What the heck is Input level?

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Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

What the heck is Input level?

io have a viewsonic G90FB

i am trying to set it up right, my kds usa broke but had better brightness
and stuff as default whatever though

what is input level 0.7V and 1.0V


how come 1.0V gives me less brightness, shoudln't it give me more if it is
more volts?


Also, is 1.0V give me more gamma rays or x ray rays?

i am thinking i should have gotten an lcd screen to not deal with this hog
wash.

 

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Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

"John Cho" <johncho@johncho.us> wrote in message
news:Xns94BBCF686BA2Ajohnchojohnchous@199.45.49.11...
>
> what is input level 0.7V and 1.0V
>

There have been two different standards for analog video
signals - one in which the difference between the "white" and
"black" levels was 1.0V, and a more recent one - and the one
which all current PC video cards use - in which this difference
is only 0.7V. However, some monitors still provide a switch
so as to be able to support either; the 1.0V standard was more
common in some "TV" video equipment.

>
> how come 1.0V gives me less brightness, shoudln't it give me more if it is
> more volts?

Nope; this is exactly how it SHOULD work. When set to accept
a "1.0V" video signal, a monitor fed with only an 0.7V signal
(which is what your PC puts out) won't see that signal as being
driven all the way to "full white" - it's undersized by 30%! Hence,
everything looks dimmer.

>
> Also, is 1.0V give me more gamma rays or x ray rays?
>

No. There is no change except in the effective gain applied
to the input video signal, and it's a little LESS when a 1.0V
input is used.


Bob M.

 

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Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

"Bob Myers" <nospamplease@address.invalid> wrote in message
news:OQpac.2045$pe2.798@news.cpqcorp.net...
>
> "John Cho" <johncho@johncho.us> wrote in message
> news:Xns94BBCF686BA2Ajohnchojohnchous@199.45.49.11...
> >
> > what is input level 0.7V and 1.0V
> >
>
> There have been two different standards for analog video
> signals - one in which the difference between the "white" and
> "black" levels was 1.0V, and a more recent one - and the one
> which all current PC video cards use - in which this difference
> is only 0.7V. However, some monitors still provide a switch
> so as to be able to support either; the 1.0V standard was more
> common in some "TV" video equipment.

This looks like some info I need here for my project. Is this digital /
analogue video? I presume the sync level would be 0V for my VGA
application; white (or max saturation for RGB) is 0.7v, but what voltage
should black be at?

Mr N.

 

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Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

"mrnobby" <no@spam.please> wrote in message
news:406c8188$0$277$cc9e4d1f@news.dial.pipex.com...
> This looks like some info I need here for my project. Is this digital /
> analogue video? I presume the sync level would be 0V for my VGA
> application; white (or max saturation for RGB) is 0.7v, but what voltage
> should black be at?

No, both of these were strictly analog video standards. The 1.0V standard
was derived from the original RS-170 standard (which, if the sync tips
are included, is actually 1.4 Vp-p). The 0.7V was another gift from the
original VGA hardware definition, and was semi-related to RS-343A and
similar-amplitude European TV practice. (RS-343A was essentially a
version of RS-170, scaled down to a 1.0 Vp-p swing.) In both cases,
the amplitude given (1.0V or 0.7V) is from white to black, as in PC practice
separate TTL syncs are used (no composite sync on video) and there
is no "setup" (the "pedestal" between the blank and black level) in the
video signal. For various odd reasons, there are actually THREE different
standards around the 0.7V black-to-white norm (0.660V, 0.700V, and
0.714V black (or blank) to white), but any of these will work OK with
the display set to accept an "0.7V" signal.

Bob M.

 

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Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

Bob Myers wrote in comp.sys.ibm.pc.hardware.video:

>
> "John Cho" <johncho@johncho.us> wrote in message
> news:Xns94BBCF686BA2Ajohnchojohnchous@199.45.49.11...
>>
>> what is input level 0.7V and 1.0V
>>
>
> There have been two different standards for analog video
> signals - one in which the difference between the "white" and
> "black" levels was 1.0V, and a more recent one - and the one
> which all current PC video cards use - in which this difference
> is only 0.7V. However, some monitors still provide a switch
> so as to be able to support either; the 1.0V standard was more
> common in some "TV" video equipment.
[snip]

Very interesting.

Therefore a new-ish video chip like the SiS651 would only put out
0.7V, but an ancient monitor like a DEC VRT19 would expect 1.0V?

I have such a combination. (Monitor modified to take separate
sync signals instead of sync on green.) Which behaves itself
beautifully at 66kHz but jiggles at 80kHz.

--
Sig goes here...
Peter D.

 

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Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

"Peter D." <psd@c17.home.invalid> wrote in message
news:cnv9k1-207.ln1@psd.alphalink.com.au...
> Therefore a new-ish video chip like the SiS651 would only put out
> 0.7V, but an ancient monitor like a DEC VRT19 would expect 1.0V?

It's possible; I don't know, off the top of my head, the
details of either product. Quite a few video chips give the
designer some control over the exact video signal level,
by setting an external reference voltage or control. IF the
levels are mismatched as you describe above, the likely
result would just be a dim image, as the monitor would never
be driven to what it considers "full white" on any input.
It is possible that part of that could be compensated for by
readjusting the video amplifier gain, but if the monitor really
were built ONLY for the 1.0V standard (which actually is
pretty rare - the 0.7V standard has been around for a long time),
it may not have the range in the video amp.

Bob M.

 

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Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

Bob Myers wrote in comp.sys.ibm.pc.hardware.video:

>
> "Peter D." <psd@c17.home.invalid> wrote in message
> news:cnv9k1-207.ln1@psd.alphalink.com.au...
>> Therefore a new-ish video chip like the SiS651 would only put out
>> 0.7V, but an ancient monitor like a DEC VRT19 would expect 1.0V?
>
> It's possible; I don't know, off the top of my head, the
> details of either product. Quite a few video chips give the
> designer some control over the exact video signal level,
> by setting an external reference voltage or control. IF the
> levels are mismatched as you describe above, the likely
> result would just be a dim image, as the monitor would never
> be driven to what it considers "full white" on any input.
> It is possible that part of that could be compensated for by
> readjusting the video amplifier gain, but if the monitor really
> were built ONLY for the 1.0V standard (which actually is
> pretty rare - the 0.7V standard has been around for a long time),
> it may not have the range in the video amp.
>
> Bob M.

The monitor was manufactured in 1992, which is pretty old for
computer equipment. The video chip is only about two years old.

Presumably the sync signals are scaled down in proportion to the
signal strength.

Thank you.

--
Sig goes here...
Peter D.

 

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Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

"Peter D." <psd@c17.home.invalid> wrote in message
news:b3ack1-pe3.ln1@psd.alphalink.com.au...

> The monitor was manufactured in 1992, which is pretty old for
> computer equipment. The video chip is only about two years old.

A '92 monitor almost certainly expects 0.7V video, although it
may have a setting (either an actual switch, or via OSD) for
1.0V.

>
> Presumably the sync signals are scaled down in proportion to the
> signal strength.

If sync-on-video (usually on the green channel) is used, yes;
otherwise, no - separate syncs are straight TTL levels.

Bob M.

 

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Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

Bob Myers wrote in comp.sys.ibm.pc.hardware.video:
[snip]

Thanks Bob.

--
Sig goes here...
Peter D.