Question about analog oscilloscopes vs digital oscilloscopes

[Wuerstchenhund]

Why?

Because it is easier to see slow changes on an analog voltmeter (this remark was about a voltmeter, not about a scope).

I see, I assumed this was about scopes not voltmeters. But no, that's correct of course.

Well, if you don't know how to interpret the position of a trace against a calibrated graticule... 

(Emphasis mine) Exactly, "interpret". Add to this the fact that the graticules on scopes are pretty coarse and on many analog scopes are sitting on a separate layer of glass or perspex which creates parallax errors and it should be obvious why you're unlikely to get more than pretty coarse results from it.

Your average decent quality analogue scope, Tek etc. had *Specifications* for accuracy and linearity.

Well, pretty much any serious test instrument has specifications, that doesn't mean they are not shit compared to modern gear.

The only difference between between a 3% accurate analogue scope and a 3% accurate DSO is that the DSO gives reassuringly precise looking digital readouts to lull the unwary into a false sense of security. On a typical 8 bit DSO you're looking at a resolution of 2 1/2 digits and that's before you even take the accuracy spec into account (7 digits at 2 1/2 digits display EDIT: assuming your waveform occupies the full ADC range) If you want accurate voltage measurements then use a DVM.

I didn't suggest you use a scope as a replacement for a precision DVM. But that doesn't change the fact that the analog scope relies on user interpretation, which is in general a pretty unreliable way to obtain results, especially in complex situations. This adds another layer of uncertainty on top of the already poor (by today's standards) specs of an analog scope.

The frequency and time measurements on a DSO are pretty good as they're derived from a crystal oscillator (f/w permitting). The only voltage readings really worth considering (above comments still relevant) are the ones attached to the cursors so that you can move them to where *you* think the various levels are, rather than trusting where the f/w thinks they might be.

On a decent DSO you don't use "read-outs" (cursors) for measuring standard parameters, you use the various measurement and analysis functions which actually use the sample data to derive the individual measurement results from. And at least on big brand scope that works pretty well and reliable, although on cheap Chinese B-brand scopes like Rigols YMMV of course (which isn't overly surprising when reading the "Yaigol" thread).

I really only see people jumping to cursors when tasked with measuring standard waveform parameter is if they either don't know how to operate a modern DSO properly or the DSO they use is shit.

But the frequency accuracy of a modern DSO is indeed pretty good (as are the various other parameters), even for cheap entry-level scopes, and magnitudes better than what the old analog critters offered (just look at the woeful specs of that Tek 475). Better scopes can also be locked to a high stability reference, which only improves the accuracy even further.

The only thing a scope (analogue or DSO) is good for is interpretation of waveforms - It you really think all those displays are giving you any sort of "precision" then you are sadly deluded. 

Or maybe you need a reality check, because just because staring at a screen for glitches is all you know doesn't mean that's all there is. The fact that you assume that measuring waveform parameters on a DSO means "use cursors" tells me that your knowledge about DSOs is very likely stuck somewhere in the early 90's.

Any normal oscilloscope is a waveform interpretation tool. The DSO can obviously capture and freeze waveforms which is it's major advantage. The measurement readouts just come free with the f/w (you really wouldn't want to pay for them!).

For you, maybe. Most time I spend with a scope is revolving around actually measuring stuff, i.e. signal variations, the various parameters you can find on non-monotonous waveforms, jitter, frequency composition, trending, deviation, you name it, and it's pretty much the same throughout the various labs I work in. Good luck deriving all these parameters from looking and "interpreting" a waveform. 

You really need a reality check re. what a decent and somewhat modern DSO is capable of. This isn't the 90's anymore.

P.S. I just pulled out the instructions for my old Tek475A, a few specs:

Vertical Deflection accuracy: Within 3% of indicated deflection
Signal delay between CH1 and CH2: 0.25ns or less
Trigger Jitter: Less than 0.2ns at 250MHz
Calibrated sweep accuracy: +/-1% 5ms/div to 10ns/div, +/-2% 5s/div to 10ms/div (+/-2% when magnified to 1ns/div).
Sweep accuracy degraded to +/-3% over -15 to +55'C temperature range 

Not quite the "generally shoddy time-base stability and the limitations of the vertical stage" that you were expecting maybe? 

No, it's actually as pitiful as I remembered it.  If you think those specs are anything to write home about, then (borrowing your own words here) you're deluded.

[Jwalling]

you guys are so enthusiastic, even more active than the computer networking forums lol, especially when it comes to tools, designs and blowing things up.

Especially blowing things up!

Next thing we'll be discussing about buying uranium from amazon and enriching it.

I've just reported you to Homeland Security!    
Enjoy your extended vacation in Guantanamo. 
 
Jay

[Martin.M]

the best blowing up is still a tantalum drop, not the stinky selenium rectifiers.
I see that sometimes (in scopes)

[Fungus]

I must admit that I've never seen one of those blow up! IIRC Dale made those, yes?

There's a lot of Chinese clones but the good ones are Dale brand, yes. Usually 1% tolerance.

I've got a couple of 1 Ohm 1% Dale resistors for use as current shunts.

I can't imagine what it take would to burst that thick aluminum case (but I'll bet it makes some noise when it happens!)

[Fungus]

Next thing we'll be discussing about buying uranium from amazon and enriching it.

I've just reported you to Homeland Security!    

No need. The NSA was already on it.   

[Gyro]

@Wuerstchenhund, it's pretty clear that we're not going to converge completely on this one. You have a pretty emotive way of putting things, and please remember that I was responding specifically to your 'lightbulb vs DVM' comment.

Please remember also that I have already suggested to the OP that a DSO is his best option at this point.

To cover your points:

Add to this the fact that the graticules on scopes are pretty coarse and on many analog scopes are sitting on a separate layer of glass or perspex which creates parallax errors and it should be obvious why you're unlikely to get more than pretty coarse results from it.

You're implying worst possible case here. Since we're talking decent scopes, any decent analogue scope in the last 40 years has used a CRT with internal graticule - there is no parallax error. The only exceptions would be things like vectorscopes with oddball graticules but we're talking scopes here. With a standard 8x10cm graticule, each major division represents 12.5%, so it is pretty easy to read to the 3% accuracy figure. You might argue that the trace might not be scalable to full screen height, but the same applies when a DSO when the full bit depth of the ADC isn't in play.

Well, pretty much any serious test instrument has specifications, that doesn't mean they are not shit compared to modern gear.

I've just scanned through the current Keysight offerings. Vertical accuracy seems to be pretty universally stated at 3% until you get up to the 10 bit Infinium-S series where it drops to 1%. At this point you're well outside the pocket depth of 99% of people reading this forum. 3% is exactly the same specified vertical accuracy as the Tek 475A.... 3% is 3%, you can't call one of them shit without calling both of them shit! I suspect that you don't want to do that. 

I didn't suggest you use a scope as a replacement for a precision DVM. But that doesn't change the fact that the analog scope relies on user interpretation, which is in general a pretty unreliable way to obtain results, especially in complex situations. This adds another layer of uncertainty on top of the already poor (by today's standards) specs of an analog scope.

Well you did say "Analog scope vs. DSO is like measuring voltage with a light bulb instead of a DVM"

Sure, open to interpretation, but with the parallax issue dismissed and the 'poor' vertical specs being equal to the DSO's then it comes down to the user's ability to read the screen. What this does do however is constantly remind you of the accuracy that the scope is capable of, the digital readouts can imply greater accuracy than the scope is actually capable of achieving.

On a decent DSO you don't use "read-outs" (cursors) for measuring standard parameters, you use the various measurement and analysis functions which actually use the sample data to derive the individual measurement results from. And at least on big brand scope that works pretty well and reliable, although on cheap Chinese B-brand scopes like Rigols YMMV of course (which isn't overly surprising when reading the "Yaigol" thread).

I really only see people jumping to cursors when tasked with measuring standard waveform parameter is if they either don't know how to operate a modern DSO properly or the DSO they use is shit.

Unfortunately most people reading this thread probably are using Rigols. Relying on the f/w to correctly identify min/max/peak/overshoot etc. on all waveforms is a bit of an act of faith, and any scope can suffer a bug. I agree that with the ultimate scope you wouldn't need to use the cursors.

But the frequency accuracy of a modern DSO is indeed pretty good (as are the various other parameters), even for cheap entry-level scopes, and magnitudes better than what the old analog critters offered (just look at the woeful specs of that Tek 475). Better scopes can also be locked to a high stability reference, which only improves the accuracy even further.

I already said in my reply that the timing accuracy of a DSO is bound to be good (it damned well ought to be) due to its crystal clock.

The fact that you assume that measuring waveform parameters on a DSO means "use cursors" tells me that your knowledge about DSOs is very likely stuck somewhere in the early 90's.

Not true actually. 

Ok, I'm playing devils advocate a bit here, I've already said that DSOs are pretty much superior in all respects these days. But goaded by your 'lightbulb' comment I felt the need to demonstrate that in terms of vertical accuracy (what else would you use a DVM...or a lightbulb for) they are both pretty much the same, and both are pretty poor in DVM terms.

[nctnico]

With all the signal processing capabilities of a DSO (high resolution, averaging, and -if you are lucky- input filtering) you can clean up a signal nicely so it is easier to make cursor measurements but in many cases I just let the scope's measurements do the work.

[egonotto]

Hallo

David Hess wrote:

"If you want to make RMS noise measurements, then oddly enough an analog oscilloscope might be better although the procedure is tricky"

How can this done???

Best Regards
egonotto

[Wuerstchenhund]

@Wuerstchenhund, it's pretty clear that we're not going to converge completely on this one.

Probably not. That's life.

You have a pretty emotive direct way of putting things

FTFY. I have no emotive feelings towards scopes or T&M gear in general. Having grown up on analog scopes, I certainly understand the fond feeling many hold for this type of scopes, but from a practical POV that's irrelevant.

What I do find annoying though is when people who look for a scope get recommendations to go for an analog scope instead of a DSO, usually with some outdated or just simply incorrect BS attached to it (and we had some really good stuff in this regard in other threads, like claims that analog scopes are "high fidelity" instruments). All this does is cause some disappointment and (worst case) monetary loss with the poor soul asking the question.

Analog scopes had their place back in the day, but the reality is that these days have long gone. Nowadays an analog scope is an antique, nothing more, and it should really not be peddled as if it was an alternative to a DSO, because it really isn't. An analog scope might be a good buy if you're completely broke and get one in fully working condition for $50 or so, or if you're into nostalgia and antique test gear, but aside from these niche cases it's pretty much just a waste of money.

, and please remember that I was responding specifically to your 'lightbulb vs DVM' comment.

I'm fully aware of that, although I still have the feeling you miss the main point of this comment, which is that an analog scope (a tool you correctly said is for looking at waveforms) doesn't give you any numbers, similar to a lightbulb which doesn't give you numbers for a voltage (although an experienced lightbulb user may well interpret the brightness level to get a reasonably close figure of voltage). A DSO however does give you numbers, pretty precise ones (within its specified accuracy of course).

To cover your points:

Add to this the fact that the graticules on scopes are pretty coarse and on many analog scopes are sitting on a separate layer of glass or perspex which creates parallax errors and it should be obvious why you're unlikely to get more than pretty coarse results from it.

You're implying worst possible case here. Since we're talking decent scopes, any decent analogue scope in the last 40 years has used a CRT with internal graticule - there is no parallax error.

Yes, I'm implying non-perfect cases here, simply because non-perfect cases come up more often than expected in real life.

And while I agree that many newer analog scopes have their graticule in the CRT glass, there are still many scopes around that haven't.

Also, I didn't say parallax error is a major issue, or that all analog scopes are affected. At the end of the day, it's just one of many properties that increase uncertainty.

Well, pretty much any serious test instrument has specifications, that doesn't mean they are not shit compared to modern gear.

I've just scanned through the current Keysight offerings. Vertical accuracy seems to be pretty universally stated at 3% until you get up to the 10 bit Infinium-S series where it drops to 1%. At this point you're well outside the pocket depth of 99% of people reading this forum. 3% is exactly the same specified vertical accuracy as the Tek 475A.... 3% is 3%, you can't call one of them shit without calling both of them shit! I suspect that you don't want to do that. 

Yes, the vertical accuracy for an 8bit DSO is 3% but that's just one of many spec data points, and for others like linearity or horizontal accuracy the difference much bigger. Just look at the time base specs of your average analog scope, it's performance specs are shit even when compared to a bottom-of-the-barrel scope like a Rigol DS1054z (and Rigol hasn't exactly shown stellar engineering when it comes to the oscillating parts in their scopes). And for an instrument that was ultimatively designed to show or measure voltage changes in the time domain, a stable time base is pretty essential. The only reason it's not much of a problem on an analog scope is because results are generally dependent on user interpretation, which introduces even higher uncertainties than the poor specs of the scope itself.

And as to the voltage accuracy of an DSO, many better 8bit DSOs offer high resolution/ERES modes which increase the vertical resolution to 10 or more bits (for example, R&S RTE/RTO scopes go up to 16bit), which is a viable way to increase vertical accuracy if the loss of bandwidth that comes with it is acceptable.

On a decent DSO you don't use "read-outs" (cursors) for measuring standard parameters, you use the various measurement and analysis functions which actually use the sample data to derive the individual measurement results from. And at least on big brand scope that works pretty well and reliable, although on cheap Chinese B-brand scopes like Rigols YMMV of course (which isn't overly surprising when reading the "Yaigol" thread).

I really only see people jumping to cursors when tasked with measuring standard waveform parameter is if they either don't know how to operate a modern DSO properly or the DSO they use is shit.

Unfortunately most people reading this thread probably are using Rigols.

The number of Rigol threads could certainly suggest that, but I'm sure there is a very large number of people here that use something else. There are certainly a lot Agilent/Keysight users (DSO6k/7k, DSOX2k/3k, some Infiniium 548xx/8k/80k/9k users) here, a fair number of Tek users, and even a few R&S and LeCroy users, plus an increasing number of GW Instek users.

Relying on the f/w to correctly identify min/max/peak/overshoot etc. on all waveforms is a bit of an act of faith, and any scope can suffer a bug. I agree that with the ultimate scope you wouldn't need to use the cursors.

Using measurements on a DSO isn't a leap of faith, not much more as using any other function of any test instrument is (how sure can you be that your analog scope is still within even it's lacklustre specs, unless of course you fully calibrate it everytime before using it in anger?). Of course there can be bugs, but DSOs with automatic waveform paremeter measurements aren't exactly a new thing (even the old LeCroy 9400 from the late 80's could do that), and at least with the big brands that is generally reliable.

But as someone who only superficially follows the various Rigol threads I can't say how mature the measurement functionality in Rigol scopes is, but personally I wouldn't touch a product, which at the end of the day is supposed to be a test instrument you want to rely on for your measurements, is thrown to market with such a large number of bugs and with the hardware idiocracies listed in the "Yaigol" thread. But I understand that the low price tag can be very tempting.

[Nozzer]

As someone whose had an analogue oscilloscope for years and am now looking to go digital, I'm astonished that anyone would consider an analogue over a digital scope. I've been equally astonished over the past few months what one can do with even a basic digital scope.

I am a little baffled why digital scopes seem to have no chop button though, and what is all this about auto buttons, help buttons etc.....

[Gyro]

@Wuerstchenhund,

Ah, more convergence than I thought then. I certainly welcome the transition from "shit" to "lacklustre"   

Yes, I've similarly gone through the evolution of test instruments from the fairly distant past to their current level of development.

I think we're coming down to an educational information here, given the many recommendations for certain 'low grade DSOs' there is a tendency to see those magical digits on the screen as 'gospel' (I understand that some do have some f/w issues with AC measurements).

I think the very large disparity between horizontal and vertical performance (something that didn't occur in analogue scopes) is part of the 'problem'. In an ideal world the displays would be maybe 7 or 8 significant digits of horizontal (timing related) measurements and 2 1/2 to 3 digits (yes you can do some clever stuff to squeeze a bit more) for vertical. Of course that would look silly, so horizontal readings get squeezed down and vertical ones pushed to the max. Of course this disparity also has relevance for slope measurements.

When I'm doing audio stuff I use a low bandwidth 16 bit scope. Yes it has uV resolution and a noise floor of -125dB but I still have to remind myself occasionally that for all its 16 bits of resolution it still only has a Y accuracy spec of +/-1%. This remains a trap for the unwary (or uninformed).

Just to inject a bit of controversy still, browsing through the rest of the 475A's specs, its Y section and trigger circuit performance does actually stand up pretty well in the modern world, even if it does lack the ADC and readouts. 

[tggzzz]

What I do find annoying though is when people who look for a scope get recommendations to go for an analog scope instead of a DSO, usually with some outdated or just simply incorrect BS attached to it (and we had some really good stuff in this regard in other threads, like claims that analog scopes are "high fidelity" instruments).

I agree, with the proviso that some people make similar un-nuanced OTT claims for DSOs.

For example...

Nowadays an analog scope is an antique, nothing more, and it should really not be peddled as if it was an alternative to a DSO, because it really isn't.

There are a few technical applications in which specific analogue scopes are still better than some DSOs, as has been mentioned elsewhere on this thread. There are many more cases where they can do the job just as well as DSOs. And as you note, some people (especially on this forum) can't afford a new scope.

... which is that an analog scope (a tool you correctly said is for looking at waveforms) doesn't give you any numbers

Nonsense. OK, it doesn't spoonfeed you with digits, but the numbers are there for the moderately intelligent. Or, if you aren't sufficiently intelligent to determine the numbers, then you aren't intelligent enough to use a scope in the first place!

Also, I didn't say parallax error is a major issue, or that all analog scopes are affected. At the end of the day, it's just one of many properties that increase uncertainty.

Parallax has the benefit that it directly and visibly has to be understood. OTOH, it is very difficult to spot and correct problems with DSOs internal algorithms.

You acknowledge that in...

But as someone who only superficially follows the various Rigol threads I can't say how mature the measurement functionality in Rigol scopes is, but personally I wouldn't touch a product, which at the end of the day is supposed to be a test instrument you want to rely on for your measurements, is thrown to market with such a large number of bugs and with the hardware idiocracies listed in the "Yaigol" thread. But I understand that the low price tag can be very tempting.

So, it appears that your "DSOs are always best" kind of statements are implicitly presuming that the DSO is actually a high-end professional-grade expensive DSO from a reputable manufacturer. In that case I probably wouldn't argue. Neither would I argue that a new Rolls Royce isn't better than a second-hand Ford Escort.

But a Ford Escort will probably get you to your destination just as well - and much better if you can't afford a Rolls Royce! That's the kind of balance and nuance missing from your statements.

[tggzzz]

Just to inject a bit of controversy still, browsing through the rest of the 475A's specs, its Y section and trigger circuit performance does actually stand up pretty well in the modern world, even if it does lack the ADC and readouts. 

My "IBM" 475A does have readouts for voltage, resistance, time and frequency. And a nice <2ns risetime

Since it is surplus to requirements, how much do you think I can sell it for

[Wuerstchenhund]

@Wuerstchenhund,

Ah, more convergence than I thought then. I certainly welcome the transition from "shit" to "lacklustre"   

Well, you can put lipstick on a pig, but it is still a pig.

I think we're coming down to an educational information here, given the many recommendations for certain 'low grade DSOs' there is a tendency to see those magical digits on the screen as 'gospel' (I understand that some do have some f/w issues with AC measurements).

I agree, but that pretty much comes down to people not knowing how to properly use the scope (which includes being aware of its limitations!), and this is a completely different (albeit still important) problem that has nothing to do with analog scope vs DSO.

And while the analog scope in general lacks any (potential misleading) numbers, it comes with its own set of traps that in the past have even cought out many experienced engineers.

I think the very large disparity between horizontal and vertical performance (something that didn't occur in analogue scopes) is part of the 'problem'. In an ideal world the displays would be maybe 7 or 8 significant digits of horizontal (timing related) measurements and 2 1/2 to 3 digits (yes you can do some clever stuff to squeeze a bit more) for vertical. Of course that would look silly, so horizontal readings get squeezed down and vertical ones pushed to the max. Of course this disparity also has relevance for slope measurements.

The voltage accuracy of a normal 8bit scope isn't much of an issue for most tasks (as you said correctly, a DVM is a better tool to measure voltage accurately), but the timebase accuracy is for a device that covers the time domain.

When I'm doing audio stuff I use a low bandwidth 16 bit scope. Yes it has uV resolution and a noise floor of -125dB but I still have to remind myself occasionally that for all its 16 bits of resolution it still only has a Y accuracy spec of +/-1%. This remains a trap for the unwary (or uninformed).

True, but again, being aware of the limitations of your test gear is completely unlrelated to the topic (analog vs digital scope).

Just to inject a bit of controversy still, browsing through the rest of the 475A's specs, its Y section and trigger circuit performance does actually stand up pretty well in the modern world, even if it does lack the ADC and readouts. 

Not sure about the Y section (*cough* linearity plus a glooming tube *cough*) but Tek's analog scopes come indeed with a great trigger performance, much better than contemporary HP scopes. It's a real shame Tek never really made the jump into the digital world, as their digital scopes have been mediocre at best.But I guess it only shows that what was great yesterday isn't necessarily something to write home about today.

[Gyro]

Just to inject a bit of controversy still, browsing through the rest of the 475A's specs, its Y section and trigger circuit performance does actually stand up pretty well in the modern world, even if it does lack the ADC and readouts. 

Not sure about the Y section (*cough* linearity plus a glooming tube *cough*) but Tek's analog scopes come indeed with a great trigger performance, much better than contemporary HP scopes. It's a real shame Tek never really made the jump into the digital world, as their digital scopes have been mediocre at best.But I guess it only shows that what was great yesterday isn't necessarily something to write home about today.

Just for curiosity's sake. Vertical linearity (displayed) less than 0.1 div. error at the centre of the screen vs upper and lower extremities. I make that <1.25%. Ok not stellar but pretty darned good for the complete analogue gain chain and electrostatic deflection using distributed Y plates in a high PDA tube (clever chaps in those days!).  I'm not actually sure how that would compare with the linearity of the input amps and an 8 bit flash ADC, it's not a widely touted figure in DSO specs. You'd probably have to go to the ADC datasheet.  ...and yes it's a real shame that Tek didn't manage to translate all that skill into the digital age. 

[alsetalokin4017]

Can your low-end digital scope do this?

(Stable display of two waveforms at different frequencies)

[rstofer]

Can your low-end digital scope do this?

(Stable display of two waveforms at different frequencies)

I must misunderstand the question...  But, yes, I can push 4 digital signals that are binary submultiples into my DS1054Z and get a stable display.  That's kind of the point.

I don't have a source of two frequency related sine waves (and they have to be related if the display is to be stable) but I would expect the scope to work the same as it does on square waves.

If there's a bigger question that I missed, I'm interested in knowing what it is.  I have a lot to learn about DSOs.  My vast 5 weeks of experience isn't all that extensive!

[Jwalling]

Can your low-end digital scope do this?

Are they asynchronous?

Does this count? (Single trigger mode - does yours do that?    )
EDIT: They are asynchronous...

Jay

[tggzzz]

Just to inject a bit of controversy still, browsing through the rest of the 475A's specs, its Y section and trigger circuit performance does actually stand up pretty well in the modern world, even if it does lack the ADC and readouts. 

Not sure about the Y section (*cough* linearity plus a glooming tube *cough*) but Tek's analog scopes come indeed with a great trigger performance, much better than contemporary HP scopes. It's a real shame Tek never really made the jump into the digital world, as their digital scopes have been mediocre at best.But I guess it only shows that what was great yesterday isn't necessarily something to write home about today.

Just for curiosity's sake. Vertical linearity (displayed) less than 0.1 div. error at the centre of the screen vs upper and lower extremities. I make that <1.25%. Ok not stellar but pretty darned good for the complete analogue gain chain and electrostatic deflection using distributed Y plates in a high PDA tube (clever chaps in those days!).  I'm not actually sure how that would compare with the linearity of the input amps and an 8 bit flash ADC, it's not a widely touted figure in DSO specs. You'd probably have to go to the ADC datasheet.  ...and yes it's a real shame that Tek didn't manage to translate all that skill into the digital age.

Confirmed on my 465, 475 and 485[1].

Clearly someone is comparing very good+expensive X with poor+cheap Y, and declaring X the winner. Some might argue that shows ignorance. In any case it is unimpressive - and completely unenlightening.

[1] I'm not a scope fetishist, honestly. I'm only going to keep the 485, so consider the 465 and 475 "on the market"

[alsetalokin4017]

Can your low-end digital scope do this?

(Stable display of two waveforms at different frequencies)

I must misunderstand the question...  But, yes, I can push 4 digital signals that are binary submultiples into my DS1054Z and get a stable display.  That's kind of the point.

I don't have a source of two frequency related sine waves (and they have to be related if the display is to be stable) but I would expect the scope to work the same as it does on square waves.

If there's a bigger question that I missed, I'm interested in knowing what it is.  I have a lot to learn about DSOs.  My vast 5 weeks of experience isn't all that extensive!

No, the signals I showed on the 125 dollar (used of course) Tek 2213a are _not_ related, or synchronous or binary submultiples. In fact they are coming from two different sources altogether.  That is the point.

The scope is using Vertical Mode triggering, hence it is triggering alternately on either channel.

[alsetalokin4017]

Can your low-end digital scope do this?

Are they asynchronous?

Does this count? (Single trigger mode - does yours do that?    )
EDIT: They are asynchronous...

Jay

And how much did that scope cost? Although since the "high end" of DSOs can run to half a million dollars, I suppose anything that costs less than a new car could be considered "low end" for DSOs.

[nctnico]

Can your low-end digital scope do this?

(Stable display of two waveforms at different frequencies)

The GW Instek GDS2000E has no problem with showing 4 different totally unrelated frequencies using alternate triggering. I used that feature recently BTW. I doubt it's little brother the GDS1000B series starting at less than $400 will have problems doing that as well.

[Jwalling]

[quote author=alsetalokin4017 link=topic=69974.msg967824#msg967824
And how much did that scope cost? Although since the "high end" of DSOs can run to half a million dollars, I suppose anything that costs less than a new car could be considered "low end" for DSOs.
[/quote]

It's a TDS784D. New I think about $34K in 2000 or so. Now you can get them for $800 to $1200 US or so on Ebay. Even a TDS744A can do this; maybe $600.

Jay

[alsetalokin4017]

Can your low-end digital scope do this?

(Stable display of two waveforms at different frequencies)

The GW Instek GDS2000E has no problem with showing 4 different totally unrelated frequencies using alternate triggering. I used that feature recently BTW. I doubt it's little brother the GDS1000B series starting at less than $400 will have problems doing that as well.

The GDS2000E series is of course quite a bit more expensive than what I'd call "low end".
I don't see anything in the GDS1000B operator's manual that indicates it has alternate channel triggering capability.
http://assets.tequipment.net/assets/1/26/Instek_GDS-1000B_Series_User_Manual.pdf
Happy to be corrected if I'm wrong.

[nctnico]

Can your low-end digital scope do this?

(Stable display of two waveforms at different frequencies)

The GW Instek GDS2000E has no problem with showing 4 different totally unrelated frequencies using alternate triggering. I used that feature recently BTW. I doubt it's little brother the GDS1000B series starting at less than $400 will have problems doing that as well.

The GDS2000E series is of course quite a bit more expensive than what I'd call "low end".
I don't see anything in the GDS1000B operator's manual that indicates it has alternate channel triggering capability.
http://assets.tequipment.net/assets/1/26/Instek_GDS-1000B_Series_User_Manual.pdf
Happy to be corrected if I'm wrong.

Page 107 of the manual says alternate trigger mode so you have to be corrected