Question about analog oscilloscopes vs digital oscilloscopes

[Wuerstchenhund]

YAWN. I was specifically NOT talking about interpolation processing (that ruins the fluidity and real-time display of a complex, varying waveform).

No, it doesn't, unless your DSO is from the 90's. Pretty much every somewhat modern DSO reaches high waveform rates when using sin(x)/x, and that includes entry-level scopes like the Agilent/Keysight DSO-X2k/3k, or cheap ones like the Rigol DS2000 (all which aren't even new designs).

Wuerstchenhund: Asking for a 5GSa/s sample rate for 1GHz BW is nonsense.

A high sample rate is good for various reasons and one of them is to prevent alias terms from corrupting the displayed waveform. A typical 500MHz scope will have a graceful frequency rolloff with flat group delay so the amount of alias rejection will be limited if the sampling rate is only 2 or 3GHz.

That is true for low bandwidth DSOs (<=350MHz) which usually come with a Gaussian frequency response similar to analog scopes, however most 500+MHz real-time DSOs have a flat response with brick wall like sharp rolloff at the top end. A typical 500MHz DSO will have a -3dB point at somewhere between 700MHz and 1GHz, with a cut-off I'd expect at some where below 1.2GHz (which only requires fs>2.4GSa/s)

Therefore, if I had to choose a DSO to replace a 500MHz analogue scope and I wanted the same frequency (and flat group delay) response then I'd want a high sampling rate to minimise the influence of alias terms when looking at complex waveforms that have spectral content up in the GHz region.

I agree, however there is is no point in a sample rate that is higher than what's required to resolve the highest frequency component your scope can actually "see", which slightly over 2x f₀. Anything higher will not result in additional details (as clearly visible in the example screenshots I posted), all it does is filling up your sample memory more quickly.

On a DSO, rather than an excessive sample rate, it's important to have a large enough sample memory to avoid dropping your sample rate (and therefore your usable real-time bandwidth) on longer time bases.

So I think 5GHz sampling would be a good/safe choice. Go down to 2.5GHz sampling and I think that the alias effects will begin to degrade the display of the wideband waveform compared to what you would see on the analogue scope.

On a 1GHz BW signal? No, it wouldn't, as demonstrated.

I guess it depends on how accurate you want the display to be? Some people will be happy to live with the degraded display at the lower sample rate. They might not care if it isn't quite right and the degradation is negligible to them?

Assuming they even understand the real degradation and don't assume that, just because something is visible on the screen, that this is necessarily a true representation of the input signal.

Operating test gear in the border areas of its specifications or confirmed performance envelope isn't really a good idea.

The other option would be to choose a scope with a steeper filter rolloff (eg max flat response) as this will be less prone to alias issues. So you could use a lower sample rate and have less problems with alias terms. But this won't have the same frequency response characteristics as the analogue scope. It's up to the user to decide if this is a good/bad thing for the range of things they want to use the scope for.

Don't forget that the 7904 vs DSO discussion was about a 1GHz sine wave initially, and a true continuous-time 1GHz sine wave is, by nature, BW limited. And as demonstrated, there's zero use in sampling a 1GHz sine wave at more than 2.5GSa/s.

And as staed above, the other question is how much use is in using a scope, especially one with Gaussian response, beyond it's rated (specified) BW, considering how the vastly attenuated and potentially phase-shifted frequency components in the border areas of it's frequency response very likely results in a distorted waveform on the screen, something that is also true for analog scopes. Especially if the true performance beyond the specified 500MHz BW has never been properly measured/assessed, as it seems to be the case with GK's Tek 7904.

[GK]

YAWN. I was specifically NOT talking about interpolation processing (that ruins the fluidity and real-time display of a complex, varying waveform).

No, it doesn't, unless your DSO is from the 90's. Pretty much every somewhat modern DSO reaches high waveform rates when using sin(x)/x, and that includes entry-level scopes like the Agilent/Keysight DSO-X2k/3k, or cheap ones like the Rigol DS2000 (all which aren't even new designs).

And a DSO from the 90's or a bit later was the context of my original comment and is specifically the era of a now well used / second hand DSO that could be had to match the equivalent real time performance of my 7904 (from the '70s) for about the same investment in $. An "entry level" scope like the DSOX3k with 500MHz analogue bandwidth is currently listed at $15,224 AUD. The DSOX2k series starts at a fraction under $5k AUD and doesn't get close to 500MHz. The DS2000 series while much cheaper than the Keysight only goes to 300MHz. A high BW to sampling rate ratio simply gives acceptable "real time" linear interpolation performance with limited processing power and a lot of these old DSOs didn't even have sinx(x) interpolation.

Don't forget that the 7904 vs DSO discussion was about a 1GHz sine wave initially, and a continuous-time 1GHz sine wave is, by nature, BW limited. And as demonstrated, there's zero use in sampling a 1GHz sine wave at more than 2.5GSa/s.

**without** reconstruction filtering

The other question is however if it's useful to use a scope, especially one with Gaussian response, beyond it's rated BW, and how much the vastly attenuated frequency components in the border areas of it's frequency response contribute to a realistic waveform on the screen, which is also true for analog scopes. Especially if the true performance beyond the stated 500MHz BW has never been measured.

This is starting to get repetitive and boring. I don't think that anyone serious would dismiss the utility or fail to grasp the usefulness of still being able to identify parasitic oscillation and interference signals significantly beyond an oscilloscopes specified -3dB bandwidth. And I can assure you, a 7904 can "see" beyond 1GHz, which is only one octave beyond 500MHz.

 

[Rupunzell]

Tek 7104, 7A29, 7B10

@ 1Ghz:


@2Ghz, on the threshold of loosing trigger.


@3Ghz, amplitude still visible, loss of trigger.


Tek 7904 or 7904A will still display a 1Ghz sine and a bit beyond with the amplitude reduced, loss of trigger with increasing input frequency decreased CRT display intensity (this is where the MCP on the Tek 7104 makes it a bit special). Been there done this.

Much of this is mostly pointless and moot as the individual involved simply does not understand or value what time domain instruments of this type have to offer that is factually better than a DSO in specific applications. This example goes far beyond simple time domain instrument frequency-amplitude response, there will be probes, connections and test set ups involved which will have an effect of information presented on the time domain instrument display.... It is up to the user to interpret and believe or dis-believe what is presented on that display. If one were to play the utter Ghz game, it is possible to mix down or down convert said sine wave and filter as needed to display Ghz sine waves as needed. There are also sampling systems for the Tek 7000 that will easily go well into the Ghz range given the signals are repetitive. The other extreme is to put in a Tek 7A22 which goes down to 10uV/Div @ 1Mhz, how many modern DSOs or any DSO can do this stand-alone without external help?

The market need for 5, 10  and beyond Ghz DSO's are driven by the Ghz data rate common in data transmission and digital stuff in general today, BUT not all of electronics is about Ghz data. As been previously mentioned to Ad nauseam, this obsession with DSO or Analog CRT absolutely depends on the application. It is also abundantly clear, many DSO users rely on the data box and converted data to interpret the information presented rather than understanding and developing the visual skills required to properly interpret the wealth of information available in a proper CRT display. The data box and covered data approach fits in nicely with design by 'puter software which tends to add an isolation layer to the design process.

Now ponder how many home electronics folks are going to tinker with several Ghz data and similar systems? Just trying to probe a system like this without altering system behavior is not going to be simple.

And no, trying to convince an individual with a over blown ego of an alternative factual reality to what that individual WANTS to BELIEVE.


Bernice

The other question is however if it's useful to use a scope, especially one with Gaussian response, beyond it's rated BW, and how much the vastly attenuated frequency components in the border areas of it's frequency response contribute to a realistic waveform on the screen, which is also true for analog scopes. Especially if the true performance beyond the stated 500MHz BW has never been measured.

This is starting to get repetitive and boring. I don't think that anyone serious would dismiss the utility or fail to grasp the usefulness of still being able to identify parasitic oscillation and interference signals significantly beyond an oscilloscopes specified -3dB bandwidth. And I can assure you, a 7904 can "see" beyond 1GHz, which is only one octave beyond 500MHz.

 

[Fungus]

Now ponder how many home electronics folks are going to tinker with several Ghz data and similar systems? Just trying to probe a system like this without altering system behavior is not going to be simple.

Yep. Buying the 'scope is only the first tiny step to measuring 1GHz+ signals.

[GK]

I suggest a 500MHzBW-5GSa/s speced DSO as an equivalent "real time" performer to my 500MHzBW 7905 as this is the kind of DSO that is most likely to have an analogue frequency response beyond -3dB best matching that of the old analogue.

Yes, I'd agree with that. However, I'm really not a scope guru or enthusiast so I only know the basics about any potential tradeoffs wrt sampling/filtering/adc/interpolation/etc when choosing the right DSO for a task.

The frequency response does look to have a gradual rolloff and if I put it in repetitive mode and stick a sig gen into it the response falls by about 17dB by 1300MHz. It still displays and measures the frequency correctly in this 'repetitive' mode. But 1300MHz is obviously way past the Nyquist limit for 2Gs/s when in real time mode.

I really don't think you would be impressed by this DSO if you saw it in real time mode when trying to display a 500MHz sinewave. It looks bad in real time mode once you get up above 300MHz. I assume the interpolation struggles a bit here as there is a lot of wobble on the signal. However, I don't have another one to compare it to so this degree of wobbliness may be a slight fault.

This is exactly the kind of thing I had in mind. That scope is typical of its age and it isn't optioned with and/or doesn't have the processing power for fluid/fast proper-sinx(x) interpolation/reconstruction filtering as seen on modern DSOs. Yes, 500MHz will not look pretty with only 4 sample points per period and what is likely just some form of linear interpolation. The "wobble" you report is normal as the sampler isn't phase-locked to the displayed sinusoid. 200MHz with ten sample points likely looks quite acceptable though. On that model I believe if you turn off interpolation you just get a display of the raw sampled data points as dots? If that DSO had a sampling rate of 5GSa/s rather than 2GSa/s then it would compare much more favorably to the 7904 in terms of equivalent real-time performance and the displayed fidelity of high-frequency waveforms.

[nctnico]

Now ponder how many home electronics folks are going to tinker with several Ghz data and similar systems? Just trying to probe a system like this without altering system behavior is not going to be simple.

Yep. Buying the 'scope is only the first tiny step to measuring 1GHz+ signals.

You can make a very simple 1GHz probe from a BNC to BNC adapter for a few dollars/euros. Secondly you don't really probe signals over 1GHz; you put a coupler or passive divider on the board which has an SMA (or similar) plug you connect to your oscilloscope.

[Fungus]

Now ponder how many home electronics folks are going to tinker with several Ghz data and similar systems? Just trying to probe a system like this without altering system behavior is not going to be simple.

Yep. Buying the 'scope is only the first tiny step to measuring 1GHz+ signals.

You can make a very simple 1GHz probe from a BNC to BNC adapter for a few dollars/euros. Secondly you don't really probe signals over 1GHz; you put a coupler or passive divider on the board which has an SMA (or similar) plug you connect to your oscilloscope.

But you still need to know a lot about electronics, sampling theory, signal reconstruction, etc., to interpret what you're seeing on screen.

The oscilloscope is just a tool, not a solution.

[nctnico]

Now ponder how many home electronics folks are going to tinker with several Ghz data and similar systems? Just trying to probe a system like this without altering system behavior is not going to be simple.

Yep. Buying the 'scope is only the first tiny step to measuring 1GHz+ signals.

You can make a very simple 1GHz probe from a BNC to BNC adapter for a few dollars/euros. Secondly you don't really probe signals over 1GHz; you put a coupler or passive divider on the board which has an SMA (or similar) plug you connect to your oscilloscope.

But you still need to know a lot about electronics, sampling theory, signal reconstruction, etc., to interpret what you're seeing on screen.

I wouldn't say you need to know a lot but as usual you need to have an idea about what kind of signal/reading you should get. This goes for any piece of test equipment. For example figuring out a DMM is set to AC when you see 0V while expecting to see a reading around 10V DC.

[Jwalling]

Thanks for the info and the closeup image

I wonder if some of the labelled resistors may be select on test resistors to optimise something during production test? The value of R703 (and the shape of the PCB track it connects to looks a bit odd for something that is a config resistor.

I'm assuming that the idea is to change a clock multiplier to step up the sampling rate?

There's an image of the 54540C board on a current ebay auction. it says 542 in places on the board but it has a white 54540 sticker on the PCB edge.

http://www.ebay.com/itm/54540-66511-Main-PCB-for-HP-54540C-/261677319734?hash=item3ced2f0636:g:5-wAAOSwubRXIiV0

I'll have a close look at it and I'll have a look in the manual to see how easy it is to take it all apart.

OK. Here's a few more close-ups. Yes it's a 54542A board, it would helped if I had only LOOKED at the damn sticker. 
The sticker reads 54542-66507. Underneath the sticker in etch, it's 54542-66501. On the second picture, the area highlighted is on the component/otherside of the board where the resistors are. I wonder if you could get  wangs_trading to take a good close-up picture of the area in question - that would save you some time. 

EDIT: That last picture of the solder-side in that Ebay listing is close but no cigar... Just a zoom in on the area with the ceramic hybrid would do the trick!

Jay

[Wuerstchenhund]

This is starting to get repetitive and boring.

Hey, something we can agree on 

And I can assure you, a 7904 can "see" beyond 1GHz, which is only one octave beyond 500MHz.

As I said, I'm not doubting it can "see" it. My doubts lie within its capabilities to accurately represent the original signal on the screen. Have you actually measured it's frequency response and phase accuracy beyond the specified 500MHz? How does the response curve look like?

It would be really interesting to see some examples (screenshots, or a video) of how the 7904 performs at complex signals >1GHz, with the signal split between the 7904 and a capable high bandwidth DSO (as a reference how the input signal really looks like).

[Someone]

The other extreme is to put in a Tek 7A22 which goes down to 10uV/Div @ 1Mhz, how many modern DSOs or any DSO can do this stand-alone without external help?

A specialty plugin is not really "part of the scope", its entirely comparable to the (also Tek) ADA400:
http://www.tek.com/datasheet/ada400a-differential-preamplifier-datasheet
Though I've seen companies hold onto 7000 series mainframes just to use the plugins (using the channel output into a sampling DSO!). Having used 7A22's I was very motivated to get an ADA400 and modify it for use on modern scopes.

[G0HZU]

That is true for low bandwidth DSOs (<=350MHz) which usually come with a Gaussian frequency response similar to analog scopes, however most 500+MHz real-time DSOs have a flat response with brick wall like sharp rolloff at the top end. A typical 500MHz DSO will have a -3dB point at somewhere between 700MHz and 1GHz, with a cut-off I'd expect at some where below 1.2GHz (which only requires fs>2.4GSa/s)

Literature from Agilent suggests that it is typical for scopes of <= 1GHz BW to have a Gaussian rolloff. 

Earlier you posted up some plots from your Lecroy scope showing the interpolation performance vs sample rate for a sine wave signal at 1GHz. Can you post up a brief (smartphone?) video of the 2.5Gs/s plot with the 1GHz sinewave to your youtube page to show us the 'fidelity' of the sine wave across numerous waveforms? How much wobble does it show on a video rather than a single shot screen grab?

Then maybe someone can do the same with a decent analogue scope. I expect the analogue scope to look good and I expect your scope to look a bit wobbly at 2.5Gs/s.

A picture is worth a thousand words but in this case I think a video will be worth even more.

[G0HZU]

EDIT: That last picture of the solder-side in that Ebay listing is close but no cigar... Just a zoom in on the area with the ceramic hybrid would do the trick!

Thanks for posting up more images.
To me it looked like the PCB artwork was subtly different in various places on the ebay picture. Is the artwork for some of these resistors even there?

[Jwalling]

EDIT: That last picture of the solder-side in that Ebay listing is close but no cigar... Just a zoom in on the area with the ceramic hybrid would do the trick!

Thanks for posting up more images.
To me it looked like the PCB artwork was subtly different in various places on the ebay picture. Is the artwork for some of these resistors even there?

Well, for one thing, the 54540C had an LCD interface while the A models had a vertically-mounted HV CRT board. That would account for a huge difference on the processor (left) side of the board. The area of concern around that hybrid in that Ebay listing looks the same, but the detail level just isn't good enough to make out what's what. 

Jay

[David Hess]

The other extreme is to put in a Tek 7A22 which goes down to 10uV/Div @ 1Mhz, how many modern DSOs or any DSO can do this stand-alone without external help?

A specialty plugin is not really "part of the scope", its entirely comparable to the (also Tek) ADA400:
http://www.tek.com/datasheet/ada400a-differential-preamplifier-datasheet
Though I've seen companies hold onto 7000 series mainframes just to use the plugins (using the channel output into a sampling DSO!). Having used 7A22's I was very motivated to get an ADA400 and modify it for use on modern scopes.

I like using the 7A13 with the 7000 mainframe's vertical output into a DSO and I even ended up making simple improvements in my 7603 to lower the output noise of the vertical output by 20+ dB.  The improvements are documented somewhere on the forum here with suggested improvements and I would have linked them but the useless search function failed me.

But the 7A13 is another plug-in to go along with the 7A22 where if you have to ask for the modern replacement, you cannot afford it; the ADA400 from Tektronix is a $2000 dollar item and the 7A13 equivalent from LeCroy originally made by Preamble is similarly expensive.  On the other hand, I can find working 7A22s on the used market for less than $100 each and AM502s (a closer match to the ADA400) for not much more.  I ended up with two 7A22s and one AM502 just buying other plug-ins and mainframes.

Your comment about the vertical output reminded me of another analog oscilloscope function which cannot be replicated with a DSO or at least a modern one, the trigger (gate on an analog oscilloscope) output.  Last time I checked, even Rigol was avoiding the term trigger output and I assume it was because it was misleading and someone in marketing was feeling unusually honest.  I can use the gate output to trigger a modern DSO but I can't use the trigger output of a modern DSO to trigger an analog oscilloscope without massive jitter.  I admit however that this function is useless to a vast majority of users although it may be one of those functions like differential comparator slideback operation where you never realize what it can do until you see it in action.

[Someone]

But the 7A13 is another plug-in to go along with the 7A22 where if you have to ask for the modern replacement, you cannot afford it; the ADA400 from Tektronix is a $2000 dollar item and the 7A13 equivalent from LeCroy originally made by Preamble is similarly expensive.  On the other hand, I can find working 7A22s on the used market for less than $100 each and AM502s (a closer match to the ADA400) for not much more.  I ended up with two 7A22s and one AM502 just buying other plug-ins and mainframes.

Your comment about the vertical output reminded me of another analog oscilloscope function which cannot be replicated with a DSO or at least a modern one, the trigger (gate on an analog oscilloscope) output.  Last time I checked, even Rigol was avoiding the term trigger output and I assume it was because it was misleading and someone in marketing was feeling unusually honest.  I can use the gate output to trigger a modern DSO but I can't use the trigger output of a modern DSO to trigger an analog oscilloscope without massive jitter.  I admit however that this function is useless to a vast majority of users although it may be one of those functions like differential comparator slideback operation where you never realize what it can do until you see it in action.

The ADA400 is available easily second hand so prices for all the options are similarly in the couple of hundred dollars. Once you've used these functions you sure get used to having them around Try a curve tracer some time!

[GK]

And I can assure you, a 7904 can "see" beyond 1GHz, which is only one octave beyond 500MHz.

As I said, I'm not doubting it can "see" it. My doubts lie within its capabilities to accurately represent the original signal on the screen. Have you actually measured it's frequency response and phase accuracy beyond the specified 500MHz? How does the response curve look like?

I don't recall stating that a 7904 will accurately transcribe a waveform with a 1GHz fundamental component, which it obviously won't. In your selective quoting you missed by prior sentence:

"I don't think that anyone serious would dismiss the utility or fail to grasp the usefulness of still being able to identify parasitic oscillation and interference signals significantly beyond an oscilloscopes specified -3dB bandwidth"

[David Hess]

Once you've used these functions you sure get used to having them around Try a curve tracer some time!

Things I never really understood the utility of until I used them include dual delta delayed sweep, alternate sweep in various forms, slideback measurements, and gate B output.

As far as curve tracers, I have a 7CT1N.  It is not much but it works.  One of my 7A22s came with the curve tracer.

When I was evaluating a Tektronix MSO5000 series I asked one of the application engineers if it could do the equivalent of dual or delta delayed sweep or even alternate sweep.  He was sure it had the equivalent of one of those capabilities but even between the two of us we just could not get it to happen.  We did manage to get the oscilloscope into an unrecoverable state requiring a reset though.

[Rupunzell]

Like this, using time base A triggered on Right Vertical, time base B triggered on Left vertical both running at different sweep rates and triggered independently. Effectively two individual O'scopes in one Tek 7000 main frame? This was first introduced by Tek in the 547(BTW, triggers to just over 250 Mhz with a vertical BW spec'ed at 50Mhz)  as alternate sweep. This alternate sweep feature in the Tek 547 was done using Gallium Arsenide switching diodes designed in the early 1960's.

Ramp volts on top, VCO output on bottom.



Tek 7A22 was introduced to the world as the 1A7 plug-in (early 1960's) for the 500 series. The design evolved to become the 1A7A by the mid-1960's. Since that time, the design has been repackaged into everything from AM502, 5A22, ADA400 (CMMR degraded) and...
There are similar offerings by Stanford Research Systems (digital controls are shut off to reduce internal digital noise once settings have been made and settled), and Preamble to this day. The trade-off in this design is driven by silicon device physics, physical realities of realizing this design and related. This is just one example of how properly done analog stuff lives on far longer than most progressive minded folks want to or could believe.


Bernice

When I was evaluating a Tektronix MSO5000 series I asked one of the application engineers if it could do the equivalent of dual or delta delayed sweep or even alternate sweep.  He was sure it had the equivalent of one of those capabilities but even between the two of us we just could not get it to happen.  We did manage to get the oscilloscope into an unrecoverable state requiring a reset though.

[David Hess]

I am only vaguely aware of the origin of the 7A22.  It has been discussed over on TekScopes@yahoogroups.com at least once and I went through the schematics back to the 3A9 and 3A10 but stopped before the 1A7.

The odd part about delta delayed sweep is that Tektronix continued providing this feature in oscilloscopes after the 7000 series for a short time.  The 2247A series of portable analog oscilloscope has it, amazingly enough the 2440 series of DSOs has it, and I think the 2465 series has it as well but I did not really understand it until I got a 7000 mainframe.  I do not remember if any of their later old DSOs had it.

[Rupunzell]

Tek 1A7 uses bootstrapping to increase common mode rejection on the front end and a number of other cleaver design tricks to get this performance in the original design. The guy at Tek who designed it is quite cleaver, creative and got it proper. Design excellence endures the test of time. Learn from this.
1A7A has a common mode spec of +/- 400 volts at 10uV per division (AC coupled) when used in a 500 series main frame. This is one of the virtues of vacuum tubes. The dynamic range is far and above what modern solid state devices are capable of even approaching. Compare this to modern digital where desirable supply voltages want to be as low as possible to reduce power waste per transition and increase edge transition rates.

"Slide back" feature of the 7A13 can be found in the modern DSO as DC offset. This is only one of the features of the 7A13, it's real value is as a diff amp with just over 100 Mhz and good common mode at the BNC connectors. A matched pair of Tek P6055 probes were intended for the 7A13 as these probes have adjustable attenuation and HF/LF response to optimize common mode rejection at the probe tip.

7A13 has an internal switch allowing the input resistors to be disconnected resulting in theoretical infinite input impedance when the voltage between + and - voltage exactly equals, essentially when the bridge circuit balances (theoretically zero current flow at bridge balance with exactly the same voltage at both half of the bridge) . Similar is found in Fluke differential voltmeters. Origins of the 7A13 goes back to the 1A5 diff plug in (+/- 500 volt common mode range possible) and that plug in has a input specific to the P6046 diff probe. They were developed together as a system. Eventually, Tek introduced the P6046 diff probe with amplifier box as a stand along system. Previous to the 1A5 was the type W plug-in for the 500 series. 


Delta time, delay sweep display was used for measurements / displays like this.


Does this feature have any meaning or value to the modern time domain user, maybe. Most time domain instrument users today have different measurement needs and the way TD instruments are used is not the same, roots of why this never ending grand standing over analog CRT -vs- DSO goes on. They are very different beast for different wilderness.


Bernice

I am only vaguely aware of the origin of the 7A22.  It has been discussed over on TekScopes@yahoogroups.com at least once and I went through the schematics back to the 3A9 and 3A10 but stopped before the 1A7.

The odd part about delta delayed sweep is that Tektronix continued providing this feature in oscilloscopes after the 7000 series for a short time.  The 2247A series of portable analog oscilloscope has it, amazingly enough the 2440 series of DSOs has it, and I think the 2465 series has it as well but I did not really understand it until I got a 7000 mainframe.  I do not remember if any of their later old DSOs had it.

[nctnico]

There are similar offerings by Stanford Research Systems (digital controls are shut off to reduce internal digital noise once settings have been made and settled), and Preamble to this day. The trade-off in this design is driven by silicon device physics, physical realities of realizing this design and related. This is just one example of how properly done analog stuff lives on far longer than most progressive minded folks want to or could believe.

I don't think anyone is debating or questioning well designed and proven analog solutions for which there is no better alternative today. Earlier this year I bought a Keysight 34461A 6.5 digit DMM. I'm quite sure that the analog section can be traced back to the 1970's or even earlier so from an accuracy point of view getting the latest model doesn't gain you much. The reason I bought the 'new model' and didn't go for a used one is because of the big TFT display, ethernet connection and the ability to create graphs & screendumps on the 34461A.

On many DSOs you can use split screen (zoom mode) to see a large part and a smaller section of the same signal which basically is equal to what delayed sweep does and having different time bases. I can show the exact same picture of the pulse and the zoomed in section on my DSO.

[Rupunzell]

There are those who could care less about screen dumps and such...

Why are these "discussions" often reduced to a contest or battle of what ever or who ever is the, "winner-victor?"
This should NEVER BE about my techno widget is better than your techno widget in my toy box.
6 months away from this sand box, same sand box upon return. Kinda sad, really.


Bernice

There are similar offerings by Stanford Research Systems (digital controls are shut off to reduce internal digital noise once settings have been made and settled), and Preamble to this day. The trade-off in this design is driven by silicon device physics, physical realities of realizing this design and related. This is just one example of how properly done analog stuff lives on far longer than most progressive minded folks want to or could believe.

I don't think anyone is debating or questioning well designed and proven analog solutions for which there is no better alternative today. Earlier this year I bought a Keysight 34461A 6.5 digit DMM. I'm quite sure that the analog section can be traced back to the 1970's or even earlier so from an accuracy point of view getting the latest model doesn't gain you much. The reason I bought the 'new model' and didn't go for a used one is because of the big TFT display, ethernet connection and the ability to create graphs & screendumps on the 34461A.

On many DSOs you can use split screen (zoom mode) to see a large part and a smaller section of the same signal which basically is equal to what delayed sweep does and having different time bases. I can show the exact same picture of the pulse and the zoomed in section on my DSO.

[nctnico]

Well you keep claiming your old toys are better, can do things newer equipment can't do and are good enough for everyone. In my case having some screendumps from my 34461A in a report made a customer of me very happy and it didn't take any effort from my side. Screendumps matter to me because I make reports with measurements regulary or I just save the screendumps for future reference. It helps a lot to be able to look back at measurement results when a project needs changes or isn't behaving as expected.

[Rupunzell]

Examples and design history are NOT claims of better, they are what they are. If there is a perception older toys are better than new, look in the mirror.

Reports and such, do all users of instrumentation require this?

Look beyond your world's perspective and points of reference.



Bernice

Well you keep claiming your old toys are better, can do things newer equipment can't do and are good enough for everyone. In my case having some screendumps from my 34461A in a report made a customer of me very happy and it didn't take any effort from my side. Screendumps matter to me because I make reports with measurements regulary or I just save the screendumps for future reference. It helps a lot to be able to look back at measurement results when a project needs changes or isn't behaving as expected.