our workshop and we used the Omega signal as the phase master to drive the local clock. However I'm interested in why you'd be measuring that GPS jitter outside of navigation needs.I have no idea why somebody would think working on a stereo audio system requires 4 inputs, that makes no sense. In fact most of my work was done by probing with a single channel, and that put bread on the table for many years without the world spinning off its axis. I've never really had much (or any I can think of) need for more than 2 channels.While "more is better" in terms of bandwidth, I'm sometimes concerned that at the bottom end of the market (ie where I'm looking) models may be pushed beyond their real practical limits in order to provide better specs. In other words, a series of oscilloscopes, say 50, 100, 200 MHz. While the 200 MHz 'scope may indeed meet the -3db spec for its front end, the rest of the machine may not really be a 200 MHz oscilloscope and is just pushed up there because it looks good on paper. I don't know if that's a fact, but is definitely a concern. I typically find the middle of a manufacturer's product lineup tends to provide the best value, but that's hardly a hard and fast rule and simply a broad generalisation.It may well be that the final arbiter on the decision will simply be the local availability of a brand/machine. While most of the mentioned brands are available, I'm not interested in paying (literally) double the price for a local bricks 'n' mortar company to courier out a purchase, when I can get the same thing through a purely online retailer. That may however limit my options. At the end of the day it's not like this is a $100,000 decision. The difference one way or the other may be a few hundred dollars from one extreme to the other, and from the advice here it seems for my application it won't make all that much difference in any case. I'm very busy with work, so I'll probably just go with something I think looks like reasonable value and move on. I'm now very keen to have the opportunity to use a DRO, as has been mentioned by others they really are a powerful piece of kit.

author: tautech
author_rank: Super Contributor
timestamp: July 03, 2018, 02:36:33 am
content: Quote from: Pete F on July 03, 2018, 01:59:53 amIt's all about the ability to convert data points into an accurate representation of the signal, the more there are the less chance of interpolation inaccuracies. DSO's with good amounts of memory depth don't even need a vector display and can show a good replication from just the data points displayed.QuoteThis could be a concern if you ever go down this rabbit hole:https://www.eevblog.com/forum/metrology/an-advanced-question-sampling-an-oscillators-signal-for-analysis/QuoteYeah I get that but there's at least a couple of examples whyDifferential measurementsData protocol decoding.QuoteSorry to be unkind:The modern instrument that is part of a series is HW and/or SW BW limited, the many brands that are now BW cracked are proof of this.QuoteOnly you can make the decision to buy abroad and then risk possible substandard warranty support.Your money, your risk.

author: Pete F
author_rank: Regular Contributor
timestamp: July 03, 2018, 03:44:59 am
content: I buy a ton of stuff abroad ... well actually tonnes if a literal interpretation is madeI can honestly say I've had more hassles with local retailers/distributers than the foreign distributers. In my experience the Australian warranty is generally a joke, where the distributer will use all manner of BS technicalities to either claim it was my fault (hence no warranty) or little more than semantics to weasel out of the claim. Obviously that's not always the case, and I've had good experiences too, very good in some cases, but my experience is that's the exception rather than the rule. I wish that wasn't the case, but that's just been my life's experience. In both cases I consider the warranty zero on a product like this, hence that is how much the premium is I'd be prepared to pay. It's a disposable consumer product and nothing more.Quote from: tautech on July 03, 2018, 02:36:33 amYes I absolutely agree, there would be many occasions when somebody working in specific areas would want 4 (or many more channels), I wasn't one of them, but that was just me. But the person was specifically referring to the requirement for a 4 channel oscilloscope in order to work on stereo audio, and I'm afraid that's just complete crap.Just because the front end of an oscilloscope is capable of xxx MHz according to the definition of that, doesn't mean it is truly an xxx MHz in a practical sense. Whether they've got to that figure by hacking or by original spec. I have used a number of oscilloscopes where up around their specified bandwidth they were all but useless from a practical perspective. So no, it wasn't BS, and if you want to believe otherwise knock yourself out. This is one area where I've found there is a big difference between a high quality manufacturer and the bottom end of the market that I'm currently looking at. The quality manufacturers sell their equipment based on a fitness for purpose, and if it's sold as being capable of xyz, chances are that's what it will do. The manufacturers of cheap products know many people buy products on paper spec and will often grossly exaggerate their claims or use nonsense "specs" to try to win a supposed advantage over competitors. I have no idea if that's the case with these DSOs, but it certainly wouldn't surprise me if it was the case. Indeed I'd be more surprised if it wasn't.

author: tautech
author_rank: Super Contributor
timestamp: July 03, 2018, 08:07:29 am
content: Quote from: Pete F on July 03, 2018, 03:44:59 amI find that truly sad that you have experienced such bad support. In some way this forum is a good place to address such poor experiences, by naming and shaming !QuoteWith a complex waveform at near rated BW there's no doubt some scopes will be better than others but rated BW is only using a pure sine wave to where no more than 3 dB attenuation occurs. That's universal to all brands.QuoteThere's a poultice of info on all manner of models and brands right here in this forum that demonstrates what some DSO's are capable of and others aren't. You of course don't have any idea if the replies you get are from members who don't have a clue or really know there stuff.I've had a good # of CRO's in days gone by and when I got my first decent DSO (TDS2012B (was then)) and fixed up a couple of other Teks, TDS210 and TSD1002 I was then sold on DSO's and just knew they'd take over the hobbyist market before much longer.Shortly after I looked at Hantek and many others and kept looking for something better until a few years back I was offered Siglent.You surprise me when you state you consider a cheap DSO a throw away consumable and in this day and age I get that, however not in my book and marketplace experience and product reliability has shown me this is indeed not the case.For many of my customers a DSO is a big expense and the models I choose to market (not bottom of the barrel) are all dearer than the prices you've indicated previously and yet with all the scope experience you have I wonder why you've set your sights at real entry level equipment.I would urge you to set your sights higher.

author: Specmaster
author_rank: Super Contributor
timestamp: July 03, 2018, 09:48:35 am
content: Sitting reading through all of these postings you have been given loads of good advice but no one in my opinion seems have got it right. Having myself only been used to analogue scopes for many years , I have just acquired a really good combiscope that now gives me the best of both worlds and is perhaps the best way into the world of digital scopes as you chose which ever mode seems to be most effective for what you want to do at the time without a major investment.Personally if I was you I'd spend a little time on checking out what has gone wrong with your old scope and it is more than likely that simply checking the caps and replacing the bad ones would bring it back into life again and also spending a little more replacing all the caps would more than likely produce a scope that would once again be a reliable and useful tool on your bench and thus leaving the way forward to perhaps looking at and buying the best DSO that you can afford and then you would again have as mentioned above, the best of both worlds.

author: nctnico
author_rank: Super Contributor
timestamp: July 03, 2018, 09:49:59 am
content: Quote from: Pete F on July 03, 2018, 01:59:53 amVery precise time distribution is one of the applications to measure jitter on 1PPS outputs. There are lots of applications for this. For example having several A/D converters 10km apart and be able to timestamp their samples with less than a nanosecond uncertainty.QuoteYou don't have to use all channels on a 4 channel scope. Once you have the 2 extra channels you will start using them and it will be more convenient.

author: Fungus
author_rank: Super Contributor
timestamp: July 03, 2018, 10:47:50 am
content: Quote from: Pete F on July 03, 2018, 01:59:53 amTo measure many components of an audio system you need to look at thedifferencebetween input and output voltage, not the difference between input voltage and ground (for example).eg. Loudspeakers, the outputs of an amplifier.That means a single measurement needs two channels.In a stereo system you might want to look at both channels simultaneously - to make sure they're equal and electrically isolated. That's four channels.Or you might want to look at the input and output of a crossover circuit simultaneously on screen. That's four channels.Quote from: Pete F on July 03, 2018, 01:59:53 amSure, but that doesn't mean you can't do it much better.

author: Pete F
author_rank: Regular Contributor
timestamp: July 03, 2018, 10:52:59 am
content: Yes it is very sad that's my experience in Australia, and why I have no sympathy for the Australian retail chain when it comes to online shopping. Don't get me wrong, I'm not one of those people who picks the brains of a retailer and then goes off and buys it cheaper online. I don't have anything to do with them and do my own research, part of which is why I'm here, and am effectively invisible to the local retailers. As far as "naming and shaming", that's not appropriate as firstly my experiences are from many different sectors and secondly I have witnessed, first hand, the enthusiasm with which some companies will commence legal action for defamation to bully critical comments to silence, despite the fact they have no hope of winning the case. Others should seek their own legal advice if presented with this situation, however I believe one of the tenets of a defamation action is that as the defendant you are forced to defend the case. If you do not you will, by default, lose the case. In Australia we have no SLAPP legislation or equivalent. All very much OT and not something I want to get in to, but trust me when I say, again in my opinion, it's generally not worth going there. Take it up with the party, and if they continue to behave in a way you feel is inappropriate then vote with your feet. ... as I have done. That's my opinion and other's opinion may well be different.I can have a functional DSO landed on my desk for a little over A$300. Many people would spend that on a couple of nights out. Less than 3 tanks of fuel. Half of a weekend away ... shall I go on?One of what I consider an outright scam I have witnessed locally is that it is my responsibility to pay for a courier for the faulty product to and from the distributer. At the very least to them. So they've sold me something that has failed within "warranty" and I'm expected to pay to courier the product to them? On a $3-400 purchase that is a significant percentage of the price. Now whether some here think a $350 DSO is good or bad is not the point, that is their opinion and thousands of people have coped just fine with their buying decision. Yes if I was you I'd "set my sights higher" and buy a more expensive oscilloscope. However I'm not you, I'm meSo I can be equally aghast as to why somebody would want to buy something that is far more expensive than another one that will be perfectly adequate for the job. I've said many times that this is no longer my occupation and quite possibly won't get much use. It's also not especially important to me. I do want to ensure the purchase will indeed do the job, but I think pretty much anything will.While I'm not a wealthy person, nor am I destitute! If this was an important thing for me I would be quite happy to spend a significant amount of money. But it's not, so I won't!I'm surprised that some people have difficulty in empathising with other people's perspective and appreciating that what may be important to them may not be important to others.As far as jitter, yes I appreciate what may be a theoretical use, I was involved with this area in regard to jitter in clocks, hence why I asked. But I wonder how many people ACTUALLY have a need to date stamp in this case an A/D converter to "nanosecond accuracy" off a GPS signal.If of interest to where I'm at with all this, I'm currently considering a Siglent SDS1202X-E. The irony of that is despite all I've said above, it's waaay over specced for basic audio/PS work I mentioned. It's also from an Australian retailer, one in fact I just bought another piece of test equipment from. Whether that eventuates we'll have to see, but I'd like to get something here before much longer. Despite being seen as an odd candidate considering my comments, I always like to keep an open mind and try not to be biased one way or the other. One of the significant considerations was the fact that many of the models popular with members here are actually quite old models. They may well have been updated, but the "bones" still seem quite ancient to me. The Siglent is a relatively new design, offers serial decodng, and I was doing some I2C work a while back where that may have been handy (probably not, but hey it's available), it has relatively generous memory for an oscilloscope in that price range, etc etc etc We'll see. The bottom line is the most basic model will cost me around A$320. The 1202 will be around twice the price. However in real terms the difference is as above; 3 tanks of fuel etc. I take the train and am a general tight-wad with money, so don't begrudge spending money ifI can see the value in doing so.As I mentioned I have been around the block a few times here and had relatively good equipment available to me, that included 4 channel oscilloscopes. I didn't use 4 channels then so see no reason why I would suddenly see a need to have one now.

author: Pete F
author_rank: Regular Contributor
timestamp: July 03, 2018, 11:08:17 am
content: Quote from: Fungus on July 03, 2018, 10:47:50 amI don't mean to be rude, but that is complete and utter crap. My career began in high-end audio, and I was involved in the area both professionally and personally for quite some time. While I went off into other areas of the industry and eventually left the industry professionally, I would sometimes revisit that area very seriously purely for my own interest. I expect that interest to continue to ebb and flow. There is almost never an instance where there is a "need" (to quote you) to monitor both channels in the manner you describe, and if so then by your logic what would you do if presented with a 5.1 or, God forbid, a 7.1 system, look for a 16 channel oscilloscope? Having made my living from this, I can assure you that 2 channels was more than adequate, and any more almost invariably sat there unused. If you want to use 4 channels then that's great, but your claim of it being a requirement is utter nonsense.

author: bd139
author_rank: Super Contributor
timestamp: July 03, 2018, 11:14:11 am
content: If you want to compare the phase relationship of two channels with differential outputs then it’s reasonable. I’ve done that and my requirements are generally noddy in that space.

author: Pete F
author_rank: Regular Contributor
timestamp: July 03, 2018, 11:22:20 am
content: Quote from: bd139 on July 03, 2018, 11:14:11 amGreat, then you best buy a 4 channel oscilloscope. One of those 12 bit ones maybe?

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 03, 2018, 11:27:53 am
content: I'm currently fixing this Delco and I'm with Pete, you don't need four channels at all.

author: tautech
author_rank: Super Contributor
timestamp: July 03, 2018, 11:43:41 am
content: Quote from: GeorgeOfTheJungle on July 03, 2018, 11:27:53 amI'm fairly sure Pete has the skills to fix most anything with a 2 ch scope and he's got enough info from replies to now make a somewhat informed decision.Good on him for coming aboard and sorting out the bits he was unsure of.Good luck Pete and give us an update when you've got your head around this new fangled DSO thing you're gunna get.

author: Pete F
author_rank: Regular Contributor
timestamp: July 03, 2018, 11:50:54 am
content: I had hundreds, maybe even thousands, of units pass across my bench and seriously can't think of a time where I really hankered after 4 channels, even when they were right there in front of me. Maybe if doing development and design work it could be useful, but even then not essential. There's obviously a world of difference between somebody doing this professionally where time is money, and somebody dicking around in their home for a bit of a laugh and a giggle. There is no way I'd want to waste that time, when quickly probing through the circuit with a single channel is almost always all that was required.Yes but it's a different world now "tautech", and while I can understand those who suggest sticking with an old school CRO, I can see these DSO are just incredible in what they can do. It's probably old news for you blokes, but for somebody like myself I find it absolutely incredible the power that is available at what at the end of the day is such an incredibly cheap price. It's an exciting world now that's for sure.

author: Specmaster
author_rank: Super Contributor
timestamp: July 03, 2018, 05:28:58 pm
content: I've never actually needed 4 channels but if there was an option of having 4 channels for not a lot more, I'd certainly take that opportunity, I have a 4 channel CRO and have used all 4 at the same time but I could have managed with 2 but 4 does give that flexibility if required.

author: rstofer
author_rank: Super Contributor
timestamp: July 03, 2018, 08:04:09 pm
content: Thanks for the previous discussion on Delayed Trigger on the DS1054Z - it works great! I knew I could shift the trigger point on the screen but I had never needed to shift beyond the left edge. Today I did and it works well!Back to the original topic...

author: tautech
author_rank: Super Contributor
timestamp: July 03, 2018, 10:15:12 pm
content: Hey Pete. When you have a new scope it might be worth wandering over to this tread and looking at what Vince did to repair his 2215:https://www.eevblog.com/forum/repair/tektronix-2215-scope-repair/

author: Pete F
author_rank: Regular Contributor
timestamp: July 03, 2018, 11:02:42 pm
content: Quote from: tautech on July 03, 2018, 10:15:12 pmCheers for that mate, I'll read through that while having my breakfast; coffee and Australian Manuka honeyThe SDS1202X-E is currently nil stock, so I'll poke around and see if I can find one elsewhere, otherwise buy a Hantek DSO5202BM if I can't find the Siglent. This is precisely the sort of thing that pisses me off about the Australian retail scene. Distributers get exclusive rights to a brand and can then do pretty much what they like (including the good ol' "Australian Premium").On a positive note, I did buy one of Dave's multimeters last night. I never looked at why mine started going a bit flaky, and don't much care. Once a piece of test or measurement equipment starts to do something other than it should I have no confidence in it and unless that problem can be sorted with 100% confidence it's gone. Multimeters aren't that expensive in the grand scheme of things and mine is old in any case. I was going to buy a Fluke (and still may) but Dave's 225 will be perfect for now.

author: tautech
author_rank: Super Contributor
timestamp: July 03, 2018, 11:16:01 pm
content: Quote from: Pete F on July 03, 2018, 11:02:42 pmThe jury's still out on that soback at ya !QuoteReally ? I went through to checkout and there was no indication that was so.https://www.triotest.com.au/store/siglent-oscilloscopes/1248-siglent-sds1202x-e-digital-oscilloscope-200mhz-2-channel-1gss-with-serial-decode.htmlProbably pay to give Trio a bell.Quote

author: Pete F
author_rank: Regular Contributor
timestamp: July 04, 2018, 12:02:33 am
content: I did contact them and that's what they said. Another couple of weeks ... apparently. The issue is they're already later than they were supposed to be, so who's to say they won't be later still? Go through their ebay store and you'll see their note.

author: tautech
author_rank: Super Contributor
timestamp: July 04, 2018, 12:35:58 am
content: Quote from: Pete F on July 04, 2018, 12:02:33 amQuite simply it's due to production pressures that stem from recent demand on a range of Siglent products.I've got SDS1202X-E and I'm waiting too, but for other models.

author: David Hess
author_rank: Super Contributor
timestamp: July 04, 2018, 12:41:21 am
content: Quote from: nctnico on July 01, 2018, 10:45:33 pmI wonder the same thing every time it comes up.Quote from: nctnico on July 02, 2018, 01:49:49 pmNo, the trigger delay function can sort of replace trigger after delay which is useful in its own way but it is not the same thing as "runs after" delayed trigger.Quote from: nctnico on July 02, 2018, 03:36:59 pmOddly enough there were some weird analog oscilloscopes which provided a delayed A sweep. The 2215 being replaced by Pete F has a delayed B sweep but the 2213, which is its lessor brother, has a delayed A sweep which is what simple DSOs should be providing because as you point out, it is so simple. It was pretty complicated for the 2213 though so I do not understand what market Tektronix was thinking of. Maybe it was a way for them to distinguish the 22xx series from earlier oscilloscopes although they dropped this function in the later single timebase 2225 and the single timebase 22xx DSOs never had it.I never cared much about the B trigger function until I started working with switching power supplies. (1) Set the A trigger to trigger off of the switching waveform, delay to reverse recovery, and then set the B trigger to trigger off of the reverse recovery waveform which would otherwise be difficult to pick out. Now you can view the reverse recovery in real time at any time/div with no jitter.I remember long ago before I understood trigger after delay cobbling together a little circuit to select the rectifier recovery so I could trigger on just it.(1) Also mildly useful to track down power line "buzz" in linear power supplies used for audio applications. Check the reverse recovery of the slow power line rectifier diodes just after the peak of the power line cycle. Place a 220 picofarad capacitor directly across each rectifier diode to fix.Quote from: Pete F on July 03, 2018, 01:59:53 amThe time acolytes have great interest in measuring jitter of the 1 pulse per second timing output available from GPS receivers. This signal is almost always synchronous to the GPS receiver clock which is asynchronous to GPS time itself producing jitter equal to the clock period. This jitter limits precision of a GPS disciplined oscillator over medium timescales unless it is corrected.QuoteI might want 4 channels so I could use them in pairs to make 2 differential measurements without expensive differential probes. Otherwise 2 channels (and an external trigger input) are plenty for almost all applications.4 channels are also needed to fully decode SPI although as I recall, one of the recent budget DSOs can do it using 2 channels with the external trigger input as a 3rd channel.QuoteProbing also becomes more difficult above 100 MHz and 200 MHz is as high as it is reasonable to still use a ground lead and that is marginal. For an analog oscilloscope, high bandwidth has another benefit; high bandwidth analog oscilloscopes use higher acceleration voltages producing brighter and sharper displays. For instance a Tektronix 350 MHz 485 with a CRT acceleration of 21 kilovolts has a better display (albeit smaller) than a 100 MHz 22xx series with a CRT acceleration of 14 kilovolts.There is a use however for a high bandwidth oscilloscope in audio applications; it is very handy for detecting spurious oscillations or "snivets". I wish there was some way to link a video here without embedding it but as Emperor Joseph II would say, "Well, there it is."

author: tautech
author_rank: Super Contributor
timestamp: July 04, 2018, 01:08:49 am
content: Quote from: David Hess on July 04, 2018, 12:41:21 amNot at all hard with a DSO with a Zoom mode.Trigger on whatever you like at a slow timebase setting and then Pan to the area of interest in the Zoom'ed window and at whatever timebase setting you want/need.It's just done different but the result is still the same.Much like in the 2nd screenshot in reply #60 from rf-loop.

author: David Hess
author_rank: Super Contributor
timestamp: July 04, 2018, 01:22:08 am
content: Quote from: tautech on July 04, 2018, 01:08:49 amOh, I have done it that way with DSOs and most analog oscilloscopes can do that without delayed sweep as well. Some analog oscilloscopes like the 2225 even have extra functions to do it this way without a delay function. The difference is that if you use trigger after delay, all jitter between the switching waveform and recovery is removed.

author: tautech
author_rank: Super Contributor
timestamp: July 04, 2018, 01:30:06 am
content: Quote from: David Hess on July 04, 2018, 01:22:08 amThe point is I mentioned 'like' and I'm sorry I wasn't entirely clear ......meaning there'd be no need to use any Trigger delay. None !You'd have 1/2 the display with the pre-trigger record and the other 1/2 with the post-trigger and it's all available by panning within the Zoom'ed window.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: July 04, 2018, 02:34:06 am
content: I'll try not to add confusion here.There is only one reason I can think of for lots of bandwidth when doing the kind of work you describe. I have on a couple of occasions found problems in audio gear that were the result of RF oscillations which then upset bias points, caused heating or even failure of transistors and the like. Things like this are easier to find and correct when you can see the birdies. Whether this is common enough for you to invest in is hard to say. As I said I have run into in a small number of cases. But I don't do that much so it might be a single digit percentage. Whether you care about this is up to you.For straight audio work, multiple channels aren't too useful, but as newer receivers often have lots of logic for switching inputs/audio presets/speaker protection/etc. I have found the ability to watch multiple signals at once useful. This surrounding logic has been the source of failure more often than the straight audio chain in my experience.Something no one has mentioned (except for disparaging remarks about some ones disfavored brand) is user interface. All DSOs I have used are really different in this area from classic analog scopes as they try to pile lots of functions onto the number of knobs they can cram onto a front panel. UIs are a very personal thing and it would be worth quite a bit of effort to find local dealers or owners of equipment you are thinking of to see how you deal with it. I can't really say that one or another is bad, but will say that I find some more congenial to me than others. The ones I find congenial are not necessarily the ones that are popular with others.Finally, for the limited amount of use you are projecting you might actually find one of the USB scopes appealing. Again, I have no specific recommendations, but many of them have plenty of bandwidth for audio work and the small size is appealing. No matter how large your lab, the instruments you can use at once are limited by the length of your arms and small instruments rule in this area. If you will already have a laptop or PC in your mix

author: Pete F
author_rank: Regular Contributor
timestamp: July 04, 2018, 03:15:22 am
content: Quote from: David Hess on July 04, 2018, 12:41:21 amYes I know what jitter is, it's an issue with all oscillators. But the question was how many people are ACTUALLY doing these sort of measurements where they are "time stamping" signals from ADCs and the jitter from the GPS reference is a real issue. This was in fact the claim made."Very precise time distribution is one of the applications to measure jitter on 1PPS outputs. There are lots of applications for this. For example having several A/D converters 10km apart and be able to timestamp their samples with less than a nanosecond uncertainty."Unless the person happens to be the lead at the Large Hadron Collider I'll be polite and say that I find the assertion that jitter errors in the above scenario are a real life problem "difficult to believe"I'm taking a look at the 2215 in between about a billion other things and have to laugh at the irony. The fault would be a perfect opportunity for a DSO as the PSU is starting but then blowing the fuse. I'd love to capture that start up. I'd like a DSO to repair an oscilloscope that I'm replacing with a DSO so I can then throw out the repaired oscilloscope. Something is definitely wrong with that picture

author: Fungus
author_rank: Super Contributor
timestamp: July 04, 2018, 09:36:08 am
content: Quote from: Pete F on July 03, 2018, 11:08:17 amI'm fairly certain I said "might", not "need" when referring to four channels.The only time I said "need" was when referring to two-channel, differential measurements. Loudspeakers, etc., are inherently differential devices. A differential measurement is the only way to measure the signal correctly when you get to that point in the circuit.If you're doing it differently then I'm going to be blunt: You can do it better.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 04, 2018, 09:41:02 am
content: Quote from: Fungus on July 04, 2018, 09:36:08 amIn that Delco in the picture, above, the loudspeakers' - are connected to earth/chassis.

author: Fungus
author_rank: Super Contributor
timestamp: July 04, 2018, 09:43:16 am
content: Quote from: GeorgeOfTheJungle on July 04, 2018, 09:41:02 amFair enough, but I don't think I've every seen even the most rabid audiophool grounding the negative terminal of his loudspeakers.("it's to avoid ground loops!")

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 04, 2018, 09:45:50 am
content: Actually, the sound of that Delco is quite good!

author: bd139
author_rank: Super Contributor
timestamp: July 04, 2018, 10:01:14 am
content: Fungus is right. This is pretty much EE 101 really. Being blunt there too.Most basic/classic hifi amps have ground referenced output. That’s only because there is a reasonable voltage headroom and dual supply available due to the transformer sitting there. Car audio amps, studio stuff, anything above class C, not necessarily. Also sources. Think balanced line (XLR etc). Things are heading rapidly in this direction because of supply voltage limitations and signal integrity requirements.How do you pull a differential signal off a balanced line or output? Math (A-B). Bye bye both channels on your scope. You can’t look at them independently as the common mode signal is present which might have more noise than signal on it. Good luck with that one.So if you’re debugging single ended to differential amp or the other way round, which is something I tend to have to do occasionally, you need at least three channels or two scopes. Plus sync off your signal source. Four channels takes up a hell of a lot less bench space than two scopes.I’d rather have a four channel scope these days. Less head scratching. Time is money or time away from something else so screw it and go four channels.Hell even fixing my old 475 analogue scope was pleasurable using a 4 channel scope to debug the trace unblanking and amplifiers (also differential output!)

author: Fungus
author_rank: Super Contributor
timestamp: July 04, 2018, 10:02:30 am
content: Quote from: GeorgeOfTheJungle on July 04, 2018, 09:45:50 amShould I be using half-inch copper pipe to ground my loudspeakers or is 8-guage wire good enough?

author: rf-loop
author_rank: Super Contributor
timestamp: July 04, 2018, 10:15:54 am
content: Quote from: David Hess on July 04, 2018, 12:41:21 amI have done it several times. Never even thinked to use any kind if oscilloscope trigger delay for it. When I have old times done these things I have many old Tektronix 7000 series analog Rolls-Royces with couple of plug'ins including different time bases with normal simple delay up to trig after delay after delayed trig. One Tek have even real independent beams and both beams have dual timebases with delayed trigs. Of course after then there was also more low grade Tek's starting from some older and many 2000 series analog scopes. With this and that delayded time bases. Also some more or less boat anchor DSO's was under and over tables.Dual independent timebases A and B and Trig B after delay after trig A is rare in cheap DSO'sBut then...When I come to 1pps jitter measurements it was never even in mind even one half of second that I use oscilloscope delay after trigger or trig and delayed sub trig and so on for this purpose.Even simplest cheap DSO can do it without any kind of delays after trig or dual time base with this and that delayed things.In any case result quality depends trigger delay time jitter + trigger itself jitter.Result quality is depending scope itself timing quality.But, it is many times more easy to trust some known external reference what have some known jitter (all have) or just so much better that no need think.Here in very simple example image is 1pps (yellow) and 10MHz very good reference with quite low jitter and drift in observation time. Just do simple things using simple methods. Here I do not need think so much how is possible scope own jitter. THis result can easy trust (enough).Of course I can use 1s delay after trig but then I need know how much jitter this 1s delay may have. With simple xtal clocked scope... this jitter is so huge that for this kind of measurements using scope delay alone is just garbage collections, waste of time and even more crap if we go to old analog sweep timing scopes (only reliable method is compare SUT and known reference signal.What scope have reference clock quality what is needed here if use 1s delay time. If then need use external reference for accuracy it can also use with cheapest DSO. Even with scope what have external reference input I will not use it for this purpose but connect reference to other input channel and 1pps to other channel and simply compare and I feel I can trust result much better.Why make simple things complex.And as can see it also do not need long memory.14 sample points memory is enough for this.And in this case, in history buffer I can look also every single acquisition if I'm interested to look ecah one separately.So its is how we do things. Some need complex things for simplest things and many times result may be then "reliable looks like" complex garbage.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 04, 2018, 10:35:46 am
content: Quote from: Fungus on July 04, 2018, 10:02:30 amOnly oxygen free copper-silver alloy.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 04, 2018, 10:49:45 am
content: Yeah, 3 channels is better than 2, 4 is better yet, etc. But the point is you don't need them as in: two is enough to do it perfectly and comfortably. Perhaps the things 4 channels advocates are saying they want to look at are not what you really need to look at to fix these things. For example, you don't need to peek at the two outputs at once. Another one: you can look first at speaker + then at speaker -, there's no need to look at both at once. Etc.

author: bd139
author_rank: Super Contributor
timestamp: July 04, 2018, 11:07:03 am
content: If it's a differential output, you might not be able to see the differential signal due to the common mode signal being large. So no that isn't the case.Even my shitty little £20 car head unit has differential outputs.

author: Pete F
author_rank: Regular Contributor
timestamp: July 04, 2018, 11:47:02 am
content: I highlighted the relevant bit you forgot you said."That's a point worth mentioning: To look at amplifier outputs, etc. youneedto connecta pair of probes and look at the difference between them. For stereothat means a four-channel oscilloscope."Quote from: bd139 on July 04, 2018, 11:07:03 amQuote from: Fungus on July 04, 2018, 09:36:08 amWhile you two guys were doing this "occasionally" and pontificating about how the pros could "do it better", I was earning my living from it and can assure you, you are talking out your clacker! All due (blunt) respect of courseLike I said, if you're designing or developing audio components, then sure, you'll probably want as many 'scope channels as you can get as you'll be tweaking things. However if you're repairing and fault finding faulty systems you barely need 2 channels, and talk about faults causing common-mode faults that can't be otherwise easily seen with a standard 2 channel oscilloscope is frankly ridiculous.

author: Pete F
author_rank: Regular Contributor
timestamp: July 04, 2018, 11:54:03 am
content: To get this thread back from theoretical Fantasy-Land to the topic. I do like the Siglent SDS1202X-E however it's not available for the moment. I found the fault with the 2215 but will need to order the part, no idea how long that will take. It seems to me the SDS1202X-E has some features that aren't found on other oscilloscopes at the same price range (eg serial decoding standard, deep memory, etc). Is that an accurate conclusion or are there others that have exactly the same features? In relation to the thread topic, it's 200 MHz and 14 M memory from memory.Cheers!

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 04, 2018, 12:43:26 pm
content: They know very well that to see a differential signal you only need one channel not four. And if you can float the DUT thingy you don't even need to float the scope's GND.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 04, 2018, 01:06:56 pm
content: Quote from: Pete F on July 04, 2018, 11:54:03 amAdmittedly, those look good on paper, so I bought one but had to return it because it couldn't decode properly at low sweep speeds. Siglent came with a FW update that "fixed" the problem I was having: their solution: disable decoding at low sweep speeds. Huh.Of the el cheapo brands I've tried, I only keep the hantek 5072p, it's a wonderful cheap scope, IMHO!

author: rf-loop
author_rank: Super Contributor
timestamp: July 04, 2018, 02:34:56 pm
content: Quote from: GeorgeOfTheJungle on July 04, 2018, 01:06:56 pmI have not available 1202XE now but using 1104XEjust running 10s/div UART decode. 300baud, bit, 1 stop, no parityBut, limiting factor is decode buffer length.In this case with continuous data stream record acquistion length is 140s. But it can decode "only" 100s what include 3000 bytes (Full duplex both Tx and Rx have 3000). But I think it can say that 10s/div is somehow "slow sweep speed".like example here: (note, decode table time is related to trigger time position)

author: David Hess
author_rank: Super Contributor
timestamp: July 04, 2018, 03:59:09 pm
content: Quote from: rf-loop on July 04, 2018, 10:15:54 amA time interval counter would be a better choice for this measurement but they are less common than oscilloscopes and older ones do not provide any statistical information.Tektronix made a special plug-in, the 7D11 digital delay, to allow the 7000 series mainframes to make exactly this sort of measurement.I used to use an oscilloscope to make this measurement all the time when doing embedded programming to measure the latency and execution time of interrupt service routines and for profiling. The histogram display produced by an oscilloscope can be very enlightening.QuoteThe problem as I outlined is that some DSOs cannot do it even though they should be able to. The cheap Rigols cannot delay past the acquisition record so a slower time/div has to be used to capture the second pulse limiting the sample resolution.QuoteIn this case it is not the jitter of an oscillator which is being measured so it is not one oscillator versus another oscillator. It is the asynchronous products of two oscillators, the GPS receiver clock and GPS time, being measured so even a mediocre oscilloscope sample clock is sufficient. An analog oscilloscope would need some help like with the 7D11 digital delay mentioned above or a DD501.This is the "hanging bridges" issue with GPSDOs. When I was using my best time interval counter to make this measurement (1 nanosecond), I could read the outside temperature which affected the GPS receiver clock from the jitter.Quote from: Pete F on July 04, 2018, 03:15:22 amThat is a common issue with repairing analog oscilloscopes which power supply problems. Digital storage oscilloscopes, even low performance ones, are particularly useful in diagnosing power supply startup problems. Below is a photograph of my 2232 and 2440 DSOs measuring a couple of signals from my working 7904 switching power supply during startup. Two things of note are the relatively low noise in the 2440 display despite peak detection and full bandwidth and even more so, the absence of noise in the second trace of the 2232 display despite peak detection and full bandwidth. I did not notice the 2232 issue at the time or I would have made a second capture showing exactly what witchcraft is going on there.

author: Fungus
author_rank: Super Contributor
timestamp: July 04, 2018, 05:28:54 pm
content: Quote from: David Hess on July 04, 2018, 03:59:09 pmYes they can. As shown earlier I can set a 1s delay at any sample rate and up to 500s at lower sample rates.One second is 40x the length of the buffer at the maximum 1GSa/sec.

author: wpwrak
author_rank: Regular Contributor
timestamp: July 04, 2018, 09:48:42 pm
content: One warning about the SDS1202X-E: there are some features you may find interesting Siglent only put in their 4-channel models, e.g., remote control from a Web browser. (And, judging from videos posted here, that Web interface seems to be very well implemented, with satisfyingly fast waveform updates.)Whether having four channels would be a real benefit depends also on what sort of digital work you expect. You can debug I2C with two channels, but already SPI is painful. And many "analog" circuits have digital components these days. I have an ancient Rigol DS1102CD and every once in a while I found myself forced to use the - abysmal (in this particular model) - "logic analyzer", just to be able to see what's happening on some bus. With four analog channels, that may not have been necessary.I'm also planning on buying a new scope and based on specs and research people in this forum have been doing, I'd also consider the Siglent SDS1000X-E series today's best overall performers. Go much lower and you may encounter unpleasant surprises. Go higher and prices skyrocket. I also appreciate that Siglent include protocol decoders, instead of either making them an - IMHO - grossly overpriced option or tempting customers to do something they ought to find unethical. Besides, having a bit of headroom never hurts.- Werner

author: Pete F
author_rank: Regular Contributor
timestamp: July 04, 2018, 11:42:12 pm
content: Thanks to the recent few contributors, that's interesting stuff. The Tek 2215 was pretty easy to diagnose and the part should be here, well, probably not until Monday now. So hopefully I'll get that back. It still has some other issues that make it more difficult to use, but hopefully it will at least provide something.The comment about 4 channels and diagnosing digital is interesting, and not something I would have considered. While I studied digital in college it's not something I really enjoyed (ironically I was much later offered a job as a Field Service Engineer with Digital DEC at one stage of my career though, go figure!). However with digital of one form or another now being embedded in even the most mundane of applications, it's certainly a good point. However having pushed the budget from an entry level Hantek DSO5072P (which I'm quite sure would do the job for me perfectly well) to a Siglent SDS1202X-E (at twice the price), I'm not going to push it any further. I can't imagine myself ever wanting to control this by web browser etc.

author: wpwrak
author_rank: Regular Contributor
timestamp: July 05, 2018, 02:19:22 am
content: Quote from: Pete F on July 04, 2018, 11:42:12 pmI was thinking of the 1104X-E, which should be "only" about 30% more expensive than the 1202X-E. The 1204X-E would cost significantly more, almost twice the price of the 1202X-E, but it seems that you should be fine with 100 MHz bandwidth anyway. Besides, the 1104X-E can apparently be "hacked" to support 200 MHz (which may or may not yield the same performance as a model sold as supporting 200 MHz, may or may not work in the future, and so on.)Access from the PC should be convenient if the PC controls other parts of the system and isn't right on your bench. (E.g., when examining a configuration change.) Maybe someone with hands-on experience with the two scopes could explain better whether it's a worthwhile feature or just a gimmick. (Like WiFi dongle support, which is also limited to 4-channel models. Signal generator and LA options, and Bode plots (requires a signal generator) are also limited to 4-channel models, but I don't know if you'd care about any of that.)- Werner

author: Pete F
author_rank: Regular Contributor
timestamp: July 05, 2018, 04:02:15 am
content: Sorry I didn't really understand what you were getting at there Werner. Like I said, the price of the 1202X-E is about as much money as I want to spend on this. No more, as it's already much more than I originally anticipated. So I'm not sure quite what you're suggesting.There is absolutely zero chance I will be examining a piece of equipment that isn't sitting right in front of me on my bench. Zero! I'm sure that feature would be handy for some people, but it's completely irrelevant for my application.The parts for the 2215 arrived already, absolutely incredible service from RS Components I have to say. I used to use them years ago and they were always good, however I order the mosfets after business hours closing last night, and here they are sitting on my desk by lunchtime the next day, free postage too. Unbelievable!!!!

author: tautech
author_rank: Super Contributor
timestamp: July 05, 2018, 07:53:28 am
content: Quote from: wpwrak on July 05, 2018, 02:19:22 amFor some it's no gimmick but a very useful feature, your requirements may vary.The webserver offers not just remote control but a way to export the imagery onto other devices easily whereas in many more expensive DSO's that might have HDMI or VGA that only offer the display imagery to another visual device.But of course it's all about 'need'.Using the WiFi dongle you can access the webserver from another WiFi device such as a tablet, laptop or even a smart phone where if you wanted you can grab a screenshot and email it or text it to another.....all wireless !We keep finding ways to use it.Here's a crappy vid I did on projecting the display wireless to a laptop connected to an 18" monitor but it could've easily been a big screen projector.https://youtu.be/W30AqcDQL18

author: Specmaster
author_rank: Super Contributor
timestamp: July 05, 2018, 07:57:44 am
content: Your link seems to be dead?

author: rsjsouza
author_rank: Super Contributor
timestamp: July 05, 2018, 10:18:35 pm
content: Based on your requirements, your price point and on the feedback others have been providing on modern entry-level oscilloscopes, I think the Siglent SDS1202X-E is your best option. It is a modern architecture, it works reasonably well (I played with it just for a brief time) and quite compact. One caveat: it may not be as durable (no track record yet) and certainly not as repairable as your Tek, but that is par for the course in such highly integrated test equipment.I couldn't help but notice you used a Kenwood oscilloscope; I still have a CS4025 that is incredibly basic but it is so easy to operate and such workhorse that I keep coming back to it (I confess I tried to pass it along a number of times, but never had the courage to actually do it).

author: Pete F
author_rank: Regular Contributor
timestamp: July 18, 2018, 04:12:11 am
content: I can't recall if the Kenwood is the same model as I had, but yes it was a no-frills but extremely well designed oscilloscope that always did precisely what it said on the packet.To close the book on this whole affair, I finished up buying the Siglent SDS 1202X-E and am quite happy with it. The build quality as as good as one would expect and it seems to operate well. It's certainly not as intuitive to use as a basic analogue oscilloscope and I often find myself staring at it trying to recall basic functions that would be immediately obvious on any analogue 'scope. Obviously with more experience with it I'll remember the functions more easily, however they still require far more keystrokes compared to simply flicking a switch in most cases on an analogue machine. The light weight of the more modern oscilloscopes also makes them a bit of a PIA for constant use and selecting keys. I think if I was still doing this professionally I would probably prefer an analogue oscilloscope for general signal tracing, fault finding, etc. I've seen others refer to maintaining and using the two types of oscilloscope and I couldn't understand why, but now see that the two types really compliment each other rather than being a substitute. Having found the fault with the Tek 2215 I will definitely fix it and keep it as an alternative. Nevertheless for somebody just starting out and only having one oscilloscope, something like the SDS 1202-E would be ideal from what I've seen.

author: Specmaster
author_rank: Super Contributor
timestamp: July 18, 2018, 06:59:40 am
content: Quote from: Pete F on July 18, 2018, 04:12:11 amYes, analogue scopes are easier to use because of their rotary switches, toggle and stay put pushbuttons, you can instantly see what the scope is set at make adjustments. Digital ones controls cannot give you the same visual feedback because it's all hidden behind many layers of on screen menus. This is one reason why so many people advise noobs to get a basic analogue one first and then add an digital later after the basic functions are learnt.They both have their place on a modern electronics bench IMO I personally have 2 analogue and 1 CombiScope on mine.

author: nctnico
author_rank: Super Contributor
timestamp: July 18, 2018, 08:25:52 am
content: Quote from: Pete F on July 18, 2018, 04:12:11 amThis can be a limitation of the user interface on the Siglent. There are many other DSOs with complicated or simple user interfaces.

author: Pete F
author_rank: Regular Contributor
timestamp: July 18, 2018, 11:05:24 am
content: Quote from: nctnico on July 18, 2018, 08:25:52 amNo it has nothing to do with the user interface in this case. "Specmaster" nailed it; there are many layers of functionality on a modern DSO, and the more capable, the more layers there will be. Contrast that to a conventional analogue oscilloscope and all the functions have their own switch/knob, with at worst a requirement to possibly pull a knob to get another function. If all the functions had their own knob/button/switch the DSO would finish up looking like the mixing console at Abbey Road Studios!That's just the nature of the beast. I'm sure some brands are also easier to use than others however.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 18, 2018, 11:48:53 am
content: Exactly this. The soft button paradigm dissociates the mechanical from the functional, aggregating functions formerly performed by precious levers, switches and potentiometers of the user's interface.If you are comparing different DSOs, then the judgment of easeness and intuitiveness is quite valid. If you are coming from a CRO, all modern DSO interfaces will seem unintuitive.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 18, 2018, 12:02:50 pm
content: Case in point: it takes a single push of a button to recall a waveform in a tek 2232: MEMORY#, and it takes two to save it: SAVE + MEMORY#. In a modern DSO you've got to go quite deep into submenus to achieve the same, it's so cumbersome that often you simply end up not using waveforms.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: July 18, 2018, 12:06:10 pm
content: Quote from: Fungus on June 30, 2018, 12:25:27 pmThis seems a bit of a backwards statement. The 'MHz' (or GHz) in the rating is the 3 dB bandwidth of the system, and thus haseverythingto do with the signal you are looking at. A 1 MHz clock is not a signal with a 1 MHz frequency. Perhaps you are trying to put this into terms for beginners, who might indeed mix up the frequency domain thinking in pure (co)sines, but saying the MHz on the badge is not related will only confuse them more, I think.You say ''rise time'' is a better measurement, but I disagree that this is true. I could care less about risetime in my applications. I care about Bandwidth - up to what frequency can I display waveforms. Sure, in digital applications the rise time may be easier to relate to the signals you are looking at, but this is not universally the case.

author: Fungus
author_rank: Super Contributor
timestamp: July 18, 2018, 12:35:20 pm
content: Quote from: rsjsouza on July 18, 2018, 11:48:53 amIt's not that they're "unintuitive", it's that they'd look likethisif they had a button for every function and a potentiometer for every adjustment:The features you use most are usually on hand or one (maybe two) buttons away.Most people now don't "come from a CRO" anyway so they don't ever see this. The questions they ask are more about all the things it can do.Quote from: GeorgeOfTheJungle on July 18, 2018, 12:02:50 pmBut a $400 DSO can save multiple waveforms it to a USB stick so you can recall them later (and even email them to somebody on the other side of the world so they can load them into their 'scope and see them over there).Plus you show a waveform on screen and still have multiple channels left over to overlay on top of it.Functionality-wise, your old Tek is very limited, that's why it can have a simple interface.

author: Pete F
author_rank: Regular Contributor
timestamp: July 18, 2018, 12:50:46 pm
content: The bandwidth of an oscilloscope has a very specific definition, and it is completely false to believe that an oscilloscope of a specific bandwidth can only display sine wave signals to that bandwidth. The definition is that the displayed waveform will be 3 dB lower than the actual signal amplitude. The oscilloscope can (and probably will) continue to display signals way above the quoted bandwidth.The rise time of an oscilloscope is also normally completely independent of the bandwidth, which is why the rise time is also quoted in the oscilloscope specifications.

author: Fungus
author_rank: Super Contributor
timestamp: July 18, 2018, 12:56:08 pm
content: Quote from: Pete F on July 18, 2018, 12:50:46 pmNo, Rise time will bestronglyrelated to the bandwidth.(it's approximately the reciprocal of it)

author: Pete F
author_rank: Regular Contributor
timestamp: July 18, 2018, 01:01:09 pm
content: Quote from: Fungus on July 18, 2018, 12:56:08 pmThat is incorrect

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: July 18, 2018, 01:04:41 pm
content: Quote from: Pete F on July 18, 2018, 01:01:09 pmUnless you can demonstrate why I doubt many people will believe you.

author: Pete F
author_rank: Regular Contributor
timestamp: July 18, 2018, 01:07:16 pm
content: This is a Tektronix paper that explains bandwidth and rise time in oscilloscopes, however there is no doubt many other sources. They are NOT related, and two oscilloscopes with the same bandwidth may have different rise times, and visa versa.https://www.ece.ubc.ca/~robertor/Links_files/Files/TEK-Understanding-Scope-BW-tr-Fidelity.pdf

author: Fungus
author_rank: Super Contributor
timestamp: July 18, 2018, 01:16:59 pm
content: Quote from: Pete F on July 18, 2018, 01:07:16 pmThat paper gives you the formula for converting rise time to bandwidth:Yes, there's always complications in real life do to extra capacitances in the wires, etc., but there's no way you can claim they're "completely independent" when there's a simple, widely used formula to approximate the relationship.(and at sub-300MHz frequencies that formula is probably quite accurate)The paper mostly talks about "Bandwidth for < 3% error", which is another thing entirely.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 18, 2018, 01:18:37 pm
content: Quote from: Fungus on July 18, 2018, 12:35:20 pmBut they aren't built like this, so they are unintuitive to the person that is used with a 1:1 button assignment interface.Intuitiveness is completely different than complexity.Quote from: Fungus on July 18, 2018, 12:35:20 pmYes. Despite you could always take a photograph of the screen, stating that you end up not using it is a bit too much. The usefulness is quite high.

author: Pete F
author_rank: Regular Contributor
timestamp: July 18, 2018, 01:30:26 pm
content: Quote from: Fungus on July 18, 2018, 01:16:59 pmIf you feel you know better than the test equipment manufacturers you can knock yourself out. The "paper" you posted even stated that!It used to be widely believed that putting butter on burns was the correct treatment too, however times change. The rise time of an oscilloscope will depend on the roll-off of higher frequencies beyond the nominal bandwidth. One again I will say that it is NOT simply related to an inverse relationship as you've claimed, from what I've seen, that fact is widely published by various highly respected manufacturers in the field. What you choose to believe is of course entirely up to you, but my money is on them knowing a bit about the topic

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 18, 2018, 01:40:00 pm
content: Quote from: rsjsouza on July 18, 2018, 01:18:37 pmLol, a pendrive? A photograph of the screen? What for? It seems to me neither of you two have ever used waveforms...for what they are.

author: Fungus
author_rank: Super Contributor
timestamp: July 18, 2018, 01:46:50 pm
content: Quote from: rsjsouza on July 18, 2018, 01:18:37 pmYes,andyou can easily zoom in using a magnifying glass. Analog 'scopes rule!

author: Pete F
author_rank: Regular Contributor
timestamp: July 18, 2018, 01:53:58 pm
content: This is HP's take on rise time/bandwidth.http://literature.cdn.keysight.com/litweb/pdf/5988-8008EN.pdfFor the average person using an oscilloscope like I just purchased, the difference between the theoretical (ie the traditional) and actual rise time is likely a moot point, however most decent 'scopes I've seen will have their rise time quoted in the specs, and this is the reason they do so.

author: nctnico
author_rank: Super Contributor
timestamp: July 18, 2018, 02:00:18 pm
content: Quote from: TheUnnamedNewbie on July 18, 2018, 01:04:41 pmIt is very simple: it depends on the input filter. If that is Guassian then the 'regular' formula applies. If the filter is more like a brick-wall filter then the risetime will be different. Look at the Keysight MSOX3104 for example.So: NO, the risetime and bandwidth are not related.

author: Fungus
author_rank: Super Contributor
timestamp: July 18, 2018, 02:01:48 pm
content: Quote from: Pete F on July 18, 2018, 01:30:26 pmOK, let's keep reading:Ah, so it can be as high as 0.45?That's a whole 28% higher than 0.35 when you start get into the GHz range.Yes, I agree. The reciprocal relationship is completely broken. Not.

author: Fungus
author_rank: Super Contributor
timestamp: July 18, 2018, 02:16:24 pm
content: Quote from: nctnico on July 18, 2018, 02:00:18 pmTechnically true, but not really relevant. Most oscilloscopes are Gaussian if we're honest.

author: Specmaster
author_rank: Super Contributor
timestamp: July 18, 2018, 02:19:02 pm
content: Quote from: nctnico on July 18, 2018, 02:00:18 pmThey are related in a way and I'm not an expert on scopes, but I do know that manufacturers are not going to spend a lot of money developing a really fast rise risetime on say a 50 Mhz bandwidth scope, they will provide a risetime suitable for frequencies upto and just maybe over the bandwidth of the said scope. Therefore it makes perfect sense that as the bandwidth of the scope increases, the makers have to provide a risetime capable of handling at least the frequency stated for the bandwidth of that scope otherwise its going to be incapable of displaying the waveform correctly above a certain frequency.

author: Pete F
author_rank: Regular Contributor
timestamp: July 18, 2018, 02:19:43 pm
content: Yep, you keep digging that hole "Fungus"Meanwhile the rest of us will move on I think.In regard the intuitiveness of the Siglent 1202, I would have to say I didn't find it especially intuitive in many areas. However that shouldn't necessarily be seen to be a criticism of Siglent, and it could well be that they are no better or worse than other similar offerings from other manufacturers. In my case I have spent many years, well decades unfortunately, using old-school analogue 'scopes so this is certainly quite a change for me. There's no denying in my mind however that the power of instrument is quite mind blowing in my opinion (especially considering the prices!), and would be completely unthinkable if I was to put it up against CROs from the same era as say my 2215. As mentioned above, I'm sure I will get used to the commonly used functions and accessing them quickly, but they will never be as quick as pretty much any analogue 'scope I've used in the past. For a hobbyist it's probably no big deal, but if I were still doing it professionally I think I would find it a bit frustrating to be honest; time is money, and when fault-finding you're changing functions a lot.

author: Fungus
author_rank: Super Contributor
timestamp: July 18, 2018, 02:45:56 pm
content: Quote from: Pete F on July 18, 2018, 02:19:43 pmWhat hole?In practice brick wall filters cannot be achieved in hardware, they have to be done in software.This means that if you want a 'scope with a a non-gaussian filter you have to sample at amuchhigher rate than Nyquist then digitally post-process it.ie. you have to massively underrate the bandwidth which isprinted on the front- inside the oscilloscope it has to actually have the bandwidth needed to match the sample rate.In other words, it's a bit of a con game played in "high-end" oscilloscopes. That Tek paper which was posted earlier is really just a sales brochure in disguise ("You want a 'scope with only 3% error in rise time instead of 30%? We sell those!").The reality is that a 'scope with 3% error is just a scope with 30% error (ie. gaussian filter) that's been derated, has a software filter applied internally, and a different label stuck on the front.If you want to believe those scopes are breaking math, well... that's up to you.

author: rf-loop
author_rank: Super Contributor
timestamp: July 18, 2018, 03:05:42 pm
content: Quote from: Fungus on July 18, 2018, 02:45:56 pmWhere from you get this trumpth. Even I have designed and done some analog "brick wall" filters and I have done these time when Intel 4004 was young child and Mot 6800 just born. Do you think this era it need DSP.

author: Pete F
author_rank: Regular Contributor
timestamp: July 18, 2018, 03:13:51 pm
content: Quote from: Fungus on July 18, 2018, 02:45:56 pmI tell you what, why don't you write to Tektronix/Keysight and tell them how they have it all wrong, and you know, for a fact, that it's all a big conspiracy to sell more high end oscilloscopes. Let is know how you get onIncidentally I didn't "massively underrate" the bandwidth that is printed on the front, in fact I specifically stated "The oscilloscope can (and probably will) continue to display signals way above the quoted bandwidth."Like I said, the difference between the actual, calculated, and archaic theoretical rise time is probably a moot point for most people, and I doubt many people here would have the actual capacity to accurately measure the rise time of a fast oscilloscope in any case. However the point is that the rise time may be of significance for some people in their applications and they may specifically seek that when looking for their test instrument. It is incorrect to assume all oscilloscopes of the same bandwidth will have the same rise time. Tektronix say that. Agilent say that. Keysight say that. In fact the only person who seems to not be saying that is youIn practice the solution if the rise time is too slow is simply to get a higher bandwidth oscilloscope. However one shouldn't assume a specific rise time based merely on quoted bandwidth, as that is not always a correct assumption.BTW my background was largely in RF, and I'm offering this emoji to the assertion that filteringneedsto be done in software

author: David Hess
author_rank: Super Contributor
timestamp: July 18, 2018, 03:14:52 pm
content: At higher bandwidth, it becomes more difficult to maintain a Gaussian response so even with analog oscilloscopes, some higher bandwidth instruments deviated from the 0.35 rule. In some cases, the same instrument was available tuned for either Gaussian response sacrificing bandwidth or higher bandwidth sacrificing transient response.Keysight and Tektronix are not making those high bandwidth 0.45 oscilloscopes without reason. They are easier and cheaper to make than one with a 0.35 Gaussian response and bandwidth sells. If you are using your oscilloscopes as a frequency domain instrument, this even makes some sense which is why it was sometimes done in the past with analog oscilloscopes.Modern oscilloscope user interfaces are not poorer because of complexity when even basic functions have been buried in menu structures or other poorly thought out interface methods; they just have poor human factors engineering. But complexity makes a good excuse.The same problem comes up with anything modern which uses skeuomorphic interface elements. What genius, other than Apple who can do no wrong, thought that was a good idea?

author: David Hess
author_rank: Super Contributor
timestamp: July 18, 2018, 03:23:41 pm
content: Quote from: Pete F on July 18, 2018, 03:13:51 pmThe only people who will respond are from marketing so why bother?QuoteThe people who are going to spend $20,000+ on a high bandwidth DSO with a non-Gaussian response are not going to be reading this thread for advice. That leaves hobbyists who do not know any better and buy toys and everybody else who will only be able to afford a crummy Gaussian response oscilloscope.QuoteWasn't the argument that rise time has nothing to do with bandwidth? Have you changed sides?

author: Pete F
author_rank: Regular Contributor
timestamp: July 18, 2018, 03:36:10 pm
content: Excellent points David. One of the functions I change quite often is to look at the DC/AC component of a test point ie changing the input coupling. I found it a bit clumsy when changing that in each channel vs what I'm previously used to which is just flicking a switch.By the same token I'm probably being a bit critical. Technology wise it's a little like winning the lottery, the complaining when the winnings are delivered in $10 bills instead of $100sI am still amazed at what that little machine is capable of doing, it's just that I'm glad I didn't throw the old Tek out when I had the chance!No David I haven't changed sides, and I have never said it has "nothing to do with bandwidth". What I said was that the rise time was NOT strictly dependent on the bandwidth. I've said that quite a number of times and provided specific data from manufacturers to support that statement.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 18, 2018, 03:54:38 pm
content: Quote from: GeorgeOfTheJungle on July 18, 2018, 01:40:00 pmPerhaps the 2232 performs additional functions but, according to its manual, the waveform storage looks no different than a modern DSO saving the actual data (either in .csv or a proprietary format) to a pendrive and being able to perform advanced analysis on it, or keep it in memory to serve as a reference waveform for simple visual comparison or automated pass/fail tests. In addition to that, DSOs can also save bitmapped images of the screen (.jpg, .png, .bmp, etc.).My surprise with your statement was that you mentioned that waveforms in a DSO are rarely used due to the added functionality that requires additional steps to properly configure it. At least in my experience that is not the case at all.

author: Fungus
author_rank: Super Contributor
timestamp: July 18, 2018, 04:55:53 pm
content: Quote from: Pete F on July 18, 2018, 03:13:51 pmSeems like you're not sure which side you're one.nb. Even a Rigol DS1054Z will displaysomethingup to about 300mHz. It'll be very very attenuated but itwillbe there.Quote from: Pete F on July 18, 2018, 03:13:51 pmThat's not what I said at all.Gaussian filtering obviouslydoesn'tneed software - we spend a lot of time and money trying toeliminateit in our hardware.Brick-wall filtering? If you know how to make a nice brick-wall filter in hardware then I'm sure Tek., et., al. will be very interested.

author: Fungus
author_rank: Super Contributor
timestamp: July 18, 2018, 05:03:48 pm
content: Quote from: Pete F on July 18, 2018, 03:36:10 pmIsn't that what 4-channel 'scopes are for, so that you can display both things simultaneously?

author: David Hess
author_rank: Super Contributor
timestamp: July 18, 2018, 06:18:11 pm
content: Quote from: Pete F on July 18, 2018, 03:36:10 pmThe trigger slope control is also commonly missing.QuoteI get annoyed when the new oscilloscope cannot, and I really mean cannot, make the same measurements as the old one or performs more poorly.Quote from: rsjsouza on July 18, 2018, 03:54:38 pmIt was mostly intended for storing and displaying reference waveforms and it works very well for this. The 2232, and 2230 with the option board, even backup the waveform reference memory. Unfortunately they cannot display the reference waveforms in analog mode.Quote from: Fungus on July 18, 2018, 04:55:53 pmThey are not brick wall but for a while Tektronix high end oscilloscopes implemented switchable 4th order Gaussian filters in hardware. These days they support something similar in software to backup the low order analog filters.Quote from: Fungus on July 18, 2018, 05:03:48 pmSo the designers intended to replace easy access to the input coupling settings with more channels?

author: Fungus
author_rank: Super Contributor
timestamp: July 18, 2018, 07:27:42 pm
content: Quote from: David Hess on July 18, 2018, 06:18:11 pmI don't think that was the explicit intention, no, but it's a nice workaround for people not in the "Two channels is enough for me!" camp.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 18, 2018, 07:35:24 pm
content: Flipping a switch is easier though, than having to reach for the other probe and swap the GND crocodiles. Ohh, and the trigger settings too.

author: Fungus
author_rank: Super Contributor
timestamp: July 18, 2018, 07:36:23 pm
content: Quote from: David Hess on July 18, 2018, 06:18:11 pmFair enough, but the basic front end still needs higher bandwidth to make these filters work.Getting back to the point: The assertion that bandwidthisn'trelated to rise time is false.With some 'scopes, you need to you know the filter type as well as the raw analog input bandwidth but you can still calculate the expected rise time. All that changes is the constant in the equation.The assertion made was that this is impossible, that rise times are completely unrelated to bandwidth.

author: Fungus
author_rank: Super Contributor
timestamp: July 18, 2018, 07:53:31 pm
content: Quote from: GeorgeOfTheJungle on July 18, 2018, 07:35:24 pmYep.Opening a menu and using the stupid scroll knob to select between DC/AC/GND is bad design in anybody's book.For basic functions like coupling it should be a single button press, even if that means shoving all the other menu items down to make space for an extra entry (one button for AC/DC, another one for GND on/off).

author: nctnico
author_rank: Super Contributor
timestamp: July 18, 2018, 08:40:52 pm
content: Quote from: David Hess on July 18, 2018, 06:18:11 pmWhen it comes to DSOs the perfect one simply doesn't exist. I have several DSOs and each has it's own specific area of excellence (not taking bandwidth into account) and price doesn't seem to be the main differentiator here.

author: Gyro
author_rank: Super Contributor
timestamp: July 18, 2018, 09:21:16 pm
content: Quote from: Fungus on July 18, 2018, 07:53:31 pmIronically, the Owon USB scopes have a much more minimalist and intuitive UI.Ironic because:1) They're cheap2) They have far more screen area available to waste than their resolution restricted, small screened cousins.Maybe they should start shipping with a stylus and / or a USB keyboards and some of the Agilent ones used to do. A simple resistive touch screen and plastic stylus would hardly break the bank.(1) Clicking on the small arrow directly brings up the measurement cursors menu for time and / or voltage.(2) Clicking on the small '+' icon (only appears when the mouse pointer is in the measurements area) immediately brings up the measurements selection menu.(3) Clicking on either of the channel numbers immediately brings up the channel settings menu.(4) Volts/div selection, Clicking brings up a normal popup+slider However if you just hover the mouse over it instead you can use the scroll wheel to increment/decrement directly.(5) Clicking here toggles between DC / AC / GND for that channel.Additional, hovering in either of the channel boxes also brings up a small 'x' icon to turn off the channel. Clicking in a greyed out channel box will turn it on again.(6) Clicking in the 'T' box brings up a slider for trigger position. It's normally easier just to drag the red trigger position flag at the top of the screen, but the 'T' box click also brings up a useful 'Reset' button to restore to the middle.(7) Time/div... Similar operation to the V/div. Clicking brings up the pop-up/slider but mouse-over and scroll wheel changes the value directly.(8 ) Clicking toggles the trigger source between Chan1, Chan2 and Ext (trigger marker on right hand edge of screen changes color to match).(9) Clicking toggles trigger polarity, works on edge, slope and pulse (icon changes to match trigger type). In Video trigger mode it toggles Odd, Even, Line etc.(10) Click to alter trigger level - Actually it's far easier and more accurate to drag the trigger marker on the right hand side if the screen, but clicking here also brings up two useful buttons to 'Reset' the trigger level and 'Set to 50%'.- <Space> brings up (or closes) the last menu selected (like clicking the Menu button)- When in numeric popups (V/div, T/div, number key will cycle through values for that number. eg. Pressing 2 will cycle 2us 20us, 200us, 2ms etc.- It will take the first letter of a menu item to select, eg. Trigger mode will take E, S, V, P etc.(Cribbed from my post in another thread).

author: David Hess
author_rank: Super Contributor
timestamp: July 18, 2018, 10:04:18 pm
content: Quote from: Gyro on July 18, 2018, 09:21:16 pmI am not convinced that a touch screen is a solution but a desk space wasting keyboard (and mouse) are definitely not in an integrated instrument.HP went for the "single master rotary encoder" interface on their instruments at one time and Tektronix almost followed them down that rat hole in the 1990s. Did nobody learn anything about interface design from that?

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 18, 2018, 10:15:51 pm
content: Speaking of desk space, it's true that size matters, in this case smaller is better and modern DSOs win by a wide margin. Good old CRT scopes take up to perhaps 3x as much desk space.@Fungus, the Rigol 1000z UI is specially annoying because it shares all the channels' control knobs.

author: Pete F
author_rank: Regular Contributor
timestamp: July 18, 2018, 11:59:36 pm
content: Quote from: Fungus on July 18, 2018, 04:55:53 pmIt seems you are becoming increasingly desperate to "win" an argument and are now resorting to pretending that people have said something, then argued against it. Bizarre! For the record it was actually YOU who said that "a 'scope with 3% error is just a scope with 30% error (ie. gaussian filter) that's been derated". I have maintained all along that an oscilloscope will measure well beyond its bandwidth and am well aware of conventional filtering.It seems very clear that you have never been a professional in this field. I only mention all this as it appears the forum has quite a few people new to the field, and the concept of bandwidth, rise time, and various other oscilloscope functions is something that seems a little confusing for somebody buying their first oscilloscope. I would strongly suggest they be guided by manufacturer's documents in this regard, and I feel the documents I linked to explain the concepts very well. There are many other documents also on the internet, mainly from EEE sources.As far as using 4 probes, all set to something different and then swapping them around as required, that would have to be the most stupid thing I've heard in a long time. What Dr Google seems to have forgotten is the trigger will be on the wrong channel when you swap probes. So the assertion is that you'll put one probe down, pick up another, change the trigger, do the measurement, move to the next point, pick up the third probe, change the trigger again, etc etc etc. If you're going to change the trigger source, then why not just change the coupling and use the one probeToo funny!When working through a board or even a single IC fault finding you'll be swapping input parameters around all the time, and being able to flick between basic functions is essential for any oscilloscope. For those buying an oscilloscope and doing this type of work I think it would be an important thing to check that you're happy with the interface before buying (or just use an old analogue 'scope). For those doing more development work where the parameters are more fixed, a multi-input oscilloscope would probably be more suitable. I made that point pages ago, as I came from the former camp where speed is king.I agree that I'm not a huge fan of touch screens, but have become more used to them over the years. They simply replace buttons in any case, and whether the multi-function button is on the screen or a button next to it really doesn't make much difference in my opinion. Anything that is multi-function will require more key strokes to obtain that function when compared to a dedicated switch, but that's just the nature of the beast I'm afraid.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: July 19, 2018, 12:05:18 am
content: User interfaces are a matter of personal preference. Look at all the flavors of Linux, all of which their designers passionately feel are better than others, sometimes with a rational basis but most often not.Listen to the opinions of others for insight into what might float your boat, but this is one area where test driving is really important. It is disheartening to have spent serious money on an instrument that turns out to drive you batty.

author: Pete F
author_rank: Regular Contributor
timestamp: July 19, 2018, 12:17:56 am
content: Quote from: Fungus on July 18, 2018, 07:36:23 pmThe assertion made, and I would know this is it was ME who made it, was: "The rise time of an oscilloscope is also normally completelyindependentof the bandwidth, which is why the rise time is also quoted in the oscilloscope specifications."I highlighted the part you seem to be so confused by. You have substitutedindependentfor unrelated, and got yourself confused with the whole concept. They areindependentin that the rise time of various oscilloscopes with the same bandwidth may vary, and the reason why that is so was provided by various documents from the manufacturers. In the past that was possibly much less likely to be so, however with the advent of "relatively" affordable modern very high bandwidth times have changed, and it's something that in some instances potential buyers may need to look more closely at.With all due respect, there's a time to know when to stop digging and accept that you've misread or misunderstood something. That's your personal business of course, but I'd respectfully suggest just accepting that and move on

author: David Hess
author_rank: Super Contributor
timestamp: July 19, 2018, 12:38:43 am
content: Quote from: GeorgeOfTheJungle on July 18, 2018, 10:15:51 pmBut I can stack my CRT oscilloscopes and with their bail, the space under them is available as well.QuoteI do not mind that so much as long as it is one button to select each channel and a full set of channel controls are included. The first microprocessor controlled oscilloscopes shared one set of horizontal controls for multiple timebases so this is hardly new.What I do not accept is sharing between the vertical, horizontal, and other controls.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 19, 2018, 12:46:35 am
content: What pisses me off is that if you hit, say, the channel 4 button twice it turns off, so when trying to select the channel you want the knobs to act on, it's easy to turn it off instead by mistake, With independent controls that can't happen.

author: Fungus
author_rank: Super Contributor
timestamp: July 19, 2018, 12:55:20 am
content: Quote from: Pete F on July 18, 2018, 11:59:36 pmNowyou'rethe one inventing things.You said you enjoyed the ease of switching between AC/DC on analog 'scopes.I simply said you can look at both on a DSO with 4 channels. I never said anything about "put one probe down, pick up another, move to the next point, pick up the third probe". Just connect two probes, see AC and DC simultaneously. Trigger doesn't change.

author: Fungus
author_rank: Super Contributor
timestamp: July 19, 2018, 01:18:08 am
content: Quote from: Pete F on July 19, 2018, 12:17:56 amWhere I come from the word "independent" means there's no relationship, that they can haveany value at all.That's not true, they're normally closely correlated.The Tek document you linked mentions 'scopes with rise times of 0.45/bandwidth. The Keysight document you linked mentions 0.5/bandwidth. 0.5/bandwidth is only 42% better than the cheapo $350 Rigol DS1054Z.Prove me wrong! If I'm persistant it's only because I want to be wrong. I love being wrong, that's why I try so hard to be so.What's the biggest deviation from 0.35/bandwidth you know of in a production oscilloscope? Is there one with even 50% deviation?Even 50% deviation wouldn't make it "completely independent". "Completely independent" is when I can chooseany number I want.Just admit that and move on.

author: Pete F
author_rank: Regular Contributor
timestamp: July 19, 2018, 01:54:43 am
content: OMG, are you serious? Mate you're wrong, you've been shown to be wrong, you admit to be wrong by quoting a 50% error, maybe that's "close enough" for you, but that doesn't mean that will be suitable for others. If you "like to be wrong" I guess today is your lucky day!I'm done with this topic. I was asked to substantiate my assertion with evidence to support it, and I have done so numerous times from the manufacturers themselves. If you want to continue to invent things, claim that it's all just a conspiracy from the manufacturers, or that people should use probes without a clue as to how they even work, then knock yourself out. I would however suggest that if you used some of that time to actually do some of this stuff your opinion may be swayed somewhat.From a more useful discussion perspective, I very much agree with David, it seems that usability has somewhat been compromised in trying to squeeze as many functions in to the units as they can. Unfortunately I think that's a bit of a sign of the times though. With so much equipment being software based it's relatively easy to add "functions" by merely adding code, but that doesn't mean that there has been any huge thought being put in to actual use. Many people will purchase sight unseen (as I did), and if brand X oscilloscope offers more "features" than brand Y, there's a good chance all other things being equal the brand X will outsell brand Y.Edit: Oh and BTW "Fungus", people like you will always try to have the last word. Every forum has people like that and this one is clearly no different. Fill you boots with the predictable BS comeback to have the final say, I have better things to do with my time than argue idiotic semantics.

author: KaneTW
author_rank: Frequent Contributor
timestamp: July 19, 2018, 02:07:40 am
content: A const./f relationship is still a relationship. Just because the constant factor changes doesn't mean the values are independent. You can't calculate the rise time from the bandwidth, but there's still a general trend. No one has been arguing that rise time always is 0.35/f or whatever.

author: Pete F
author_rank: Regular Contributor
timestamp: July 19, 2018, 02:29:27 am
content: Quote from: KaneTW on July 19, 2018, 02:07:40 amThe constant factor changes and (with modern equipment) is generally unknown these days, therefore they are independent. That is a basic rule of maths.

author: Fungus
author_rank: Super Contributor
timestamp: July 19, 2018, 02:57:41 am
content: Quote from: Pete F on July 19, 2018, 02:29:27 amAt best, the rise time is what amathematicianwould call a "limited dependent variable".Quote from: Pete F on July 19, 2018, 01:54:43 am(the best example you've shown so far is only 42% more than 0.35 but I'll let that pass)What that statement means is that if you tell me the bandwidth of an oscilloscope, I can tell you the rise time to within 25%,without any other information.To me that indicates that rise time is closely related to bandwidth - it only deviates from it by a maximum of 25%.Quote from: Pete F on July 19, 2018, 01:54:43 am"Done with", apart from the post you madeafterthat one.

author: KaneTW
author_rank: Frequent Contributor
timestamp: July 19, 2018, 03:51:12 am
content: No, an independent variable would be completely unrelated to the other. That's not the case.Rise time is Theta(1/f), where Theta is the Landau-theta ---https://en.wikipedia.org/wiki/Big_O_notation

author: Mr. Scram
author_rank: Super Contributor
timestamp: July 19, 2018, 04:03:01 am
content: Quote from: Fungus on July 18, 2018, 07:53:31 pmThe DS1054Z isn't known for its refined user interface. I'm not sure that's what you can expect from such a cheap yet capable device either. Analogue oscilloscopes costed one or two orders or magnitude more in their day, so they'd better be well thought out. If course, interfaces are a confusing mix of preference and what you're used to too.

author: Fungus
author_rank: Super Contributor
timestamp: July 19, 2018, 05:55:00 am
content: Quote from: KaneTW on July 19, 2018, 03:51:12 amAn example of "independent" would be the sample memory:If you tell me the bandwidth of the oscilloscope it tells menothing at allabout how much memory it has.That's independent.

author: Fungus
author_rank: Super Contributor
timestamp: July 19, 2018, 05:58:38 am
content: Quote from: Mr. Scram on July 19, 2018, 04:03:01 amIt doesn't cost extra money to manufacture with a different menu layout. Stuff like the example above means they simply don't care.

author: Mr. Scram
author_rank: Super Contributor
timestamp: July 19, 2018, 06:25:29 am
content: Quote from: Fungus on July 19, 2018, 05:58:38 amDevelopment and iterative testing isn't free. Far from it. They've built a perfectly serviceable device. The amount of work it would take to make it just right would add cost and interfere with their goal of building a very affordable device. People love to rip the DS1054Z apart for its flaws, but Rigol really broke ground when it comes to value for money. It still doesn't seem to have been surpassed in that regard, which is a testament to the choices they made.I'll point at Dave finding that it's often the software that lets devices built very well otherwise down. We've seen more than a few pieces of gear falling apart because their software wasn't easy to use. Software development isn't trivial or easy and therefore far from cheap. Good things rarely come free.

author: bd139
author_rank: Super Contributor
timestamp: July 19, 2018, 07:36:29 am
content: Software can cost a lot more than the hardware design does.The DZ1054Z software is ok. It’s a compromise. After a few weeks it is committed to muscle memory so it’s not an issue.As for coupling on the DS1054Z, press the channel then the coupling button a couple of times. You don’t need to use the encoder. The menu is informational only. The only thing that I consider annoying is that the channel select and enable/disable is on the same keys so periodically if I’ve forgotten which channel is selected (which is half way across the scope on the screen) I’ll end up turning it off rather than select it.

author: tautech
author_rank: Super Contributor
timestamp: July 19, 2018, 07:55:10 am
content: Quote from: bd139 on July 19, 2018, 07:36:29 amAnd the memory between the ears.The UI is just that and all are different whether it's a DSO or CRO.Most that have spent years using the same scope initially have difficulty coming to grips with a new UI.After using only a D83 for a few years I got an HP1740 and thought HTF do you drive this thing ?With the increased functionality of the modern scope, things have to be buried in menus and how they are laid out or similar functions are grouped is the key to getting to grips with things quickly.It doesn't take long to get used to a certain layout/structure IF you're a competent scope user that knows how to go about obtaining the result you need.QuoteYep, that's how the Siglents work too....toggle to the next menu item.QuoteIs there no visual indication which channel is the controls 'active' channel ?I thought the Z had a lit button showing which was the active channel.

author: bd139
author_rank: Super Contributor
timestamp: July 19, 2018, 08:05:50 am
content: On the DS1054Z The channel buttons illuminate to show which channels are enabled but the actual current channel is on the screen down well away from the context. It'd be nice if they had a red LED behind the channel button as well as a green one as a solution. Red one is active channel. Green/red is enabled.Still the best interface on a digital scope is the HP 54600 series if you ask me.

author: tautech
author_rank: Super Contributor
timestamp: July 19, 2018, 08:20:06 am
content: Quote from: bd139 on July 19, 2018, 08:05:50 amOK thanks, that sounds a bit different to the new 4ch Siglent with the same single shared control....if I'm getting this right.Anyways, the active channel button (to the shared control) is always lit and channel ON indication is given from the channel box on the display. So you might have a # of channels ON but the one that's active to the control is the only button that's lit. Some have grizzled that it should be different but the indication of ON and 'active' is staring you in the face.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 19, 2018, 08:21:43 am
content: Quote from: Pete F on July 19, 2018, 02:29:27 amNope! It simply becomes a formulatr=x/fwhich can be used with whatever value of constant you require.Rather like Ohm's Law, in fact.There is little magic about 0.35, it is just the number which works for a network with a Gaussian response, which, for many years was the most common.

author: Specmaster
author_rank: Super Contributor
timestamp: July 19, 2018, 08:28:28 am
content: Thats what I love about my combiscope, although it is all driven via push buttons the same as a normal digital scope, it still retains all the normal controls that you would find on an analogue scope but behind buttons rather than rotary abs toggle switches, a push of a button toggles to the next setting eg, AC,DC,GND, Timebase and V/div each have 2 buttons, 1 increases, the other decreases. All the other clever digital functions are behind on screen menus so you can drive this either way with relative ease.

author: Fungus
author_rank: Super Contributor
timestamp: July 19, 2018, 09:35:58 am
content: Quote from: bd139 on July 19, 2018, 07:36:29 amYes you do - to select the item.And there's a chance of it rotating and selecting the wrong thing, gah!I've said many times that the Rigol would be much better if you could press the menu button to open the menu, use the blue up/down buttons to select the item, press the menu button again to select it. Far more intuitive and reliable than using the encoder.Quote from: Mr. Scram on July 19, 2018, 06:25:29 amTrue, but arranging the menus will only be a tiny part of that cost.Making the menus work with both buttons and encoder might be a day or two of work but only if the existing code is really messy.Quote from: Mr. Scram on July 19, 2018, 06:25:29 amMost of the work in the firmware will be in driving the FPGAs, doing all the math, displaying stuff on screen, adding multiple UI languages, etc.

author: Fungus
author_rank: Super Contributor
timestamp: July 19, 2018, 09:43:00 am
content: Quote from: bd139 on July 19, 2018, 08:05:50 amIt's actually inmanyplaces on screen. eg. All the measurement icons on the left hand side change color to match the selected channel.Channel 1 selected:Channel 3 selected:They found that time to dothatduring the development process, why are some of the basics so bad?

author: bd139
author_rank: Super Contributor
timestamp: July 19, 2018, 09:49:09 am
content: That's way away from the buttons on the right hand side of the screen however. you have to do a visual mapping between which channel, colour etc which is far from ideal. If they had the channel buttons lined up with the activated channel indicators on the bottom of the screen that would be orders of magnitude less shit. Perhaps that's one for the vertical format scopes from Japan (great idea they had with those).For ref, you only have to press the encoder to close the menu. The coupling select can be whacked until you have the coupling you want or just left there.To note, if you want the menu to bugger off without touching the encoder, just hit the up arrow above the channel coupling soft key as well.

author: Fungus
author_rank: Super Contributor
timestamp: July 19, 2018, 09:55:53 am
content: Quote from: bd139 on July 19, 2018, 09:49:09 amYep, but sometimes it's a long menu with a dozen items and you want the item above the current one.Quote from: bd139 on July 19, 2018, 09:49:09 am...which is stupid. The up/down arrows should go up/down the menu. The menu button should be used to close it.If you want to close the menu without changing anything then it could be the big "clear" button at the top. Pressing the blue up/down arrows for that goes totally against the principle of "least surprise".

author: bd139
author_rank: Super Contributor
timestamp: July 19, 2018, 10:04:31 am
content: I'm good with a big clear button.Here I designed an oscilloscope with a better layout:Say I want to measure channel 3 rise time. Whack (channel 3) (measure) (time) (risetime)Soft buttons probably better on right looking at ergonomics.Edit: to note that encoders are fine for setting numbers but not for picking menu selections. They are shit for that.

author: Fungus
author_rank: Super Contributor
timestamp: July 19, 2018, 10:23:11 am
content: Quote from: bd139 on July 19, 2018, 10:04:31 amYep, it's not a difficult concept. I don't know oscilloscope manufacturers do it that way.(especially when a scope has clearly labelled up/down buttons right next to the menu buttons)

author: Mr. Scram
author_rank: Super Contributor
timestamp: July 19, 2018, 10:23:48 am
content: Quote from: Fungus on July 19, 2018, 09:35:58 amI don't think you're understanding the problem. It's not about having a guy of girl move a box to X and Y. That's trivial. It's about figuring out what works best and feels most intuitive. That's by no means a small or simple task and can in some projects take months or even years and many iterations. Companies use heat maps, eye tracking, focus groups and all sorts of methods to figure out what actually works. That's not cheap or simple. If it was just dragging a few boxes around designing good websites would take a few days at worst. That also turns out to be quite hard. UX design is quite hard to do right, which pretty much is why we're having this discussion.I honestly mean no offence, but you kinda sound like the typical engineering guy. "What'dya mean people 'ave to use it, gov'ner? It werks, don' it?"

author: bd139
author_rank: Super Contributor
timestamp: July 19, 2018, 10:27:26 am
content: To note, user studies don't always have a positive correlation with a successful UI. We spent lots of money finding that out. I have done a lot of user interface stuff in the past and also discovered that.Knowing the problem domain and people's workflows and all the horrible things competitors do that make people want to gouge their own eyes out gets you a lot further. Make the common tasks fast and in your face. Make the less common tasks discoverable. Visual cues everywhere. Consistency and colour. Even the size of UI elements is important. But above all, the interface has to line up with existing expectations and user's thought processes.Lest you end up with some fucked up shit like windows 8 was.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: July 19, 2018, 10:32:33 am
content: Yep, it's not so easy to pull off a good human/user interface. Rarely happens by accident.

author: Mr. Scram
author_rank: Super Contributor
timestamp: July 19, 2018, 10:34:53 am
content: Quote from: bd139 on July 19, 2018, 10:27:26 amThat's one of the reasons it's a complicated matter. There isn't a guaranteed route to success and things aren't always what they seem. Humans are a fickle lot. It a nasty mess of psychology combined with past experiences, worn in behaviour and many other factors.In the earlier years of the feature phone there was for example quite a noticeable difference between Asian and Western phones. Just a different design approach based on different expectations.

author: tautech
author_rank: Super Contributor
timestamp: July 19, 2018, 11:05:22 am
content: Quote from: bd139 on July 19, 2018, 10:04:31 amChannel select buttons tooooooo far from the vertical control.Sorry that won't fly !QuoteSome are, some aren't.The best have an indent encoder and large knobs. Just a bigger knob improves a DSO heaps, swap one over if you don't believe me.

author: Specmaster
author_rank: Super Contributor
timestamp: July 19, 2018, 11:07:33 am
content: While I don't have any experience of purely digital scopes, I do feel that the control layout of my combiscope is about right, so I can after a few minutes of getting to grips with the button controls, jump on it and use as a conventional analogue scope by using the grey buttons in the red squares shown in the photo, these being the vertical controls for both channels and the timebase/horizontal. Switching into digital mode still uses these same controls plus the others in varying degrees according to what you are trying to achieve.In digital mode, the buttons most used to access the various settings for the other controls such as measure for example are going to be the 6 light grey buttons on the right of the screen to select on screen options.Perhaps this method could be the best for a person making the switch from analogue to digital as the problem with digital scopes really only seems to be with people who have either used and or own analogue scopes before.

author: nctnico
author_rank: Super Contributor
timestamp: July 19, 2018, 11:16:16 am
content: Quote from: bd139 on July 19, 2018, 10:27:26 amYes. I installed that once in a VM. After Windows 8 started I scratched my head, frowned and rolled the VM back to Windows 7.

author: bd139
author_rank: Super Contributor
timestamp: July 19, 2018, 11:28:16 am
content: Quote from: tautech on July 19, 2018, 11:05:22 amI agree. That was within the limitations of the form factor. The Japanese scopes in vertical format have a better solution there.Quote from: tautech on July 19, 2018, 11:05:22 amOh I agree entirely. But better is not best

author: Fungus
author_rank: Super Contributor
timestamp: July 19, 2018, 12:17:13 pm
content: Quote from: Mr. Scram on July 19, 2018, 10:23:48 amNo, that's how you make horrible things like Windoiws8/10, or justify your high consultancy fees.A lot of user interface design is simple common sense.

author: Specmaster
author_rank: Super Contributor
timestamp: July 19, 2018, 12:24:56 pm
content: Quote from: Fungus on July 19, 2018, 12:17:13 pmIt's a massive advantage if at least one person in the design team actually have used scopes so that they have a good knowledge of commonly used controls within each section so that they can be ergonomically positioned close to each other within their respective functional group.

author: Fungus
author_rank: Super Contributor
timestamp: July 19, 2018, 12:31:00 pm
content: Quote from: Specmaster on July 19, 2018, 12:24:56 pmBefore you do any of that you have to think whether or not a twisty-push-knob is a good way to navigate menus.And especially if a twisty-knob without detents is a good way to navigate menus (I believe the encoder they use has a detent option, most of them do)

author: Specmaster
author_rank: Super Contributor
timestamp: July 19, 2018, 01:43:39 pm
content: Quote from: Fungus on July 19, 2018, 12:31:00 pmDetent are a must have in that situation, no excuses.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 19, 2018, 04:17:10 pm
content: Quote from: Mr. Scram on July 19, 2018, 10:34:53 amI think you nailed it, especially the past experiences and worn in behaviour. Based on how my kids are naturally adapted to touch screens, I suspect the newer generations would probably be very uncomfortable at the number of buttons in your combiscope and would much rather have a mix between a touch interface (for channel selections, and pinch zoom, for example) and a lot less buttons or even a keypad (for more accurate settings, for example).The manufacturers have been migrating towards touch interfaces not without reason - the demand will surely be there.

author: David Hess
author_rank: Super Contributor
timestamp: July 19, 2018, 05:58:17 pm
content: Quote from: rsjsouza on July 19, 2018, 04:17:10 pmThe situation is more complicated than that. Touch interfaces are great for portable devices where interface area is limited but also trade performance for flexibility. They take more time and effort to accomplish the same thing once a user becomes experienced. For instance contrast a keyboard centric user interface versus mouse and keyboard. Adding a touch screen makes things even slower. Newer users lack experience with older interfaces so do not know what they are missing.QuoteTouch interfaces have their own problems including smudged screens, screen glare, and poor feedback. And then there is thegorilla armissue in some applications.

author: bd139
author_rank: Super Contributor
timestamp: July 19, 2018, 06:07:54 pm
content: Have to agree with touch screens being bad. They’re imprecise, impossible to use unless you are directly focused on the element you are trying to manipulate, don’t work if they’re not relatively clean and the elements have to be very large comparatively as instantaneous positioning is difficult.A large insurance company here recently switched their front office mobile sales over to iPads. They’re back on laptops again already after only 9 months because the mistakes that are being made are slightly terrible.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 19, 2018, 07:06:06 pm
content: Oh yeah, I don't disagree with both of you - I am not discussing the pros and cons of one interface over the other and I grew (and prefer) using "non-virtual/mechanical" UIs as well. However, that doesn't mean this change will never happen - in my opinion and experience it certainly will change to cater to the preference of the majority, which is quickly moving towards touchscreen.In my opinion, if left to the manufacturers alone, a touch screen would be the ideal interface as it reduces the material costs of ever shrinking profit margins. That, tied to an ever growing population completely familiar with touchscreens, will set the trend towards less buttons. It may not become an HP's "single button" product line of the 1980's/1990's, but it is certainly being reduced with offers with shared controls and functions per button, which are tolerated by more and more customers.

author: Mr. Scram
author_rank: Super Contributor
timestamp: July 19, 2018, 07:10:14 pm
content: Quote from: Fungus on July 19, 2018, 12:17:13 pmA lot of engineering is common sense. That doesn't mean you can just slap a bridge together. Neither good engineering nor good UX design tend to happen by accident, to paraphrase GeorgeOfTheJungle.

author: KaneTW
author_rank: Frequent Contributor
timestamp: July 19, 2018, 07:29:29 pm
content: UI design is not as easy as just using common sense, and it's a really bad misconception many software engineers have. Good UI design is hard.I like the touchscreen interface on my RTB2004, but I'm also paying appropriately for the quality.

author: nctnico
author_rank: Super Contributor
timestamp: July 19, 2018, 07:37:16 pm
content: Quote from: bd139 on July 19, 2018, 06:07:54 pmI disagree with you. I'm a product of the early 70's but I like touch screens IF the UI has been designed for a touch screen. Slapping a touch screen onto a UI designed for a mouse is a recipy for dissaster. However if you look at the MicSig tBook and R&S RTB2000/RTM3000 then the touch screen makes a lot of sense because the UI has be optimised for it. On the R&S scopes the physical buttons are kinda redundant.

author: David Hess
author_rank: Super Contributor
timestamp: July 19, 2018, 07:39:24 pm
content: A lot of interfaces suffer that fate when they move into the larger consumer space. We face theEternal Septemberof test equipment. HP was just tragically ahead of their time being courageous.Yes, I just compared Rigol and Apple to AOL.Quote from: Fungus on July 19, 2018, 12:17:13 pmDoesn't interface design fall under human factors engineering? Wasn't there a classic book written on the subject?Microsoft and Apple have been throwing a lot of basic interface principles under the bus for the sake of unifying desktop and portable interfaces. This was just a bad idea and they should feel bad for attempting it.Apple had already lost the desktop market so they had nothing to lose but Microsoft tried to use their desktop dominance to leverage a position in portable devices. That was great for a majority of new consumers but it sucks for people who want to get actual work done and I expect eventually that part of the market to split off and tell Apple and Microsoft to fuck off. They certainly are not going to release an interface catering to these people despite them encompassing the entire desktop/workstation using population for a long time.Quote from: Mr. Scram on July 19, 2018, 07:10:14 pmOddly enough, I know how to slap a working bridge together with common sense. Masonry does not produce an efficient bridge but that is why the Romans were able to do it without engineering. Modern engineering is about building efficient structures and the same might be said about modern product design but efficient for whom?I laugh now every time I see some product with a stylishly curved enclosure. That is code for "don't stack this because our thermal engineering sucks".

author: Mr. Scram
author_rank: Super Contributor
timestamp: July 19, 2018, 08:02:28 pm
content: Obviously completely off-topic, but what makes you think Romans didn't engineer their structures? Things like aqueducts are actually remarkably efficient considering the available technology at the time, although they also developed various technologies we still use or use again today. Concrete is a well known example of an invention lost to time and reinvented later. They may not have know how to calculate things like we do today, but they certainly had a more than trivial understanding of how forces are distributed in structures and how different materials react to pressure and tension.

author: nctnico
author_rank: Super Contributor
timestamp: July 19, 2018, 08:07:06 pm
content: Quote from: David Hess on July 19, 2018, 07:39:24 pmHold your horses here. I'm very sure the Romans used engineering (=math + limits based on materials testing) to build their buildings. Unfortunately very little of the knowledge has been preserved so what we are left with are a huge amount of buildings. There are lots of buildings from the Roman era which still stand today and that is not by chance. Some still hold world records for their size and type of construction.

author: David Hess
author_rank: Super Contributor
timestamp: July 19, 2018, 08:26:45 pm
content: Masonry is one of the few examples of a building material which can be used to scale up structures without regard to the square-cube law because it is orders of magnitude stronger in compression than its crush limit. So the Romans did not need to know how masonry reacts to pressure; they could build a model and scale up. But this same construction technique is inefficient which is why Roman structures lasted so long.They figured out how to keep the center of gravity within their structures by trial and error like the Egyptians figured out theunstable slope angle. No engineering was needed.

author: Mr. Scram
author_rank: Super Contributor
timestamp: July 19, 2018, 08:46:54 pm
content: Quote from: David Hess on July 19, 2018, 08:26:45 pmYou do need to understand how forces work to make arches work, especially when used in large numbers next to each other. There are some very amusing Gothic churches that show what happens when the understanding isn't quite right, and quite a few more that didn't survive. Of course, Romans also built with marble, concrete and various other materials. The Roman waterworks also involved a lot more than just arches, including underground high pressure pipework. It's hard to overestimate their knowledge of materials and their application.Besides, building models is engineering too. Things like sky scrapers, racing cars and boat hulls are tested in model form today. Until very recently, this was pretty much the only way to do it.

author: David Hess
author_rank: Super Contributor
timestamp: July 19, 2018, 09:56:51 pm
content: Quote from: Mr. Scram on July 19, 2018, 08:46:54 pmOne of my mechanical engineering books has a great photograph of bent columns at Salisbury Cathedral; just looking at it makes my hair stand up. They got lucky.QuoteIt is different when you only have to worry about compression and your material of choice will never crush. That leaves keeping the center of gravity within the structural elements but the Romans never figured that out and limited themselves to arches (And domes? I forget but domes have their own problem.) which work great and scaling up models which works when crush strength is not an issue. You could build a sky scraper out of stone but it would be awfully heavy.

author: Mr. Scram
author_rank: Super Contributor
timestamp: July 19, 2018, 10:26:43 pm
content: Quote from: David Hess on July 19, 2018, 09:56:51 pmThey built domes for sure. The Pantheon is a massive concrete dome that stands until this day. It's was the largest dome in the world for 1300 years and it's still the largest unreinforced concrete dome in existence. They used different concrete mixes for different parts of the dome to optimize strength versus weight. It's also built progressively thinner as it gets taller, despite the inside being basically a perfect sphere and seemingly decorative patterns on the inside further lighten the dome without compromising strength.All this doesn't point towards and "build 'm heavy and build 'm high" approach. It suggests the builders were very aware of the fact that a heavy monolithic dome wouldn't survive and they expertly applied their knowledge to lighten the structure as much as was needed. Even if they got lucky, it shows that they were very much aware of the different structural properties of various materials.