EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: MrAl on November 28, 2022, 05:25:36 am
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Hello there,
What is the going best brand name for a scope these days?
I saw one that advertised 100MHz but it tested at only 30MHz bandwidth so i can see some of them lie drastically about their product specs.
I'd like to know the best name for actual working well and not lying about the bandwidth.
Is there a best name or a group of best names?
I may want to stay away from Techtronics though because they may be out of my price range right now.
I was thinking something like maybe Rigol, Siglent, or Hantek, or Techtronics if they have a lower price range model.
Any current trends here?
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It's just about one thing only, available budget determines everything.
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Best brands are expensive.
Rohde & Schwarz
Tektronix
Keysight
Yokogawa
LeCroy
Good brands
Rigol
Siglent
GW Instek
Micsig
Owon
Stay away from
FNIRSI
YEAPOOK
Hantek
Daniu
All the other cheap Chinese brands that all use the same hardware.
Most likely missed some brands. There are so many threads about which is the best scope for me here on the forum, like this one https://www.eevblog.com/forum/beginners/need-advise-on-a-new-oscilloscope-to-meet-my-requirement-but-lost-on-brans/ (https://www.eevblog.com/forum/beginners/need-advise-on-a-new-oscilloscope-to-meet-my-requirement-but-lost-on-brans/)
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I saw one that advertised 100MHz but it tested at only 30MHz bandwidth so i can see some of them lie drastically about their product specs.
That brand is the exception, I'm not aware of any brand that isn't an "Aliexpress special" that lies about basic specs.
I may want to stay away from Techtronics though because they may be out of my price range right now.
PS: I wasn't aware that "Techtronics" makes oscilloscopes. :o
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So sad for Hantek hahahaha :palm:
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So sad for Hantek hahahaha :palm:
Yep, but they brought it on themselves with the DSO2X1X series. There are a lot of issues with this one and they can't get a handle on fixing them properly.
Used it yesterday while measuring on a 27MHz remote control transmitter, and got unreliable results. Had to break out the Rigol MSO5074 I also have to get it done properly. And you know it is bad when you can't trust what you see on the screen. Advantage of the Hantek is that it boots quicker and is silent, but that is it.
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I think mine quite good for price/performance
With $120 I got DSO + WG + 2 channel high bw Rms AC milivolt metter quite accurate when comparing with my Fluke 8805A (only 50kHz bw). That's all my needs for analog calibration audio equipments.
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I saw one that advertised 100MHz but it tested at only 30MHz bandwidth so i can see some of them lie drastically about their product specs.
That brand is the exception, I'm not aware of any brand that isn't an "Aliexpress special" that lies about basic specs.
I may want to stay away from Techtronics though because they may be out of my price range right now.
PS: I wasn't aware that "Techtronics" makes oscilloscopes. :o
Yes Techtronics makes oscilloscopes, in some other universe i bet (ha ha).
In this one they just dont spell it that way (ha ha ha, big typo).
You can see how long it has been since i have used one of their scopes.
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I think mine quite good for price/performance
With $120 I got DSO + WG + 2 channel high bw Rms AC milivolt metter quite accurate when comparing with my Fluke 8805A (only 50kHz bw). That's all my needs for analog calibration audio equipments.
So which scope did you get for $120 i assume that 120 is in USD?
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Best brands are expensive.
Rohde & Schwarz
Tektronix
Keysight
Yokogawa
LeCroy
Good brands
Rigol
Siglent
GW Instek
Micsig
Owon
Stay away from
FNIRSI
YEAPOOK
Hantek
Daniu
All the other cheap Chinese brands that all use the same hardware.
Most likely missed some brands. There are so many threads about which is the best scope for me here on the forum, like this one https://www.eevblog.com/forum/beginners/need-advise-on-a-new-oscilloscope-to-meet-my-requirement-but-lost-on-brans/ (https://www.eevblog.com/forum/beginners/need-advise-on-a-new-oscilloscope-to-meet-my-requirement-but-lost-on-brans/)
Thanks much for the detailed list that is probably good enough for me right now and it does have quite a few brands that i was interested in.
Glad you mentioned the Hantek i was looking closely at those, now i wont anymore :-)
The FNIRSI (strange name looks like a scrambled English word game) has been confirmed that it is not 100MHz by the manufacturer. They are stating that it is 40MHz so i think still lying a little because a test done here (was that you) shows 30MHz and the test i did on the scope of the person i know who just bought one shows 30MHz also.
What they actually said though was that "It is 40MHz but can reach to 100MHz in some cases". So they must have put in a Mr. Magoo magic chip in there that suddenly increases the bandwidth to 100MHz when Pluto is in the 7th house and you are not observing the scope display screen :-)
I am a little surprised that Owon is in the "Good" list i thought it was a wackadoodle name too :-)
I dont know anything about it really though. I'll have to check pricing.
Is the order of the "Good" scopes in descending order of quality or preference or anything like that?
Thanks again very interesting.
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The lists are randomly compiled.
Owon has some interesting models but probably is on the low end of the good list. Don't have any experience with them though.
Placed Hantek on the avoid list because of the DSO2D10 I have and it is not very good. Believe they do have some older models that are not that bad, but for prices that get you Siglent or Rigol scopes.
The FNIRSI models can measure just shy of 100MHz based on the fact that they sample with 200MSa/s, but above somewhere in the 40MHz range, they start to calculate a perfect sine based on the measured frequency and amplitue and show that on the screen.
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Yes I got my Hantek 2 weeks ago, bought directly from taobao. Just only $120 (usd) # 850RMB for 2C10 version and free shipping in China local.
I think mine quite good for price/performance
With $120 I got DSO + WG + 2 channel high bw Rms AC milivolt metter quite accurate when comparing with my Fluke 8805A (only 50kHz bw). That's all my needs for analog calibration audio equipments.
So which scope did you get for $120 i assume that 120 is in USD?
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> Placed Hantek on the avoid list because of the DSO2D10 I have and it is not very good. Believe they do have some older models that are not that bad
I put Hantek on my own avoid list due to the older DSO2150. It was abysmal, except in the sense that it served as a life lesson in the importance of placing a monetary value on time & risk during purchasing decisions.
I can personally confirm pcprogrammer's categorization on: R&S, Tek, Keysight, LeCroy, Rigol, Siglent, GW Instek, Micsig, Hantek. Good list :-+
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Best brands are expensive.
So we can add rigol (27000€ for the DS70000 3Ghz) and siglent(11876€ for the SDS6000A 2Ghz) to them too. ;)
Stay away from
FNIRSI
YEAPOOK
Hantek
Daniu
I would count owon also to this and Uni-T...
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You get what you pay for, that's alway the truth.
I don't recommend any Hantek but for audio hobbies it is good DSO for price range. You have to know your demand.
Even if the DSO is bad the built-in WG is good function.
I left mine burning run 24hrs for testing, looped back DSO + WG and its was steady and smooth.
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I can personally confirm pcprogrammer's categorization on: R&S, Tek, Keysight, LeCroy, Rigol, Siglent, GW Instek, Micsig, Hantek. Good list :-+
As a Micsig & Rigol user, I agree this list! Hantek has no much reputation here in China, lol.
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Best brands are expensive.
So we can add rigol (27000€ for the DS70000 3Ghz) and siglent(11876€ for the SDS6000A 2Ghz) to them too. ;)
Stay away from
FNIRSI
YEAPOOK
Hantek
Daniu
I would count owon also to this and Uni-T...
I agree WRT Uni-T. Not that the scope I got off them all those years ago was that terrible, it wasn't for a (not so cheap) DSO of that era, but it did have some issues that in 12 years were never addressed. Not even a single FW update. They have absolutely NO support and will not respond to requests or reports or anything else, for that matter. I would never again spend more than $50 on any Uni-T product.
Owon I don't know much about but what others have said and that they get sold through Ali-Express and such. Never a great sign.
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Stay away from
FNIRSI
YEAPOOK
Hantek
Daniu
All the other cheap Chinese brands that all use the same hardware.
anything else.
Fixed for you.
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Owon I don't know much about but what others have said and that they get sold through Ali-Express and such. Never a great sign.
You can also get micsig scopes on Aliexpress, does that mean they are crap too?
I don't have experience with either brand, but what I have read on the forum about the micsig is that most users are very happy with them.
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Stay away from
FNIRSI
YEAPOOK
Hantek
Daniu
All the other cheap Chinese brands that all use the same hardware.
anything else.
Fixed for you.
What are you trying to say here?
That these brands are any good?
Go and read the reviews about their products and you will see they are crap. And I can attest this for certain about the two FNIRSI scopes that are sold under at least four brand names. Did my homework on them :-DD
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Best brands are expensive.
So we can add rigol (27000€ for the DS70000 3Ghz) and siglent(11876€ for the SDS6000A 2Ghz) to them too. ;)
I know they also have expensive scopes, but for as far as I know they are still not ranked up there with the renowned brands from the first list.
They do have good value for money in the lower price brackets for sure, which I believe can't be said for the brands on the first list. Due to the name there is a certain mark up in price there.
But to be fair I only have worked with a Yokogawa (DL9705) scope in comparison with a Rigol (MSO5074). The other cheap ones I have, I don't really count as proper scopes. (FNIRSI 1013D, FNIRSI 1014D and Hantek DSO2D10)
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I think the best brand name for an oscilloscope would the "The Scopinator".
"The Scopinator 2.0 - scopinates your signals like no other"
(you have to say it in a Strongbad voice)
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You can also get micsig scopes on Aliexpress, does that mean they are crap too?
No, because they're more expensive on Aliexpress than in a regular store.
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Owon I don't know much about but what others have said and that they get sold through Ali-Express and such. Never a great sign.
You can also get micsig scopes on Aliexpress, does that mean they are crap too?
I don't have experience with either brand, but what I have read on the forum about the micsig is that most users are very happy with them.
I think your reading too much into what I wrote. First, I did not say everything on Aliexpress is bad, it's just not a great sign. Aliexpress is known as one of the best places on the planet (2nd only to Wish) to get truckloads of your favorite useless crap and reputable companies tend not to sell there. Second, I never used the word crap to describe Owon or anyone else. That, of course, dos not mean Owon are not crap. They could very be, or some of their product could be crap and other just fine. I don't know, and I know even less about Micsig. I'm guessing though that Micsig do not have an "official" store on Aliexpress. Fungus is right though, I can get them for less on Amazon or though other dealers.
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What are you trying to say here?
Stay away from anything else. I agree with you.
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The lists are randomly compiled.
Owon has some interesting models but probably is on the low end of the good list. Don't have any experience with them though.
Placed Hantek on the avoid list because of the DSO2D10 I have and it is not very good. Believe they do have some older models that are not that bad, but for prices that get you Siglent or Rigol scopes.
The FNIRSI models can measure just shy of 100MHz based on the fact that they sample with 200MSa/s, but above somewhere in the 40MHz range, they start to calculate a perfect sine based on the measured frequency and amplitue and show that on the screen.
Yes i realize that scopes can 'measure' beyond their actual tested bandwidth it's just that then the amplitude becomes reduced for those upper frequencies so it would only be useful on a sine wave. A square wave would show signs of high frequency cutoff and thus becomes somewhat rounded.
The test i had to use was with a square wave of known rise time because we didnt have a frequency generator that goes above 24MHz.
For my Instrustar scope they quote it at 20MHz BW but i measured 15MHz, a little different not too bad i guess, i didnt need it for high frequency work anyway so what the heck. It's a PC type though have to use it with a PC or Laptop which is sort of a pain.
I got a little guy with only 1MHz sampling rate and seems like it's not good for anything, but i was able to easily read all the signal patterns of every IR remote control i had. It was something like $24 dollars USD ha ha. One channel only the Instrustar has 2 channels.
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'Best' is always related to requirements, money and -if possible- the ability to improve a product yourself and still get a good deal.
Sometimes I buy equipment from an A-brand, sometimes I buy equipment from a low cost brand and do some improvements to it. It all starts with careful research into what I need and how much money I can spend. Like most people I like to spend as little as possible. But sometimes you just have to bite the bullet and just spend the money to buy something good. Cry once and smile forever. Over the years I have bought various pieces of equipment (not necessarily electronics related) that I regret buying. But having the crappy machine also kind of prevents me from upgrading because I already have a machine that sort of works. IOW: it is easy to get stuck in your own momentum.
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For my Instrustar scope they quote it at 20MHz BW but i measured 15MHz, a little different not too bad i guess,
You must have gotten a real good one. I picked one of these a few years back for shits and giggles because it was the absolute cheapest 20MHz (advertissed) scope. I think I paid $55 CDN for it and was going to use it on my vintage computer bench. However, mine measures a lot worse than yours.
The first shot is a 500KHz reference @ 5V amplitude. The cursors are set for -3dB.
The 2nd shot is at 10MHz. You can see it is well below the -3dB point. This is barely an 9MHz scope
As a backup, the 3rd shot is a 2ns rise time oscillator. You can see being as generous as I can the rise time on the Instrustar is 46ns, giving us a bandwidth of about 8.7MHz. Which agrees with the measurement above.
Not a stellar performer. And the bandwidth is just the beginning of the disappointment. Definitely should be added to the "Do not buy!!!!!!" category.
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'Best' is always related to requirements, money and -if possible- the ability to improve a product yourself and still get a good deal.
Sometimes I buy equipment from an A-brand, sometimes I buy equipment from a low cost brand and do some improvements to it. It all starts with careful research into what I need and how much money I can spend. Like most people I like to spend as little as possible. But sometimes you just have to bite the bullet and just spend the money to buy something good. Cry once and smile forever. Over the years I have bought various pieces of equipment (not necessarily electronics related) that I regret buying. But having the crappy machine also kind of prevents me from upgrading because I already have a machine that sort of works. IOW: it is easy to get stuck in your own momentum.
Yeah that's what i am seeing it is coming down to, a tradeoff.
I also see some other functions which are nice too so it's a tough decision to make.
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For my Instrustar scope they quote it at 20MHz BW but i measured 15MHz, a little different not too bad i guess,
You must have gotten a real good one. I picked one of these a few years back for shits and giggles because it was the absolute cheapest 20MHz (advertissed) scope. I think I paid $55 CDN for it and was going to use it on my vintage computer bench. However, mine measures a lot worse than yours.
The first shot is a 500KHz reference @ 5V amplitude. The cursors are set for -3dB.
The 2nd shot is at 10MHz. You can see it is well below the -3dB point. This is barely an 9MHz scope
As a backup, the 3rd shot is a 2ns rise time oscillator. You can see being as generous as I can the rise time on the Instrustar is 46ns, giving us a bandwidth of about 8.7MHz. Which agrees with the measurement above.
Not a stellar performer. And the bandwidth is just the beginning of the disappointment. Definitely should be added to the "Do not buy!!!!!!" category.
Wow that's amazing, that it could be so much different than mine. Maybe it was made in a different place or a fake copy?
Are you using the right probes too? I use 100MHz rated probes.
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The lists are randomly compiled.
Owon has some interesting models but probably is on the low end of the good list. Don't have any experience with them though.
Placed Hantek on the avoid list because of the DSO2D10 I have and it is not very good. Believe they do have some older models that are not that bad, but for prices that get you Siglent or Rigol scopes.
The FNIRSI models can measure just shy of 100MHz based on the fact that they sample with 200MSa/s, but above somewhere in the 40MHz range, they start to calculate a perfect sine based on the measured frequency and amplitue and show that on the screen.
Hey i was wondering, what do you think about the Owon scopes that also have a 22000 count multimeter built in? They look feature ridden for around $150 USD or so. The screen isnt as big as the more main stream ones, but that doesnt really bother me at all.
They are claiming units rated for 40, 70, and 100Mhz. All have that built in 22000 count meter which i would really love to have in a portable device. I cant take my bench meter anywhere :-DD
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Are you using the right probes too? I use 100MHz rated probes.
Direct connection. The FG is a Siglent SDG1062X connected by 18" of coax. The fast risetime oscillator connects directly to the scope input.
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The fast risetime oscillator connects directly to the scope input.
Do you have a link to a vendor or project for that device?
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I would only put Owon's VDS1022/VDS1022I on the category of good price/performance ratio. Others reported several issues with their offers, including some videos from Dave himself.
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Do you have a link to a vendor or project for that device?
Unfortunately not yet. I may do a video on the next version of it. Even if I don't do the video I'll do a post in this forum on the project.
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Hey i was wondering, what do you think about the Owon scopes that also have a 22000 count multimeter built in? They look feature ridden for around $150 USD or so. The screen isnt as big as the more main stream ones, but that doesnt really bother me at all.
They are claiming units rated for 40, 70, and 100Mhz. All have that built in 22000 count meter which i would really love to have in a portable device. I cant take my bench meter anywhere :-DD
There are some threads about these handhelds here on the forum. Believe Hantek also has one, but think the reviewers like the Owon better. Just search for the model numbers and you will find the threads.
As said I don't have experience with Owon myself, but do think they have some interesting models due to them having 14 bit ADC's, which of course up's the price.
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The fast risetime oscillator connects directly to the scope input.
Are you making these Billy ?
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Are you making these Billy ?
I may, once I have them where I want them and there is enough demand for them. Otherwise I can just make the files available.
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Are you making these Billy ?
I may, once I have them where I want them and there is enough demand for them. Otherwise I can just make the files available.
I drew one up much the same in Altium and was to home etch it but TT with current printer is a mess so needing one quick I splashed out and got the Leo Bodnar one, expensive but to get down to a 30ps edge totally worth it.
He's put his price up 10 GBP so at 60 now there's plenty of room to undercut him with a cheaper product.
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
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He's put his price up 10 GBP so at 60 now there's plenty of room to undercut him with a cheaper product.
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
Mine will not be going down to 30ps! I'll be looking to get it below 2ns, but by the same token it could be built for about $5.
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He's put his price up 10 GBP so at 60 now there's plenty of room to undercut him with a cheaper product.
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
Mine will not be going down to 30ps! I'll be looking to get it below 2ns, but by the same token it could be built for about $5.
Yep it's darn fast and came with a 20 GHz sampling scope readout and RT measurement.
Leo is a member here so it might be worth you digging through his topics where IIRC the development of his pulser is documented.
2ns I can better from any SDG6000X AWG and in reality beating that with a home knocked together pulser using a ****14 IC wasn't gunna be easy so I bit the bullet and got that one from Leo which featured in the very recent Defpom review of our SDS6204A.
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Billy
https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/ (https://www.eevblog.com/forum/projects/yet-another-fast-edge-pulse-generator/)
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The bigger problem with Leo Bodnar's (at least the one fitted with the BNC) is that it's out of stock. I don't know how often he does a build run, but I speculate that pandemic shortages have had an effect and that when he does get stock it goes pretty fast?
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The bigger problem with Leo Bodnar's (at least the one fitted with the BNC) is that it's out of stock. I don't know how often he does a build run, but I speculate that pandemic shortages have had an effect and that when he does get stock it goes pretty fast?
It might be just demand as when reality hits that building something as fast as Leo’s is not straightforward and he’s having trouble meeting demand. I’ve had mine for a year and stock at that time was no problem and UK to NZ delivery was pretty quick, a couple weeks IIRC.
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The bigger problem with Leo Bodnar's (at least the one fitted with the BNC) is that it's out of stock. I don't know how often he does a build run, but I speculate that pandemic shortages have had an effect and that when he does get stock it goes pretty fast?
They say they should be back in stock in the next few days.
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He's put his price up 10 GBP so at 60 now there's plenty of room to undercut him with a cheaper product.
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295 (http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295)
Mine will not be going down to 30ps! I'll be looking to get it below 2ns, but by the same token it could be built for about $5.
Do you have a SDG1032X ?
They're specified max 3.8 ns square wave RT straight outta the box and somewhat better than the SDG2000X models. Only the SDG6000X is a little faster and they ain't exactly cheap.
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Yep it's darn fast and came with a 20 GHz sampling scope readout and RT measurement.
Leo is a member here so it might be worth you digging through his topics where IIRC the development of his pulser is documented.
2ns I can better from any SDG6000X AWG and in reality beating that with a home knocked together pulser using a ****14 IC wasn't gunna be easy so I bit the bullet and got that one from Leo which featured in the very recent Defpom review of our SDS6204A.
Well, I'm hoping this thing will be a bit faster than 2ns (not by much .. I'm realistic) but be something the hobbyist guy with a 200MHz or less scope can check out his system bandwidth for a tad less than the SDG6000X. :) Or do TDR measurements.
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Do you have a SDG1032X ?
They're specified max 3.8 ns square wave RT straight outta the box and somewhat better than the SDG2000X models. Only the SDG6000X is a little faster and they ain't exactly cheap.
I do. I have an "improved" one. But this thing is just project for the fun of it .. to see what I can do for really, really cheap.
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Yep it's darn fast and came with a 20 GHz sampling scope readout and RT measurement.
Leo is a member here so it might be worth you digging through his topics where IIRC the development of his pulser is documented.
2ns I can better from any SDG6000X AWG and in reality beating that with a home knocked together pulser using a ****14 IC wasn't gunna be easy so I bit the bullet and got that one from Leo which featured in the very recent Defpom review of our SDS6204A.
Well, I'm hoping this thing will be a bit faster than 2ns (not by much .. I'm realistic) but be something the hobbyist guy with a 200MHz or less scope can check out his system bandwidth for a tad less than the SDG6000X. :)
:)
Yes it's real nice having all this gear and bit disappointed I didn't check the SDS6204A 2 GHz BW before recently selling our hacked improved SSA3021X. Defpom came up with some figure for BW with Leo's pulser and another with the TG output from his CMU200 and annoyingly I can't argue otherwise without checking it myself with another RF gen. Best I have now is some old HP 520 MHz thing that's a PITA to use as there's a mechanical fault in it that has the frequency adjustment stick. :--
Maybe I need get the SVA1032X and it's TG out............
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Very fast risetime pulse gen:
http://www.starlino.com/build-a-really-fast-pulse-generator-50ps-rise-time-using-an-ultra-fast-sige-comparator.html (http://www.starlino.com/build-a-really-fast-pulse-generator-50ps-rise-time-using-an-ultra-fast-sige-comparator.html)
Interesting stuff but this here:
Luckily Analog Devices offers an inexpensive ADCMP580 demo board, I picked mine from Mouser for around 50 dollars.
Is actually meant as a joke - follow his link to the demoboard on mouser and see the price...
The chip itself cost about 25 bucks..
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Are you making these Billy ?
I may, once I have them where I want them and there is enough demand for them. Otherwise I can just make the files available.
Before you get all wound up about risetime, be aware that risetime tells you nothing about the bandwidth on an oscilloscope. When using risetime the assumption is that the 0.35 number is constant for all oscilloscopes. Unfortunately it isn't. The only proper way to measure the bandwidth of an oscilloscope is to sweep the input using a levelled RF generator.
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Before you get all wound up about risetime, be aware that risetime tells you nothing about the bandwidth on an oscilloscope. When using risetime the assumption is that the 0.35 number is constant for all oscilloscopes. Unfortunately it isn't. The only proper way to measure the bandwidth of an oscilloscope is to sweep the input using a levelled RF generator.
I wouldn't say nothing. Neither would Tektronix. Neither would physics. It's not absolutely accurate, but it will let you find out if your FNIRSI is more like 30MHz than 100MHz or your SDS1104X-E is more like 120MHz than 100MHz.
Of course the proper way is to sweep the frequencies, but not everyone can afford a 500MHz AWG to check out their 200MHz scope. However, they could probably swing $5 or $10 for a handful of readily available components and a PCB.
A small few of the folks around here ( ::) ) are not fixing heart-lung machines or calibrating self-guided nuclear missiles. They just want to have a little fun with electronics and their lab kit. Knowing the BW or their $600 scope to +/- 10% might be enough.
All that said, please rest assured I'll check myself before I wreck myself and not get too wound up. :-+
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Well, you can buy a simple function generator to check the bandwidth of an oscilloscope. Like one from Uni-t or Feeltech. That is a lot more useful compared to wasting money on a device that just outputs a square wave. And likely the 1kHz calibrator output of the oscilloscope already has steep enough edges.
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Before you get all wound up about risetime, be aware that risetime tells you nothing about the bandwidth on an oscilloscope. When using risetime the assumption is that the 0.35 number is constant for all oscilloscopes. Unfortunately it isn't.
"Nothing" is a bit overstated--risetime gets you in the ballpark for bandwidth and whether the factor is 0.35 or 0.45 is a detail. And I'd say that in a lot of cases, perhaps most, where the factor does significantly diverge from 0.35, the user may actually be more concerned about rise time than actual bandwidth.
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Well, you can buy a simple function generator to check the bandwidth of an oscilloscope. Like one from Uni-t or Feeltech. That is a lot more useful compared to wasting money on a device that just outputs a square wave. And likely the 1kHz calibrator output of the oscilloscope already has steep enough edges.
A cheap 30MHz FG is not going to tell you much about the BW of your 200MHz scope unless it has a rise time of less than 2ns. They don't. No probe compensation calibrator I know of does either.
The fact is the transient response of a system is directly related to it's bandwidth and with careful measurements you can get a very close determination of that bandwidth.
Here are some articles on it. If these don't give you enough information, there dozens.
https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=9817 (https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=9817)
https://www.signalintegrityjournal.com/blogs/12-fundamentals/post/853-back-to-basics-bandwidth-and-rise-time (https://www.signalintegrityjournal.com/blogs/12-fundamentals/post/853-back-to-basics-bandwidth-and-rise-time)
https://eng.libretexts.org/Bookshelves/Electrical_Engineering/Electronics/Operational_Amplifiers%3A_Theory_and_Practice_(Roberge)/03%3A_Linear_System_Response/3.05%3A_RELATIONSHIPS_BETWEEN_TRANSIENT_RESPONSE_AND_FREQUENCY_RESPONSE (https://eng.libretexts.org/Bookshelves/Electrical_Engineering/Electronics/Operational_Amplifiers%3A_Theory_and_Practice_(Roberge)/03%3A_Linear_System_Response/3.05%3A_RELATIONSHIPS_BETWEEN_TRANSIENT_RESPONSE_AND_FREQUENCY_RESPONSE)
Besides, a high slew rate pulse generator has many other uses.
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Before you get all wound up about risetime, be aware that risetime tells you nothing about the bandwidth on an oscilloscope. When using risetime the assumption is that the 0.35 number is constant for all oscilloscopes. Unfortunately it isn't.
"Nothing" is a bit overstated--risetime gets you in the ballpark for bandwidth and whether the factor is 0.35 or 0.45 is a detail. And I'd say that in a lot of cases, perhaps most, where the factor does significantly diverge from 0.35, the user may actually be more concerned about rise time than actual bandwidth.
See if your calculator tells us which model this is.
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See if your calculator tells us which model this is.
We don't have enough information. We would need to know the minimum rise time of the pulse generator. if it's only capable of 2ns, then this could be any scope with a BW > 200MHz. If the pulse generator is capable of much faster than 2ns, then this is any model of Siglent that has about a 200MHz actual BW except the 1000 series scopes.
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See if your calculator tells us which model this is.
We don't have enough information. We would need to know the minimum rise time of the pulse generator. if it's only capable of 2ns, then this could be any scope with a BW > 200MHz. If the pulse generator is capable of much faster than 2ns, then this is any model of Siglent that has about a 200MHz actual BW except the 1000 series scopes.
Just checking someone would ask for that. >:D
30ps
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Then my guess would be an SDS2204XP.
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Well, you can buy a simple function generator to check the bandwidth of an oscilloscope. Like one from Uni-t or Feeltech. That is a lot more useful compared to wasting money on a device that just outputs a square wave. And likely the 1kHz calibrator output of the oscilloscope already has steep enough edges.
A cheap 30MHz FG is not going to tell you much about the BW of your 200MHz scope unless it has a rise time of less than 2ns. They don't. No probe compensation calibrator I know of does either.
I own and have owned several oscilloscopes that have calibrator outputs with very steep edges. And ofcourse a cheap generator isn't going to cut it but then again a 200MHz bandwidth oscilloscope isn't in the budget class either and doesn't need checking of the bandwidth; it will work. It is the bottom of the barrel, sub US $100 scopes that require some testing to determine actual bandwidth and a cheap 60MHz function generator (even those go way beyond 30MHz) is good enough to do that. And it is useful as a general tool. And then again, Aliexpress and Ebay are full of low cost HF generator boards that are suitable up to hundreds of MHz with a reasonably constant amplitude.
The fact is the transient response of a system is directly related to it's bandwidth and with careful measurements you can get a very close determination of that bandwidth.
Again, the number 0.35 doesn't apply to digital osciloscopes in general because the first order roll-off isn't a given. You may be off by +/-25% if you use the risetime.
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Then my guess would be an SDS2204XP.
Based on what calculated BW ?
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Based on what calculated BW ?
Yes, and my limited exposure to other 2000 and higher Siglent scopes. It might also be a 2000HD model, but the base 5000 and 6000 both are much higher BW than 200MHz so should show quite a bit less than 2ns.
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I could also add that it being 3pm in NZ you are likely still at work so this would probably not be an "improved" scope.
But, as I said, I'm just guessing.
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Then my guess would be an SDS2204XP.
Based on what calculated BW ?
Yes, and my limited exposure to other 2000 and higher Siglent scopes. It might also be a 2000HD model, but the base 5000 and 6000 both are much higher BW than 200MHz so should show quite a bit less than 2ns.
Yes but the pic title already tells you the model series is 2kX+ so now where are your calcs ?
TBH your guess of SDS2204X Plus could conceivably be miles out unless you do your homework on the BW of each model in this series.
I could also add that it being 3pm in NZ you are likely still at work so this would probably not be an "improved" scope.
But, as I said, I'm just guessing.
Nope, it's NIB unaltered.
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Again, the number 0.35 doesn't apply to digital osciloscopes in general because the first order roll-off isn't a given. You may be off by +/-25% if you use the risetime.
Tektronix suggest using .45 for most DSOs. Others suggest .40. Being the physicist I am, I just wave my hands and use .425. :-DD
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Yes but the pic title already tells you the model series is 2kX+ so now where are your calcs ?
TBH your guess of SDS2204X Plus could conceivably be miles out unless you do your homework on the BW of each model in this series.
The BW of the 200 series are 100MHz, 200MHz and 350MHz (and sometimes 500MHz)
So, calcs ..
Tr=~ 0.425/BW
100MHz: Tr =~ 0.425/100MHz = 4.24ns
200MHz: Tr =~ 0.425/200MHz = 2.12ns
350MHz: Tr =~ 0.425/350MHz = 1.21ns
Your screen shot showed 2ns so 200MHz is the closest.
I didn't notice the filename so now I'll say I'm 95% sure it's and SDS2204XP.
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Yes but the pic title already tells you the model series is 2kX+ so now where are your calcs ?
TBH your guess of SDS2204X Plus could conceivably be miles out unless you do your homework on the BW of each model in this series.
The BW of the 200 series are 100MHz, 200MHz and 350MHz (and sometimes 500MHz)
So, calcs ..
Rt=~ 0.425/BW
100MHz: Rt =~ 0.425/100MHz = 4.24ns
200MHz: Rt =~ 0.425/200MHz = 2.12ns
350MHz: Rt =~ 0.425/350MHz = 1.21ns
Your screen shot showed 2ns so 200MHz is the closest.
I didn't notice the filename so now I'll say I'm 95% sure it's and SDS2204XP.
:)
It is but......
https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg2958288/#msg2958288 (https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg2958288/#msg2958288)
SDS2104X Plus has a -3dB BW of ~185 MHz and is the reason it's supplied with 200 MHz rated probes.
Based on that you might trim your calcs to better fit with a 30ps pulser. ;)
Yeah, I set you up. :P
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Well, I didn't know that about the SDS2104XP even though I have one. Nice scope!
I actually "improved" it within minutes of getting it out of the box so never tested in it's NIB mode.
There is actually a story about my "improvement journey" which I will relate to the forum when I verify some things. As it is right now I'm seeing about 700MHz BW using a frequency sweep, but this is one of the things I need to verify. More on all this later in a different thread.
Anyway, our little banter here verified my assertion that a transient response can get us very close. Can you do a frequency sweep on that scope to see how close we came? It might even be a tad better than the 185MHz.
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Based on that you might trim your calcs to better fit with a 30ps pulser. ;)
That is the problem: in the end you can't determine the exact bandwidth using a pulser because you don't know what the roll-off 'factor' of the front end is.
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Well, I didn't know that about the SDS2104XP even though I have one. Nice scope!
I actually "improved" it within minutes of getting it out of the box so never tested in it's NIB mode.
There is actually a story about my "improvement journey" which I will relate to the forum when I verify some things. As it is right now I'm seeing about 700MHz BW using a frequency sweep, but this is one of the things I need to verify. More on all this later in a different thread.
Anyway, our little banter here verified my assertion that a transient response can get us very close. Can you do a frequency sweep on that scope to see how close we came? It might even be a tad better than the 185MHz.
IIRC SDS2504X Plus BW is nearly 600 MHz and it's reported somewhere in the 2kX Plus thread.
First SDS2104X Plus we got hands on is what I tested and as reported in the link to post above and I flat out didn't believe it was ~185 MHz but tested with 3 yes 3 sinewave sources confirmed it was. :o
I'd never seen the likes of rated BW exceeded by 85% in any instrument.
Missing my now sold SSG3021X already. :(
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That is the problem: in the end you can't determine the exact bandwidth using a pulser because you don't know what the roll-off 'factor' of the front end is.
No one said exact. We're not going for exact using this method. In this little exercise I came up with 200MHz, we don't know the actual, but it is assumed to be 185MHz for now. That's an error of less than 10%. If you had a Tr of 2ns doing a transient test you'd be correct in saying "My scope has about a 200MHz bandwidth". Which is really quite significant if your scope is advertised as a 100MHz scope. Likewise, if you did the test on your supposed 100MHz scope and got 13ns you'd be safe in saying the rating of the scope is an out and out lie and reality is more like 30MHz.
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Missing my now sold SSG3021X already. :(
Now, that would be an awesome SG. I see them for $3600 CDN for the base model .. more than I can really ever afford after just spending nearly $4500 CDN on two scopes, an AWG, a DMM and a DC load in the last 4 months. All Siglent. I'm afraid such a thing is out of my hobby league.
I'll have to continue to live with my ADF4350 .. :(
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Missing my now sold SSG3021X already. :(
Now, that would be an awesome SG. I see them for $3600 CDN for the base model .. more than I can really ever afford after just spending nearly $4500 CDN on two scopes, an AWG, a DMM and a DC load in the last 4 months. All Siglent. I'm afraid such a thing is out of my hobby league.
Yeah that's the trouble, they don't get lots of use unless you're right into RF. Even a SDG6052X is not exactly cheap but either of these base models can be improved. >:D
However even if we were to replace it with the same SSG and again improve it to 3.2 GHz that's not high enuf to test what's coming from Siglent. :o
SSG5000X can do it but that's another jump in cost. :scared:
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.. 3.2 GHz that's not high enuf to test what's coming from Siglent. :o
Sounds very interesting! But also sounds like something I'll never own.
When will it be announced?
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.. 3.2 GHz that's not high enuf to test what's coming from Siglent. :o
Sounds very interesting! But also sounds like something I'll never own.
When will it be announced?
When we spot it on the HQ website and know it exists for real. Only heard whispers about it thus far.
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...
IIRC SDS2504X Plus BW is nearly 600 MHz and it's reported somewhere in the 2kX Plus thread.
First SDS2104X Plus we got hands on is what I tested and as reported in the link to post above and I flat out didn't believe it was ~185 MHz but tested with 3 yes 3 sinewave sources confirmed it was. :o
I'd never seen the likes of rated BW exceeded by 85% in any instrument.
...
Recall our SDS2104X Plus after "enhancement" with the kind help of folks here, returned something like 618MHz BW :-+
Best,
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And then again, Aliexpress and Ebay are full of low cost HF generator boards that are suitable up to hundreds of MHz with a reasonably constant amplitude.
Yes, but these $$ SI5351, ADF435x, etc. PLL synthesizer boards usually don't output sine wave, which complicates things. However, the amplitude of the fundamental frequency component can still be measured on the scope via FFT if the test point frequencies are chosen such that none of the harmonics alias exactly to the fundamental frequency in the 1st Nyquist band, enabling the separation of fundamental and harmonics via FFT, despite aliasing. If the test point frequencies are furthermore selected such that the fundamental falls onto a FFT bin frequency, then scalopping loss can be avoided. Reference measurements for the fundamental frequency amplitude of each test point can be done with a (tiny)SA if frequency-invariant amplitude is not granted.
EDIT: Btw, isn't the tinySA able to output sine wave when used as signal generator? At least the Ultra?
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And then again, Aliexpress and Ebay are full of low cost HF generator boards that are suitable up to hundreds of MHz with a reasonably constant amplitude.
Yes, but these $$ SI5351, ADF435x, etc. PLL synthesizer boards usually don't output sine wave, which complicates things.
No it doesn't. Near the maximum bandwidth you'll see a sine wave anyway because the 2nd harmonic is typically not very strong while the 3rd harmonic is 3 times the fundamental frequency.
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Are you using the right probes too? I use 100MHz rated probes.
Direct connection. The FG is a Siglent SDG1062X connected by 18" of coax. The fast risetime oscillator connects directly to the scope input.
Oh ok that sounds good, but i wonder if that 18 inches of coax is affecting the readings. As long as it is good coax i guess you're ok there.
I think the FAST family TTL is around 2ns rise time. There are ways around that too by doing a little calculation that includes the rise time of the input wave. If you could have someone with a better scope measure that, i could provide you with a formula to compensate.
Interesting little gadget though. What main chip is that based on? That really tells all.
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Are you making these Billy ?
I may, once I have them where I want them and there is enough demand for them. Otherwise I can just make the files available.
Before you get all wound up about risetime, be aware that risetime tells you nothing about the bandwidth on an oscilloscope. When using risetime the assumption is that the 0.35 number is constant for all oscilloscopes. Unfortunately it isn't. The only proper way to measure the bandwidth of an oscilloscope is to sweep the input using a levelled RF generator.
There is a way to compensate for the rise time of the input wave if that is what you are talking about.
Also, when they quote the 0.35 constant what levels are they touting the rise time is measured at?
Is it the 10 percent to 90 percent thresholds, or something else?
There is also the settling time which is rarely mentioned, which i see affects some digital scopes.
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I would only put Owon's VDS1022/VDS1022I on the category of good price/performance ratio. Others reported several issues with their offers, including some videos from Dave himself.
Hi,
Would you happen to have a link to one of Dave's reviews?
I searched but didnt find one yet, except with other members reviews.
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Are you making these Billy ?
I may, once I have them where I want them and there is enough demand for them. Otherwise I can just make the files available.
Before you get all wound up about risetime, be aware that risetime tells you nothing about the bandwidth on an oscilloscope. When using risetime the assumption is that the 0.35 number is constant for all oscilloscopes. Unfortunately it isn't. The only proper way to measure the bandwidth of an oscilloscope is to sweep the input using a levelled RF generator.
There is a way to compensate for the rise time of the input wave if that is what you are talking about.
Also, when they quote the 0.35 constant what levels are they touting the rise time is measured at?
Is it the 10 percent to 90 percent thresholds, or something else?
No, this is not the threshold but it is a factor that says how steep the signal amplitude drops with increasing frequency. The number 0.35 only applies when an oscilloscope has a 1st order (RC) roll-off. However, in order to maximise bandwidth and minimise aliasing, a lot of DSOs have much steeper (higher order) filters for which the number 0.35 no longer applies. Since this number is typically not specified (although Keysight does for some of their oscilloscopes IIRC), you can't use a steep edge to determine bandwidth accurately. To make matters worse, the bandwidth can also depend on the V/div setting. For low V/div settings the signal needs to be amplified first instead of attenuated and the amplifier may have a different bandwidth than the attenuator. You see some claiming bandwidths that far exceed what the oscilloscope specifies but it can be completely different at low V/div settings. In the end the manufacturer should specify what the oscilloscope is capable off at all V/div settings. Again, testing with a function / frequency generator at various levels gives you a far more detailed picture of what is going on.
This is what I measured on my GW Instek GDS-2204E:
(https://www.eevblog.com/forum/testgear/best-brand-name-for-an-oscilloscope/?action=dlattach;attach=1652497;image)
There is also the settling time which is rarely mentioned, which i see affects some digital scopes.
You mean overload recovery time?
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I would only put Owon's VDS1022/VDS1022I on the category of good price/performance ratio. Others reported several issues with their offers, including some videos from Dave himself.
Hi,
Would you happen to have a link to one of Dave's reviews?
I searched but didnt find one yet, except with other members reviews.
Duckduckgo'ing for "eevblog owon oscilloscope" yields:
https://www.eevblog.com/forum/testgear/are-owon-oscilloscopes-worth-it/ (https://www.eevblog.com/forum/testgear/are-owon-oscilloscopes-worth-it/)
https://www.youtube.com/watch?v=RmJ2pZloW18 (https://www.youtube.com/watch?v=RmJ2pZloW18)
https://www.youtube.com/watch?v=-F4H-zC_i0s (https://www.youtube.com/watch?v=-F4H-zC_i0s)
And the Owon VDS1022/VDS1022I megathread, including even a much improved version of the software modified by the community:
https://www.eevblog.com/forum/testgear/owon-vds1022i-quick-teardown-(versus-the-hantek-6022be)/ (https://www.eevblog.com/forum/testgear/owon-vds1022i-quick-teardown-(versus-the-hantek-6022be)/)
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Oh ok that sounds good, but i wonder if that 18 inches of coax is affecting the readings. As long as it is good coax i guess you're ok there.
Properly terminated coax is a much better bet than any passive probe. That 18" bit of coax will out perform my 500MHz Tek 6139 probes.
Interesting little gadget though. What main chip is that based on? That really tells all.
It's a 74AC14. It should be able to get sub 2ns Tr, but just. Maybe 1.7ns. That's what I'm after.
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The bigger problem with Leo Bodnar's (at least the one fitted with the BNC) is that it's out of stock. I don't know how often he does a build run, but I speculate that pandemic shortages have had an effect and that when he does get stock it goes pretty fast?
It looks like they are in stock today. My order is in..
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It looks like they are in stock today. My order is in..
Thanks! My order is in too. I honestly have no business monkeying around with this stuff (I'm really a software guy). But for whatever reason I find it fascinating, so paying a bit less than $100 is easily justified as on-going education.
I still look forward to any info you post about your device (from the looks of it, I think I might actually be able to successfully assemble it in spite of my lack of soldering skill).
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I still look forward to any info you post about your device (from the looks of it, I think I might actually be able to successfully assemble it in spite of my lack of soldering skill).
The next one is going to have SMD resistors. They will be pretty big ones .. 1206. Those are fairly easy to solder. Almost as easy as thru-hole.
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The next one is going to have SMD resistors. They will be pretty big ones .. 1206. Those are fairly easy to solder. Almost as easy as thru-hole.
The bigger the better! I'm currently working a "project" that consists of adding eight 0 Ohm resistors to a board to enable some signals to get to a connector. The pads are for 0402 SMD resistors and my workmanship is pathetic. I can manage to get one on and working in a single sit-down, but I find it so frustratingly difficult and ends up so cosmetically awful (probably awful more than just cosmetically, too) that I can't bring myself to try the next one for another week or so.
I can't believe all the posts I see where people say they can do 0402 work without magnification - those things are not much larger than a grain of sand!
Anyway - my sad story is really more suitable for the Beginner's forum. I should stop drifting this thread off-topic anymore.
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The next one is going to have SMD resistors. They will be pretty big ones .. 1206. Those are fairly easy to solder. Almost as easy as thru-hole.
The bigger the better! I'm currently working a "project" that consists of adding eight 0 Ohm resistors to a board to enable some signals to get to a connector. The pads are for 0402 SMD resistors and my workmanship is pathetic. I can manage to get one on and working in a single sit-down, but I find it so frustratingly difficult and ends up so cosmetically awful (probably awful more than just cosmetically, too) that I can't bring myself to try the next one for another week or so.
I can't believe all the posts I see where people say they can do 0402 work without magnification - those things are not much larger than a grain of sand!
With good eyesight and mine's long gone 1mm x 0.5mm (0402) component soldering is quite achievable.
Iron tips not need be small but you need a corner or point of the tip to get to the pad and heaps of flux and a reasonably fine leaded solder to make a tidy job.
Technique is everything with SMD.
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I still look forward to any info you post about your device (from the looks of it, I think I might actually be able to successfully assemble it in spite of my lack of soldering skill).
The next one is going to have SMD resistors. They will be pretty big ones .. 1206. Those are fairly easy to solder. Almost as easy as thru-hole.
Easier then thru hole, because there is no clipping of the leads. 0805 is also still doable for older eyes, but it is easier with a microscope.
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I can't believe all the posts I see where people say they can do 0402 work without magnification - those things are not much larger than a grain of sand!
Soldering is definitely doable if you have good eyesight but for a final check of the solder joints, you'll need to use a magnifier. Also having really good lighting is a must. I have about 400 Lux >95% CRI at my workbench surface level.
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Oh ok that sounds good, but i wonder if that 18 inches of coax is affecting the readings. As long as it is good coax i guess you're ok there.
Properly terminated coax is a much better bet than any passive probe. That 18" bit of coax will out perform my 500MHz Tek 6139 probes.
Interesting little gadget though. What main chip is that based on? That really tells all.
It's a 74AC14. It should be able to get sub 2ns Tr, but just. Maybe 1.7ns. That's what I'm after.
That looks reasonable then. I was thinking of the FAST version or FASTr version of TTL.
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I would only put Owon's VDS1022/VDS1022I on the category of good price/performance ratio. Others reported several issues with their offers, including some videos from Dave himself.
Hi,
Would you happen to have a link to one of Dave's reviews?
I searched but didnt find one yet, except with other members reviews.
Duckduckgo'ing for "eevblog owon oscilloscope" yields:
https://www.eevblog.com/forum/testgear/are-owon-oscilloscopes-worth-it/ (https://www.eevblog.com/forum/testgear/are-owon-oscilloscopes-worth-it/)
https://www.youtube.com/watch?v=RmJ2pZloW18 (https://www.youtube.com/watch?v=RmJ2pZloW18)
https://www.youtube.com/watch?v=-F4H-zC_i0s (https://www.youtube.com/watch?v=-F4H-zC_i0s)
And the Owon VDS1022/VDS1022I megathread, including even a much improved version of the software modified by the community:
https://www.eevblog.com/forum/testgear/owon-vds1022i-quick-teardown-(versus-the-hantek-6022be)/ (https://www.eevblog.com/forum/testgear/owon-vds1022i-quick-teardown-(versus-the-hantek-6022be)/)
Those look interesting too, i was hoping for reviews on the 200 series which i think are the 240, 270, etc. These are 40MHz and 70MHz rated units. Not sure which ones are newer, the 200 series or the ones you show here i guess that is the 1000 series.
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Are you making these Billy ?
I may, once I have them where I want them and there is enough demand for them. Otherwise I can just make the files available.
Before you get all wound up about risetime, be aware that risetime tells you nothing about the bandwidth on an oscilloscope. When using risetime the assumption is that the 0.35 number is constant for all oscilloscopes. Unfortunately it isn't. The only proper way to measure the bandwidth of an oscilloscope is to sweep the input using a levelled RF generator.
There is a way to compensate for the rise time of the input wave if that is what you are talking about.
Also, when they quote the 0.35 constant what levels are they touting the rise time is measured at?
Is it the 10 percent to 90 percent thresholds, or something else?
No, this is not the threshold but it is a factor that says how steep the signal amplitude drops with increasing frequency. The number 0.35 only applies when an oscilloscope has a 1st order (RC) roll-off. However, in order to maximise bandwidth and minimise aliasing, a lot of DSOs have much steeper (higher order) filters for which the number 0.35 no longer applies. Since this number is typically not specified (although Keysight does for some of their oscilloscopes IIRC), you can't use a steep edge to determine bandwidth accurately. To make matters worse, the bandwidth can also depend on the V/div setting. For low V/div settings the signal needs to be amplified first instead of attenuated and the amplifier may have a different bandwidth than the attenuator. You see some claiming bandwidths that far exceed what the oscilloscope specifies but it can be completely different at low V/div settings. In the end the manufacturer should specify what the oscilloscope is capable off at all V/div settings. Again, testing with a function / frequency generator at various levels gives you a far more detailed picture of what is going on.
This is what I measured on my GW Instek GDS-2204E:
(https://www.eevblog.com/forum/testgear/best-brand-name-for-an-oscilloscope/?action=dlattach;attach=1652497;image)
There is also the settling time which is rarely mentioned, which i see affects some digital scopes.
You mean overload recovery time?
Oh so i guess we see some differences AGAIN between CRT and DSO scopes, that's a pain in the neck.
The settling time is the time to settle to within 99 percent of maximum, and that is an important spec of any ADC. I think the percentage used can be different though, such as 95 percent or something. So if you shoot a 1v high square wave into the front end and the scope display starts to rise, it's the time it takes to get to 99 percent of the full max which in this case would be 0.99 volts. This could be a lot longer than the rise time. This was a big concern for me when i was designing a 100MS/s scope way back in the early 1990's.
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A suitable ADC driver can charge the S&H capacitor to settling within the sample interval.
At the end, the settling time of the overall system is still predominantly determined by the impulse/step response of the analog frontent.
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Lots of really great discussion and comments here about measuring scope bandwidth!
We get so many questions about this topic, I actually made a video explaining the basic concepts of "bandwidth" in oscilloscopes. Probably a bit too introductory for most of the people posting here, but it does cover a few things discussed in this thread such as calculating BW from rise time, the different frequency responses (Gaussian vs. flat), etc.
One thing I didn't cover is how to measure the bandwidth of an oscilloscope (i.e. procedures, techniques), but it seems like this might be a good topic for a future video. I've already learned a few things from this thread myself :)
https://www.youtube.com/watch?v=FhT8TpuI7ek (https://www.youtube.com/watch?v=FhT8TpuI7ek)
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Oh so i guess we see some differences AGAIN between CRT and DSO scopes, that's a pain in the neck.
The settling time is the time to settle to within 99 percent of maximum, and that is an important spec of any ADC. I think the percentage used can be different though, such as 95 percent or something. So if you shoot a 1v high square wave into the front end and the scope display starts to rise, it's the time it takes to get to 99 percent of the full max which in this case would be 0.99 volts. This could be a lot longer than the rise time. This was a big concern for me when i was designing a 100MS/s scope way back in the early 1990's.
I will politely comment on that..
In my opinion it is not "between CRT and DSO scope" but how industry was making and looking at scope usage (and design that stems from that) 30 years ago as opposed to today. And also technology gap.
Perfect impulse response (that was industry standard many years ago) proved to be suboptimal for many other things people do with scopes.
For example my Keysight MSO3104T has practically flat BW until it's 1GHz BW. If I'm looking at signal in frequency domain (FFT) or verifying amplitude of 868 Mhz oscillator it will show excellent amplitude accuracy. All while having "only" 450ps risetime. If I wanted to do the same on scope with Gaussian response (that would yield perfect impulse response) i would need at least 2GHz scope for same amplitude flatness up to 1 GHz.
There are digital scopes that have Gaussian response. They are just not common anymore.
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Oh so i guess we see some differences AGAIN between CRT and DSO scopes, that's a pain in the neck.
The settling time is the time to settle to within 99 percent of maximum, and that is an important spec of any ADC. I think the percentage used can be different though, such as 95 percent or something. So if you shoot a 1v high square wave into the front end and the scope display starts to rise, it's the time it takes to get to 99 percent of the full max which in this case would be 0.99 volts. This could be a lot longer than the rise time. This was a big concern for me when i was designing a 100MS/s scope way back in the early 1990's.
I will politely comment on that..
In my opinion it is not "between CRT and DSO scope" but how industry was making and looking at scope usage (and design that stems from that) 30 years ago as opposed to today. And also technology gap.
Perfect impulse response (that was industry standard many years ago) proved to be suboptimal for many other things people do with scopes.
For example my Keysight MSO3104T has practically flat BW until it's 1GHz BW. If I'm looking at signal in frequency domain (FFT) or verifying amplitude of 868 Mhz oscillator it will show excellent amplitude accuracy. All while having "only" 450ps risetime. If I wanted to do the same on scope with Gaussian response (that would yield perfect impulse response) i would need at least 2GHz scope for same amplitude flatness up to 1 GHz.
There are digital scopes that have Gaussian response. They are just not common anymore.
Actually you can make the oscilloscope Gaussian again by turning the bandwidth limit on. Higher frequency oscilloscopes typically have various bandwidth limits (with 1st order roll off) so you can make the tradeoff yourself.
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Oh so i guess we see some differences AGAIN between CRT and DSO scopes, that's a pain in the neck.
The settling time is the time to settle to within 99 percent of maximum, and that is an important spec of any ADC. I think the percentage used can be different though, such as 95 percent or something. So if you shoot a 1v high square wave into the front end and the scope display starts to rise, it's the time it takes to get to 99 percent of the full max which in this case would be 0.99 volts. This could be a lot longer than the rise time. This was a big concern for me when i was designing a 100MS/s scope way back in the early 1990's.
I will politely comment on that..
In my opinion it is not "between CRT and DSO scope" but how industry was making and looking at scope usage (and design that stems from that) 30 years ago as opposed to today. And also technology gap.
Perfect impulse response (that was industry standard many years ago) proved to be suboptimal for many other things people do with scopes.
For example my Keysight MSO3104T has practically flat BW until it's 1GHz BW. If I'm looking at signal in frequency domain (FFT) or verifying amplitude of 868 Mhz oscillator it will show excellent amplitude accuracy. All while having "only" 450ps risetime. If I wanted to do the same on scope with Gaussian response (that would yield perfect impulse response) i would need at least 2GHz scope for same amplitude flatness up to 1 GHz.
There are digital scopes that have Gaussian response. They are just not common anymore.
Actually you can make the oscilloscope Gaussian again by turning the bandwidth limit on. Higher frequency oscilloscopes typically have various bandwidth limits (with 1st order roll off) so you can make the tradeoff yourself.
That is very true, it converts 1GHz scope to 200 or 500MHz scope and user have control...
I actually use 200Mhz BW limit on Siglents most of the time I work with passive probes. Or whenever I don't need full BW.
I wish MSOX3104T had more BW limits in addition to 20Mhz.
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A suitable ADC driver can charge the S&H capacitor to settling within the sample interval.
At the end, the settling time of the overall system is still predominantly determined by the impulse/step response of the analog frontent.
Yes i am sorry i misspoke, of course it was the front end i was talking about the the ADC 'system'.
The front end settling time is the thing i looked at most when designing the front end.
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Lots of really great discussion and comments here about measuring scope bandwidth!
We get so many questions about this topic, I actually made a video explaining the basic concepts of "bandwidth" in oscilloscopes. Probably a bit too introductory for most of the people posting here, but it does cover a few things discussed in this thread such as calculating BW from rise time, the different frequency responses (Gaussian vs. flat), etc.
One thing I didn't cover is how to measure the bandwidth of an oscilloscope (i.e. procedures, techniques), but it seems like this might be a good topic for a future video. I've already learned a few things from this thread myself :)
https://www.youtube.com/watch?v=FhT8TpuI7ek (https://www.youtube.com/watch?v=FhT8TpuI7ek)
Yes that is the way i have been doing it, sweeping a sine was up in frequency until you see the amplitude drop to 1/sqrt(2) which is the -3db point.
Since to do this test for a higher frequency scope like 100MHz you have to have a signal generator that can produce sine waves up to at least 100MHz. I did not have that for testing a scope that was said to be 100MHz but was really 30MHz but my frequency gen only goes up to 24MHz anyway, so i had to use the pulse method and assume that the pulse rise time was what the spec said it would be, and calculate the 90 percent threshold for the rise time of the scope given a first order LP filter front end.
You can get this number by noting the charge time for an R and C filter:
1-e^(-t/RC)
and note that the 3db cutoff point for an RC LP filter comes from:
w=1/RC
which is:
2*pi*f=1/RC
and solving for RC i get:
RC=1/(2*pi*f)
then substitute that into the charge time above:
1-e^(2*pi*f*t)
and then given your frequency f and equating that to 0.9 the equation becomes:
1-e^(2*pi*f*t)=0.9
and solving that for any 'f' we get approxmately:
t=0.366/f
and many people use t=0.35/f which is ok too really because it's just an estimate anyway.
It is possible that the 0.35/f formula comes from the 10 percent and 90 percent thresholds but i did not look into it, but since the time comes out slightly shorter i would think it was because of that.
However, since the rise time of the test pulse is never perfect and often more like 3ns, i like the longer time of 0.366/f as that helps a little to include the rise time of the input test pulse which of course makes the rise time on the scope slightly longer. The development of the formula for that is slightly more complicated because then we can not use a pulse with 0 rise time we have to use a ramp with whatever rise time we assume we will be working with. Some here use 2ns i think from a digital logic circuit.
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Oh so i guess we see some differences AGAIN between CRT and DSO scopes, that's a pain in the neck.
The settling time is the time to settle to within 99 percent of maximum, and that is an important spec of any ADC. I think the percentage used can be different though, such as 95 percent or something. So if you shoot a 1v high square wave into the front end and the scope display starts to rise, it's the time it takes to get to 99 percent of the full max which in this case would be 0.99 volts. This could be a lot longer than the rise time. This was a big concern for me when i was designing a 100MS/s scope way back in the early 1990's.
I will politely comment on that..
In my opinion it is not "between CRT and DSO scope" but how industry was making and looking at scope usage (and design that stems from that) 30 years ago as opposed to today. And also technology gap.
Perfect impulse response (that was industry standard many years ago) proved to be suboptimal for many other things people do with scopes.
For example my Keysight MSO3104T has practically flat BW until it's 1GHz BW. If I'm looking at signal in frequency domain (FFT) or verifying amplitude of 868 Mhz oscillator it will show excellent amplitude accuracy. All while having "only" 450ps risetime. If I wanted to do the same on scope with Gaussian response (that would yield perfect impulse response) i would need at least 2GHz scope for same amplitude flatness up to 1 GHz.
There are digital scopes that have Gaussian response. They are just not common anymore.
Yes when i said "CRT" i was talking about the old types back in the day before digital ones became more popular.
However, when i tested a friends scope and included the rise time of the input pulse, i got the same bandwidth as was tested in this forum somewhere that i read. The test here was 30MHz and the measurement i did with the pulse was 30MHz, but that obviously was a low end scope.
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Yes that is the way i have been doing it, sweeping a sine was up in frequency until you see the amplitude drop to 1/sqrt(2) which is the -3db point.
Since to do this test for a higher frequency scope like 100MHz you have to have a signal generator that can produce sine waves up to at least 100MHz.
Yes, this is how I measure oscilloscope bandwidth, although I realize that most hobbyists don't have signal generators that go up to the GHz range :) If I were going to to a video on this topic ("Understanding Oscilloscope Bandwidth Measurements" or similar), I would want to include approaches that don't require (very) high frequency generators.
I also think it's helpful to measure beyond the nominal 3dB bandwidth in order to graph out the frequency response (Gaussian, flat, something in between). As some others have commented, a scope is sometimes useful (well) past its 3dB bandwidth -- such as when measuring a reasonably pure sinusoid -- as long as you take the decrease in level accuracy into consideration. This also requires graphing the frequency response past the 3 dB point.
Another reason to graph this out is that the frequency response may have (non-trivial) ripples or other irregularities even within the 3 dB bandwidth. One advantage of scopes with a Gaussian frequency response is that they tend to have lower passband distortion than a flat / brick wall response.
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Another reason to graph this out is that the frequency response may have (non-trivial) ripples or other irregularities even within the 3 dB bandwidth. One advantage of scopes with a Gaussian frequency response is that they tend to have lower passband distortion than a flat / brick wall response.
Agree, any "ripples" in the amplitude response usually involves "ripples" in group delay, and why "Guassian" or Bessel (max flat Group Delay) responses are desirable. Since a scope is often employed to monitor digital signals, for example the well known "Eye Diagram", the instrument of measure should not introduce significant artifacts in the measurements, since the usual objective is to visualize the waveform of interest and not be significantly "colored" by the measurement instrument. This is where "equalization" comes into play, as folks do in digital channel communications to reduce ISI.
Since you are involved with R&S and knowledgable regarding DSO behavior, do you know if they employ "equalization" within the scope to help normalize the response? Would think this might be a post ADC FIR Equalization "Filter".
BTW excellent oscilloscope video :-+
Best,
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Since you are involved with R&S and knowledgable regarding DSO behavior, do you know if they employ "equalization" within the scope to help normalize the response?
Yes, we use DSP-based correction filters to provide a "flat" frequency response.
BTW excellent oscilloscope video :-+
Thanks! I've done several videos recently that explain various "intermediate" level scope topics (like ENOB, acquisition rate / blind time, etc.) and I have several more similar videos (on triggering, sampling rate, FFT, etc.) in the works.
I cover most of our major T&M product lines (sig gens, spec ans, VNAs, scopes, power sensors, EMC, etc.) here at R&S, so unfortunately I can't spend all of my time on scope-related content. :) For example, I just finished a webinar and whitepaper on EVM (error vector magnitude):
https://www.rohde-schwarz.com/us/solutions/test-and-measurement/rf-microwave-components/amplifiers/white-paper-understanding-evm_256149.html (https://www.rohde-schwarz.com/us/solutions/test-and-measurement/rf-microwave-components/amplifiers/white-paper-understanding-evm_256149.html)
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Since you are involved with R&S and knowledgable regarding DSO behavior, do you know if they employ "equalization" within the scope to help normalize the response?
Yes, we use DSP-based correction filters to provide a "flat" frequency response.
Does that also apply to entry-level models, or only to more expensive ones?
Is every unit individualy measured and corrected?
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Does that also apply to entry-level models, or only to more expensive ones?
Is every unit individualy measured and corrected?
I'll need to check with the division on that one. Will let you know what they say :)
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Since you are involved with R&S and knowledgable regarding DSO behavior, do you know if they employ "equalization" within the scope to help normalize the response?
Yes, we use DSP-based correction filters to provide a "flat" frequency response.
Does "flat" apply to group delay, or just amplitude response?
Best,
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Does "flat" apply to group delay, or just amplitude response?
My understanding is that it corrects both amplitude and phase, but I'll double check.
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Does "flat" apply to group delay, or just amplitude response?
My understanding is that it corrects both amplitude and phase, but I'll double check.
It should be both AFAIK..
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Yes that is the way i have been doing it, sweeping a sine was up in frequency until you see the amplitude drop to 1/sqrt(2) which is the -3db point.
Since to do this test for a higher frequency scope like 100MHz you have to have a signal generator that can produce sine waves up to at least 100MHz.
Yes, this is how I measure oscilloscope bandwidth, although I realize that most hobbyists don't have signal generators that go up to the GHz range :) If I were going to to a video on this topic ("Understanding Oscilloscope Bandwidth Measurements" or similar), I would want to include approaches that don't require (very) high frequency generators.
I also think it's helpful to measure beyond the nominal 3dB bandwidth in order to graph out the frequency response (Gaussian, flat, something in between). As some others have commented, a scope is sometimes useful (well) past its 3dB bandwidth -- such as when measuring a reasonably pure sinusoid -- as long as you take the decrease in level accuracy into consideration. This also requires graphing the frequency response past the 3 dB point.
Another reason to graph this out is that the frequency response may have (non-trivial) ripples or other irregularities even within the 3 dB bandwidth. One advantage of scopes with a Gaussian frequency response is that they tend to have lower passband distortion than a flat / brick wall response.
Yes it's too bad getting a hold of a very high frequency generator is not that cheap, and i am not sure i want to shell out for one just to be able to tests scopes.
I have a PC board that goes up to 40MHz but i'd have to dig it out and hook it up to a microcontroller to get it going again.
If you have a really really good scope around you may be able to offer a small service to members. Measure the rise time of one of their oscillators and hand them that spec. They can use that to get some idea how their scope is behaving. I think it's important to know the rise time though and if the actual wave front was graphed, that would be even better. Using maybe a 20 point algorithm the bandwidth could be estimated.
I see that some are saying that digital scopes are not that simple though so not sure if this would work for every scope out there, just the ones with an equivalent first order low pass filter front end.
I think a square wave test tells us a lot of information even if it is lower frequency because the harmonics present go way up there if the rise and fall times are sharp. I can transmit a 100k square wave modulated signal to a radio at 7MHz or something like that so the harmonics are reaching up pretty high there.
Maybe i should look into this more.
I know a square wave gets very curvy as the higher frequencies get more attenuated, but i dont think it helps unless we know the slope of the rise and fall times.
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I'd never seen the likes of rated BW exceeded by 85% in any instrument.
R&S RTC1002 with the 100 MHz option enabled has a bandwidth of 200+ MHz. According to my estimates, about 250 MHz.