Can you figure this out...

[Matty]

Just for a laugh.  Can you guess what signals are going into the scope...
https://youtu.be/TPWfcFm9oi4

[ZeTeX]

Whatever it is, do it with a digital scope, I dare ya.

[ataradov]

X is sine wave, Y is a modulated sine wave?

Whatever it is, do it with a digital scope, I dare ya.

What problems do you see doing this with a digital scope?

[ZeTeX]

X is sine wave, Y is a modulated sine wave?

Whatever it is, do it with a digital scope, I dare ya.

What problems do you see doing this with a digital scope?

That most of the digital scopes will not show the wave form so smooth and sharp. I would like like to see it on a digital scope actually to see how good and smooth the wave form.

[ataradov]

That most of the digital scopes will not show the wave form so smooth and sharp. I would like like to see it on a digital scope actually to see how good and smooth the wave form.

I'm far tool lazy to replicate this myself, bu here is a video of Tek doing a reasonable job displaying things and doing some measurements at the same time:
 

[Matty]

Whatever it is, do it with a digital scope, I dare ya.

Makes no difference.  You can still see the 'ripple'.

X is sine wave, Y is a modulated sine wave?

Thats 70% right.  There is another 30% to go.

[Brumby]

Are you after frequency and amplitude relationships...?

[Delta]

X-Y mode, sine waves with a 1 Hz difference?

[Brumby]

Just eyeballing .....

X axis:
   Sine wave of frequency f ; amplitude according to X axis amplifier gain
Y axis:
   Sine wave of frequency 3f ; amplitude 100%  **
   Sine wave of frequency 3f +/- 1 ; amplitude ~60%  **
   Sine wave of frequency something like 50-60f ; amplitude ~5%  (the ripple)
Z axis:
   No discernable AC input

** There is also a slight frequency variation of the 3f figure of something just under 2Hz

[Matty]

wow Brumby, that's a hell of answer.  But that's not quite it.  I was expecting a more simple answer

ANSWER   (highlight to see):
Quick Answer:
X and Y both have a sine waves of different frequencies.
Y also has Amplitude  Modulation added on.
X also has Frequency Modulation added on.

Longer Answer:
As this is a Lissajous curve, X and Y have a ratio of ~3:1, you can see there 3 'curves' on the X axis.
The Y Amplitude  Modulation is very small about 1Hz, to see the bouncing.
The X Frequency Modulation is much higher about 10Khz in this case.

In a previous post I typed 'ripple' in quote marks, which I guess was misleading

[Brumby]

OK - Yes, it's a Lissajous figure.  Didn't think to include the obvious.

Approximate frequency ratio determined by the number of points of contact on two adjacent sides of a rectangular box containing the figure.  Actual frequency ratio will include the speed of 'shift'.

My first sighting of such was in the logo for the ABC (Australian Broadcasting Commission) television station (VHF Channel 2 in Sydney, in the day.)

A little bit more stylised these days:

[jonovid]

Just for a laugh.  Can you guess what signals are going into the scope...

My first sighting of such was in the logo for the ABC (Australian Broadcasting Commission) television station (VHF Channel 2 in Sydney, in the day.)

yes something from the Australian Broadcasting Corporation   
if you want the politics.    its in the datasheet 

[Brumby]

I speak of it's incarnation at the time of my first encounter.

It became the Australian Broadcasting Corporation some time later ... 1983 I believe.


And, yes, it did have it's fair share of issues with those running the place wanting to maintain objectivity up against the political forces that were in play.

[Brumby]

... but stuff the politics - I just wanted to make a Lissajous figure of my own.

[calexanian]

We had too make that waveform in the modulation section of intro to electronic communications class. It was said before. X axis sine wave with some ripple or something on it, and y axis sine wave modulated at either a low frequency, or a roll and tumble if its up higher in frequency. Cant tell cause I can't see the scope settings.  I made it with four XR2206 circuits because we also had to modulate the X axis too.

[Brumby]

This example has a sine wave on the X axis - but the ripple is on the Y axis.

[ZeTeX]

That most of the digital scopes will not show the wave form so smooth and sharp. I would like like to see it on a digital scope actually to see how good and smooth the wave form.

I'm far tool lazy to replicate this myself, bu here is a video of Tek doing a reasonable job displaying things and doing some measurements at the same time:
 

On a 11k$ scope, sure, I meant "cheap" digital scopes..

[tom66]

That most of the digital scopes will not show the wave form so smooth and sharp. I would like like to see it on a digital scope actually to see how good and smooth the wave form.

I'm far tool lazy to replicate this myself, bu here is a video of Tek doing a reasonable job displaying things and doing some measurements at the same time:
 

On a 11k$ scope, sure, I meant "cheap" digital scopes..

My Rigol DS1054Z actually does a reasonable job of YouScope, which is of a similar order. It has no issue at all displaying Lissajous figures.

[ZeTeX]

That most of the digital scopes will not show the wave form so smooth and sharp. I would like like to see it on a digital scope actually to see how good and smooth the wave form.

I'm far tool lazy to replicate this myself, bu here is a video of Tek doing a reasonable job displaying things and doing some measurements at the same time:
 

On a 11k$ scope, sure, I meant "cheap" digital scopes..

My Rigol DS1054Z actually does a reasonable job of YouScope, which is of a similar order. It has no issue at all displaying Lissajous figures.

Who knew, I taught most of the cheap digital scopes will struggle with stuff like that.

[ataradov]

Who knew, I taught most of the cheap digital scopes will struggle with stuff like that.

Here is a video of a Rigol DS1054Z doing similar thing:



And here is some coll art that would be impossible on an analog scope (without fast beam blanking):