Neal McLain wrote:
> I agree with Garrett. Your local cable company HAD to build a
> separate network in order to carry NTSC television signals. A cable
> network is vastly different from the telephone network: it has to
> carry much higher frequencies (by about 14 octaves), and it serves an
> entirely different market.
The telephone system extensively uses coaxial cable to multiplex phone
and TV signals. Indeed, the phone co has been carrying TV signals for
years. The telco could've integrated cable signals into its existing
plant and billing systems. There would've been definite economies of
scale to be gained if they used telco standards.
> Huh? That's news to me. CATV plant uses essentially the same "work
> methods" as telcos: same poles, same pole hardware, same type of
> supporting strand, same trenches, same pedestals, same rights-of-way,
> same easements, same construction methods. ...
> In fact, CATV constructions cost were often higher. Because most CATV
> networks were built half-a-century after telco networks, construction
> costs in existing neighborhoods were often substantially higher than new
> construction would have been. But these differences resulted from
> having to work around existing facilities, not from different "work
> On the other hand, CATV labor costs were often lower than telco's
> because CATV companies were usually non-union. Furthermore, a CATV
> headend costs less than a telephone central office, but that doesn't
> affect the construction cost of the outside-plant network.
I've seen and dealt with cable construction by various companies. To
say "non union labor" is an understatement. Cable companies got day
laborers off the street and ragged 2nd-hand equipment. Lines were
strung on poles FAST. They disregarded the wishes of communities and
shoved their work through, irritating the heck out of property owners
and towns, knowing once the work was done the town likely wouldn't
litigate. Cable reliability is far less than phoneco; their
underground lines are very shallow.
Cable used existing infrastructure -- the same poles power and phone
lines already used, they just added theirs. Because the cable is a
common signal, it is much simpler to run than providing a unique
channel for each subscriber.
So, either the costs of cable are so high that the phoneco should've
done it to provide for economies of scale, OR, cable laying isn't so
expensive that others couldn't do it too.
> Telephone service over CATV networks wasn't realistically possible
> until VOIP came along (some would say it still isn't).
I dare say VOIP and other value-added services were in mind when they
went to fibre (another rush job).
> Because local loop plant won't carry NTSC television signals. The only
> way a telco could/can provide CATV is by building a coax (or, nowadays,
> HFC or all-fiber) network.
A great many phone subscribers do not have a dedicated pair of copper
wires between their home and the CO. There are various ways of
multiplexing the line (see the discussion on party lines) plus the use
of concentrators. The Bell Labs history and "Bell Labs Record"
describes many of those techniques. As mentioned, telcos know about
coax and TV.
> And because, under federal law, the telcos' "natural monopoly" didn't
> apply to CATV service. Any telco that wanted to offer CATV still had to
> get a franchise from every LFA.
Telcos couldn't do so because of a policy decision, not a technical
one. The long distance network was built to carry voice, TV, and
radio. The local loop can be set up to carry high speed data and at
one time could carry pulsed signals (not modulated) for Teletype