I agree that BPL is in it's infancy. The notching (usually around 60db isolation) on HAM frequencies does work. The notching doesn't stop governmental meddling. I don't think I ever said that. But you do have to be pretty sharp to do van eck phreaking (which is what all the TEMPEST requirements are about, btw).

You have to remember that many of the guys building BPL worked in telecom for years (decades) and many of them are HAMs as well.

Me? My expertise is in DSL. I just happen to know some guys in a couple of BPL startups. If you need my credentials, see:

http://www.ietf.org/rfc/rfc3276.txt
http://www.ietf.org/rfc/rfc3705.txt
http://www.ietf.org/rfc/rfc3705.txt
http://www.ietf.org/internet-drafts/...hdslbis-00.txt
http://www.ietf.org/internet-drafts/...ext-scm-02.txt
http://www.ietf.org/internet-drafts/...ext-mcm-02.txt

Is BPL cheaper than satellite? Depends upon which direction you want a high data rate, dude. For high downstream and relatively low upstream rates, satellites and a regular old modem work just fine. If you need symmetric rates, they don't.

There aren't too many places that DSL won't work well in the US either. Multiple g.shdsl lines (see symmetricom's offerings, for example) are a good solution. If the co-op utilities can't afford to run multiple phone lines to your house, it might be another story.

BPL works great for places where there is a power line in place but one or fewer older copper phone lines in place. That is, rural areas that (for whatever reason) need 1mbps (or higher) upstream data rates.

They work really well for power stations (surprise!). A power company owns it's own power lines, wants to put tv monitors in those remote stations, or run many SCADA-capable devices. IP (over broadband over powerlines) works great.

Another example is in the third world, where a place is LUCKY to have a single power line and there is NO money to run optic fiber or phone lines (or drop in a cell tower matrix for that matter). Any connectivity is better than none.

If it's cheap enough, I'd use it. I've seen some of the BPL players. The demo system I helped set up used cable modems and plain ole isolators to modulate/demodulate (MO-DEM) the signal onto and off of the power lines.

It's NOT the technology.

The ARRL hysteria MAY be because of SOME manufacturers leaving out HAM notching. Or turn it off (which a marketing guy left alone with a box might do, can't help that, never have been able to help that). I have no vested interest in BPL. Don't really care. But, as a geek, don't blame the technology - it works, it's done right in the cases I've seen. If one doesn't have the expertise to understand the technology, I gently suggest that one not go about screaming "the world is coming to and end". Because it isn't.

Hope this helps. Hope this doesn't get me banned again

Bob

 

..........Bob, If it doesn't interfere with ham communications then I'm ALL for its utilization. A far as having a Predisposed opinion, I, like the rest of my ham brothers are only reacting too the quality of the discussion that is currently being presented by all sides concerned. Specifically, it seems that the BPL folks haven't presented a very "interference Free" product. Ultimately, I'll just have to live withever the end result turns out to be. Utilities , when confronted with a clear case of interference by a Ham from their equipment have been less than forthcoming in locating and correcting the problem. So , you can see where Hams might have a case for harboring a "Predisposed opinion" in reference to the utilities and their attitude for their rollout of BPL.
..........I, appreciate your enlightened discussion of the issues. I'll pursue some of those URL's when I have Time, thanks, s.kuteman

 

For "interference free", I CAN show you one (it's in Cullman, Alabama). There is another one just North of me near Coldwater, Tennessee. Both built by a Vanderbilt EE PhD (who also built one of the first cable modems). As near as I can tell, he built them to prove he could build them ('cause he SURE isn't gonna get rich off of them).

As for other manufacturers? No clue. In fact, the ARRL is probably right about some of them (there are still slimeballs in our enlightened age, unfortunately).

For example, if I build a modem with a HAM notch in the frequency spectrum used to carry the data, but also build in a way to disable the notch (which most engineers must do, as such enabling/disabling is often specified in the international compliancy specifications - ITU, IEEE, ETSI, etc.), then a field operator can disable it.

This is not cause for condemnation of the technology - it is cause for condemnation of the operators. Which gets back to an earlier post of mine about hounding your local utilities. Ask them which units they are using and find out if they

a) have HAM notching.
b) have disabled the HAM notch.
c) if so, ask them WHY (or ask them if they are just stupid or something)

I've spent enough time of this thread, guys. Last post.

Bob