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Oscilloscope Bandwidth!

T

Terry Given

Jan 1, 1970
0
John said:
I've finally become a full convert to digital, color, LCD scopes. My
personal scope (in my office) is a Tek TDS2012, which handles 90% of
what I do. The digital storage, averaging, and FFT things are neat, as
it the fact that you can hold it in one hand.

John

I carried my pair of 7904's from MIT to Worcester square, in the south
end, with a backpack full of books. I regretted it the following day.
Incidentally, I bumped into Win there that day, also looking at books,
although I'm sure he doesnt remember (although I waffled about the 3MJ
flywheel I was working with) :)

Cheers
Terry
 
M

Myauk

Jan 1, 1970
0
One question, again!

I measured the composite video signal by setting the display to PM5644
test card.
The problem is that although setting to time/div = 5,10,20 micro
second, volt/div = 200, 500 milli volts, and trigger values around 40,
344,420 and -100 milli volts, I just could not get the stable captured
waveform. (colour burst was clearly seen in each wave from, but there
are several different patterns displayed every time I pressed the
RUN/STOP button.). Isn't it normal? I am using TDS 744A 500 MHzz
Tektronix oscilloscpe.
More over I would like to have the best possible settings for measuring
Y Pb Pr and S Video Y, C signals.
Can anybody share me the links for example measurement of those video
signals?
Or some example waveforms.
I have some measured waveform but still I would like to have more just
for knowledge.
 
P

Peter Bennett

Jan 1, 1970
0
One question, again!

I measured the composite video signal by setting the display to PM5644
test card.
The problem is that although setting to time/div = 5,10,20 micro
second, volt/div = 200, 500 milli volts, and trigger values around 40,
344,420 and -100 milli volts, I just could not get the stable captured
waveform. (colour burst was clearly seen in each wave from, but there
are several different patterns displayed every time I pressed the
RUN/STOP button.). Isn't it normal? I am using TDS 744A 500 MHzz
Tektronix oscilloscpe.

It is normal to see a "mess" during the "active picture" portion of
the scan line, as you are looking at all scan lines at once. If,
instead of the PM5644 test signal, you look at a colour bar or gray
scale test signal, the active portion of the video signal will make
more sense.
More over I would like to have the best possible settings for measuring
Y Pb Pr and S Video Y, C signals.

To see these signals independently, you would have to look somewhere
within the equipment where they exist as independent signals. It
sounds like you are looking at a composite video signal at present - a
normal oscilloscope can't isolate the individual colour components in
that signal.
Can anybody share me the links for example measurement of those video
signals?
Or some example waveforms.
I have some measured waveform but still I would like to have more just
for knowledge.

--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca
 
M

Myauk

Jan 1, 1970
0
To see these signals independently, you would have to look somewhere
within the equipment where they exist as independent signals. It
sounds like you are looking at a composite video signal at present - a
normal oscilloscope can't isolate the individual colour components in
that signal.

Actually I am measuring different outputs, not isolating them from
CVBS.
The outputs I am going to measure are YPbPr, S Video, and Composite
Video Outputs from a DVD Player.
Is there any test discs available in the market for colour bar output?
 
J

joseph2k

Jan 1, 1970
0
Myauk said:
Actually I am measuring different outputs, not isolating them from
CVBS.
The outputs I am going to measure are YPbPr, S Video, and Composite
Video Outputs from a DVD Player.
Is there any test discs available in the market for colour bar output?

In your position i would just record one. But i may be wealthier than you.
 
M

Myauk

Jan 1, 1970
0
Thank you very much for all your answers and encouragements.
Now I am working well with my measurements.
I have almost finished reading XYZ of oscilloscope to understand more
about digital oscilloscopes.
And I found the required PAL and NTSC Test Discs for my wave form
measurement.
I also found the complete list of test patterns for NTSC and PAL at
www.convergent-design.com.
Without the discussion this group, I would not be able to do this that
fast for my first measurements.
I am now quite motivated to buy an oscilloscope very soon.
:)
Best Regards
 
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