Dragon's Lair Fans - Arcade Lifestyle
General Chat => Technical Area => Topic started by: level42 on April 06, 2014, 10:57:49 PM
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I received the Voltcraft DS)-1062D (aka as the Hantek/Tekway with similar model numbers) scope last friday and did some first tests with it this weekend.
Thought it would be fun to have a look at some signals on the Amplifone monitor in my SW cockpit and show some screenshots:
Here you see the X (yellow) and Y (Blue) signals of the running attract screen.
The signals represent the voltages that make the electron beam move across the screen. You can _not_ see wether the beam is on or off though, as this is a third signal and this would require a 4 channel scope to see.
So, if we just look at the X wave form, imagine that the top of the waves is the farthest left of the screen and the lowest points of the wave is the far right.
The Y signal, same thing, but here the top is the top of the screen and the bottom....you guessed it.
(Note: I do not actually know if this is true, it might be inverted but that doesn't really matter all that much ;))
You can see that the waveforms are all "crazy" and that is simply because it is drawing all the elements on the screen that we want to see as the game.
What you can notice about the waveforms:
1) You can actually see two waveforms over each other. This is because the scope cannot trigger ("hold") on the signal because of it's irregularity.
2) You can easily see the X signal is higher then the Y signal. (In technical terms, the amplitude is higher). This is normal, because the X axis of the screen is wider than the Y axis.
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Now if we switch the game to test mode and select a Hash screen (like this):
(http://retrocoinop.com/images/SW-Monitor-XY-Issue/adjust-x-y-size.jpg)
we have a non-moving screen which makes it a lot easier for the scope to trigger on. So we now get a steady picture on the scope that looks like this:
It's now pretty easy to see what is going on. If you look at the yellow wave the beam is first moved to the far left of the screen (while it is off, but we can only assume that). When it's at the peak the beam is turned on and it draws the line by moving the beam from left to right, and thus the signal is moving back to it's lowest point.
When it has reached that point the beam is turned off and is moved back to the left again.
In the mean time you can also see what the Y signal is doing. It goes to a certain position (beam off) on the top (or bottom, not sure) of the screen and then stays at the same level for as long as the X signal is drawing the line horizontally. Then it jumps (beam off) to the next horizontal line. Etc. etc.
If you count the peaks on the X signal (12) and count the horizontal lines on the hash screen you see they match :)
After that, the roles of X and Y get swapped and the vertical lines are being drawn....
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Now maybe some of you know that a vector monitor is actually a sort of oscilloscope and that an oscilloscope can be used to show the picture that a vector game produces (my video about this is still an unexplainable hit on youtube with over 50000 views (!): https://www.youtube.com/watch?v=_1zI8tmQ-T8 )
So, can a digital scope so this as well ?
Yes it can...but....not as nice as the analogue scope does to be honest....
This is the same hash-screen as showed above. I have no clue why the Voltcraft shows it only in the right lower quadrant of the screen and there doesn't seem to be any adjustment that I can change to fix that...
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I do like this option of the Voltcraft though, something completely impossible on an analogue scope.
Here you see both the X and Y signals (on top) AND the resulting XY screen:
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In fact, you can even save the moving picture as an animated GIF (to the USB stick you can connect to the front of the scope).
This actually gives a pretty good impression of how it looks in reality on the screen of the scope.
This does show the "slowness" of the Voltcraft compared to the analogue scope.
By the way, this is the diamond test-screen you are seeing, like this:
http://www.dsbelec.iinet.net.au/Final_Test-03.jpg
Sadly the animation doesn't cycle but click and you'll see it once.
https://dl.dropboxusercontent.com/u/16677442/snap_40.gif
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Nice, nice, see you enjoy your new toy. Keep us posted on the ros and cons off the digital scope.
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Great topic, had no idea how does a scope work, well illustrated. :spaceace:
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Hahaha, and now I have a 200Mhz scope instead of a 60Mhz and it cost......nothing....I like that :)
I don't really NEED 200Mhz but......IF you can do it so easy.....why not ? :D
Used this method....so easy....
https://www.youtube.com/watch?v=x1phUe93ZeQ
I included the tool for......you never know why ;)