🚀 go-pugleaf

In article <tih.725986398@barsoom> tih@barsoom.nhh.no (Tom Ivar Helbekkmo) writes:

   Of course, one could argue that the VCR ought to have a battery backup
   for its clock, but I've got one of the cheaper models, and of course
   this is a feature that they reserve for people who can shell out
   bigger bucks for the thing than I can.

Backup power supplies - usually big capacitors rather than batteries -
for clocks on things like VCRs are very cheap: perhaps costing a few
pennies.

   However, I got to thinking about this: Why the heck doesn't my VCR
   automatically find out what the current time is?  Why doesn't my clock
   radio and other appliances that have clocks do the same thing?

A good question, but the answer is simple: cost. A backup power supply
for the clock is at least a couple of orders of magnitude cheaper than
a decent radio clock receiver or a teletext decoder. Another problem
is the diversity of time signals in the world: which one should the
VCR manufacturer include? WWV? DCF? MSF? OMEGA? GPS? (The last two are
probably best for availability throughout the world. However, they
ain't cheap. The cheapest GPS clocks cost $5-600 - roughly twice that
of a VCR.)

   It seems to me that something essential is missing here...  There are
   radio stations and TV stations all over the place, transmitting a lot
   of stuff on different channels at the same time, so why don't we
   already have a standard for time information transmittal that these
   appliances can utilize?

Probably because it's simpler and cheaper to put a quartz oscillator
on the device. There are so many world-wide clock and broadcast
standards that adding this feature to a VCR (say) would be a difficult
technical and political problem. It would also add expense and
complexity which could make sales harder to come by.

   And even without a general time broadcast system, the following could
   be done: Since a VCR has a TV receiver, there ought to be info
   contained within the normal TV broadcast signal telling the current
   time (probably specified as UTC, with the local time zone switch
   settable on the VCR), so that the VCR can keep its internal clock
   running correctly.

TV teletext services already do this (at least in the UK). However, it
is up to the broadcaster to determine the accuracy of the teletext
time information. Some may be less bothered about this than others - I
have seen cable-supplied teletext with times minutes away from GMT. [UK
broadcasters sync their teletext clocks to the UK MSF signal.] This
would add extra complexity in the user interface to household gadgets
that are already over-complicated. [eg - how do you tell the VCR what
timezone it's in or which channel's teletext to believe?]

		Jim