Analog vs digital X-Y mode

[chirality]

I'm curious, of all the <$2000 DSOs on the market as of 2018, which make/models do XY-mode the best (by best, I mean most analog-like)? Keysight? Tek? Rhode & Schwarz? Siglent?

[tautech]

I'm curious, of all the <$2000 DSOs on the market as of 2018, which make/models do XY-mode the best (by best, I mean most analog-like)? Keysight? Tek? Rhode & Schwarz? Siglent?

In a few days we'll know how well the SDS1*04X-E XY mode has been improved as it's just been enhanced in the latest firmware.

[chirality]

In a few days we'll know how well the SDS1*04X-E XY mode has been improved as it's just been enhanced in the latest firmware.

That's great to hear. Please keep me updated! I'm in the market for a DSO and the Siglent is attractive. I just definitely don't want to see an XY mode like this:

[tautech]

In a few days we'll know how well the SDS1*04X-E XY mode has been improved as it's just been enhanced in the latest firmware.

That's great to hear. Please keep me updated! I'm in the market for a DSO and the Siglent is attractive. I just definitely don't want to see an XY mode like this:

Yes, to properly evaluate it it needs be videoed.

The new FW I've mentioned is discussed here:
https://www.eevblog.com/forum/testgear/siglent-sds1104x-e-in-depth-review/msg1555936/#msg1555936

It's not up on the Siglent websites yet but should be in the next few days.

[CopperCone]

In a few days we'll know how well the SDS1*04X-E XY mode has been improved as it's just been enhanced in the latest firmware.

That's great to hear. Please keep me updated! I'm in the market for a DSO and the Siglent is attractive. I just definitely don't want to see an XY mode like this:

That looks like some kind of 1970's casino sign from Las Vegas. 

[Rich@RohdeScopesUSA]

I'm curious, of all the <$2000 DSOs on the market as of 2018, which make/models do XY-mode the best (by best, I mean most analog-like)? Keysight? Tek? Rhode & Schwarz? Siglent?

There are several videos of the RTB2000’s XY mode available from 3rd party reviewers, including one pretty thorough one here:



Mikes Electric Stuff has also played around with it a bit with some unique combinations:

https://mobile.twitter.com/mikelectricstuf/status/959025632830197761

-Rich

[nfmax]

Last year I had occasion to use XY mode on my Keysight MSO-X 2024A, to characterise the transfer function of an opto-isolator circuit (tweaking for best noise margins with lowest power dissipation). It worked beautifully, including a simulated 'spot' following the signal - which was a triangle output from the built-in generator. First time I'd ever tried XY mode, though!

[tautech]

In a few days we'll know how well the SDS1*04X-E XY mode has been improved as it's just been enhanced in the latest firmware.

That's great to hear. Please keep me updated! I'm in the market for a DSO and the Siglent is attractive. I just definitely don't want to see an XY mode like this:

Yes, to properly evaluate it it needs be videoed.

The new FW I've mentioned is discussed here:
https://www.eevblog.com/forum/testgear/siglent-sds1104x-e-in-depth-review/msg1555936/#msg1555936

It's not up on the Siglent websites yet but should be in the next few days.

Well I've managed to find a copy of the new SDS1004X-E series FW and the XY mode is dramatically improved.
With lowest memory depth set it really flies for a cheap DSO. 
But unfortunately even just a 10s video is 30+MB on my phone so it's too big to post here. 
Tonight might be YT A/c setup night.  Done.

https://youtu.be/wUCdaVq3kL0

[borjam]

I'm curious, of all the <$2000 DSOs on the market as of 2018, which make/models do XY-mode the best (by best, I mean most analog-like)? Keysight? Tek? Rhode & Schwarz? Siglent?

In a few days we'll know how well the SDS1*04X-E XY mode has been improved as it's just been enhanced in the latest firmware.

Any plans for the two channel SDS1202X-E? Seems that despite belonging to the same "family" firmware development is diverging a lot.

[tautech]

In a few days we'll know how well the SDS1*04X-E XY mode has been improved as it's just been enhanced in the latest firmware.

Any plans for the two channel SDS1202X-E? Seems that despite belonging to the same "family" firmware development is diverging a lot.

The last 1202X-E FW was back in Jan so any improvements it supports that's been added to the 4ch X-E should follow in time. The divergence is due to the substantial additional functionality the 4 ch models provide and the need to get all that stuff right.

[bd139]

Someone should try this on an HP 546xx. They have a superior X-Y mode. Not bad for 1994...

https://youtu.be/D2uEvRPd4w8

[chris_leyson]

Nice tutorials from Jerobeam Fenderson

[nctnico]

At least some DSOs can do color grading in XY mode:

[JohnnyMalaria]

I've put together a short sequence of videos to show why an ancient analog scope beats the crap out of a budget DSO in XY mode. There's no audio but there's a description which I've included here, too.

Budget digital storage oscilloscopes offer many advantages over analog CRT oscilloscopes but one area they suck at is XY mode.

This mode is important for looking at, for example, rotation of quadrature signals in the complex plane. This short video has back-to-back clips of an XY signal rotating at different angular rates. The analog oscilloscope is a Tektronix 475 manufactured in 1974. The DSO is a Rigol DS1104Z manufactured in 2017.

The first two clips are slowly rotating and the two oscilloscopes compare very well.

When the rotation speed of signal in the second example is increased, the DSO simply gets in wrong. The direction of the rotation is incorrect as is the speed. This is because the DSO captures a finite amount of the signal and displays it once complete.

In contrast, the analog oscilloscope displays the signal in real-time without interruption. A good analogy is the effect of video or film frame rate on the appearance of rotating aircraft engine propellers or rotating spoked car wheels. There's no way to tell if the observed rotation speed and/or direction is correct.

At much faster rotation speeds, the DSO yet again presents misleading information (clip 4).

Clip 5 shows how the DSO XY mode doesn't display significant amounts of the signal and the signal it does display lacks the extraordinary detail shown on the analog oscilloscope.

Finally, clip 6 shows that the DSO displays all of the signal but at a much lower resolution than the analog oscilloscope and the rotation is in the wrong direction.

It is common to compare these types of oscilloscopes using simple Lissajous figures but, frankly, the only real application of this is in 1950's sci-fi movies. Looking at changes of XY signals in the complex plane involves much more complex signals with intricate detail.

The analog oscilloscope may be 43 years older than the DSO but for budget DSOs, the analog one beats them by miles.

Professional grade DSOs generally offer far superior XY rendering than the budget ones but you can't beat the real-time, continuous and varying intensity of the analog equipment.

[alsetalokin4017]

Well, to be fair, it is possible to get a _slightly_ better display of the ScopeClock on the Rigol DS1054Z than what was shown in the OP.

But it definitely looks better on the analog scopes.

[joeqsmith]

I had someone ask me about the X-Y mode on one of my old scopes.  I was not sure what they were asking so I ran is various settings. One comment I had was about the sparse amount of data.  I suspect they were thinking audio and I was looking at much higher frequencies.   

Is the goal here just use use a scope for art?   I watched some of these fancy YT videos like the one linked above.   I then tried using Labview to put together a simple program to use the sound card but it was far too slow.   I ripped some of the audio tracks from YT and then tried it with some of the dedicated PC sound card scopes.  Looks like they may do a decent job.   YT compresses the audio so the graphics don't look very impressive but the dedicated programs far exceed what I could do with Labview.   I tried playing these files into one of my scopes and could post a clip but it's not very impressive with the YT compression.   At best you would have some idea on the update rate of my old scopes. 

As mentioned, I think if the goal is to benchmark the visual effects, a standard audio clip may be a good place to start.       

The letter 'D'

[JohnnyMalaria]

Is the goal here just use use a scope for art?   I watched some of these fancy YT videos like the one linked above.

Sometimes science is art

I created the clips with preset waveforms from my function generator (such as chirp, FM modulation etc). The signals were demodulated about a fixed frequency to generate a quadrature pair which are the XY signals (like a lock-in amplifier).

My real-world application is demodulation of a modulated photodetector signal from nanoparticles moving in a liquid. The phase information in the signal relates to the position of the particles. If the particles are just moving randomly, the XY trace will show a random walk. If there is linear motion such as due to movement in an electric field, the phase will change linearly and the XY trace will rotate. Observing this directly and live on a CRT scope in XY mode is tremendously valuable. It tells me if there are issues with sample or hardware and I can "see" when the particles are moving due to the electric field (which is the primary purpose of the experiment). Without this, I'd be working "blind". It is analogous to the use of vectorscopes for video. For my particular application, the frequencies are in the audio band.

[joeqsmith]

Someone should try this on an HP 546xx. They have a superior X-Y mode. Not bad for 1994...

https://youtu.be/D2uEvRPd4w8

Hunting around this site, I found were this same post was made in 2012 or so.  Someone had the raw file but the links were dead.  Doing a quick Google search, the are still available if we wanted to use this as some sort of benchmark.    Just search for oscillofun.flac. 

Is the goal here just use use a scope for art?   I watched some of these fancy YT videos like the one linked above.

Sometimes science is art

I created the clips with preset waveforms from my function generator (such as chirp, FM modulation etc). The signals were demodulated about a fixed frequency to generate a quadrature pair which are the XY signals (like a lock-in amplifier).

My real-world application is demodulation of a modulated photodetector signal from nanoparticles moving in a liquid. The phase information in the signal relates to the position of the particles. If the particles are just moving randomly, the XY trace will show a random walk. If there is linear motion such as due to movement in an electric field, the phase will change linearly and the XY trace will rotate. Observing this directly and live on a CRT scope in XY mode is tremendously valuable. It tells me if there are issues with sample or hardware and I can "see" when the particles are moving due to the electric field (which is the primary purpose of the experiment). Without this, I'd be working "blind". It is analogous to the use of vectorscopes for video. For my particular application, the frequencies are in the audio band.

If you wanted to detail a setup, we could use this as a test case as well.   Or if you wanted to model it in software and create a raw WAV file, that may make things even easier and possible allow more people to run it for you.   

[joeqsmith]

Link to the oldest thread I could find showing oscillofun.

https://www.eevblog.com/forum/suggestions/audio-signals-quality-in-x-y-mode-what-is-important-what-is-not/msg164751/#msg164751

[james_s]

I use the XY mode on my 465B scope while working on vector arcade game boards, it's a lot more convenient than trying to rig up a fullsized vector monitor which are rare and valuable in addition to being bulky, fragile and requiring some odd voltages.

[joeqsmith]

Oscillofun does appear to a much cleaner source.   I took a few screen shots while it was playing.   

[JohnnyMalaria]

Audio is too restrictive because of the limited bandwidth. It precludes the ability to compare technologies in the 100kHz+ range and sub ~20Hz. It also introduces variation due to different soundcard characteristics such as THD, equalization, DAC jitter etc.

A 2-channel DDS arbitrary waveform generator allows for better control, consistency and wider bandwidth (DC to many MHz). In my case, I have a FeelTech FY2300 that goes to 20MHz. It's basically the same as the 6600 but with a lower max. frequency and a different physical form.

The simplest test is to set up a sine wave on both channels at the same frequency somewhere in the 10s of Hz region with a 90deg phase difference between them. Then introduce a small frequency difference (say 1Hz). In XY mode, an ellipse should appear to "rotate" at 1Hz. Increase the frequency difference and compare the scopes. At some point, the DSO will show its weakness due to the buffered acquisition. Increase the frequency of both channels to the next decade and repeat the frequency difference observations. Repeat this for each decade. You could also have one channel at 3 times the frequency of the other to generate a Lissajous figure and then add small frequency differences to cause rotation.

Now choose an arbitrary waveform for one channel and keep the other as a sinusoid. Do a similar investigation of decade and frequency difference. At lower frequencies, the CRO will prevail but at higher decades the DSO will start to show detail that is too fast for the human eye to pick out on the CRO. This is because the weakness of the DSO at lower frequencies becomes a benefit at higher ones.

In my case, I have a '74 Tektronix CRO and a 2017 Rigol DS1104Z.

In essence, you need to compare both technologies at the frequency range that is important to you. For me, it's a no brainer to use both and pick the most suitable one for your application.

Playing around with different combinations of arbitrary waveforms on each channel as a function of decade and frequency difference is a revealing exercise.

I am curious to learn how the more expensive DSOs fair across the frequency range.

[alsetalokin4017]