Why not coax cable for everything?

Question

I have a friend that loves to oversimplify everything to the point of it becoming a joke, but recently he asked me a question that seemed so simple and fundamental that I couldn't come up with an answer. Why can't you just use coax cable to connect everything? Sattallite companies, cable companies and even so-called fiber optic systems such as U-Verse and fios all use good old coax at some point between them and your tv to transmit HD video and audio, so why then are we made to shell out for Toslink cables, HDMI, DVI and others? Why don't they just use simple F style connectors? Aside from marketing I can't think of a reason.

Answer 1

The signal changes as at different points in the transmission path. At some points it may be digital or RF or baseband.

It is best, and even necessary, to use the proper cable for the signal at that particular point in the path. Even coax cable has very different properties, depending on the type of cable in play. If you have a cable modem, it is probably receiving and transmitting digital signals over coax cable, usually at the lower end of the frequency spectrum for that cable, and usually using a simple RF digital encoding technique. But this cable cannot approach the bandwidth needed for certain signals. Coax is best for RF frequencies and shielding the signal from external noise sources. It is not a good choice for baseband signals where it may attenuate the signal or loose digital data, and not a replacement for fiber optic cable with much higher bandwidth and true digital transmission without RF modulation being required.

Answer 2

You can do everything those "digital" cables can do using plain old "RG6" coax.  But to get the same results you have to use up to 6 times as many...Click this link right here: http://www.avtruths.com/budgetcables.htm...

And as great as HDMI is, with it's pure digital signal, it doesn't always offer the best picture and sound quality...Click right here: http://www.avtruths.com/hdmi.html

Answer 3

Electrically, it's possible to do an awful lot more with coax than most people are aware. However, what formats like HDMI (or DVI) offer are multiple conductors, so separate signals can be transmitted concurrently.  

See the attached link for a company that makes coax speaker cables - the concept is incredibly simple, but the mechanics of actually building the design are unbelievably difficult.

Answer 4

coax cable dont have as good quality as HDMI,, but i do agree that the would be a good idea but it would be more expensive and then you would not have upgrades if you want better quality