Hi Tom,
Same with my MSOX3104T, a pain to use. Really it is the waveform capture and playback that is most useful. I use external generators for anything else. Now that would be a great web control app for Keysight, within the stock web control.
I find add-on functionality with most instruments inconvenient to use. The function is there but not really useful.
Same with my MSOX3104T, a pain to use. Really it is the waveform capture and playback that is most useful. I use external generators for anything else. Now that would be a great web control app for Keysight, within the stock web control.
I find add-on functionality with most instruments inconvenient to use. The function is there but not really useful.
As has been pointed out frequently in this thread, digital oscilloscopes are more complex and you need to fully understand how they work to get the most out of them. If you're just starting, a used analogue 'scope is a much better bet, but beware that it will be old and may fail irreparably (EHT transformer). Once you know how to drive a 'scope, consider a digital. The trouble is that cheap new digital oscilloscopes prioritise bells and whistles that register in the advertising spiel, not their core ability. Sadly, there's a reason why good oscilloscopes cost more and it often doesn't show up in the written specifications. My most frequently used 'scope is a Tek TDS3032; lovely ergonomics and still very capable. When I need a better FFT, I reach for the Tek MSO54. Bigger, and much heavier to get on the bench. Be aware that just because a 'scope's ADC produces 12 bits, that doesn't mean they're all correct. No, sir! When you get to better 'scopes, you'll find people talking about Effective Number Of Bits (ENOB) and it's very rarely more than 8-9 because that's all an oscilloscope needs. Trying to use an oscilloscope as a spectrum analyser and measure anything other than gross distortion is not a good idea.
Amateur radio rallies (UK) and hamfests (USA) are great places to pick up a cheap analogue oscilloscope. Last year, I bought a very nice little Telequipment 10MHz 'scope for a friend for £35. Admittedly, I had to repair an input switch, but it was still good value.
Amateur radio rallies (UK) and hamfests (USA) are great places to pick up a cheap analogue oscilloscope. Last year, I bought a very nice little Telequipment 10MHz 'scope for a friend for £35. Admittedly, I had to repair an input switch, but it was still good value.
Hi!
No measurement equipment is perfect and all have their limitations.
If the limitations meet your needs, you are good to go even with the cheap ones.
Example of my case. I have a very entry level 8-bit scope (Hantek rebranded to a local vendor) and I play with audio and switching circuits most of time,
Using only the bare scope, I'm limited to 48dB (or 0.4%) measurements. Any other more precise measurement, I perform using other means, such as adding filters, pre-amplifying the signal to rescale it etc.
To get used to my scope, I've prepared several sine wave files in 16bits/44.1kHz using Audacity with different harmonic distortions.
I added 3rd harmonic 10%, 1%, 0.5% and 0.1%.
Then I've played these files back and measured them with the scope. I could see clearly what the scope was or was not able to measure.
See below: I can measure 0.5%, 1%, 10% distortion, but I cannot measure 0.1% since I reach the noise level.
No measurement equipment is perfect and all have their limitations.
If the limitations meet your needs, you are good to go even with the cheap ones.
Example of my case. I have a very entry level 8-bit scope (Hantek rebranded to a local vendor) and I play with audio and switching circuits most of time,
Using only the bare scope, I'm limited to 48dB (or 0.4%) measurements. Any other more precise measurement, I perform using other means, such as adding filters, pre-amplifying the signal to rescale it etc.
To get used to my scope, I've prepared several sine wave files in 16bits/44.1kHz using Audacity with different harmonic distortions.
I added 3rd harmonic 10%, 1%, 0.5% and 0.1%.
Then I've played these files back and measured them with the scope. I could see clearly what the scope was or was not able to measure.
See below: I can measure 0.5%, 1%, 10% distortion, but I cannot measure 0.1% since I reach the noise level.
Yep. Oscilloscopes are not precision instruments. Keep in mind how they're used: The operator reads the waveform height or zero crossing points manually off the screen and compares with the graticule on the screen. A good operator might be able to get better than, say, ±1 % precision that way, but forget about umpteen digits of precision.
If you want to know the amplitude of the signal, use a voltmeter.
If you want to know the frequency of the signal, use a frequency counter.
If you want to know the distortion of the signal, use a distortion analyzer or spectrum analyzer.
Etc.
Unless you're happy with the 60-80 dB dynamic range commonly offered in a digital scope. And forget about reading anything but gross distortion on an analog scope.
That said, a scope is incredibly useful for showing wave shapes and that can be very helpful in debugging of analog circuits.
Tom
If you want to know the amplitude of the signal, use a voltmeter.
If you want to know the frequency of the signal, use a frequency counter.
If you want to know the distortion of the signal, use a distortion analyzer or spectrum analyzer.
Etc.
Unless you're happy with the 60-80 dB dynamic range commonly offered in a digital scope. And forget about reading anything but gross distortion on an analog scope.
That said, a scope is incredibly useful for showing wave shapes and that can be very helpful in debugging of analog circuits.
Tom
Right, an oscilloscope shows waveform shape. Mind you, when looking at a trace, noise is important to see, and especially noise on an eye pattern. A cheap analogue scope will show an eye pattern (0.5uS/div), but you need a really good digital to even be passible.
Example. My Agilent 54642D shows sort of an eye pattern, the Keysight MSOX3104T shows something I can work with. The older Philips PM3070 and PM3365 have the best patterns, really clean. The analogue oscilloscopes are the clear winners for noise and clean traces. Look at the prices those digital scopes were. They are getting better, but sub $1K scopes will not get you there.
As for measurements, the MSOX3104T is reasonably accurate for amplitude and time / frequency. Rise time and stuff like that. FFT is poor compared to a spectrum analyzer, so I don't use the FFT in the DSOs, I use the appropriate spec-an for that job. Amplitude, the correct meter. Frequency, a good frequency counter.
I don't believe in wasting time messing around with the wrong instrument when you may well get the wrong answer doing that. You should never fight your tools.
Keep in mind that many instruments do not stay in tolerance. The better ones are more likely to (the 34401A's haven't been out yet) keep their calibration. Then also figure out the accuracy in counts for each range, use the maximum date from cal figures. The results may shock some of you when you see that last digit is a joke. Then figure out the AC accuracy and resistance.
Now for a sobering thought. Many meters I had to certify brand new failed. That's new out of the box, I opened them. Some from really good names which I will not mention. Never assume the best case.
Example. My Agilent 54642D shows sort of an eye pattern, the Keysight MSOX3104T shows something I can work with. The older Philips PM3070 and PM3365 have the best patterns, really clean. The analogue oscilloscopes are the clear winners for noise and clean traces. Look at the prices those digital scopes were. They are getting better, but sub $1K scopes will not get you there.
As for measurements, the MSOX3104T is reasonably accurate for amplitude and time / frequency. Rise time and stuff like that. FFT is poor compared to a spectrum analyzer, so I don't use the FFT in the DSOs, I use the appropriate spec-an for that job. Amplitude, the correct meter. Frequency, a good frequency counter.
I don't believe in wasting time messing around with the wrong instrument when you may well get the wrong answer doing that. You should never fight your tools.
Keep in mind that many instruments do not stay in tolerance. The better ones are more likely to (the 34401A's haven't been out yet) keep their calibration. Then also figure out the accuracy in counts for each range, use the maximum date from cal figures. The results may shock some of you when you see that last digit is a joke. Then figure out the AC accuracy and resistance.
Now for a sobering thought. Many meters I had to certify brand new failed. That's new out of the box, I opened them. Some from really good names which I will not mention. Never assume the best case.
Ditto. I have its liitle brother, the TDS2014. I got it over 20 years ago. I have a collection of well over 10 scopes, but the 2014 is my 'daily driver' for exactly the same [ergonomic] reasons you cite. My first scope was a 20MHz Kenwood and my most expensive one is a Tek MDO3024. I have a collection of Tek 7000 mainframes with all manner of plug-ins. In truth, I could do 99% of everything I need with the Kenwood... (and you can find them dirt cheap if you know how to find them on Ebay). I'd have to pay attention to settings on the Kenwood, whereas the Tek tells me on-screen, which is why it gets the most use. The Kenwood trace is sharper than any other scope I've seen. I saw a video tour of Accuphase on YT recently and noticed that every bench has a Kenwood... My Tek 7000s and HP analogue scopes are the most fun to use, but [alas] I have to pay the rent...time is money and all that, so I go with the tool that gets to the root of the problem the fastest, which is invariably the humble and less visually impressive 2014.
As Jim Williams (his favorite scope the Tek 547) said: "A digital scope doesn't lie, it just doesn't always tell the truth."
Hi,
when I read all the latestposts about how problematic digital scopes are .... I wonder: "Have You all forgotten how much worse -and not just restricted- analog scopes were/are?"
Especially the last 10 to 15 years there´s been such a progress in technical specs and precision, besides all those vast functional upgrades.
What is for example the lowest mV/div range on Your old analog scope? 10mv? 20mV?
Something the cheapest handheld gadget scope can do nowadays costing 20$.
1mV/div is typical, often even 0,5mV/div.
Noise figures? Bandwidth? Dynamic range? Precision of readout values? Multitudes of triggers? Analyzing capabilities? What else?
Come on boys ... gimme a break. 😎
jauu
Calvin
when I read all the latestposts about how problematic digital scopes are .... I wonder: "Have You all forgotten how much worse -and not just restricted- analog scopes were/are?"
Especially the last 10 to 15 years there´s been such a progress in technical specs and precision, besides all those vast functional upgrades.
What is for example the lowest mV/div range on Your old analog scope? 10mv? 20mV?
Something the cheapest handheld gadget scope can do nowadays costing 20$.
1mV/div is typical, often even 0,5mV/div.
Noise figures? Bandwidth? Dynamic range? Precision of readout values? Multitudes of triggers? Analyzing capabilities? What else?
Come on boys ... gimme a break. 😎
jauu
Calvin
Agreed, a good new digital 'scope is much more flexible than an old analogue (they often went to 1mV/div, by the way). But to use a digital 'scope properly still requires more skill than an analogue. All you had to be able to do on an analogue 'scope was to trigger it properly and what you saw was likely to be the truth. With a digital 'scope, you do need to think about the sample rate you've set and which sample mode. I'm not criticising (I gave away my last analogue 'scope twenty years ago), but for a novice, an analogue 'scope is a safer bet than a cheap digital 'scope.
Hi Calvin,
I have to say ... as someone who started with a single trace, recurrent sweep 500KHz Stark tube scope. Oscilloscopes progressed greatly throughout time. Everything got better. I have an HP 1722A, Tek 777613 frame, 465, 2235, 2465B and others. I also have some Philips PM 3070 and PM 3365A - an early "Combiscope". Also, a few cheap digitals, Agilent 54642D and Keysight MSOX3104T. From those and others I have used (didn't own) I have a very good feel and cross section of how things developed and the general capabilities of each type. The only scope I no longer have is the Stark, my first scope. The Philips and some Tek scopes read out amplitude and frequency at the touch of a button, but they are analogue.
Based on that I have to strongly disagree with your comments. When I need to see detail and low noise, I grab an analogue oscilloscope.
One basic problem is that there is no such thing as a digital oscilloscope. That's a misnomer. It is a digital acquisition system. It samples the signal and can display it as the familiar oscilloscope screen we all know and love. Just as easily it can also display that data as an FFT. It doesn't matter. To get bandwidth, they have to reduce the number of sample bits. They are increasing that but it is horribly expensive to do so. The amount of noise the ADC and the analogue signal conditioning before it creates on inexpensive scopes is pretty high also. Limited vertical resolution hides details on top of that. Then we get to the real issue. It is a sampling system, and therefore may be subject to aliasing. If may display a waveform that appears to be correct, but it isn't. As the operator, you have got to know that. All this costs more than an analogue scope does with equivalent sensitivity, noise and speed.
Okay, so it boils down to what you are doing and what you actually need. To know, you need experience. Without familiarity and experience you tend to believe whatever the instrument tells you (both meters and oscilloscopes). The features are attractive and designed to sell the product. Just like a poorly built car with bells and whistles. The features sound really neat, but how well does the thing actually work for it's primary purpose, and then how well do the features work? It is a trade-off and that involves money too. My daily driver is very expensive, $25K approx. My analogue scopes decades older do some things better, sad to say. I still use them.
To say current digital oscilloscopes are better than an analogue oscilloscope is, I think, entirely false. Maybe the ones individuals cannot afford are (they go past $250K in price), but mere mortals are often better served by an old analogue oscilloscope. Not unless you don't need low noise and detail. But then, that is what analogue audio is all about.
I have to say ... as someone who started with a single trace, recurrent sweep 500KHz Stark tube scope. Oscilloscopes progressed greatly throughout time. Everything got better. I have an HP 1722A, Tek 777613 frame, 465, 2235, 2465B and others. I also have some Philips PM 3070 and PM 3365A - an early "Combiscope". Also, a few cheap digitals, Agilent 54642D and Keysight MSOX3104T. From those and others I have used (didn't own) I have a very good feel and cross section of how things developed and the general capabilities of each type. The only scope I no longer have is the Stark, my first scope. The Philips and some Tek scopes read out amplitude and frequency at the touch of a button, but they are analogue.
Based on that I have to strongly disagree with your comments. When I need to see detail and low noise, I grab an analogue oscilloscope.
One basic problem is that there is no such thing as a digital oscilloscope. That's a misnomer. It is a digital acquisition system. It samples the signal and can display it as the familiar oscilloscope screen we all know and love. Just as easily it can also display that data as an FFT. It doesn't matter. To get bandwidth, they have to reduce the number of sample bits. They are increasing that but it is horribly expensive to do so. The amount of noise the ADC and the analogue signal conditioning before it creates on inexpensive scopes is pretty high also. Limited vertical resolution hides details on top of that. Then we get to the real issue. It is a sampling system, and therefore may be subject to aliasing. If may display a waveform that appears to be correct, but it isn't. As the operator, you have got to know that. All this costs more than an analogue scope does with equivalent sensitivity, noise and speed.
Okay, so it boils down to what you are doing and what you actually need. To know, you need experience. Without familiarity and experience you tend to believe whatever the instrument tells you (both meters and oscilloscopes). The features are attractive and designed to sell the product. Just like a poorly built car with bells and whistles. The features sound really neat, but how well does the thing actually work for it's primary purpose, and then how well do the features work? It is a trade-off and that involves money too. My daily driver is very expensive, $25K approx. My analogue scopes decades older do some things better, sad to say. I still use them.
To say current digital oscilloscopes are better than an analogue oscilloscope is, I think, entirely false. Maybe the ones individuals cannot afford are (they go past $250K in price), but mere mortals are often better served by an old analogue oscilloscope. Not unless you don't need low noise and detail. But then, that is what analogue audio is all about.
On the subject of digital acquisition systems, a few years ago I needed measurements in the 200kHz region. That's too fast for a DMM (I had 34401A and 34410A) but an oscilloscope couldn't give the detail; there's a bandwidth gap between DMMs and oscilloscopes. The solution? I bought the (at the time) recently introduced) dScope M1 with the 300kHz bandwidth option. I fully expected kickback from everywhere and accusations that I was buying an audio toy for my own use, but nary a complaint was made. And it did the job; I needed a means of establishing whether I had genuinely made a low noise power supply >20kHz. Now that I have much more time (and have gained further expertise), I simply make a low noise amplifier to use as an oscilloscope pre-amplifier. It seems that you often need to start by buying an expensive bit of kit, and from using that you learn how to make your own kit that is just as good, or better. But you need that one expensive bit of kit to give you the leg up that allows you to discern whether what you are doing is right.
But how do you know if the reason you can't make a piece of unfamiliar kit do what you want is due to user incompetence or the kit is actually faulty? Or maybe it's just not very good? I can easily imagine using up most of a week's rental getting to grips with the kit. Especially if it was a LeCroy oscilloscope. For all that LeCroy pioneered vast amounts of record length (and the processing power to use it), they had a lot to learn about ergonomics. Maybe they're better now? Just before I retired an idea was floated at work that instead of technical bods having their own kit on their own bench, there would be a central store from which you would book an oscilloscope or spectrum analyser as needed. No doubt some bean counter, somewhere, had noticed kit on benches that wasn't powered up and being used at the time of their visit. And they didn't bother to ask whether it might have individual setups stored or be linked into the network and have programs written such that at the touch of a few buttons a sophisticated experiment would begin running. What likelihood would there be of getting a damaged piece of kit from the central store? And even if it worked, you'd have to go through and set it up as you needed it. I informed my boss (politely) that any suggestion that I share the equipment on my bench (for which I had put up all the purchase arguments and haggled on price with the manufacturer) would lead to my immediate resignation. Fortunately, he was of a similar view and understood the importance of an efficient bench. All of my bench equipment at home is anchored together with GPIB firehose, enabling computer control. Obviously, you can't do that with an analogue oscilloscope...
lol!
Techs and engineers are very territorial over their test equipment! No skilled person would dare touch another's kit!
I completely agree with you. Before I had stuff connected with GPIB (and I still do), it was the fear of injury (your wrath) that kept people's hands off your gear. In the calibration lab I worked at, we had bench equipment and communal equipment. Like calibrators and the HP 3458A. We had to check each piece before use, and perform weekly cross-checks for confidence. Same for lab standards like resistors.
Luckily for most of my career, I purchased the equipment used. One of my beliefs was that you can never afford to fight your test equipment. That leads to lost time and mistakes. For DSO's, I bought HP because they handled as a scope should. I found Tek a little more clunky, others have the reverse opinion. Depends on how you think. Other brands, indecipherable what their engineers were thinking, so difficult to use.
So when assessing equipment for purchase I would check them out at trade shows (unless it was cheap equipment). If they are difficult to figure out, I won't even check it out. Once I find one that is easy to understand, I'll ask for a demo on my bench. I have purchased a lot of test equipment over the years to solve a measurement problem. One really good thing is that I often solve that issue, and the same piece of equipment continues to be useful down the road. It's also recommended to figure out if you can use two or more in conjunction to achieve your goal, or a jig can solve the issue. I'll buy an older used piece that satisfies a need rather than always buying new. If I buy new, there were many darned good reasons to do so.
These days if you buy something that requires additional bandwidth or features, software licenses can be added. So you haven't lost anything if you needed to extend the capabilities of some test equipment. In the old days you would have to trade it in for new or demo stock. Just check on new equipment that it can be enhanced past what you need via software license.
Techs and engineers are very territorial over their test equipment! No skilled person would dare touch another's kit!
I completely agree with you. Before I had stuff connected with GPIB (and I still do), it was the fear of injury (your wrath) that kept people's hands off your gear. In the calibration lab I worked at, we had bench equipment and communal equipment. Like calibrators and the HP 3458A. We had to check each piece before use, and perform weekly cross-checks for confidence. Same for lab standards like resistors.
Luckily for most of my career, I purchased the equipment used. One of my beliefs was that you can never afford to fight your test equipment. That leads to lost time and mistakes. For DSO's, I bought HP because they handled as a scope should. I found Tek a little more clunky, others have the reverse opinion. Depends on how you think. Other brands, indecipherable what their engineers were thinking, so difficult to use.
So when assessing equipment for purchase I would check them out at trade shows (unless it was cheap equipment). If they are difficult to figure out, I won't even check it out. Once I find one that is easy to understand, I'll ask for a demo on my bench. I have purchased a lot of test equipment over the years to solve a measurement problem. One really good thing is that I often solve that issue, and the same piece of equipment continues to be useful down the road. It's also recommended to figure out if you can use two or more in conjunction to achieve your goal, or a jig can solve the issue. I'll buy an older used piece that satisfies a need rather than always buying new. If I buy new, there were many darned good reasons to do so.
These days if you buy something that requires additional bandwidth or features, software licenses can be added. So you haven't lost anything if you needed to extend the capabilities of some test equipment. In the old days you would have to trade it in for new or demo stock. Just check on new equipment that it can be enhanced past what you need via software license.
Semantics. A scope is a device used to visualize time-domain waveforms. Its basically a voltmeter with fast ballistics, usually low-ish accuracy/precision, and some kind of memory (even if its just phosphor-based).
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Hi Mark,
Not semantics at all. They operate in a completely different fashion. The basic underlying mechanism is utterly and completely different.
A DSO or MSO is a data sampling system. Period. The data is collected, arranged, possibly math performed. Then it is displayed according to the programming in the CPU section. With an oscilloscope (the real thing), the input signal is scaled, possibly filtered and applied to the deflection plate in the CRT. Period. The trigger is picked off and the signal delayed to give the trigger time to work.
If you wish to oversimplify anything you can argue any point of view you want, but you lose relevance completely. The fact you can display the digital data similarly as a classic oscilloscope does has no bearing on how it actually operates inside. This is what makes then completely different.
Not semantics at all. They operate in a completely different fashion. The basic underlying mechanism is utterly and completely different.
A DSO or MSO is a data sampling system. Period. The data is collected, arranged, possibly math performed. Then it is displayed according to the programming in the CPU section. With an oscilloscope (the real thing), the input signal is scaled, possibly filtered and applied to the deflection plate in the CRT. Period. The trigger is picked off and the signal delayed to give the trigger time to work.
If you wish to oversimplify anything you can argue any point of view you want, but you lose relevance completely. The fact you can display the digital data similarly as a classic oscilloscope does has no bearing on how it actually operates inside. This is what makes then completely different.
And an analog storage scope was an analog sampling system. Not to mention the old analog sampling scopes of yore that required repetitive waveforms.
Also, doesn't matter if the underlying tech is different. By that reasoning next you'll be arguing a Tesla isn't a car. Now of course, its possible to think of reasons why DSOs are not scopes and why Teslas really are cars, but it involves choosing arguments that lead to the desired result. Its not out of basic principle.
Also, doesn't matter if the underlying tech is different. By that reasoning next you'll be arguing a Tesla isn't a car. Now of course, its possible to think of reasons why DSOs are not scopes and why Teslas really are cars, but it involves choosing arguments that lead to the desired result. Its not out of basic principle.
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We were not talking about those. You picked a special case to try and apply to common usage.
The flood screens weren't sampled by they way. The sweep was continuous. I had one.
In the beginning, I had an early digital acquisition system made by Norland. It was a "Prowler". Mine had an 8 bit channel and a 12 bit channel. The purpose was not the same as an oscilloscope and they differentiated what it was called. Early 1980's thing I think.
If you have used each type since early times, you would be well aware of their differences in operation. This is about the same thing as calling a volume control in a box (possibly with input selector) a "Passive preamp". A nonsense term that hides the true nature. That device doesn't amplify anything, so why label it in a confusing way except to mislead people?. Same for a digital oscilloscope. It is a similar function only, with critical differences in the way it worked.
The flood screens weren't sampled by they way. The sweep was continuous. I had one.
In the beginning, I had an early digital acquisition system made by Norland. It was a "Prowler". Mine had an 8 bit channel and a 12 bit channel. The purpose was not the same as an oscilloscope and they differentiated what it was called. Early 1980's thing I think.
If you have used each type since early times, you would be well aware of their differences in operation. This is about the same thing as calling a volume control in a box (possibly with input selector) a "Passive preamp". A nonsense term that hides the true nature. That device doesn't amplify anything, so why label it in a confusing way except to mislead people?. Same for a digital oscilloscope. It is a similar function only, with critical differences in the way it worked.