Rep Power: 785

Why is it that RCA cables can only carry one channel of audio each, whereas other cable mediums (fiber optic, coaxial and most notable digital coaxial) can carry multi channels in several different modes?

 
Rep Power: 0

There really is no difference between RCA and digital coax cable other that the extra shielding on the digital coax. You can use them interchagably(sp) but may notice a bit of sound a drop in sound quality if you have multiple cables and power wires running close to it.

Fibre optic and coaxial are a different design of cables altogether unlike RCA and digital coax which are virtually the same type of cable. Fibre optic is immune to electrical interference since it used light signals to transfer information. But it also has a limited frequency range of 20hz - 20khz. Coax and digital coax have a range of 5hz - 30khz.

Coaxial cable I don't know too much about other than that is what allows me do download **** more quickly.

Hope this helps a bit

 
Rep Power: 327

Because thats just the way it is...

 
Rep Power: 785

that's just how it was designed?

 
Rep Power: 0

fiber optic, coax, and digital coax all carry information in different wavelengths along the same cable. Fiber optic can handle the most data at once, because it can use all the different spectrums of light to carry different bits of data.

 
Rep Power: 327

yup...i'm not an engineer, so I dont know WHY it was done that way, but that's just how they did it. I guess it was created back in the 70's and 80's, so they probably just did whatever they could with their primitave technology...

 
Rep Power: 0

what grenloch said

 
Rep Power: 785

I'm aware of why fiber optic works the way it does, I was curious as to why single wire stuff was like that... oh well I guess I got my answer

 
Rep Power: 305

Analog vs. Digital.

The RCA's on a car stereo or home stereo are transmitting analog information (low wattage AC)

S Video cable is just more wires in a small package.

Fiber optic is a digital transmission.

 
Rep Power: 0

actually fiber optics work not by using diferrent wavelengths of light but rather by pulsing a single one. At least single mode fiber does that, the boost in transfer rate coems from the fact that light travels faster than electricity, the other method of conveying data that is most common(thought sometimes in long range comm work wavelengths and entire wave forms may be utilized.), now because it travels faster the theoretical switching speed(on transition from on to off to on) is faster as well, which = more 1/0 transmitted in a given span of time.

Now if we are talking about multimode fiiber then all the above applies and there may be as many as 7 'paths' internal to the single strand of fiber that allow for multiple simultaneous transmissions much the way that frequency manipulation on a single coax line allows for hundres of channels...but then we have other things like frequency hopping and spread spectrum and such that complicate the coax side of things even more.

i hope this has helped obfuscate things for you a little more.

 
Rep Power: 345

I'm pretty sure electricity travels at the speed of light as well.

In attempt to recap everything, the significant difference between your given examples, RCAs vs. digital [optical, digital coaxial], is that we use the RCA cables for an analog signal that is read by an amplifier that is expecting an analog signal within the frequency range of human hearing.

In digital cables, both coaxial and optical, they do not transmit data through analog signals, they transmit 0s and 1s and a very fast rate. the other end must know that it is a digital signal, and expect to decode the signal into whatever it is [sound signal, tv, etc]. Optical and digital coaxial are more or less the same for our purpose, they have two possible signals, lightn/off for the optical, and voltage:high/low for the coaxial.

The sound is converted to a digital signal, then sent down as 1s and 0s, then converted back to an analog signal sent to our speaker for us to hear. In one second, for example, the digital signal could have the bandwidth to send information for 5 seconds of sound, which can be broken into 5 different sound signals.

In the analog signal, the sound is already converted back to analog signals, exactly like your power lines going from your amp's output to the speakers.

 
Rep Power: 0

well thats actually a tricky question, it depends on how we look at electricity, if we look at the movement of the same atomic particle(the electron)from one ond of a wire to the other(something that only happens in DC transmissions)then actually electricity moves extrememly slowly. But when we talk about its speed we talk about the end result, which is to say one electron in, one electron out. the exiting electron leaves the material at the speed of light and thats correct. The speed of the electron entering a conductor however does not, and is variable based on the materials conductivity. so the speed of the charges themselves is directly proportional to the current.

light on the other hand will pass through glass the 'photon' entering and exiting at the same speed. and of course theres no intereference from electromagnetic sources.


anyone else bored?

 
Rep Power: 0

Well put.

Not to nitpick, but electrons do not move at the speed of light. Even in a super conductor, they in the neighborhood of 2/3c. But you are right about the speed depending upon the resistance of the material.

Also, the speed of light in a substance is not c. Works the same way. The increased internal index of refraction reduces the speed of photons travelling through it. Think of the material like a big (price is right) Plink-O board, with the particle trying to fall through it.

 
Rep Power: 0

right light will be slowed slightly by the resistance of the glass, and native impurities in the structure. Just not enough to really put it even in the ballpark with an electron exiting copper wire. The plinko effect(i rather like that)of the light as it passes through is actually what makes multimode fiber possible. the light simply plinko's at a different attitude through the same larger diameter fiber line...i think multimode fiber is on the range of 2.5x the diameter of single mode iirc.