> Anyway, these devices seem to be controlled by some kind of digital
> link. I assume this is over the air, like a pager transmitter, but it's
> an example of what a household data line could do in the future.
Wireless (UHF, mostly) remote meter reading and load management systems are
already in place now and work well. Look for a tall vertical antenna on top of
a phone pole somewhere in your neighborhood - it's a collinear of some sort.
Nothing I've seen proposed for BPL as possible utility subscriber
infrastructure requires anything more than a few bytes per transaction and it's
not time-critical. Why would the utilities go through all the trouble and
expense of replacing a functioning system with a hugely expensive
high-bandwidth system for these minimal transactions? The answer is that they
won't because it's a huge waste of money.
Here's an example of a similar system. You would think that to speed up the
transactions, gas stations and the like would be using the latest dial-up modem
technology to get the maximum bits per second. But they're using old 2400 baud
modems...why? Because the transactions are so small (hello, card #, amount,
handshake, goodbye), a 2400 baud modem can connect, transfer, and disconnect
while a V.90 50 kbps modem would still be training to get the maximum data rate.
Utility infrastructure is a many-short-transactions model while the BPL model
is a few-big-transactions model. They don't work the same way. It would be
like using a race car to deliver the mail.
73, Ward N0AX
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