Powerline modem

They're a little nervous about losing some (largely unused) amateur bands, and the powerline thing certainly has the potential to cause some trouble, too. So they are a little sensitive right now, can't blame them for that. But, there are a helluva lot of documented cases of amateur radio transmissions interfering with just about everything else that's electronic, and IMO the high level of hand-wringing from the ARRL on this subject is a little ironic. :-) (You largely said the same thing I think, James.)

-John O

When I was a kid, we had a flat rate electric water heater. It could be turned off by the power company, during periods of high demand, using a power line carrier system. The power companies also used the power lines to carry low speed data. However, neither of those systems required anywhere near the bandwidth of BPL, nor were they likely to cause interference.

In misc.industry.utilities.electric John wrote: | Don Lancaster wrote: | |> I guess I was involved in the earliest of powerline carrier |> communications. Back in 1961 at Femco. |>

|> It did not work then and it will not work now. |>

|> Ferinstance, an ancient Diablo 630 printer has such a good noise filter |> that it takes out any X-10 device within 200 feet. | | Powerline communications doesn't work in the 21st century? Really? Gosh | somebody forgot to tell these people: |

| | PPL has had running broadband Internet over powerline services in select | markets for a few years now. Some other utilties have similar programs. | | | Utilities not only have another revenue stream and an efficient Internet | distribution method, but also gain the benefit of a communications channel | to/from their meters. | | The ARRL (amateur radio group) has spoken out against some powerline | communications, out of fears that it will cause interference to them.

Hams continue to speak out well after BPL is operating. The interference is documented. Further, BPL is, itself, ruined by nearby transmitters.

Although any wire infrastructure can carry data, it does have limits based on many factors. And power lines are not designed for high data rates. They are unshielded, and as a result are susceptible to interference, and radiate their own interference. Phone lines also have documented problems, but at least they are twisted. The only part of the power lines that are twisted are the triplex overhead drops.

BPL is going to be very limited in top speed. As bandwidth goes up, so goes the sensitivity to noise and interference. Things like electronic ballasts operating between 20 kHz and 50 kHz are going to be another interference source.

The power companies are just playing a "me, too" game on this. They wanted in on the "riches" the internet was bringing to telephone and cable companies. But as the bandwidth demands of the market top 100 mbps, power companies are going to be playing the tune "where'd they go?". It's a bad investment for the power companies. Right now, I wouldn't put any money in their stock.

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| Phil Howard KA9WGN       | http://linuxhomepage.com/      http://ham.org/ |
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Hello Peter,

In Germany they send around control signals to turn on "night storage heaters". Basically a huge block of bricks that is heated up off-peak and then a fan kicks out the stored heat during the day. Usually there are several such units per residence. The control of these via the power grid is very reliable. I believe they can selectively turn on groups of them but there were some restrictions as to which areas could receive the control signals to within the prescribed specs.

Anyone who wants to check that out and can read German could search Google for the terms "Nachtspeicherheizung" and "Rundsteuerung".

Meter reading could be done staggered. That way the amount of data can be spread out over each month. Pretty much in the same way that the meter reader travels their monthly route.

But there is one obstacle to all this. I heard from someone in the power biz that occasionally it was said "so-and-so does not like these research projects if they lead to the elimination of jobs".

Regards, Joerg

Hello James,

We did have interference but very little. When I listened to BBC on long wave (200kHz, not used in the US) you could hear a faint weeeezzzzzt when these PLC signals came along. It had its upside though, this was usually the sign to call it a day.

Regards, Joerg

Note however that these systems use signalling frequencies of 200 Hz to 1500Hz and are 'one way'. Bandwidth and other constraints limited capacity originally to 12 to 25 on / off channels. Injection may be at zone substations (signal passes through one transformer) or at grid exit points (signal passes through two transformers). These would be electronic system nowadays, older ones used three phase alternators to generate the signal ane electromechanical receivers (eg reed relay to respond to signal and motor driven cam for selection).

It seems interesting that none of these technologies has made significant inroads into meter reading for smaller customers. About the only development that has been widely adopted is a hand held computer to replace the meter reading book.

There has been talk of these systems going hand in hand with demand side management eg real time pricing, but efforts to reduce the cost of these systems to a lever where they are worth adopting seem so far to be without success.

The most successful niche seems to be a low bandwidth system for rural areas (where meter reading costs are very high) which does not require transformer bridging (

).

Only 100 Mbps? That's a hell of a lot more then dial-up, which is the only hope of any Internet access at all (save satellite) in much of the USA where cable is not available and DSL lines are not available either due to DSL's numerous limitations. It's a lot more then DSL capabilities and cable broadband offerings too.

You forget that the power utilities aren't setting out to do this to become Internet companies, they were looking for efficient ways to communicate with their meters (and utility controlled thermostats). Being able to offer and sell Internet broadband access is a nice side effect of having the infrastructure.

PPL has done quite nicely the last few years and is a fairly conservatively run company.

Maybe where you live. Here the gas company reads the meter electronically via radio as they drive down the street and similar story for the electricity company.

Don Lancaster wrote: (snip)

You should try a *new* Diablo. Much better. ;-)

I read in sci.electronics.design that John wrote (in ) about 'Powerline modem', on Thu, 10 Feb

2005:

This can be done very well using frequencies below 150 kHz which don't create huge EMI problems.

Not at any price; the emission levels 3 to 30 MHz are 60 dB or so above those currently accepted. It's very far indeed from a marginal increase.

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Regards, John Woodgate, OOO - Own Opinions Only. 
The good news is that nothing is compulsory.
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If you haven't already discovered it, there is a lot of helpful information on the Freescale Semiconductor web page for the DSP568xx family. There are a couple of brochures on power line modems and power meters implemented with the DSP568xx family. This link is a good place to start:

You may also want to contact your local Freescale representative, as they can point you to more detailed information the implementation of power line modems on the DSP568xx family.

-Gary