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Well, there's zero quantization noise, so I was wandering if some applications find that important?
Such as? Because I can't think of anyYes, really. Didn't you know? if you convert an analog voltage to a digital representation of that voltage, you'll introduce quantization noise.
but for most (all?) practical purpose it doesn't matter (that's what he meant with "can you differentiate"), storage is much more valuable than the quantization noise that's introduced with sampling/converting.
I read once a paper from tek that given the size of the CRT and the linearity of the circuit, sampling at 8bit was sufficient to mimick an analog scope. Signal is too low in amplitude? That's what amplifiers are for -
Well, there's zero quantization noise, so I was wandering if some applications find that important?
Such as? Because I can't think of any
Measuring wideband white noise, and hence signal-to-noise. Easy and fast on an analogue scope, tricky on a digitising scope (display technology, quantisation).QuoteYes, really. Didn't you know? if you convert an analog voltage to a digital representation of that voltage, you'll introduce quantization noise.
but for most (all?) practical purpose it doesn't matter (that's what he meant with "can you differentiate"), storage is much more valuable than the quantization noise that's introduced with sampling/converting.
I read once a paper from tek that given the size of the CRT and the linearity of the circuit, sampling at 8bit was sufficient to mimick an analog scope. Signal is too low in amplitude? That's what amplifiers are for
Spectrum analysis and allied measurements are a good counter-example.
Amplifiers have their own "infelicities", e.g. frequency response, noise and headroom. -
Measuring wideband white noise, and hence signal-to-noise. Easy and fast on an analogue scope, tricky on a digitising scope (display technology, quantisation).
True, i had actually that in mind as an optionQuoteSpectrum analysis and allied measurements are a good counter-example.
but we're talking about scopes here
correct me if i'm wrong, but in the frequency domain we use intruments that downconvert a portion of the spectrum so it can be acquired with low samplerate / high resolution converters (unless the bandwidth of interest is low enough that direct sampling can be used such as in audio analyzers) so in theory the quantization noise can be lowered enough to be lower than the noiseQuoteAmplifiers have their own "infelicities", e.g. frequency response, noise and headroom.
agreed -
Well, there's zero quantization noise, so I was wandering if some applications find that important?
Such as? Because I can't think of any
Well that's the same question I'm asking, I don't know, that's why I asked!Yes, really. Didn't you know? if you convert an analog voltage to a digital representation of that voltage, you'll introduce quantization noise.
but for most (all?) practical purpose it doesn't matter (that's what he meant with "can you differentiate"), storage is much more valuable than the quantization noise that's introduced with sampling/converting.
I read once a paper from tek that given the size of the CRT and the linearity of the circuit, sampling at 8bit was sufficient to mimick an analog scope. Signal is too low in amplitude? That's what amplifiers are for
Well in audio we routinely see 16 bits because of quantization noise, why do you think we see 12bit DSOs as well as 8bit? its to increase dynamic range, increase the vertical resolution. -
Read between the lines! That comparison was between digital scopes and analog scopes, those things with thick traces and 10x8cm CRTs. Compared to those 8bit resolution is adequate.
Todays digital scopes use 8-12" screen with full HD resolution, even more if they connect directly to your PC, there is already a benefit in higher resolution converters when you display the waveform, let alone when you zoom in into a previous acquisition, and when you perform analysis on the data.. all thing you can't do with an analog scope anyway.
The point being that quantization noise while it's present, it's irrelevant if it's something you can't do with an analog scope anyway -
1st: on CRT scope you can only see what you see on a screen with your eyes. Noise that is too small to see cannot be seen..
2nd: noise is noise. Digital, analog, periodic, stochastic. It is garbage added to our signal in process of measurement.
3rd: if noise is smaller than what you can resolve on screen it doesn't exist for that particular purpose.
4th: no, you cannot see to more than 8-9 bit of resolution on analog scope. It doesn't have perfect focus, and screen is too small
5th: no you cannot see 16bit quantization noise while looking at screen with full range signal on it (as analogous to CRT scope). You don't have screen with 65536 pixels vertically. 12 bit is 4096 pixels vertically.
Only reason you can "see" quantization effects is that you have digitized data in numeric format where you can easily look at 5th decimal and say "look there is a step".
Make an experiment: create 8, 10, 12 and 16bit sinewave as an array (in any software) and then plot them on screen.
You will see what I mean.
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Besides familiarity and ease of use, there are two main reasons why I still keep a Tek analog scope on the bench:
7CT1N curve tracer plugin
7A22 diff amp
I'm still waiting for a DSO maker to offer anything remotely as useful as these two plugins. -
Yes, really. Didn't you know? if you convert an analog voltage to a digital representation of that voltage, you'll introduce quantization noise. If you actually watch that video, you'll see he's not talking about quantization noise.
agree it is there, but i mean on which part quantization noise is visible there on the screen? or when it matters? -
agree it is there, but i mean on which part quantization noise is visible there on the screen? or when it matters?Well, there's zero quantization noise, so I was wandering if some applications find that important?
oo weally? can you differentiate white noise vs black noise? analog vs digital noise? english noise vs asia noise? have you heard about sinc(x)?
https://www.tek.com/en/support/faqs/why-does-my-digital-oscilloscope-have-more-noise-then-my-analog-oscilloscope
Yes, really. Didn't you know? if you convert an analog voltage to a digital representation of that voltage, you'll introduce quantization noise. If you actually watch that video, you'll see he's not talking about quantization noise.
That's the question I'm asking! That's what the OP is asking, when/why/if would an analog scope ever be preferable to a digital one, try answering rather than asking me my own question! -
Spectrum analysis and allied measurements are a good counter-example.
but we're talking about scopes here correct me if i'm wrong, but in the frequency domain we use intruments that downconvert a portion of the spectrum so it can be acquired with low samplerate / high resolution converters (unless the bandwidth of interest is low enough that direct sampling can be used such as in audio analyzers) so in theory the quantization noise can be lowered enough to be lower than the noise
That's one type of spectrum analyser; there are others. One keyphrase used by HPAK is "dynamic signal analyser", e.g. https://www.keysight.com/us/en/product/35670A/fft-dynamic-signal-analyzer-dc1024-khz.html
Many scopes now have an option to post-process captured samples using an FFT. Limitations (compared with "RF" SAs) are linearity and quantisation leading to spurious spurs. -
Well in audio we routinely see 16 bits because of quantization noise, why do you think we see 12bit DSOs as well as 8bit? its to increase dynamic range, increase the vertical resolution.
dynamic range is different, noise floor is different.
sorry that was look like a claim that analog scope has zero quantization noise. but since digital scope's quantization noise is also invisible (as you've implicitly agree) so basically not much different application between both, other than soothing phosphor glow, or if you want to miss modern digital features such as storage recording, digital encoding, SW FFT, bode plot etc.. someone will tell we can bode plot in analog scope, agreed, just not on top east made analog scope..
agree it is there, but i mean on which part quantization noise is visible there on the screen? or when it matters?
Yes, really. Didn't you know? if you convert an analog voltage to a digital representation of that voltage, you'll introduce quantization noise. If you actually watch that video, you'll see he's not talking about quantization noise.Well, there's zero quantization noise, so I was wandering if some applications find that important?
oo weally? can you differentiate white noise vs black noise? analog vs digital noise? english noise vs asia noise? have you heard about sinc(x)?
That's the question I'm asking! That's what the OP is asking, when/why/if would an analog scope ever be preferable to a digital one, try answering rather than asking me my own question!
if the analog scope minimum sensitivity is 1mV/div, then not much different with budget digital scope, furthermore, noise is noise and shown in digital scope, using markers and lines should do the trick directly, not so much i think with analog that you need to increase phosphor intensity to see more hidden noise and guestimating from the glow thickness by eyes. if you meant 500uv/div and lower sensitivity analog scope, then top east brand dont have it, its only available in used tek high end analog scope market.
Measuring wideband white noise, and hence signal-to-noise. Easy and fast on an analogue scope, tricky on a digitising scope (display technology, quantisation).Well, there's zero quantization noise, so I was wandering if some applications find that important?
Such as? Because I can't think of any
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please not the "FSA/DSA/analog" all = sampling scope again! SA has -200dB noise floor, you cant see that on any analog nor digital scope.Spectrum analysis and allied measurements are a good counter-example.
but we're talking about scopes here correct me if i'm wrong, but in the frequency domain we use intruments that downconvert a portion of the spectrum so it can be acquired with low samplerate / high resolution converters (unless the bandwidth of interest is low enough that direct sampling can be used such as in audio analyzers) so in theory the quantization noise can be lowered enough to be lower than the noise
That's one type of spectrum analyser; there are others. One keyphrase used by HPAK is "dynamic signal analyser", e.g. https://www.keysight.com/us/en/product/35670A/fft-dynamic-signal-analyzer-dc1024-khz.html
Many scopes now have an option to post-process captured samples using an FFT. Limitations (compared with "RF" SAs) are linearity and quantisation leading to spurious spurs. -
For a brief, shining moment, when the $A was above parity with the $US, a new DSO was affordable for those of us on a restricted budget, but these days, we are confronted with things like a SDS-1102DL+ for $A598.00 plus GST.
Wow, Wavecom are really taking the piss !
https://www.wavecom.com.au/product_view.php?id_product=1035&gclid=CjwKCAiAv9ucBhBXEiwA6N8nYE8M2VLDpCwIWvijQbOtvdgxNkJWnPk-W3c
$100 + GST cheaper for the same 100 MHz 2ch model at the Oz master importers Trio:
https://www.triotest.com.au/brands/siglent/digital-oscilloscopes/sds1000dl-seriesQuoteor a DS1052E for $A429.00 plus GST. at EMONA
And Dave fucks a perfectly good one taking it on a mud run instead of offering it so some needy and destitute pensioner.
Even a Digitech/El Crappo from Jaycar is $A549.00 GST included.
They do have a 25MHz toy for a more affordable $A239.20 GST incl.
On ebay there are some Hantek, Owon, & FNIRSI things at around $A300.00, but I'm dubious about them.
Rigols & Siglents are not much different than buying locally.
Even ancient TDS210s & 220s are around $A300.00 & upwards.QuoteI guess I will have to fix my Tek 7613!
Just hope you don't need a working scope to do that !
The (PSU) fault, luckily (in one way) doesn't need a decent 'scope to fix it---the little 10MHz Analog Digitech would do----it's just getting the motivation to do it.
The biggest problem is that everything else is jostling for position on the queue, & my "get up & go" has got up & went!
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Well in audio we routinely see 16 bits because of quantization noise, why do you think we see 12bit DSOs as well as 8bit? its to increase dynamic range, increase the vertical resolution.
dynamic range is different, noise floor is different.
sorry that was look like a claim that analog scope has zero quantization noise. but since digital scope's quantization noise is also invisible (as you've implicitly agree) so basically not much different application between both, other than soothing phosphor glow, or if you want to miss modern digital features such as storage recording, digital encoding, SW FFT, bode plot etc.. someone will tell we can bode plot in analog scope, agreed, just not on top east made analog scope..
agree it is there, but i mean on which part quantization noise is visible there on the screen? or when it matters?
Yes, really. Didn't you know? if you convert an analog voltage to a digital representation of that voltage, you'll introduce quantization noise. If you actually watch that video, you'll see he's not talking about quantization noise.Well, there's zero quantization noise, so I was wandering if some applications find that important?
oo weally? can you differentiate white noise vs black noise? analog vs digital noise? english noise vs asia noise? have you heard about sinc(x)?
That's the question I'm asking! That's what the OP is asking, when/why/if would an analog scope ever be preferable to a digital one, try answering rather than asking me my own question!
if the analog scope minimum sensitivity is 1mV/div, then not much different with budget digital scope, furthermore, noise is noise and shown in digital scope, using markers and lines should do the trick directly, not so much i think with analog that you need to increase phosphor intensity to see more hidden noise and guestimating from the glow thickness by eyes. if you meant 500uv/div and lower sensitivity analog scope, then top east brand dont have it, its only available in used tek high end analog scope market.
Measuring wideband white noise, and hence signal-to-noise. Easy and fast on an analogue scope, tricky on a digitising scope (display technology, quantisation).Well, there's zero quantization noise, so I was wandering if some applications find that important?
Such as? Because I can't think of any
Well yes, an analog scope as you know, cannot have quantization noise. But my scope has an 8 bit vertical resolution, that's 256 resolution yet the display has a vertical pixel resolution of 480. There are quantization effects that are undoubtedly present, my question was to anyone, especially professional engineers, whether there are ever cases, domains, situations where an analog scope (perhaps one of the more recent analog high end scopes) is advantageous.
There may well be no such situations at all, ever, but I don't know so wanted to see if any experts here could point out examples.
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Before I retired I used to travel to sites in some countries to assist the local agent or sub- company with problems.
The typical anecdote was the the DSO scope would be unpacked, the tech would start pecking away at the menu screens and it would be morning coffee time before scope was displaying a usable trace.
Saying "Now , let us look at the dv/dt on THAT edge af THAT Channel" would elicit another pecking session.
I recently got a basic DSO to help the aged 466 ASO on the hobby bench.
But most of the time I still switch on the 466.
I use single shot a lot on the inverters.
Unfortunately, the DSO GWI1202B has a "Default" button right under the "Single Shot" and next to the timebase knob!
Bumping that default button is a mild disaster, needing another pecking session. -
Bumping that default button is a mild disaster, needing another pecking session.
if it only give bad things to you, just peel the rubber button off so there is no more disaster.. -
Just tried, thanks. It did not come off with some force, so I'm scared of breaking it.
Scope is still in warranty, Maybe I will wait until warranty is over.
I had though of making a little flap or milling aluminum surround guard to glue on but there is very little space around the button -
We've been using "analog" scopes for well over 60 years, got our 1st analog scope (Heathkit) when 12, and utilized just about every Tektronix analog scope ever made. Even did custom plug-ins if any folks remember those from Tek, they were the metal case plug-in and blank front panel with a prototype PCB inside and interface connector. Had many "custom plug-in functions" for the various Mainframe Type Tek analog scopes we utilized.
From an old (very old) analog diehard it took some time to "pull the trigger" on a modern DSO for ourself, having the old "analog" bias prevented this for awhile!!
Now after some time using such, comparing an analog scope to a modern low noise, high resolution DSO is like comparing a Simpson 260 to a Keysight 34465A or Keithley DMM6500. We keep a couple Tek 2465s around just to remind us of how good these newer DSO are, and to play around with just as reminders of days of old
Best, -
Well yes, an analog scope as you know, cannot have quantization noise. But my scope has an 8 bit vertical resolution, that's 256 resolution yet the display has a vertical pixel resolution of 480. There are quantization effects that are undoubtedly present, my question was to anyone, especially professional engineers, whether there are ever cases, domains, situations where an analog scope (perhaps one of the more recent analog high end scopes) is advantageous.
There may well be no such situations at all, ever, but I don't know so wanted to see if any experts here could point out examples.
And what do you thing CRT scope has no noise? How thick is the trace? There is a limit on "analog resolution", it is called noise floor.
It is same as "megapixel wars" in SLR cameras, where saying "film is analog" doesn't mean it has unlimited resolution. It doesn't, it has grain. And "analog resolution" (sharpness) of lenses is also a thing...
Decent DSO of today will have less noise (despite 8 bits) than most CRT scopes with exception of few special ones.
And higher bit (10bit and up) will have more detail than any analog CRT scope.
And FFT, math, measurements, analysis, mask test, single shot capture, decodes... And huge screens in comparisons. Networking, remote control, easy saving of data and screenshots...
There is only one thing where CRT is still better : X-Y mode for scope art.. And as someone here mentioned, some of the fancy CRT modular scopes had some special modules that have no equivalent, but that is not a analog/digital difference.
Those a niche enough there is no imperative for manufacturers to invest into developing that anmore. If there was need for it, it would be made. -
Well yes, an analog scope as you know, cannot have quantization noise. But my scope has an 8 bit vertical resolution, that's 256 resolution yet the display has a vertical pixel resolution of 480. There are quantization effects that are undoubtedly present, my question was to anyone, especially professional engineers, whether there are ever cases, domains, situations where an analog scope (perhaps one of the more recent analog high end scopes) is advantageous.
There may well be no such situations at all, ever, but I don't know so wanted to see if any experts here could point out examples.
And what do you thing CRT scope has no noise? How thick is the trace? There is a limit on "analog resolution", it is called noise floor.
It is same as "megapixel wars" in SLR cameras, where saying "film is analog" doesn't mean it has unlimited resolution. It doesn't, it has grain. And "analog resolution" (sharpness) of lenses is also a thing...
Decent DSO of today will have less noise (despite 8 bits) than most CRT scopes with exception of few special ones.
And higher bit (10bit and up) will have more detail than any analog CRT scope.
And FFT, math, measurements, analysis, mask test, single shot capture, decodes... And huge screens in comparisons. Networking, remote control, easy saving of data and screenshots...
There is only one thing where CRT is still better : X-Y mode for scope art.. And as someone here mentioned, some of the fancy CRT modular scopes had some special modules that have no equivalent, but that is not a analog/digital difference.
Those a niche enough there is no imperative for manufacturers to invest into developing that anmore. If there was need for it, it would be made.
I don't disagree, my OP was intended to find out if there were any specialized industries or situations in which an analog scope was preferred. For example, what was the highest ever bandwidth CRT scope? was it a higher frequency than the highest bandwidth DSO today?
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There is only one thing where CRT is still better : X-Y mode for scope art..
Here's another: where a scope (analogue or digitising) with analogue sampling head is still the best: dealing with overload.
If you want to observe the full-scale transient settling time of an op-amp's or DAC's output to 0.1%, then an analogue sampling head is still required.
Any front-end analogue circuit will be overloaded and have "unhelpful" recovery from overload characteristics. In contrast, the analogue sampling head simply ignores any input (including overload) until the sampling instant. If I could get the thermal paper, I'd be able show a photograph of a chart recorder displaying 150ps risetimes
Of course, given an analogue sampling head, a pen chart recorder is sufficient for plotting the transient. No need for this fancy high speed display rubbish overkill.
I refer readers to the aphorism in my .sig. -
As a practical matter in this modern age, there are no analog oscilloscopes in production that are as good as, say, a Tektronix 7904 or 2465.
I still use a 7603, but to operate a good Tektronix analog scope means having the dedication to maintain it yourself, just like owning a Saab. -
There is only one thing where CRT is still better : X-Y mode for scope art..
Here's another: where a scope (analogue or digitising) with analogue sampling head is still the best: dealing with overload.
If you want to observe the full-scale transient settling time of an op-amp's or DAC's output to 0.1%, then an analogue sampling head is still required.
Any front-end analogue circuit will be overloaded and have "unhelpful" recovery from overload characteristics. In contrast, the analogue sampling head simply ignores any input (including overload) until the sampling instant. If I could get the thermal paper, I'd be able show a photograph of a chart recorder displaying 150ps risetimes
Of course, given an analogue sampling head, a pen chart recorder is sufficient for plotting the transient. No need for this fancy high speed display rubbish overkill.
I refer readers to the aphorism in my .sig.
What you say is absolutely correct. But.....
OP doesn't (and neither we are) talking about these types of scopes. They are very limited in usability and quite special.
These are not what people call analog CRT scopes. Such is popular lingo, sorry. Same as when people say digital sampling scope they mean Realtime DSO. Most never saw or used analog sampling scope and have no interest in it.
He specifically wants a comparison between classic analog CRT (direct writing of CRT with analog X/Y beam deflection) and modern real time DSO as a replacement.
We better not venture where more confusion will be brought in the picture..
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Besides familiarity and ease of use, there are two main reasons why I still keep a Tek analog scope on the bench:
It might not be long before Curve Tracers become another DSO feature but in the meantime while you're nursing that old gear along (no disrespect implied) you might like to look at what some have done in their spare time and follow a few links to observe where it led them:
7CT1N curve tracer plugin
7A22 diff amp
I'm still waiting for a DSO maker to offer anything remotely as useful as these two plugins.
https://www.eevblog.com/forum/testgear/fooln-around-with-dso-awg/
What's so special about the diff amp plugin that differential probes can't do ?
I'd really like to know. -
I guess I will have to fix my Tek 7613!
Just hope you don't need a working scope to do that !
The (PSU) fault, luckily (in one way) doesn't need a decent 'scope to fix it---the little 10MHz Analog Digitech would do----it's just getting the motivation to do it.
The biggest problem is that everything else is jostling for position on the queue, & my "get up & go" has got up & went!
Man do I know that problem too !
Shame we weren't visiting the lad this year as I'd happily bring some tools and help you fix it. Got aircon for them darn hot days you get this time of year ?