Modern oscilloscope views: YT, XY but where is XYZ ? - Page 1
Forum section: electronics / beginners

author: Ivan7enych
author_rank: Regular Contributor
timestamp: May 31, 2017, 02:58:58 pm
content: Hello to all,Stupid question, years ago I had an old analog oscilloscope, it had not only 2 usual modes "Y versus Time" and "Y versus X", but also had Z input, where I can put any signal to change electron beam intensity and thus vary trace brightness.As a result I could for example make an simple analog TV from oscilloscope, putting AV signal to Z input and horizontal + vertical raster signals to usual 2 X Y channels.Nowadays I see no modern 4 channel oscilloscope with this feature.Oscilloscope makers could for example make a feature, to put 1 and 2 channel to X and Y, then 3rd channel to brightness, (and 4th channel to color of the trace). May be there's no practical engineering application, but this could be a big fun to play with.

author: Brumby
author_rank: Unknown
timestamp: May 31, 2017, 03:11:34 pm
content: I have an old Hitachi V-152B with that.It was an easy way to add a third channel of information - albeit of a very limited nature. In my experience, the practical opportunities for it to be useful were extremely infrequent and for those moments when you wanted more than two channels - it was somewhat inadequate.This is using a scope as a scope - not a TV.These days, with the price of modern scopes starting so low, you can get a 4 channel unit and get full detail on not only a 3rd, but a 4th channel as well.IMO, the Z-input has little value in any scope. I know I don't even look for it on scope spec sheets.

author: macboy
author_rank: Super Contributor
timestamp: May 31, 2017, 03:18:40 pm
content: Quote from: Brumby on May 31, 2017, 03:11:34 pmThe peopleover in this threadwill disagree.

author: Brumby
author_rank: Unknown
timestamp: May 31, 2017, 03:27:07 pm
content: Yes.... well......

author: w2aew
author_rank: Super Contributor
timestamp: May 31, 2017, 03:52:00 pm
content: The current Tek DPO5000, 7000 and 70000 series scopes all have XYZ mode, although these are performance scopes geared towards the professionals. Even the older TDS3000 series has XYZ.

author: stj
author_rank: Super Contributor
timestamp: May 31, 2017, 05:38:05 pm
content: i wouldnt buy a scope that didnt have it.

author: Ivan7enych
author_rank: Regular Contributor
timestamp: May 31, 2017, 05:39:58 pm
content: Quote from: w2aew on May 31, 2017, 03:52:00 pmThank you!I have older Tek TDS744A (with InstaVu, not DPO) - it doesn't have it. Also my new Agilent 3014A doesn't have it, in XY mode channels 3 and 4 are disabled.

author: David Chamberlain
author_rank: Frequent Contributor
timestamp: May 31, 2017, 06:16:11 pm
content: Quote from: stj on May 31, 2017, 05:38:05 pmI would and have.

author: stj
author_rank: Super Contributor
timestamp: May 31, 2017, 06:32:39 pm
content: your not repairing vector-scanning arcade games then.

author: Brumby
author_rank: Unknown
timestamp: June 01, 2017, 12:01:49 am
content: Quote from: stj on May 31, 2017, 06:32:39 pmI know I haven't, but it does present a valid use case.I stand corrected.

author: timb
author_rank: Super Contributor
timestamp: June 01, 2017, 12:24:11 am
content: There are also some use cases where you can hook the gate signals from a standalone frequency counter up to the Z input of a scope, in order to visually see where on a waveform it's actually counting, where the trigger happens, etc. (That portion of the waveform will be intensified, like using the A-Inten mode of a scope to intensify the portion of A-Sweep that's being shown in the B-Sweep.)There was an HP app note or article about this, but I can't seem to find it at the moment.

author: Ash
author_rank: Regular Contributor
timestamp: June 01, 2017, 01:21:40 am
content: I have a Rhode & Schwarz HMO3004 that is a 4 channel, or 3 channel + 8 logic, or 2 channel + 16 logic scope. It has XY, XYY (2 Ys against the same X), and XYZ / XYYZ modes.I've not used them in anger yet, but I have a function generator (HP3314A) that includes a blanking output that is designed to drive a Z channel. This is designed so you can sweep a frequency span and display it nicely on a scope for measuring frequency responses. The X-drive ramp output is related to frequency and the Y axis is the DUT output. Then you use the blanking Z output to both blank the display during the "retrace" as the sweep resets, and also to intensify certain sections of the sweep as frequency markers.Bit like this (although he doesn't seem to have a Z axis on the generator he is using.. and I can't quickly find an real exampe.. might have to make one some day and upload it):Ash.

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: June 01, 2017, 02:41:48 am
content: Quote from: macboy on May 31, 2017, 03:18:40 pmI also used it some years ago when I was building a vector-scanned laser display system. A possibly high power laser beam would be moved around by means of programmable mirrors and could be turned on and off with a solenoid-driven gate. In testing the system I would connect X and Y laser channels to the scope in X-Y mode and the solenoid to the Z- input to get a usable rendition of the final image on screen.

author: eKretz
author_rank: Frequent Contributor
timestamp: June 01, 2017, 10:43:14 pm
content: Quote from: Ivan7enych on May 31, 2017, 05:39:58 pmIf you had a later TDS 'D' model you'd have XYZ mode. To wit, my TDS754D:My TDS754A doesn't have XYZ mode either. They added it to the later models, not sure which alphabetical variant was the first to get it. Tek's "InstaVu" and "DPO" are basically the same thing except the latter has some better added features and is snappier. Oh, and BTW, XYZ is only available to be selected in the menu if the scope is in DPO mode.

author: jwm_
author_rank: Frequent Contributor
timestamp: June 02, 2017, 01:57:27 am
content: I have really wanted that too on various occasions. With a modern scope it would ok do be great if it could control color rather than intensity as an option, when using my octopus curve tracer I was thinking it would be super nice to plug the base voltage into the z axis and see each curve in its own color.I have wondered whether a little breadboardable display that did nothing but be an intensity graded xyz display with analog inputs would be useful.

author: timb
author_rank: Super Contributor
timestamp: June 02, 2017, 12:24:24 pm
content: Quote from: eKretz on June 01, 2017, 10:43:14 pmI just checked on my TDS754C and the RO menu disappears when in InstaVu mode. Shame, as that would have been cool to have.Though it's been my experience XY/XYZ modes suck on pretty much all digital scopes, especially on older models like the TDSxxx series. For one thing it's almost always a "Triggered XY" mode, which is *not* the same thing as a classic analog scope's XY mode (which is untriggered). You also have to set the timebase pretty low to get the sampling rate up (to increase the fidelity of whatever vectors you're trying to draw), the problem with that is then you *really* need the scope to have a large sample memory. That generally makes older scopes pretty laggy and significantly slows down screen refresh. Newer scopes still aren't that much better in terms of XY modes.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 02, 2017, 01:18:20 pm
content: XYZ as a 3D plot would be interesting. Also a waterfall X/Z plot to show delays over time.

author: metrologist
author_rank: Super Contributor
timestamp: June 02, 2017, 01:25:23 pm
content: I just remembered this video

author: stj
author_rank: Super Contributor
timestamp: June 02, 2017, 02:04:44 pm
content: this raises an interesting question,how useable is XY mode on modern DSO's?is the screen update rate good enough, or do moving images just skip about?

author: w2aew
author_rank: Super Contributor
timestamp: June 02, 2017, 04:14:27 pm
content: Quote from: stj on June 02, 2017, 02:04:44 pmFor the modern DSOs that I've used in XY and XYZ mode - I'd call it "acceptable", but certainly doesn't match the truly live/smooth result that comes naturally from an analog scope. The DSO can render a shape/trace for very slowing changing inputs that would show up as a moving dot on an analog scope, so in that corner case the DSO is better than a CRT. But, for most live, dynamically changing inputs, the CRT is better. Newer DSOs are getting better at this...

author: stj
author_rank: Super Contributor
timestamp: June 02, 2017, 06:01:10 pm
content: yes, i asked because you dont really see the screen refresh rates mentioned with reasonable priced scopes like Rigol, Siglent or GW-Instek.

author: Ivan7enych
author_rank: Regular Contributor
timestamp: October 25, 2019, 11:26:52 am
content: Sorry, I raise up this old thread.I just found undocumented XYZ mode in my Agilent MSOX3000!This oscilloscope has XY mode and locks X to channel 1 and Y to channel 2, but if you put any signal to Trigger Input - it will work as bynary Z input! I've found this accidentally, wondering why I see only half of XY picture, when signal generator Trigger Out was connected to oscilloscope Trigger In.Here it is seen in my video (in russian).0:40 - I disconnect Trigger Input and half picture become full picture.1:15 - I connect 3rd generator to Trigger Input

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: October 25, 2019, 01:19:30 pm
content: What would be interesting is a scope that would do XYZ plotted as a 3D image, with the scope controls adjusting the viewpoint.

author: Yansi
author_rank: Super Contributor
timestamp: October 25, 2019, 01:39:25 pm
content: Meow!

author: MarkL
author_rank: Unknown
timestamp: October 25, 2019, 02:27:09 pm
content: Quote from: Ivan7enych on October 25, 2019, 11:26:52 amActually, it is in the user manual. It's called "blanking" and has a fixed on/off threshold of 1.4V.

author: free_electron
author_rank: Super Contributor
timestamp: October 25, 2019, 02:53:33 pm
content: Quote from: Ivan7enych on May 31, 2017, 02:58:58 pmZ modulation would require another sampler running at the same time storing an 'intensity byte' per sample. you just doubled your memory requirements and probably did a lot worse when it comes to the processing required for visualisation.These kind of shenanigans are useless for real applications. if you need this kind of stuff : sample Z with one of the channels ,dump the trace data and send it though some software on the computer.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: October 25, 2019, 04:35:44 pm
content: Quote from: free_electron on October 25, 2019, 02:53:33 pmBut a 4-channel scope will already have this.I suspect Z-mod inputs were common in the analogue days simply because theye were very easy to implement. Can't say I've ever found a use for it, though it does allow for some fun playing around

author: atmfjstc
author_rank: Regular Contributor
timestamp: October 25, 2019, 07:14:13 pm
content: This gets me thinking... if all you have is a XY display, and you're satisfied with isometric instead of true 3D, one could rig up a resistor network to the inputs to project XYZ to XY. The equations are linear, something like:X' = aX -bYY' = aX +bY + cZ(I forget the exact coefficients)

author: Ivan7enych
author_rank: Regular Contributor
timestamp: October 25, 2019, 10:05:50 pm
content: Quote from: free_electron on October 25, 2019, 02:53:33 pmHere is an example of real application.First picture -X Y - current probes on stepper motor coilsOn second picture I put step pulse from controller to Z inputThis highlights each microstep and hides all transitions.

author: artag
author_rank: Super Contributor
timestamp: October 25, 2019, 11:14:22 pm
content: Quote from: free_electron on October 25, 2019, 02:53:33 pmFine for static data - Matlab and many other plotting libraries are commonly used for this sort of visualisation. But it's much rarer to do live visualisation in plotting software. The nearest thing to a common computer-based live display is probably chart recorder emulation, though I think I've seen something more like a 3D plot in audio analysis.It emphasises once again that test equipment shouldn't be closed, single-task stuff. It should be acquisition hardware with a user-programmable UI.