- Tue Feb 08, 2005 5:54 am
One of the biggest obstacles is the amount of bandwidth required.
Take the case of a single user wanting to watch a program that was
on Channel 2 two days ago. First, the TV station which carried the
older show cannot transmit the show to this single user on Channel
2. If the station did, the current broadcast to all other users would be 'walked on'. Using a channel of another station would not work for the same reason. Some currently unused frequency would be required.
Now expand the scenario to the case of two users simultaneously wanting to view two different past shows at two different times from
different networks. Each station would need to transmit the old shows on some currently unused frequency for the reasons given
above. Furthermore, the two unused frequencies must not be the
same or each of the speacial users telecasts would 'walk' on each
Carrying on, it can be seen that each speacial user must have his
own private channel in the currently unused frequency spectrum.
Given that each video channel is a minimum of 6 MHz wide and that
there are over 300 million potential users of this service in the US
alone leads to the conclusion that the airwaves will be come totaly
saturated very quickly.
One way to reduce the number of airwave channels required is to go
to a form of cable - either Coax or Fiberglass. In theory, cable systems are closed from the outside world.
In this case, each special user will be required to have his own
dedicated cable over which he can receive his special telecasts.
However, each dedicated closed cable could use the same frequency
as the other cables. Only the programming on each cable will be
different as selected by the users. Note that each of the dedicated
cables will have to extend to each television broadcasting station the
user whishes to view. This approach reduces the airwave bandwidth
requirements at the expense of installing one heck of a lot of cable.