[RFI] ECM...etc.

[Ward Silver]

> 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