ECN Forum Forums General Topics of the Trade General Discussion Area Piggyback Internet?

I came across an article which says that an internet provider is using the incoming ac lines to piggyback their signal.Simply plug your computer in and you're online.

What would be the drawbacks to such an arrangement?

Russell

Can't think of any other than possibly speed, reliability and availability in all areas. Don't know anybody who has tried this so I couldn't compare to DSL or broadband. Certainly easy enough to install though.

One BIG drawback is spelled R-F-I.

Putting these high frequency signals over unshielded powerlines will play havoc with other uses of the radio spectrum. Shortwave, public safety, and amateur communications could be rendered just about impossible!

Lots more info on why BPL should never have gotten off the drawing boards:
http://www.arrl.org/tis/info/HTML/plc/

Unfortunately, now that MBAs are running the FCC instead of engineers, crap like this gets approved as a gift to the corporate interests that grease the wheels in Washington...

The first systems that came out behaved like NJwirenut describes. The manufacturers claim to have addressed the interference issue in later systems. It is mainly a solution for that "last mile" to the user with performance in the tens of megabits.

They CLAIM to have fixed the problems, but experiments in BPL deployment areas have proven otherwise. Watch the videos of the tests for yourself at:
http://www.arrl.org/tis/info/HTML/plc/#Video

I can't see how it could be POSSIBLE to "fix" the problem here, short of completely shielding the power grid or suspending the laws of physics. Putting RF signals onto long spans of unshielded wires by DEFINITION creates antennas which radiate the signals.

In addition to the RFI issues, such radiation creates the possibility for unauthorized access to the data stream by anybody with a scanner and a computer...

[This message has been edited by NJwirenut (edited 03-07-2004).]

How about: Lower the power used for signalling, make more sensitive receivers and improve the error checking and correcting.

NJwirenut

It seems you have already made up your mind on this.

Is there something you are not letting us know?

Like you are a Ham radio operator or something like that?

Maybe I am wrong, but your posts project a feeling of anger on this subject.

How about: Lower the power used for signalling, make more sensitive receivers and improve the error checking and correcting.

Lowering power might help a bit in the near field, but HF radio signals can propagate worldwide, even at low power levels. A BPL system here in the states could be clobbering radio communications on the other side of the world.

More sensitive receivers would only exacerbate the flipside of the interference issue--interference TO the BPL system by radio transmitters! In some tests, a simple CB or ham radio set near the powerlines was enough to totally disrupt the BPL connection. Improved error correction might reduce this, at the expense of connection speed, and increased radiated interference from the system (more hash as CRC packets bounce back and forth).

And yes, I am a ham radio operator. But it isn't just hams who are up in arms about this. FEMA, police/fire/ambulance, and aircraft comms groups have all filed comments against BPL with the FCC.

As far as "anger" over the issue, it is more frustration with what I (and many others) see as the FCC abdicating it's mission to maintain a usable spectrum for ALL users, in favor of giveaways to corporate interests. Comissioner Powell would much rather score points by promoting mega media mergers and raging against Janet Jackson's boobs than consider technical issues that might impact some corporation's IPO.

[This message has been edited by NJwirenut (edited 03-07-2004).]

Glad to see you are keeping an open mind.

Bob

Just wanted to add that the website NJwirenut linked to has a good list of references. It's not as biased as you would expect.

It seems to me that ADSL lines would have the same effect. Unshielded wires carrying a high frequency. Strangely, I haven't heard anyone complain about that yet.

The radio astronomers have a just cause: They aren't in control of the transmitters. "Hey, mr Spaceman, could you please go to UHF?"

What I don't understand is why special consideration should be given to radio amateurs? The cellphone operators have been forced to change band several times. The analogue TV network will be closed down to give room for digital. Even radio controlled model planes have been forced to change band. So have the police and other forces. This is a process that has been going on since the radio first was invented. Why not make the amateur radios digital? That should make them much less susceptible to interference.

Isn't this a little bit like the talk of computers being very sensitive, needing clean power and a shielded environment? When the elevator starts, the flourescent lights flicker but the computers couldn't care less. We have used electric welders next to the computers and, yes, the screens go 'boink' but no other problems are apparent.

{Edited to change tone a little}

[This message has been edited by C-H (edited 03-07-2004).]