Why would modern digital scopes only offer 2.5kpts memory depth? - Page 1
Forum section: electronics / testgear

author: Ecklar
author_rank: Regular Contributor
timestamp: January 16, 2015, 07:58:40 pm
content: Why do I still see numerous digital oscilloscopesthat cost more that $ 1000 US only offer2.5kpts memory depth? Yeah, TektronixIs one that comes to mind. When the Chinese easilyoffer 1,000,000 depth on scopes that costless that $ 400 and you can easily get 14M pointsOn Rigol for a little more.Memory must be one of the cheapest componentsof a system today. To the point where it's simply a commodity.And since the 2.5K scopesalready have memory in place then the softwareand system is set up for it. Is there somedisadvantage to having greater memory depthor is there some workaround so you canSo the same job without it?Why wouldn't Tektronix just add loads of memorywithout increasing costs and then addressthe market. Please don't tell me they'restupid…. Since I'd like to get the reasoning.

author: Howardlong
author_rank: Super Contributor
timestamp: January 16, 2015, 08:05:34 pm
content: I strongly suspect there are tens of thousands of these scopes used in universities across the world who have coursework attached to them.So whether it's natural attrition from studes blowing them up or just lecturers being too lazy to update the course work, there is still a market for these scopes.I still have one, it's been very good to me, but yes, I have better spec'd units too now.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 16, 2015, 08:19:36 pm
content: Quote from: Ecklar on January 16, 2015, 07:58:40 pmThe Teks aren't "modern" - they are archaic designs that Danaher are tyring to squeeze the last drop out of whilst the competition have been pissing all over them at the low end for years.If they didn't have the Tek name they'd have been toast long ago.

author: jadew
author_rank: Frequent Contributor
timestamp: January 16, 2015, 08:22:02 pm
content: Quote from: mikeselectricstuff on January 16, 2015, 08:19:36 pmWas about to say the same thing but you beat me to it.They don't care about the low end market so they don't put any effort in updating these outdated designs, they will eventually stop selling - if they didn't stop already.

author: electr_peter
author_rank: Unknown
timestamp: January 16, 2015, 08:25:36 pm
content: QuoteBecause they are not modern in a real sense.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 16, 2015, 08:39:15 pm
content: Quote from: jadew on January 16, 2015, 08:22:02 pmThough I wonder how many scops Rigol has to sell to make the same profit as Tek make when some mug buys a TBS series...

author: pickle9000
author_rank: Super Contributor
timestamp: January 16, 2015, 08:49:52 pm
content: Quote from: mikeselectricstuff on January 16, 2015, 08:39:15 pmTequipment said in one post 200pcs ds1054z coming in just after the new year (regular order size?). They are consistently sold out and about 3 weeks between restocking. No idea on the margin on these but if they can get them into the educational market they will make a killing in a few years.

author: nowlan
author_rank: Frequent Contributor
timestamp: January 17, 2015, 02:11:09 am
content: Is the 2.5k not tied to their fpga ram?

author: EEVblog
author_rank: Unknown
timestamp: January 17, 2015, 05:29:39 am
content: They are not modern, they are based on 20yo architecture.That "Danaher Way" is to extract every last cent out of every product until it can milk no more.

author: devanno
author_rank: Regular Contributor
timestamp: January 17, 2015, 06:00:54 am
content: In addition to the comments about the logical age of the Tek o'scopes, etc. The more memory you have, the more processor cycles it takes to keep it refreshed. Older designs may just not have the bus nor bandwidth in the processor to update and process all those memory points. Look at what happens to your sample rate as you increase memory depth, and you'll see what I mean.

author: Howardlong
author_rank: Super Contributor
timestamp: January 17, 2015, 02:30:05 pm
content: I do wonder how much Tek, Agilent, LeCroy etc actually care about a segment of the market that's under $2,000, and why should they?In real terms accessiblity to an oscilloscope has never been so good. I know that there was no way I could justify purchasing a new scope 20 years ago at that time in my career or bearing in mind how much they cost in real terms back then. Blimey, I remember buying my own TDS2024 ten years ago for £1,800, that hurt.

author: coppice
author_rank: Super Contributor
timestamp: January 17, 2015, 02:34:27 pm
content: Quote from: EEVblog on January 17, 2015, 05:29:39 amIts often a requirement from their customer, especially defence customers. "Parts must be available for XXX years" is a common requirement in big supply contracts, but "Further new units must be available for XXX years" is also a common requirement. They want to be able to get people used to one model, and have it ingrained in their manuals.

author: coppice
author_rank: Super Contributor
timestamp: January 17, 2015, 02:38:03 pm
content: Quote from: Howardlong on January 17, 2015, 02:30:05 pmVolume. The high end of their range is the one they are always questioning. They rarely produce the most extreme product that they could, because the volume would be so low they'd never be able to set a realistic price that would let recover their NRE.

author: MarkL
author_rank: Unknown
timestamp: January 17, 2015, 03:17:45 pm
content: Quote from: nowlan on January 17, 2015, 02:11:09 amLike the TDS3000 series with its 10k pts, I believe the TDS2000 with 2.5k pts uses the same technology, but is reduced in size for cost saving.They use a technology called "Fast In Slow Out" (FISO) which uses a CCD to gather analog data at high speed and then digitizes it during a slower read-out phase after the acquisition is complete. So there is no FPGA or high speed acquisition RAM like you would find on a modern scope. The CCD is also what gives these scopes more noise and significant warm-up drift.EDN article with a little more detail:http://www.edn.com/electronics-products/other/4316014/Popularly-priced-DSOs-aim-to-outsell-market-leaderTek has a some patents on the technology dating from the mid 90's: 5,321,656 and 5,200,983 and I'm sure there are others.A breakthrough 20 years ago. But really. It needs to go away now.

author: Pjotr
author_rank: Frequent Contributor
timestamp: January 17, 2015, 03:51:36 pm
content: Quote from: coppice on January 17, 2015, 02:34:27 pmDuh...Not with Tek. I was planning a new lab set up and new scopemeters for the service department in the beginning of 2000. Invited Tek to what they had to offer and asked for after life support. There wasn't anything at all! When the product goes out of production, servicing by Tek stopped as wellThat alone was reason to leave Tek for what it was and moved to Fluke.

author: coppice
author_rank: Super Contributor
timestamp: January 17, 2015, 04:06:24 pm
content: Quote from: Pjotr on January 17, 2015, 03:51:36 pmYou just weren't significant enough to get their attention. Buy a lot of one model and they will keep it available, either just for you or for everyone. Governments are usually the only buyers big enough to get this kind of treatment.

author: Pjotr
author_rank: Frequent Contributor
timestamp: January 17, 2015, 04:18:14 pm
content: Yes, modern times with old performanceandprice tags

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: January 17, 2015, 07:33:38 pm
content: Quote from: Howardlong on January 17, 2015, 02:30:05 pmOh, they do. ForAgilentKeysight the entry level is very important, they make good money not because the profit per scope is high but because of the numbers they shift. These scopes are also used as a vehicle to bring the name (which recently changed for a second time) out there (a problem that Tek doesn't have to the same extend), and if Keysight scopes are almost omni-present including in schools then chances are that they will be the vendor to go for new purchases.LeCroy has had entry level scopes since the late 90's. LeCroy also saw them as a vehicle to get their name out more, but (unlike Agilent/Keysight) LeCroy never considered the low end market relevant enough to justify more serious investments. Therefore all their entry level scopes were (and still are) simple rebadge jobs. Their first one (LightRunner LP) was an Iwatsu rebadge, as was the later WaveJet 300/300A Series. Because these scopes are pretty expensive, in around 2009 LeCroy decided to also rebadge some Siglent low end scopes (sold as 'WaveAce'). While the Iwatsu rebadges were good although basic and very expensive scopes, the Siglent rebadge didn't go down that well as these scopes suffered from very embarrassing firmware problems of which many never were fixed (typical Siglent), and lead to quite a few angry customers.Tek, well, they know that they do still have a very big advantage which is their name (HP was well known but with two subsequent name changes getting their name 'stuck' is more difficult, and LeCroy is really only a name for high end scopes), and for the last ten years or so they're milking this advantage out by flogging off outdated designs, which as Dave says is typical for a Danaher company. The only problem for Tek is that the later generation of EE's hasn't grown up with the fond memory of Tek's glory days of yesteryear, so they have to convince with their products (which at least for scopes are overwhelmingly rather poor).QuoteIndeed. And thanks to high integration and cheap processing you get quite a lot even in a typical entry level scope like the DS1000z these days.

author: edavid
author_rank: Super Contributor
timestamp: January 17, 2015, 08:09:26 pm
content: Quote from: MarkL on January 17, 2015, 03:17:45 pmThat article is just Agilent FUD. Has Tektronix ever said that they still use a FISO architecture? Who would they get to fab the chips? No one has a non-sensor CCD process any more.

author: coppice
author_rank: Super Contributor
timestamp: January 17, 2015, 08:13:11 pm
content: Quote from: Wuerstchenhund on January 17, 2015, 07:33:38 pmPeople keep saying that, but isn't LeCroy still a major owner of Iwatsu? These things seem more like actual LeCroy products.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: January 17, 2015, 09:11:16 pm
content: Quote from: coppice on January 17, 2015, 08:13:11 pmLeCroy was never an owner of Iwatsu. They once invested a large sum when LeCroy choose them to produce the WaveRunner(2) LT and WavePro 900 Series (both built by Iwatsu but designed by LeCroy). They also allowed Iwatsu to sell the WaveRunner(2) LT as Iwatsu scope in Japan while LeCroy sold it as their own in the rest of the world (a similar deal is now going on with Siglent and the SDS3000 aka WaveSurfer 3000).LiteRunner and WaveJet are designed by Iwatsu, not by LeCroy. The firmware is also made by Iwatsu. This also shows in the general scope layout and the menu structure, which is clearly different from LeCroy-designed scopes (which, for example, all have the horizontal controls on the left, not on the right).The Iwatsu partnership still continues, although for one scope in the entry level only (the 'new' WaveJet 300T is another Iwatsu rebadge). For mid-range and high-end it stopped with the introduction of the X-Stream scopes (WaveMaster 8000, WavePro 7000, WaveRunner 6000, which came out between 2001 and 2003).

author: wreeve
author_rank: Unknown
timestamp: January 17, 2015, 09:50:40 pm
content: To be fair to Tektronix....I don't see a "Tektronix jitter problem / ac couple problem" thread on here!

author: MarkL
author_rank: Unknown
timestamp: January 18, 2015, 11:22:51 pm
content: Quote from: edavid on January 17, 2015, 08:09:26 pmIf you like, here's another article that's less fuddy:http://www.edn.com/electronics-news/4362126/Leading-Edge-4362126But, point taken that there's no explicit information what Tek is using today.I would think, however, Tek didn't invest the resources to re-architect the entire acquisition portion of their ASIC in these TDS models, such as in their jumps from plain to B to C version in the TDS3k. If they did they would at least give it more memory. The acquisition specs for these units have been unchanged for the last 20 years. Another clue is that they all lack high resolution (boxcar averaging) which is another feature that can't be done with their CCD architecture.What is it about a non-sensor CCD process that a contract fab couldn't do for Tek?

author: edavid
author_rank: Super Contributor
timestamp: January 18, 2015, 11:35:10 pm
content: Quote from: MarkL on January 18, 2015, 11:22:51 pmThere aren't really contract fabs, only foundries. A foundry wouldn't develop a new CCD process (or any process) just for Tek, because it wouldn't be cost effective. It would be much cheaper to design a flash ADC + SRAM front end in a normal logic process.

author: EEVblog
author_rank: Unknown
timestamp: January 19, 2015, 12:04:15 am
content: Quote from: edavid on January 17, 2015, 08:09:26 pmIf they aren't then there is absolutely no reason to have the exact same 2.5KB memory as used 20 years ago.Rumor has it have have huge stockpiles of those old chips.

author: edavid
author_rank: Super Contributor
timestamp: January 19, 2015, 12:16:38 am
content: Quote from: EEVblog on January 19, 2015, 12:04:15 amSo you are saying that they use 15 year old chips in new scopes? That doesn't really add up either.

author: aviphysics
author_rank: Contributor
timestamp: January 19, 2015, 02:23:47 am
content: Low end ought to be important, because it will play a role in what students get trained on. When students grow up and file requisition forms for new scopes, I bet a lot of them are buying the brand they used as students.I also bet that organisations ordering lots of units pay the list price.

author: EEVblog
author_rank: Unknown
timestamp: January 19, 2015, 02:39:41 am
content: Quote from: edavid on January 19, 2015, 12:16:38 amNope, more likely whenever the last buy was. Doesn't have to be 15 years ago.The problem with verification is that no one is dumb enough to buy one and tear it downHappy to be proven wrong of course, but in either case Tek look like fools. Either using 20yo tech in their latest scope, or designing new hardware and only giving it the same 2.5K memory.The thing is that 2.5K value, it just does not make sense using any modern design technology, you'd at least round it to 4K for example.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 19, 2015, 08:29:36 am
content: Quote from: edavid on January 19, 2015, 12:16:38 amWhy not ? If the process was going obsolete it is entirely reasonable they'd do enough wafers for foreseeable future production and then a few more for luck.Remember that a lot of the cost of a chip is packaging and test, and they only need to do this once they actually need the chips for production.

author: nfmax
author_rank: Super Contributor
timestamp: January 19, 2015, 09:31:55 am
content: Just a guess, but maybe, when Tek sold their fab (to Maxim, was it?) part of the deal was a commitment to buy some large, over-optimistic number of the chip in question?

author: nctnico
author_rank: Super Contributor
timestamp: January 19, 2015, 10:15:27 am
content: Quote from: EEVblog on January 19, 2015, 02:39:41 amI also find it hard to believe Tek still uses a 20 year old chip in a new scope. Even if the chips are 10 years old they are not getting better in storage. I'm more inclined to believe the 2.5k memory is a limit which is tied into the software. In a DSO the software development costs are easely 50 times higher than the cost of developing hardware so it pays off quickly to keep the software as it is.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 19, 2015, 10:30:18 am
content: Quote from: nctnico on January 19, 2015, 10:15:27 amLike I said, they probably don't store complete chips, with issues like solderability degredation, they store wafers, and package & test them as required.

author: coppice
author_rank: Super Contributor
timestamp: January 19, 2015, 10:34:09 am
content: Quote from: mikeselectricstuff on January 19, 2015, 10:30:18 amHow long can you store bare die before they start to degrade? The question doesn't often come up, as people don't usually want to store them this long.

author: Whales
author_rank: Super Contributor
timestamp: January 19, 2015, 10:45:18 am
content: Quote from: coppice on January 19, 2015, 10:34:09 amIt would be interesting to see how delicate they are to age. Chuck them in an esky with a nitrogen atmosphere? Does anyone know anything about end-wafer storage?

author: coppice
author_rank: Super Contributor
timestamp: January 19, 2015, 11:03:49 am
content: Quote from: Whales on January 19, 2015, 10:45:18 amhttp://www.micross.comspecialise is die banking, and claim "Bare die products can be safely stored for many years" with suitable storage in an inert atmosphere, but just how big is "many"?

author: ivan747
author_rank: Super Contributor
timestamp: January 19, 2015, 12:08:30 pm
content: That sounds like a question for Vincent a.k.a free-electron.

author: EEVblog
author_rank: Unknown
timestamp: January 19, 2015, 12:27:09 pm
content: Quote from: nctnico on January 19, 2015, 10:15:27 amThey wouldn't be 20 year chips, but the design dates back to the original TDS200 series from 20 years ago.IIRC is was the TDS200 series, then the TDS1000 series, then TDS1000B, then TDS1000C, and now this TBS1000, all with the same 2.5KB of memory.There might have even been revision of the chip somewhere along the line, but it still retained the internal fixed 2.5KB of sample memory.The TDS1000/B/C series scope are not that old in the scheme of things, so they must have been producing them until they released the TBS1000 at the end of 2012.QuoteAlmost certainly not. The TDS200 series very famously had 2.5KB of sample memory in the ASIC, it is a pure hardware limit, just like agilent have their sample memory in their Megazoom ASIC's and they can't increase it.QuoteAll evidence points toward them very substantially upgrading the processor and software O/S in the scope. From the 68000 in the old TDS200 to something new that can handle all the new features in the TBS, which are actually pretty extensive. Colour display, mask testing, educational info etc.It seems inconceivable that the 2.5KB limit is now a software limitaton when it's always famously been a front end sampling ASIC hardware limitation with the TDS200/1000 series scopes.

author: philpem
author_rank: Frequent Contributor
timestamp: January 19, 2015, 01:19:36 pm
content: Quote from: EEVblog on January 19, 2015, 12:27:09 pmI've been inside a TDS2000B - it's still a 68K CPU. Can't remember which one, though, sadly.Typical Danaher, milk it for all it's worth, and then milk it some more, watch it kick the bucket, then flog it a wee bit...