EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: NemoVanHelden on December 02, 2012, 09:41:26 pm
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Hi,
Thanks to the help from users in this forum i had decided to buy an Agilent DSOx2002A. While I`m waiting for the store to get a hold of one for me, i`ve been offered to buy the Tektronix TDS3052 used for a about 20% the cost of a brand new DSOx2002A. Now, this seems like a good deal since it has 500MHz BW (if it works that is). I still need some of the features of the Agilent though, so my question is if i should:
a) Get both. 500MHz could be nice to have for future use and the Agilent (70MHz) have some features the Tek doesn`t.
b) Get the Tek and a separate function generator and cancel the Agilent buy.
or
c) Get only the Agilent as i had decided to initially.
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A Tek TDS3052 for about $1K? :o
In that case:
d) Buy the Tek and then resell it on ebay for $3K+, thus getting yourself a new Agilent for FREE! + pocket money
Dave.
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I've got a TDS3034 and an MSOX3054A, among others. The Agilent pisses all over the tek in every way (update rate and user-friendliness primarily). I never thought I'd say that because I've always been a Tek man. The TDS3054 used to be my main scope, but now I hate it.
If you can afford both, get them both, but given the choice I'd go for Agilent plus function gen. As I always say, try them both on demo and make up your own mind!
Having said all that, a TDS3052 for 170 quid is bloody bloody bloody good, and I'd snap his hand off.
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I've got a TDS3034 and an MSOX3054A, among others. The Agilent pisses all over the tek in every way (update rate and user-friendliness primarily). I never thought I'd say that because I've always been a Tek man. The TDS3054 used to be my main scope, but now I hate it.
To be fair, you're comparing the new Agilent to a Tek TDS series scope whose basic design and user interface is nearly a decade old. The TDS3000 series has been (and continues to be) so popular, even now, that Tek has been unable to discontinue it in favor of the newer DPO/MSO3000 series. The DPO/MSO series were designed to be the replacements of the older TDS series, but customers continue to buy the TDSs for some reason.
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I completely agree, you're absolutely right.
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A Tek TDS3052 for about $1K? :o
In that case:
d) Buy the Tek and then resell it on ebay for $3K+, thus getting yourself a new Agilent for FREE! + pocket money
Dave.
20% of ~1K is 200, sounds like a bargain to me if you can really sell it for 3K. :D
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20% of ~1K is 200, sounds like a bargain to me if you can really sell it for 3K. :D
Ah yes, but it's still a bargain at even $1K
Cheapest TDS3052 on ebay is $3800.
I'd try listing it at $2999 and see who bites.
I'd buy it for $1K without thinking, at $200 I'd take a hundred thanks!
You could easily sell it quick for $2K, more might take longer but someone will bite.
Dave.
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Once you've flipped the Tek as someone who went through this recently I'll throw in another vote for the Agilent.
Looked long and hard at 100Mhz 4ch scopes and in the end went with a DSOX-3014A and couldn't be happier. Quite a few things in the DSOX's favor:
- Free WaveGen, I really can't say how awesome this is
- 4 G/s sample rate
- High res mode
- Easy upgrade to 200Mhz/MSO w/ software key
I feel like the DSOX-2014A would have worked as well but I wanted the AWG and 2M samples.
Dave's reviews on both series were spot on as well, absolutely love the scope.
Keep in mind that when you shop around don't expect to pay list for new. I walked out the door for just $3k before taxes.
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Thanks for all the inputs and good advice guys. Unfortunately, the seller gave the wrong model info (which explains the extremely good price). Anyway, my Agilent DSoX2002A is now on the way and I`m really looking forward to getting my hands on it. It was a bit more expensive than i had initially planned, but I guess I`ll just call it an early christmas present to myself ;D
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I can tell you why people continue to by TDS series oscilloscopes, it is because they changed the probe interface, to use your old differential probes current probes etc with the newer scopes you have to by an insanely expensive adapter, or buy new probes, even more insanely expensive. Some companies like the one I work for have a a fortune invested in probes that they would like to continue to use.
You could by Agilent scopes instead because they have an adapter for older Tektronix probes that is actually cheaper than Tektronix own adapter!
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- Easy upgrade to 200Mhz/MSO w/ software key
It's probably just me, but I'd flatly refuse to buy any product that pulls this stunt. Hardware with X capability, but the software is crippled to something less, then you have to pay money to have it work the way it was originally designed to. It's plain dishonest and insulting, and I won't stand for it.
Not to mention that even making a scope that isn't 500MHz bandwidth these days is an exercise in deliberately crippled capabilities. And useless for most modern digital logic work.
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Not to mention that even making a scope that isn't 500MHz bandwidth these days is an exercise in deliberately crippled capabilities. And useless for most modern digital logic work.
So you think every scope on the market should be 500MHz bandwidth huh?
Then please explain:
a) Why quite a few scope makers don't even offer a 500Mhz bandwidth scope.
b) Why the likes of Agilent (and others) have physically different bandwidth front ends in their scopes. i.e you cannot software upgrade the 200MHz model to the 350Mhz or 500MHz model for example. They use physically different front ends. Why do you think that is?
Dave.
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He must not have a HDTV or cellphone either, both of which have crippled functions unless you pay the fee to unlock them. TV the ability to have the audio split out to allow external DAC's or a second video output stream, and the cellphone wireless tethering turned off in firmware unless you pay extra per month.
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Not to mention that even making a scope that isn't 500MHz bandwidth these days is an exercise in deliberately crippled capabilities. And useless for most modern digital logic work.
So you think every scope on the market should be 500MHz bandwidth huh?
Then please explain:
a) Why quite a few scope makers don't even offer a 500Mhz bandwidth scope.
b) Why the likes of Agilent (and others) have physically different bandwidth front ends in their scopes. i.e you cannot software upgrade the 200MHz model to the 350Mhz or 500MHz model for example. They use physically different front ends. Why do you think that is?
Dave.
The point I'm trying to make, is that present day sampling technology allows at least 500MHz to be done cheaply enough that it could easily be incorporated in even cheap scopes - if they wanted to. That 100MHz scopes are even available from the like of Tek and HP, is more the result of them wanting to maintain a 'price/feature' scale that maintains a large price difference across their range. For the purpose of retaining a seeming justification for the medium to high prices. It's a pricing spectrum solely driven by marketing considerations, not actual engineering and manufacturing cost factors.
Sure, they're in business to make a profit. But when they push that to the extent of getting outright extortionist
(performance unlocking via software keys) and deliberately making inferior front ends just to preserve a market illusion that better ones are significantly more costly, then I'm out.
The same practices occur in Tek's TLA logic analyzers. Speed and memory 'upgrades' that are just performance unlocking keys. It's a really evil practice in my opinion.
As for smaller manufacturers with only low-end scopes - sure, so they either don't know how to do things like stripline ICs with GaAs samplers or whatever, or they can't do it because of patent restrictions. But this isn't relevant to what larger test equipment companies could do if they weren't so 100% focused on gouging maximum dollars from their customers. By maintaining artificial 'low end' capability limitations, among other practices.
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He must not have a HDTV or cellphone either, both of which have crippled functions unless you pay the fee to unlock them. TV the ability to have the audio split out to allow external DAC's or a second video output stream, and the cellphone wireless tethering turned off in firmware unless you pay extra per month.
Well, yes and yes. But for other reasons mainly. No HDTV because I lost interest in watching broadcast/cable TV programming years ago. Wasn't even aware the 'software crippling' poison had crept into TVs.
Cell phones - still use a very old one, mainly due to a philosophical position related to avoiding distraction from the real world when I'm out in it. I simply choose not to become part of the 'constantly engrossed in the little screen' syndrome. And yeah, my old Nokia is no longer locked to a particular carrier.
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The point I'm trying to make, is that present day sampling technology allows at least 500MHz to be done cheaply enough that it could easily be incorporated in even cheap scopes - if they wanted to.
Please explain why the cheap scope makers don't do that, if it's so cheap and easy. Why don't they have 500MHz and really blow the others out of the water?
That 100MHz scopes are even available from the like of Tek and HP, is more the result of them wanting to maintain a 'price/feature' scale that maintains a large price difference across their range. For the purpose of retaining a seeming justification for the medium to high prices. It's a pricing spectrum solely driven by marketing considerations, not actual engineering and manufacturing cost factors.
I've mentioned this before.
It takes a massive amount of engineering to develop new scope technology like the Agilent 2000X/3000X for example.
If they gave all the full functionality at the lowest possible price point then they would go out of business. The result? No more scope innovation.
Innovation costs money.
They have to make the higher margins on the higher end units (in different market segments) so they can make big enough profits to keep the company afloat ad to be able to afford offering innovative technology at the low end, and keep the R&D innovation happening.
You might not like it, but it's a simple business fact.
As for smaller manufacturers with only low-end scopes - sure, so they either don't know how to do things like stripline ICs with GaAs samplers or whatever, or they can't do it because of patent restrictions.
They can't do it because it takes massive money and R&D resources to do it. Guess were the money comes from to do that?
Dave.
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The point I'm trying to make, is that present day sampling technology allows at least 500MHz to be done cheaply enough that it could easily be incorporated in even cheap scopes - if they wanted to.
Please explain why the cheap scope makers don't do that, if it's so cheap and easy. Why don't they have 500MHz and really blow the others out of the water?
Where did I say it was easy? I'm saying specifically that bandwidths in the 500Mhz range are something the large instrument makers learned how to do cheaply long ago, even in digital scopes. In fact _especially_ in digital scopes since the high bandwidth stuff is confined to the input sampling circuits, not required all the way through to a screen. There's little 'research investment' required for this kind of capability, the sampling technology is well established and the rest of a digital scope is just a PC and LCD screen. There's nothing needed but industrial case style design.
Which they _still_ tend to stuff up - for instance one of those 'lunchbox' Tek scopes I used for work a while ago, in which the screen backlight CCFL tube and inverter circuits seemed to be completely unshielded behind the plastic fascia, resulting in the scope itself emitting a severe EM ~40KHz smog that made it impossible to work on millivolt-level analog circuits within a few feet of the scope.
Anyway, to answer your question 'why don't they do it?' it's simple. If they marketed a 500MHz scope for under $1000, about 90% of their customers would buy that, and there'd be a huge hole in their pricing structure. Few would buy anything in the $1000 to $10,000 range, unless they also lowered prices on GHz scopes down into that range. Yes, that would really hurt their profit margin.
But nonetheless, a 500MHz scope these days is no harder to make than a low-end laptop. So why don't they cost about the same? For the same reason as Apple products are overpriced - because they can get away with charging more.
That 100MHz scopes are even available from the like of Tek and HP, is more the result of them wanting to maintain a 'price/feature' scale that maintains a large price difference across their range. For the purpose of retaining a seeming justification for the medium to high prices. It's a pricing spectrum solely driven by marketing considerations, not actual engineering and manufacturing cost factors.
I've mentioned this before.
It takes a massive amount of engineering to develop new scope technology like the Agilent 2000X/3000X for example.
If they gave all the full functionality at the lowest possible price point then they would go out of business. The result? No more scope innovation.
Innovation costs money.
You're distorting my argument, to make it invalid. I didn't say 'full functionality at lowest possible price'. That makes it sound like I was saying there should be 20GHz scopes for $500. But what I said was, companies like Tek & HP, that have fully mastered the technology of high bandwidth scopes, only offer scopes under 500MHz as an artificial way of maintaining a wider price spectrum. They _could_ just drop that pretense, and offer scopes of 500MHz (at least) as their low cost low end models. If they wanted to.
They have to make the higher margins on the higher end units (in different market segments) so they can make big enough profits to keep the company afloat ad to be able to afford offering innovative technology at the low end, and keep the R&D innovation happening.
You might not like it, but it's a simple business fact.
I'm not complaining (much) about the cost of high end scopes. Sure, the R&D costs there may be horrific. But on that topic, I noticed you reviewed a.. what was it? 15GHz Tek scope, that cost $40K? (I may be misremembering the figures.)
[Edit: found it again: www.youtube.com/watch?v=ZOurdJomEoc (https://www.youtube.com/watch?v=ZOurdJomEoc#ws) 13GHz, $140K. I was way off!]
But I have a 20GHz HP 4 channel digital scope (with 20GHz TDR no less) that was made around 1987. 25 years ago! So I tend to think the claims of 'ongoing R&D costs' may be a bit overblown at that end of the price structure also. After all, the only part that needs real R&D is the sampling head; the rest is just pretty standard PC architecture and some Windows software application development.
As for smaller manufacturers with only low-end scopes - sure, so they either don't know how to do things like stripline ICs with GaAs samplers or whatever, or they can't do it because of patent restrictions.
They can't do it because it takes massive money and R&D resources to do it. Guess were the money comes from to do that?
Yes, we all know small dodgy companies aren't capable of doing it, though it's often only because they can't license the patents. But those 'massive money & R&D resources' also don't have to be applied over and over, to achieve the same low end scopes year after year, for decades. The pricing structures of the large scope makers are a kind of insult to the intelligence of buyers, in that they imply we should believe there is such a need for continued high cost R&D to produce low end scopes.
Or, are you saying it's reasonable to use low end scope sales (at artificially high prices) to subsidize the R&D for high end scopes? It sounds like you are.
Then there's several other cans of worms such as the destruction of traded-in equipment, to maintain market price/demand for new models. And the whole 'restricted technology' pile of garbage, wherein high end gear is only available to 'approved customers' - ie those who can be trusted/watched to be sure they don't use it for things like DRM circumvention. But don't get me started on that. <CPU emulators, grumble grumble...>
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That is why I use Linux...........
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Of course, so you are saying that a 4GS ADC doesn't cost much eh? You must really consider what goes into a 500GHz scope. 4GS ADCs don't come cheap
It's not about the marketing, it's about the raw costs. 4GS ADCs the last time i've seen the prices is actually more than the prices the scopes are going for ...
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Of course, so you are saying that a 4GS ADC doesn't cost much eh? You must really consider what goes into a 500GHz scope. 4GS ADCs don't come cheap
It's not about the marketing, it's about the raw costs. 4GS ADCs the last time i've seen the prices is actually more than the prices the scopes are going for ...
500MHz, not 500GHz, I'm sure you meant.
You do realize that digital scopes don't work like audio digitizers, and don't try to always sample sequentially along a single shot waveform, right? They end up working this way at low frequencies, but not at higher frequencies. This is something that distinguishes the really high end scopes from the cheap ones - how fast a single shot waveform can the scope capture. Cheap ones don't even try to do single shot capture at anything like their stated bandwidth, and those are the ones I'm talking about.
The bandwidth a digital scope achieves, depends on the narrowness of the S+H capture circuit and the time resolution by which the sample point can be scanned relative to the trigger point, not the duration of the subsequent AtoD conversion. The sample points are scanned along the waveform relative to the trigger point over many cycle times. Yes, it's nice to get the conversion cycle time as short as possible, since the shorter that can be made, the fewer cycles of the source waveform are required to build up a reliable picture of the waveform.
But for repetitive signals, it really doesn't matter what the AtoD conversion time is, relative to the signal frequency. Only the sample window width and it's positioning accuracy matter.
Did you imagine that a (say) 20GHz digital scope has an 80GHz AtoD?
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Where did I say it was easy? I'm saying specifically that bandwidths in the 500Mhz range are something the large instrument makers learned how to do cheaply long ago, even in digital scopes.
And you know the actual price of doing these front ends, how exactly?
If you are right, then please explain why Agilent have entirely different front ends for the 100-200MHz models, and the 350MHz-500MHz models.
And this is the company that is really milking these software options to the max.
If they could afford to put the 500MHz front end in the 100MHz, don't you think they would have done that? Instead of making you send the thing back to the factory for a mother replacement?
In fact _especially_ in digital scopes since the high bandwidth stuff is confined to the input sampling circuits, not required all the way through to a screen. There's little 'research investment' required for this kind of capability, the sampling technology is well established and the rest of a digital scope is just a PC and LCD screen. There's nothing needed but industrial case style design.
Err, it's the front end attention, protection, amplification, and noise floor over bandwidth that is the hard part!
Anyway, to answer your question 'why don't they do it?' it's simple. If they marketed a 500MHz scope for under $1000, about 90% of their customers would buy that, and there'd be a huge hole in their pricing structure.
You missed the entire point. See question above about why the 100MHz model does not have the 500MHz capability.
That 100MHz scopes are even available from the like of Tek and HP, is more the result of them wanting to maintain a 'price/feature' scale that maintains a large price difference across their range. For the purpose of retaining a seeming justification for the medium to high prices. It's a pricing spectrum solely driven by marketing considerations, not actual engineering and manufacturing cost factors.
Yes, but that does NOT extend to 500MHz like you have claimed is cheap to do. In the case of the Agilent for example, that is only true up to 200MHz. The 70MHz and 100MHz are software crippled.
It costs a lot more to do a 500MHz than it does to do a 200MHz front end, which is why they physically put different front ends in the thing and charge a lot more for it.
And once again, you are not factoring in the profit they have to make to recoup the large R&D expenditure to develop these scopes.
You have no idea how much they are making on the baseline units for example. Would that alone be enough to keep the company afloat and innovating?
If the answer is yes, then you may have a valid point. But if it's not enough, and they are relying on the larger profit margins from the higher end models, then you are wrong.
You're distorting my argument, to make it invalid. I didn't say 'full functionality at lowest possible price'. That makes it sound like I was saying there should be 20GHz scopes for $500. But what I said was, companies like Tek & HP, that have fully mastered the technology of high bandwidth scopes, only offer scopes under 500MHz as an artificial way of maintaining a wider price spectrum. They _could_ just drop that pretense, and offer scopes of 500MHz (at least) as their low cost low end models. If they wanted to.
Sure, but can they do it at an affordable and sustainable price?
Do you have inside info on the numbers?
The 500MHz front end cost them more than the 200MHz front end, and that's a fact.
Or, are you saying it's reasonable to use low end scope sales (at artificially high prices) to subsidize the R&D for high end scopes? It sounds like you are.
How do you know the prices are "artificially" high? Do you have numbers to back that up?
Then there's several other cans of worms such as the destruction of traded-in equipment, to maintain market price/demand for new models.
You'll get no argument from me there.
I have video footage of a whole bunch of nice scopes that must be destroyed by order of De Führer >:(
Dave.
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But nonetheless, a 500MHz scope these days is no harder to make than a low-end laptop. So why don't they cost about the same? For the same reason as Apple products are overpriced - because they can get away with charging more.
How many laptops do the big laptop manufacturers like HP, Dell and Apple sell compared to the number of scopes Agilent, Tektronix or Rigol sell? How many CPUs does Intel sell compared to the number of ASICs Agilent uses, or the number of specialty ADCs National sells?
I'm not complaining (much) about the cost of high end scopes. Sure, the R&D costs there may be horrific. But on that topic, I noticed you reviewed a.. what was it? 15GHz Tek scope, that cost $40K? (I may be misremembering the figures.) But I have a 20GHz HP 4 channel digital scope (with 20GHz TDR no less) that was made around 1987. 25 years ago! So I tend to think the claims of 'ongoing R&D costs' may be a bit overblown at that end of the price structure also.
The Agilent 90000 series scope you're probably referring to is a real-time oscilloscope with 40 GS/s of sampling rate (13 GHz single shot bandwidth) and 1 Gpoints of memory. This is a huge leap from a 20 GHz digital sampling oscilloscope with a single shot bandwidth in the kHz. Good luck using that for capturing and decoding a fast serial data stream (which is about all these scopes are used for).
You do realize that digital scopes don't work like audio digitizers, and don't try to always sample sequentially along a single shot waveform, right? They end up working this way at low frequencies, but not at higher frequencies. This is something that distinguishes the really high end scopes from the cheap ones - how fast a single shot waveform can the scope capture. Cheap ones don't even try to do single shot capture at anything like their stated bandwidth, and those are the ones I'm talking about.
Almost all of the cheap 100 MHz scopes (eg. Rigol, Owon, Hantek) have a sampling rate of 1 GS/s, and are capable of single shot captures at that their rated bandwidth. Even the nineties-era Tektronix low-end lunchbox scopes could do that. Equivalent time sampling introduces its own set of issues. For example the (extremely common) serial data use case, which is not a repetitive signal.
Did you imagine that a (say) 20GHz digital scope has an 80GHz AtoD?
No, it will have a ~ 45 GS/s (example (http://www.tek.com/datasheet/oscilloscope/dpo70000-dsa70000-mso70000-digital-and-mixed-signal-oscilloscopes)) sampling rate. They can get away with less than 4-10x oversampling because the front-end has a much steeper roll-off ('brick wall' or maximally flat response). See the first few pages of this Agilent appnote (http://cp.literature.agilent.com/litweb/pdf/5989-5732EN.pdf) for more details.
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Of course, so you are saying that a 4GS ADC doesn't cost much eh? You must really consider what goes into a 500GHz scope. 4GS ADCs don't come cheap
It's not about the marketing, it's about the raw costs. 4GS ADCs the last time i've seen the prices is actually more than the prices the scopes are going for ...
It's not just the ADC. In fcat you can argue it's not the ADC at all...
Take the Agilent X series for example. They use the same ADC in their entire range from the $1K 70MHz X model through to the $12K 500MHz model, and likely the 1GHz model as well. So it seems that they can afford to put the same ADC in all the models.
But they don't do the same thing with the front end. They have three different front end circuits, 200MHz, 500MHz, and 1GHz. I wonder why...
Dave.
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Almost all of the cheap 100 MHz scopes (eg. Rigol, Owon, Hantek) have a sampling rate of 1 GS/s, and are capable of single shot captures at that their rated bandwidth. Even the nineties-era Tektronix low-end lunchbox scopes could do that. Equivalent time sampling introduces its own set of issues. For example the (extremely common) serial data use case, which is not a repetitive signal.
The 1996 Era Tek TDS200 scopes stared the "real-time" sampling rate trend.
The first low end player to do it was Rigol in 2004.
Ever since then almost every scope on the market worth anything, even at the low end, has used real time sampling rate. i.e. >4-5 times the bandwidth.
TerraHertz's comment that low end scopes use repetitive sampling is nearing a decade out of date!
Dave.
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And you know the actual price of doing these front ends, how exactly?
No more than you do. Which is, not at all. I'm just going by what I've seen of how scope front ends work - programmed attenuator, protection, buffer, sampler, AtoD. This is such old, well established technology, and with stripline ICs and VLSI can be miniaturized so small and made so standard, that it _should_ be cheap.
And yet Tek, Agilent etc claim it isn't. We can't know their true costs, I'm just saying I don't believe they justify their low end scope pricing stuctures.
If you are right, then please explain why Agilent have entirely different front ends for the 100-200MHz models, and the 350MHz-500MHz models.
My point is that they're choosing to make the lowest end one, solely to justify the higher price of the next model up the scale. You can't argue against that by pointing out that they produce the two versions. Ultimately, neither of us can prove our opinions are true though.
And this is the company that is really milking these software options to the max.
Thus demonstrating their tendency to dishonest pricing structures.
If they could afford to put the 500MHz front end in the 100MHz, don't you think they would have done that? Instead of making you send the thing back to the factory for a mother replacement?
We're going round in circles here. No, they wouldn't, because it would reveal that they _could_ do 500MHz for less, thus pulling their whole pricing scale lower.
In fact _especially_ in digital scopes since the high bandwidth stuff is confined to the input sampling circuits, not required all the way through to a screen. There's little 'research investment' required for this kind of capability, the sampling technology is well established and the rest of a digital scope is just a PC and LCD screen. There's nothing needed but industrial case style design.
Err, it's the front end attention, protection, amplification, and noise floor over bandwidth that is the hard part!
All of which is necessarily confined to a little block of a few cubic cm behind the BNC connectors, and a design which for basic scopes does not need to be changed for years, regardless of how much they choose to mess with the overall scope packaging and UI.
That 100MHz scopes are even available from the like of Tek and HP, is more the result of them wanting to maintain a 'price/feature' scale that maintains a large price difference across their range. For the purpose of retaining a seeming justification for the medium to high prices. It's a pricing spectrum solely driven by marketing considerations, not actual engineering and manufacturing cost factors.
Yes, but that does NOT extend to 500MHz like you have claimed is cheap to do. In the case of the Agilent for example, that is only true up to 200MHz. The 70MHz and 100MHz are software crippled.
It costs a lot more to do a 500MHz than it does to do a 200MHz front end, which is why they physically put different front ends in the thing and charge a lot more for it.
And once again, you are not factoring in the profit they have to make to recoup the large R&D expenditure to develop these scopes.
And you're pretending that there's been any actual R&D needed in the last 10 years for any kind of scope below 500MHz. Are you serious? What R&D? They don't even have to develop the processor designs any more, since they are likely Intel PC reference designs, just adapted a little to fit the form factor. It's ALL just industrial design, making the boxes look nice, changing around the probe interface connectors, improving the software for waveform display.
"70MHz, 100MHz" Bah. If the people responsible for this insult were around 20 years ago, we'd have had to pay money to slide the "Full/20MHz" bandwidth switch on old analog scopes.
You have no idea how much they are making on the baseline units for example. Would that alone be enough to keep the company afloat and innovating?
If the answer is yes, then you may have a valid point. But if it's not enough, and they are relying on the larger profit margins from the higher end models, then you are wrong.
And neither do you. Also you're forgetting the 'make them cheaper and you'll sell more' rule. Not to mention other advantages to society if more people could afford basic electronic test equipment.
You're distorting my argument, to make it invalid. I didn't say 'full functionality at lowest possible price'. That makes it sound like I was saying there should be 20GHz scopes for $500. But what I said was, companies like Tek & HP, that have fully mastered the technology of high bandwidth scopes, only offer scopes under 500MHz as an artificial way of maintaining a wider price spectrum. They _could_ just drop that pretense, and offer scopes of 500MHz (at least) as their low cost low end models. If they wanted to.
Sure, but can they do it at an affordable and sustainable price?
Do you have inside info on the numbers?
The 500MHz front end cost them more than the 200MHz front end, and that's a fact.
How do you know? Also, even if it does, how could you know that the 500MHz version they make, wasn't deliberately targeted to a cost range, rather than designed to make it as cheaply as possible? Plus, what would be the volume savings if they were selling more of them due to NOT making the 200MHz one?
It's very naive to assume that corporations, even ones we as EEs instinctively want to support, never let their overriding imperative (maximizing profits) lead them into reasoning that is really quite evil on some levels.
Or, are you saying it's reasonable to use low end scope sales (at artificially high prices) to subsidize the R&D for high end scopes? It sounds like you are.
How do you know the prices are "artificially" high? Do you have numbers to back that up?
Sigh. No of course not. I'm presenting a line of reasoning, based on perceived actions (software crippled bandwidths, and that 200MHz scope models even exist so long after tech for much higher bandwidths should have become standard baseline products) that suggests the pricing structures are artificial.
Then there's several other cans of worms such as the destruction of traded-in equipment, to maintain market price/demand for new models.
You'll get no argument from me there.
I have video footage of a whole bunch of nice scopes that must be destroyed by order of De Führer >:(
Ouch. But I recall you telling me that kind of thing didn't happen in Australia; the reason there's little 2nd hand testgear available is just that out market is so much smaller. Nothing to do with significantly more insane rules/Führers here.
You should publish it, with names and addresses. But I guess you can't, or you would have already.
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It's not just the ADC. In fcat you can argue it's not the ADC at all...
Take the Agilent X series for example. They use the same ADC in their entire range from the $1K 70MHz X model through to the $12K 500MHz model, and likely the 1GHz model as well. So it seems that they can afford to put the same ADC in all the models.
See? A case of do the R&D once, use it for all models, then let the marketing dept decide the features vs pricing structure.
But they don't do the same thing with the front end. They have three different front end circuits, 200MHz, 500MHz, and 1GHz. I wonder why...
I'd guess the 1GHz version is 50 ohm? But for the high impedance ones, 200/500MHz, you keep arguing that because two different versions are made, that proves they have to do it that way.
Bear in mind that if they did try to maintain a pricing scale from 70/100/200/500 MHz while using the exact same input hardware for all, how long do you think they'd get away with it before customers became enraged?
You're the one with access to the guts of all these versions. Why don't you take photos of the input blocks for the 200, 500 and 1GHz versions, then think about what the relative manufacturing costs would be, roughly. Maybe I'm wrong, maybe the 500MHz version simply couldn't be made for a similar cost to the 200MHz one, no matter the volume production scaling. But I'd be surprised.
TerraHertz's comment that low end scopes use repetitive sampling is nearing a decade out of date!
Ha ha ha.. oh well, that's what I get for only being able to afford second hand gear.
It's true, I was not aware baseline scopes had gone to real time sampling right up to the full bandwidth.
Though still, in the case of high speed digital serial like USB, LPC, LVDS, SATA, etc, does anyone ever want to sample single shot waveforms? Thats what serial protocol analyzers are for, while scopes are for checking signal integrity, eye patterns and such. For which repetitive waveform sampling is fine.
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Thus demonstrating their tendency to dishonest pricing structures.
My point is that they're choosing to make the lowest end one, solely to justify the higher price of the next model up the scale.
...they wouldn't, because it would reveal that they _could_ do 500MHz for less, thus pulling their whole pricing scale lower.
For the purpose of retaining a seeming justification for the medium to high prices. It's a pricing spectrum solely driven by marketing considerations, not actual engineering and manufacturing cost factors.
They _could_ just drop that pretense, and offer scopes of 500MHz (at least) as their low cost low end models. If they wanted to.
It's very naive to assume that corporations, even ones we as EEs instinctively want to support, never let their overriding imperative (maximizing profits) lead them into reasoning that is really quite evil on some levels.
...suggests the pricing structures are artificial.
Not to mention other advantages to society if more people could afford basic electronic test equipment.
Typical socialist banter, especially the last one which is an absolute classic. "Isn't it terrible that the nasty evil corporations, who only exist to chase dollar signs, exploit overseas workers and destroy the environment, keep their prices deliberately high to prevent Africa developing..." or some such bollocks. The things are expensive, deal with it. And if you don't like their attitude, don't buy. Simple.
...I've seen of how scope front ends work - programmed attenuator, protection, buffer, sampler, AtoD. This is such old, well established technology, and with stripline ICs and VLSI can be miniaturized so small and made so standard, that it _should_ be cheap.
And yet Tek, Agilent etc claim it isn't. We can't know their true costs, I'm just saying I don't believe they justify their low end scope pricing stuctures.
All of which is necessarily confined to a little block of a few cubic cm behind the BNC connectors, and a design which for basic scopes does not need to be changed for years, regardless of how much they choose to mess with the overall scope packaging and UI.
And you're pretending that there's been any actual R&D needed in the last 10 years for any kind of scope below 500MHz...It's ALL just industrial design, making the boxes look nice, changing around the probe interface connectors, improving the software for waveform display.
If it's so simple, make one! You'll sell shit loads if you can get the price to, say $1/MHz. After all you don't need to do any R&D, you can design it on the back of a fag packet in 5 minutes. You'll put those nasty corporations out of business overnight and stop those evil capitalists exploiting Chinese children once and for all.
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Typical socialist banter, especially the last one which is an absolute classic. "Isn't it terrible that the nasty evil corporations, who only exist to chase dollar signs, exploit overseas workers and destroy the environment, keep their prices deliberately high to prevent Africa developing..." or some such bollocks. The things are expensive, deal with it. And if you don't like their attitude, don't buy. Simple.
Except that if anything, I'm a Libertarian. Nonetheless...
"corporations, who exist only to chase <profit>" is true. That is by definition, charter and structure, exactly what corporations do. And cannot do anything but. The debate over whether it's a good idea to allow the existence of immortal, soulless abstract entities, legally granted the same rights (or better in some cases) as living persons, and who's implicit objectives are in conflict with fundamental human needs, is another whole topic.
"Exploit overseas workers" is true. Deal with it. Not to mention having transfered the jobs from local workers in the first place. All for profit maximization, and screw the national economy.
"Destroy the environment" is also in many cases true. Comes from that 'no ability or desire to do anything but maximize profits' thing.
Your "... Africa" bit is pure strawman bollocks. However with the 'keep from developing' part you're getting close to a truth. I didn't originally want to touch on this aspect but since you bring it up... google 'Agenda 21'. And don't bother trying to pretend it's some wacky conspiracy theory. It's real, it's a UN initiative, budget, power, official website, international conferences, the whole globalist works. I won't bother trying to explain it here, too complicated. A few primer links here: http://everist.org/archives/links/ (http://everist.org/archives/links/)!_Agenda_21.txt
Then do some reading on the phrase 'disruptive technology', who was talking about it, and why. Enjoy the deep, deep rabbit hole.
Another linked theme is why western societies over the last few decades suddenly decided there was no social obligation to ensure the next generation had a decent education, without burdening them with crippling debt. But I suppose now your 'socialist hackles' are rising again, so little point trying to tell you it's all part of the same deliberate trend. Nope, despite that we have a highly technology-dependent civilization, any talk of needing to keep a useful fraction of the population technically capable (and that includes having access to useful test gear) is just socialist babble, right?
If it's so simple, make one! You'll sell shit loads if you can get the price to, say $1/MHz. After all you don't need to do any R&D, you can design it on the back of a fag packet in 5 minutes. You'll put those nasty corporations out of business overnight and stop those evil capitalists exploiting Chinese children once and for all.
Now you're being silly/abusive, and distorting what I said. Which wasn't that it's 'simple', just that the existing test equip companies have been doing this for so long _they_ could make lower end scopes cheaply if they wanted to.
Oh, and notice that there are quite a few small companies that are in fact doing small, cheap USB-based sampling heads, with scope software for PCs. I'm quite hoping these start to give companies like Agilent & Tek some serious competition, and force Tek/Agilent to quit their 'low end high prices' games.
Except of course, there's the patents problem...
And if you don't like their attitude, don't buy. Simple.
Exactly right. I don't. I buy older gear that does the job I need it for, *and* I can get full maintenance manuals with schematics.
If you want to know how politically extreme I can be, here's an example: I think it should be illegal to sell any product without the *full* technical documentation being freely publicly available. That includes all schematics, binaries, source code, etc. (Well, not so much 'illegal', but with arrangements that advantage entities that *do* make that information available. Something like a clear compliance branding, that only products where all the docs are available qualify to carry the mark. Thus letting the market encourage compliance.)
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And you know the actual price of doing these front ends, how exactly?
No more than you do. Which is, not at all.
Actually, I do know more.
The head of scope development (or some such, forget the exact title) at Agilent told me that the 500MHz front end costs a lot more than the 200MHz front end. Which is why they were not able to offer the 500MHz front end in base model, and hence have full software bandwidth upgradability from 70MHz to 500MHz in the scope. That is what they were shooting for but they could not do it.
So your assertion:
I'm saying specifically that bandwidths in the 500Mhz range are something the large instrument makers learned how to do cheaply long ago, even in digital scopes. In fact _especially_ in digital scopes since the high bandwidth stuff is confined to the input sampling circuits,
is clearly wrong on two levels.
One being the actual price of a 500MHz front end.
And second being that the high bandwidth stuff is confined to the sampling circuit, which as everyone knows, it is not. There is a lot of input circuitry before the ADC that is not easy to design at high bandwidths.
Dave.
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Actually, I do know more.
The head of scope development (or some such, forget the exact title) at Agilent told me that the 500MHz front end costs a lot more than the 200MHz front end. Which is why they were not able to offer the 500MHz front end in base model, and hence have full software bandwidth upgradability from 70MHz to 500MHz in the scope. That is what they were shooting for but they could not do it.
Sigh. Well, I don't want to create bad feelings. So please take this as an abstract observation. You're running a popular electronics forum and product review youtube channel. Companies like Tek & Agilent will make an effort to be sure you get the 'right ideas'. This is only natural. So anyway, a guy tells you the 500MHz one costs a lot more than the 200MHz one (the way they chose to make it.) Do you see the slight problem with equating this to proof that it has to be that way, and there couldn't be anything behind this state of affairs other than purely honest efforts to build the best, cheapest products they could? (From people who do things like software crippling of bandwidth, requiring a payment to unlock.)
So your assertion:
I'm saying specifically that bandwidths in the 500Mhz range are something the large instrument makers learned how to do cheaply long ago, even in digital scopes. In fact _especially_ in digital scopes since the high bandwidth stuff is confined to the input sampling circuits,
is clearly wrong on two levels.
One being the actual price of a 500MHz front end.
And second being that the high bandwidth stuff is confined to the sampling circuit, which as everyone knows, it is not. There is a lot of input circuitry before the ADC that is not easy to design at high bandwidths.
Bearing in mind that the _design_ problems were solved long ago, and what we're taking about here is solely the manufacturing cost. But anyway...
I don't consider the first point disproved just because some guy at Agilent tells you otherwise. I'm sure being given loads of lovely gear to review gives you a warm glow towards them, but it doesn't logically prove they don't fib.
The second - oops that was just my poor phrasing. I meant the input circuits up to the sampler. Recall previously I made it clear I'm aware it's the whole chain, from the BNC through to the sampler. (And of course for real time sampling, right through to the memory buffer.)
The one big mistake I made was not realizing that real time sampling capability up to rated bandwidth has worked it's way down to low end digital scopes since the last time I used any (not quite a decade ago.) I suppose I should have expected that.
However, I'd be happy with scanned sampling up to 500MHz for a cheap price, since how many applications actually need real time sampling? Not that many. I don't personally have any such need, and where I might need to see complex single shot sequences it's always going to require a logic or protocol analyzer not a scope.
Still moot I guess. There's no chance I'm ever going to be buying a recent model digital scope, especially given my other equipment buying priorities. Specific objective, struggling to acquire required gear in any form I can. Recent purchase - a gamma spectrometer, $1200. Next one, hopefully, something with as many GHz of fiber optic detector bandwidth as I can afford, and ideally spectral analysis too. That's going to be very ouchy, and won't happen for a while.
Just curious - that video of deemed-doomed scopes you mentioned, was that at some company we're talking about here? If so, you should extrapolate that mindset through other elements of the corporate philosophy, and see where it leads you. Not nice people.
Years ago I used to worship HP & Tek. It was a painful disillusionment to realize they changed, and became no different from any other extortionist corporation.
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And you're pretending that there's been any actual R&D needed in the last 10 years for any kind of scope below 500MHz. Are you serious? What R&D? They don't even have to develop the processor designs any more, since they are likely Intel PC reference designs, just adapted a little to fit the form factor. It's ALL just industrial design, making the boxes look nice, changing around the probe interface connectors, improving the software for waveform display.
I'm not a huge fan of tech equipment manufacturers - and I certainly don't expect them to be truthful about everything they publicly say - but it seems you're a bit behind in DSO design in more ways than just real time sampling to full BW. You're forgetting one of the major ongoing drawbacks of DSOs: their blind time. This is a simple mathematical fact - and the impetus, I believe, behind much recent R&D from Agilent. DSOs can ALWAYS use faster throughput - and until the associated blind time is equivalent to or better than the typical vertical blanking interval of an analog scope, more R&D will likely be required.
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-You do realize that digital scopes don't work like audio digitizers, and don't try to always sample sequentially along a single shot waveform, right?
-The sample points are scanned along the waveform relative to the trigger point over many cycle times. Yes, it's nice to get the conversion cycle time as short as possible, since the shorter that can be made, the fewer cycles of the source waveform are required to build up a reliable picture of the waveform.
-Did you imagine that a (say) 20GHz digital scope has an 80GHz AtoD?
wake up buddy. it's 2012... the time of time-interpolated sampling scopes is 20 years behind us... Yes 20 GHz analog bandwidth scope these days DO sample at 40 or 60 GHz ... and that is single shot. they use pipelined ADC's to do this work. Those are essentially charge shifters where every step in the pipe digitizes one or 2 bits and then the remainder charge is shifted on to the next step in the pipe.
Even the cheape rigols do 500 megasamples/s single shot these days. analog devices has plenty of ADC that run at those speeds.
The era of 'equivalent time' sampling is dead. It died together with the tektronix TDS5xx and TDS7xx series scopes.
Agilent hasn't done equivalent or time-interpolated sampling since they launched the infiniium machines almost 18 years ago. The ADc in those machines do run at full throttle. I have an old infiniium that has four a/d each clocked at 4 GHz. no problemo. Wanna do faster ? they interleave two adc to get 8 Gs/s.
And those machines , as well as the current models, are not simply a sampling head with a pc to do the post processing. in an Agilent scope the pc actually does almost no post processing... it's all done in hardware using massive ASIC's that can handle the raw data throughput. That's why they tell you how many waveforms a second they can capture. They tell you what is their blind time. And it s pretty darn short.
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To be honest, at the high end of the performance range, both types of instruments exist.
Very high bandwidth real-time digital scopes do indeed include extremely high speed ADCs. Different manufacturers differ in their implementations. Tek uses a single high speed S/H (sample and hold) that feeds a few muxed ADCs running at several GHz. Agilent fans the signal out to hundreds of muxed S/H+ADCs. Both schemes give you 100GS/s or more effective single-shot sample rates.
There are ALSO modern equivalent time sampling scope being produced today too. They often sample at a low rate, like 100 to 200kHz or so. The scope does a very precise job of knowing when each sample occurs with respect to the trigger. This type of scope is for repetitive signals, or those that are synchronous with some repetitive trigger event. Advantages of this type of instrument are that they are very accurate, since the samplers run slower, they are usually 14-16 bit converters vs. the 8-bit converters used in real time scopes. Also, these equivalent time sampling scopes can have analog bandwidths of 50, 60, 70GHz or more.
Both techniques are still in use, each with their own applications.