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Analog versus digital oscilloscopes 2

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Trader:
I don't know why the post (https://www.eevblog.com/forum/beginners/analog-versus-digital-oscilloscopes/) was closed, but I think this is an interesting topic and there is no need for censorship in a technical forum. A lot of people can learn about the technical differences, advantages, and disadvantages over the years.


Talking about PRICE, a good Analog scope is MUCH better than a good Digital Scope.

Most of the time you just need to see Signals, you don't need fancy options as serial communication or FFT, etc; it is better to use a dedicated logic or spectrum analyzers.

I'm not sure what is the analog scope with the highest bandwidth, but up to 500MHz, a good analog scope will cost between 1/3 or 1/10 of a Rigol MSO5074 or Siglent SDS2104X Plus (hobbyist or officially upgraded) and 1/10 or 1/30 of a Tektronix, Keysight, Rohde & Schwarz, LeCroy, etc.

And, as I said, 99% of the time you just want to see the waves. (good analog scopes also created several excellent features to compensate for the lack of storage.)

PS: Or an "intermediary" Digital Phosphor Oscilloscope (DPO); there are +-1GHz models costing similar to a 100MHz DSO.

TimFox:
Just as with "real cameras", i.e. film-based, it is hard to find good analog oscilloscopes anymore.  Similarly, I won't give up mine (or my large-format film cameras) in this life.
My basic reply to this question, based on many years with both, is that if you don't know what the problem is, it is better to start with an analog oscilloscope (with sufficient bandwidth).
If you know what's going on, but need to make a measurement, the digital oscilloscope is better.  Similarly, if you need to freeze a waveform, especially a non-periodic waveform, the digital oscilloscope is better.
One technology for which I have no nostalgia is the analog storage oscilloscope.

Siwastaja:
All details about some quantization effects are totally unimportant.

The large difference is that basically what is called a "digital oscilloscope" today is a storage oscilloscope, and very good at said storage features.

While analog storage oscilloscopes exist, they are way more limited in this "storage", and most analog scopes beginners buy are not storage oscilloscopes at all.

The big difference here is, a storage oscilloscope can capture and store a waveform, for example, to record one incident, be it a digital communication packet, or a non-repetitive analog phenomenon like someone shouting an obscenity at a microphone, or recording an earthquake. You can record quite long observations, then zoom in and out, scroll it...

Analog oscilloscopes are pretty good to observe repetitive signals, for example to look at how an amplifier works when you can feed the amplifier with a repetitive signal from a Function Generator. Or to look at the triangle wave an fixed-frequency PWM SMPS generates under steady conditions...

But the big difference is, they are different instruments altogether, a digital storage oscilloscope can do so many more things an analog scope is completely unsuitable for. Especially nowadays almost every beginner wants to do something with an Arduino or similar at some point, and needs to look at UART or SPI or just GPIO. Analog scope is nearly useless for this. So you would need two scopes --

except that you won't, because the reverse is only true if very small details are important (and they usually aren't). Even a remotely modern digital storage oscilloscope can replace an analog one in 99.9999% of cases, although maybe it sometimes happens that you do have a really high BW repetitive signal and can't afford to buy an expensive 1GHz digital scope but happen to find a good deal of an used analog top performer. But I doubt it, the best analog scopes have already found their homes.

rdl:
I have a Tektronix 2247A and a Rigol DS1052E and I use both. But, unless I actually need some feature only on the digital scope, I use the Tektronix just because the screen is 1000x nicer to look at.

TimFox:
To clarify why I like an analog CRO when I don't know what the problem is:  Since the analog scope does not periodically sample the waveform, it will show "fuzziness" or similar when an unexpected high-frequency waveform or noise is superimposed on the "regular" stuff.  The user can expand the timebase to examine what can't be resolved at the slower time/div.  So long as the hf stuff is within the analog bandwidth, it will be visible even if not resolved due to the finite width of the trace on the phosphor face.
With a DSO, if you have an unexpected high-frequency waveform, it may show an alias from periodic sampling that can be confusing.
An example from the past:  the first decent digital oscilloscope we had at work had 100 MHz bandwidth and displayed 10 k points (which was not bad for that time in history).  We were tracing down unexpected noise in a complex system and saw a very clean sinusoidal waveform close to 60 Hz, but which did not synchronize to the line.  Eventually, we discovered that we were seeing a 10 MHz clock waveform alias at a timebase setting appropriate for 60 Hz:  it was the roughly 6 ppm difference in calibration between the external clock and the internal clock of the DSO.  (To check for aliases, change the timebase and see if the apparent frequency, in Hz, changes.  That was the lesson learned from that episode.)

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