Products > Test Equipment
Does old test equipment really ever become truly obsolete?
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tggzzz:

--- Quote from: 2N3055 on May 24, 2024, 10:43:25 am ---Other point is that it is obvious that users don't need it so much as you think. Otherwise it would be in every scope....

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That may be true, but one doesn't follow from the other!

Checkbox marketing/engineering is a real phenomenon :(
2N3055:

--- Quote from: tggzzz on May 24, 2024, 01:25:25 pm ---
--- Quote from: 2N3055 on May 24, 2024, 10:43:25 am ---Other point is that it is obvious that users don't need it so much as you think. Otherwise it would be in every scope....

--- End quote ---

That may be true, but one doesn't follow from the other!

Checkbox marketing/engineering is a real phenomenon :(

--- End quote ---

Nah, it is called market research...  :-DD
joeqsmith:
That was my very first oscilloscope. 


--- Quote from: newbrain on May 23, 2024, 01:46:22 pm ---
--- Quote ---Does old test equipment really ever become truly obsolete?
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Yes.
(Attachment Link)

When I was twelve, it was a wonderful experience.
I bought it for peanuts (mine was marked Fairchild, not Dumont), but my parents weren't so amused to have my desk repaired, as it almost collapsed under the weight.

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David Hess:

--- Quote from: pdenisowski on May 24, 2024, 10:27:47 am ---
--- Quote from: David Hess on May 24, 2024, 01:31:48 am ---And while we are at it, FFTs should also include a noise marker function, which depends on the RBW.  Your FFT reports its RBW, right?  RIGHT?
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Maybe I'm misunderstanding you, but our oscilloscopes report and allow you to explicitly set RBW when in FFT/spectrum mode.  I can make and post a more detailed video showing this if you like, but here's a quick example

https://youtu.be/acE3d4TpiW4?t=34

Noise markers are, in my experience, more of a spectrum analyzer feature than an oscilloscope feature.  Noise markers also require correction for both RBW and the filter shape (which is not user-adjustable), so this is typically handled automatically by the instrument  I mention this in a different video :)

https://youtu.be/pL0pY-t8KWY?t=84
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I did not go into detail, but the application is to make noise density measurements, which requires knowing either the RBW, which depends on FFT bin size and FFT window as described in your video, or having an equivalent to the noise marker function found on spectrum analyzers.  Most DSOs have neither, so one is left to determine the unreported and undocumented RBW, which can then be used to normalize the measurement made by or on the DSO.  The noise marker function commonly associated with spectrum analyzers does it all in one step.

DSOs should be really good at this with trivial effort, yet most (all?) are almost totally useless at it.  Offhand I do not know of any DSOs which support it (1), and your example of a Rohde & Schwarz model reporting RBW is a step forward.  The alternative is to import the waveform data to a computer and calculate it there, of if you are someone like me, use an *obsolete* *analog* oscilloscope to make accurate spot noise measurements and then calculate the noise density over the area of interest from that.  Modern DSOs can make accurate spot noise measurements, accounting for their filter's shape factor, like an *obsolete* *analog* oscilloscope, right?  RIGHT?

(1) Old LeCroy DSOs should be able to do it, but I think that is only through their considerable user defined math capability, and you still have to determine the RBW yourself.


--- Quote ---
--- Quote from: David Hess on May 24, 2024, 01:31:48 am ---The point of the above is that the FFT function is usually a check-off toy on most "modern" DSOs.

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Everyone has different needs or priorities when using an oscilloscope, but FFT / spectrum analysis is a critical feature for many of our customers.  I could give a fairly long list of all the different ways it is used, but there have many been posts and discussions about this here on EEVblog.
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I think there is a major difference between FFTs on entry level DSOs and high bandwidth DSOs by the major manufacturers.  The later provide useful performance at RF while supporting triggered or gated measurements.  The former seem more like a marketing check-off.  Sometimes I think one of the check-off DSOs would be useful for making distortion measurements, except everything interesting is slightly below the level that they can measure.

Now what entry and mid level DSOs could do with their FFTs is network analysis ... but they discard the phase information, unlike some obsolete DSOs of the past.


--- Quote ---Again, my apologies if I'm misunderstanding you.  One thing I've learned over many years working in the test equipment industry is that people often have very different ways of describing measurements, tests, etc.  And of all the instruments I've worked with, oscilloscopes are definitely the ones where terminology varies the most among users and instruments :)
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Some of the variation in terminology comes about for marketing advantage.  It makes it difficult for knowledgeable customers to figure out which instruments support which features.


--- Quote from: 2N3055 on May 24, 2024, 10:43:25 am ---Keysight MSOX3000T  I have can show both magnitude and phase, but it has only 64kPts for FFT so that is a limiting factor.
So it is not like nobody has it.
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The serious LeCroy models can do it.  Old obsolete Tektronix DSOs can do it.  Your example is the first time I have heard of an HP/Agilent/Keysight model that can do it, but there it is, albeit barely in the manual.


--- Quote ---Other point is that it is obvious that users don't need it so much as you think. Otherwise it would be in every scope....
--- End quote ---

Based on my experience in college and industry, I think it comes down to most potential users not being able to understand it.  The usual solution is to get a dedicated network analyzer, which will become obsolete immediately after it is no longer needed because it is so specialized.
2N3055:
12 bit Siglents do report bin size and RBW adjusted for window.
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