S-video cable length

[pandy]

No, it's the other way around, that's where your lack of knowledge resides. Can you get a picture with noise? yes. Is it recommended for capturing? No.

? DFP... coax cable shielding efficiency is around 90..100dB - if you have noise issues or other interference's then this is probably issue with your setup... noise generated by cable... this is few ohm resistor - calculate noise level https://www.omnicalculator.com/physics/resistor-noise - cable introduce perhaps few microvolts noise... over 2 m of the RG-59 attenuation loss for 10MHz should be around 0.05dB max

[pandy]

Pandy stop doubling down, You're not making any sense dude.

Dude - you obviously have no technical knowledge so you are not even aware of bullshit you are producing... no worries - you are not alone - there is many people like you on this poor planet...
Are you able to read coax cable datasheet, understand figures? Don't think so...

[dellsam34]

Just so you know we are not talking about RG-59 in this thread, In case if you missed the title. and I'm done with your mumbo jumbo, so go ahead have the last stab. I'm just noting your back paddling from 1000ft.

[Cornucopia]

Some of the differences of length opinions can be cleared up if you consider Balanced vs Unbalanced topologies. Example: RCA unbalanced audio (-10dB consumer level) vs. XLR balanced audio (+4dB pro level), besides the difference in voltage allowing for more signal at pro level so longer runs before degradation is too much, balanced cable isolates the signal from (most) noise, allowing the signal to travel much farther without problems building up before being unacceptable. Thus those RCA line level cables I would not run past 15-25 feet, while XLR line level I have easily run 100-400 feet.
Of course, shorter is always better, so "use good judgement", as my mom always used to say.

<edit>so, VGA, twisted pair ethernet, etc are balanced.


Scott

[pandy]

Just so you know we are not talking about RG-59 in this thread, In case if you missed the title. and I'm done with your mumbo jumbo, so go ahead have the last stab. I'm just noting your back paddling from 1000ft.

How do you know dude what cable is inside? Perhaps it is RG-59 or RG179 or similar - there is coaxial cable inside unless cable is totally crap dude, easily proved your technical incompetence with few links, you didn't wrote single fact correctly, all you can do is some smooth, rounded bs - let say snake oil - as you don't even understand simple numbers dude... ignorance is bliss but in free time get some lecture - https://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect?useskin=vector https://en.wikipedia.org/wiki/Illusory_superiority?useskin=vector

[Sharc]

...... poor sources (like VCR video driver) may have issues to deal with cable capacity - RG-59 nominal capacity is over 50pF per 1 meter i.e. video amplifier must be capable to deal with few hundreds pF load at least...

If properly terminated the source will 'see' the wave impedance (also called surge impedance) of the coax which is by design 75 Ohms for example, resistive at the specified frequency.
Btw the 'Balun' couplers for the extensions mentioned in the catalogs use balanced (twisted wire pairs, 150 Ohms) Ethernet Cat 6 cables on the extended section rather than Coax. Baluns stands for 'balanced-unbalanced' (Coax<->Twisted pairs). Never tried it as I have no use for such extensions. Balanced wires suppress common mode noise effectively.

[dellsam34]

Some of the differences of length opinions can be cleared up if you consider Balanced vs Unbalanced topologies. Example: RCA unbalanced audio (-10dB consumer level) vs. XLR balanced audio (+4dB pro level),

Yes for this reason XLR are used in the professional field to eliminate the noise by phase reversing, have been used in concerts to hookup long run microphones, It's mostly wireless now, not sure if wired microphones are used anymore.

[pandy]

Some of the differences of length opinions can be cleared up if you consider Balanced vs Unbalanced topologies. Example: RCA unbalanced audio (-10dB consumer level) vs. XLR balanced audio (+4dB pro level), besides the difference in voltage allowing for more signal at pro level so longer runs before degradation is too much, balanced cable isolates the signal from (most) noise, allowing the signal to travel much farther without problems building up before being unacceptable. Thus those RCA line level cables I would not run past 15-25 feet, while XLR line level I have easily run 100-400 feet.
Of course, shorter is always better, so "use good judgement", as my mom always used to say.


Scott

Balanced offer some advantage over unbalanced where grounding (grounding loop) can be issue - that's why it is preferred in "pro" - it is easier to control overall signal path, and balanced usually doesn't isolate from noise - noise (interferences) are self-canceled. Good coax cable has shielding efficiency better than 100dB so interferences should be not a problem with properly routed coax cable. And you can use coax cable with signal levels 50..100V easily so way over "pro" levels.
And shorter is not always better...

[pandy]

...... poor sources (like VCR video driver) may have issues to deal with cable capacity - RG-59 nominal capacity is over 50pF per 1 meter i.e. video amplifier must be capable to deal with few hundreds pF load at least...

If properly terminated the source will 'see' the wave impedance (also called surge impedance) of the coax which is by design 75 Ohms for example, resistive at the specified frequency.
Btw the 'Balun' couplers for the extensions mentioned in the catalogs use balanced (twisted wire pairs, 150 Ohms) Ethernet Cat 6 cables on the extended section rather than Coax. Baluns stands for 'balanced-unbalanced' (Coax<->Twisted pairs). Never tried it as I have no use for such extensions. Balanced wires suppress common mode noise effectively.

Still, long coax cable is seen by source as complex impedance not as resistive load - if your output video amplifier is incapable to deal with high capacity load then your problems are visible... high current buffer usually solve problems.
And baluns can be made for other impedances like 120ohm - my point was that you can transmit analog signals over way longer (OP question) cables passively - no active amplifier - debunking myth. 3..10ft is silly length even for GHz signals, 300..500ft can be problem, 3000..5000ft you have problem.

[Cornucopia]

Some of the differences of length opinions can be cleared up if you consider Balanced vs Unbalanced topologies. Example: RCA unbalanced audio (-10dB consumer level) vs. XLR balanced audio (+4dB pro level), besides the difference in voltage allowing for more signal at pro level so longer runs before degradation is too much, balanced cable isolates the signal from (most) noise, allowing the signal to travel much farther without problems building up before being unacceptable. Thus those RCA line level cables I would not run past 15-25 feet, while XLR line level I have easily run 100-400 feet.
Of course, shorter is always better, so "use good judgement", as my mom always used to say.


Scott

Balanced offer some advantage over unbalanced where grounding (grounding loop) can be issue - that's why it is preferred in "pro" - it is easier to control overall signal path, and balanced usually doesn't isolate from noise - noise (interferences) are self-canceled. Good coax cable has shielding efficiency better than 100dB so interferences should be not a problem with properly routed coax cable. And you can use coax cable with signal levels 50..100V easily so way over "pro" levels.
And shorter is not always better...

Potato - potahto (re: bolded segment).

Of course, any cable that has shielding is better at noise rejection than an equivalent cable that doesn't.
Any cable that has balanced topology is better than an equivalent cable that is unbalanced.
Any cable, with its stated resistance per distance will lose less signal than an equivalent cable with higher resistance per distance, and this is where cable gauges come into play. For equivalent gauge cables, per a specific signal, there is less resistance (and hence signal loss) for shorter cable distances than for longer cable distances. Would love to be given a real-world example where this isn't true.
Any signal in a cable that has a higher voltage will have a better signal to noise ratio than a lower voltage signal in an equivalent cable, assuming equivalent levels of noise. This SNR allows for longer cable lengths without unacceptable degradation than would a low SNR signal.

You are throwing around lots of theoreticals but not really comparing apples to apples. Coax makes sense for some formats and uses, and one of those uses requires long runs, but those uses are not really applicable (especially with digital - not counting fiber) in the circumstances of the OP, so the reference to coax, while theoretically technically sound, is totally impractical and tangential.

Scott

[dellsam34]

This is typical Cornucopia, I see it in these forums all the time where folks like us being using these cables since the 80's, and these Google graduates that post links from the internet having little to no experience with the subject being discussed.

[Sharc]

For "long" cables (> ~1/4 wavelength which is about 30 feet for a 6 MHz sine wave in the cable) one has to take signal reflexions due to impedance mismatch into account, in addition to the constraints due to signal attenuation and electromagnetic interference (SNR). Reflexions will cause ghosts. I am just wondering about the suggested Balun adaptors. A "balun" junction connecting a 75 Ohms S-video port to an Ethernet cable (150 Ohms) creates a reflected wave at each end which is attenuated by about 10dB only, travelling back an forth, attenuated by 2x cable attenuation for each round trip. The delayed echoes have to be put in relation to the video horizontal scanline duration (ghosts) and received useful signal amplitude to estimate the visual ghosting effect..... just a quick thought.

[pandy]

Potato - potahto (re: bolded segment).

Of course, any cable that has shielding is better at noise rejection than an equivalent cable that doesn't.
Any cable that has balanced topology is better than an equivalent cable that is unbalanced.
Any cable, with its stated resistance per distance will lose less signal than an equivalent cable with higher resistance per distance, and this is where cable gauges come into play. For equivalent gauge cables, per a specific signal, there is less resistance (and hence signal loss) for shorter cable distances than for longer cable distances. Would love to be given a real-world example where this isn't true.
Any signal in a cable that has a higher voltage will have a better signal to noise ratio than a lower voltage signal in an equivalent cable, assuming equivalent levels of noise. This SNR allows for longer cable lengths without unacceptable degradation than would a low SNR signal.

You are throwing around lots of theoreticals but not really comparing apples to apples. Coax makes sense for some formats and uses, and one of those uses requires long runs, but those uses are not really applicable (especially with digital - not counting fiber) in the circumstances of the OP, so the reference to coax, while theoretically technically sound, is totally impractical and tangential.

Scott

Well... nope - there is some reason why you have STP, FTP and UTP cables - everything depends from your environment situation - of course you can try to present this as purely theoretical/semantic issue. But in real life this is not such simple.
And definitely statement :

Any cable that has balanced topology is better than an equivalent cable that is unbalanced.

is wrong.

Signal level is convention - no one prevent you to increase signal level to higher unless you need provide compatibility - then you need to follow rules.
And how the heck physical cable properties can be theoretical?
Being electronics engineer with 30+ years practical experience I'm comparing apples to apples - just don't like bs and "snake oil" religion.
Debunking snake oil myth is totally practical and definitely not tangential - 3ft more will not ruin your signal unless your setup is screwed from the very first point..
If you have no technical knowledge then you writing bs about snake oil myth or 3 ft coax or less and mixing 50/75 equipment in your setup then you complaining on interferences and noise as you have signal discontinuity and capacitive coupling.

Q. Why would I want to drive a capacitive load?

A. It's usually not a matter of choice. In most cases, the load capacitance is not from a capacitor you've added intentionally; most often it's an unwanted parasitic, such as the capacitance of a length of coaxial cable.

If coax cables are so wrong accordingly to you then why there are so frequently used? Why people taking 8..16m of the LMR-200 to connect WLAN antenna with station?
This is not theory but practice - i can understand people not exposed on these problems, but i don't understand why people saying such radical statements.
Already proven in hard facts my points - all i can get in exchange is round shaped bs...

Btw resistance is usually unimportant in signal cables. And long coax can be used for digital as well as balanced cables - everything depends on usage case.

[pandy]

For "long" cables (> ~1/4 wavelength which is about 30 feet for a 6 MHz sine wave in the cable) one has to take signal reflexions due to impedance mismatch into account, in addition to the constraints due to signal attenuation and electromagnetic interference (SNR). Reflexions will cause ghosts. I am just wondering about the suggested Balun adaptors. A "balun" junction connecting a 75 Ohms S-video port to an Ethernet cable (150 Ohms) creates a reflected wave at each end which is attenuated by about 10dB only, travelling back an forth, attenuated by 2x cable attenuation for each round trip. The delayed echoes have to be put in relation to the video horizontal scanline duration (ghosts) and received useful signal amplitude to estimate the visual ghosting effect..... just a quick thought.

If you have impedance mismatch then yes but what in case where you have impedance matched and there is no reflections ?
Reflections are symptom for problem - you have damaged coax cable, open connection, short connection - to solve issue you are using TDR and fixing problem but this getting us to same point as before - if your setup is correct then there is no issue even if you add 10ft more of coax cable, if you have wrong setup then 3ft more of coax is not your primary issue... So in first point make proper setup and/or solve setup problems...

[lollo]

3ft more will not ruin your signal unless your setup is screwed from the very first point

We all agree on that, and this also answers to the question from OP. Case closed