[muglo] Re: Max Dist eMac to TV?Technical info

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Just a little technical note to explain distance issues with regards to
s-video signals vs digital signals and why cable length is more crucial to
digital equipment than analog devices:

In computers, digital signals are usually created as two distinct voltage
levels representing a "0" or a "1". The high level will be defined as a
voltage range, say for example 3.5 to 5.0 volts. The low range might be
defined as 0.0 to 1.8 volts. The range between  1.8 and 3.5 volts would be
considered indeterminate and could possibly result in a "0" or a "1" being
interpreted by the circuitry. In computers, the strategy is to keep signal
levels at their extremes to preserve the data integrity.

As communication cables get longer, all signal levels degrade. Signal levels
at the receiving end will decrease in value and random electrical "noise",
which is everywhere, can start to play a significant role.

When the cable gets too long, the high level signals will decrease in value
such that they can be misinterpreted as low level signals. If the weakened
signals are amplified back to their original levels, any induced electrical
"noise" will also be amplified. This amplified "noise" can reach values
where it will be detected by the circuitry as data. This will alter the
information in the transmission and in most cases, be catastrophic (to the
information at least).

S-video is a high-quality analog (proportional) signal. Its amplitude too,
will degrade with distance. However, amplification can successfully be used
to restore signals to their original levels without substantially altering
the information. Any electrical "noise" that gets picked up will be
amplified too. In this case, "noise" will will alter some of the video
levels, creating artifacts in the screen information.

The eye is a very tolerant device. In the best case scenario, these may not
even be visible to the eye or may manifest themselves as "snow" in the worst
case scenario. If the cable is too long, the signal may drop below
acceptable values (whatever the viewer won't tolerate) or disappear
completely.

All electrical conductors pick up electrical "noise". This is usually
unwanted electrical energy collected from electric fields in our
environment. Our modern equipment is quite good at maintaining a high
"signal to noise ratio" (SNR) which is what keeps our computers operating
effectively and our video equipment appearing crisp and audio systems
sounding clean.

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On 04/08/28 09:06 PM, "Barry Takayesu" <prestige.print@xxxxxxxxxxx> wrote:

>> Hi
>> Using the Apple Video Adapter and s-video cable what is the max distance
>> that the cable can carry the signal between an eMac and a Sony Wega TV?
>> I'm hoping 30 ft but suspect I'm wildly optimistic!
>> Thanks for your help.
>> Bob
> 
> Bob:
> 
> Some info here. They offer a 49 foot cable.
> 
> http://www.broadbandutopia.com/svideocable.html


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