The PLT monster refuses to die

Sponge Bob

Not if Intel can help it.

Their Homeplug branded PLT gear is shipping in increasing quantities. Its mentioned on page 9 of 21 of this somewhat interesting recent Intel PDF here.

Even worse, Intel seem to be building one of them feckin alliances around this technology which may result in 'in home' deployments where your toaster can talk to your kettle kinda vibe...using the mains .

They mutter about having a standard by end 2006 .

While the odd control signal or dhcp type of service is one thing an announcement was made on HDTV streaming over powerline at Cebit last week so its not just low volume control signals they are thinking of . This is called Homeplug AV

Unlike other PLT tech , this gear is supposed to be used in the home not cross country but one greatly fears the side effects of Coronation St beaming out of the Miliking Machine in the cowshed or Gerry Ryan coming out of teh Baby monitor.

As with most new technology, Comreg haven't a clue and are waiting for guidance from the ERO before they issue a consultation of sorts where they pretend to have though the matter thru and given it due consideration ....yadda yadda

Enforce anything???? Certainly not !

watty

It is being used in some businesses near Temple Bar and some schools. You can buy a a pair to plug socket bricks for Ethernet in PC World months ago. I already highlighted this here.

There should be banning of all these products till an assessment is done. It is my understanding they have no RF licence and simply get a CE mark on same basis as a plugtop poser supply.

Blaster99

Unshielded random RF, what could possibly go wrong...

Is it banned anywhere else? If not, let's not worry about it. Most countries have competent regulatory regimes and if they're not worried, there's no real need for us to worry.

bminish

Sponge Bob wrote:

Their Homeplug branded PLT gear is shipping in increasing quantities. Its mentioned on page 9 of 21 of this somewhat interesting recent Intel PDF here.

The homeplug alliance actually did some testing with the ARRL and as a result implemented notching of the Amateur bands although it is not clear if the updated homeplug standard also inlcudes notching by default.
Of course this does not protect SW broadcasting but then it has to be up to the broadcasting representative to fight their own corner
This homeplug stuff operates at much lower power levels than access PLT and will in general only be an issue in the premises that it is installed in and the immediate vicinity.
One other thing, homeplug suffers badly from ingress interference

In the US they have the infamous FCC part 15B rule which basically makes the owner of said item responsible for any interference created. In FCC land if your Part 15B device is causing me interference you have to solve the problem.

It's my opinion that Part 15B (which is weak law in any case) and is designed to cover 'unintentional emissions' should not cover any device that actually requires the presence 'unintentional emissions' to operate.

The situation concerning the legality of homeplug in Europe is murky at best and I wonder how it manages to be compliant with the EMC directive. Next time I see these devices on sale I may have to acquire a pair for testing purposes.

.brendan

watty

Let me know if you need any spectrum analysers or stuff.

Usually every 3rd house on same phase, so that has implications for interference an security. I winder is a ferrite clamp on the mains cables at the meter enough to stop the signal coming in or out and what secuity it has.

bminish

watty wrote:

Let me know if you need any spectrum analysers or stuff.

I am resonably well covered in that area, the trickier part of the measurement problem is ensuring that measurements made will reference back to established standards.

Of course the 'standard' measurement techniques used for EMC compliance often fall far short of what is required for assessing actual interference levels to radio users.
For example the oft relied upon small loop that is used for HF measurements places the noise floor of the testing apparatus 10's of dB above the noise floor as seen on a receiver connected to a typical antenna.

Usually every 3rd house on same phase, so that has implications for interference an security. I winder is a ferrite clamp on the mains cables at the meter enough to stop the signal coming in or out and what secuity it has.

Propagation past the meter has always been a problem for PLT, I suspect that this holds true for Homeplug too.
Access PLT has tried to solve this by using more power or by bypassing the Meter. Neither approach works very well.
More power makes it harder for the PLT system to reuse frequencies within a location (tight frequency reuse is essential if more than a small area is to be covered)
Bypassing meters (for HF) also couples back interference from each house (from Switch mode power supplies, thermostats, Boiler igniters etc) back to the local grid raising the overall noise floor that the PLT system needs to deal with

When we tested the impact of ingress interference (Nearby HF transmissions) on the Mainnet PLT equipment in Tuam we took down the entire system from quite a distance.
With the probable exception of the Motorola system which uses proper LC notch filters all PLT systems are very prone to ingress.
Ingress interference is a big issue for PLT yet it is one that they would like to keep very, very Quiet about.

.brendan

Blaster99

How's PLT working out these days? Is it commercially viable?

I thought all of those humeplug yokes use encryption? This stuff has been pretty well covered by 802.11 at this stage, you'd think.

Urban Weigl

From what I've seen, they usually offer 56-bit encryption.

SMC EZ Connect 85 Mbps Turbo Powerline to Ethernet Adapter:
http://www.komplett.ie/k/ki.asp?sku=317367

You can see the typical specs there. I'm guessing they may still be popular because they can often reach where wifi has trouble, though to be honest that could be solved with a WDS repeater, so I'm not sure.

bminish

Hmm, does not seem to deliver anything close to the claimed 85Mbs in actual use.
http://www.tomsnetworking.com/2006/02/06/homeplug_turbo_adapter_round/

.brendan

Urban Weigl

To be honest, I am not the least bit surprised: there seems to be a general trend of quoting optimal speeds and including any overheads as well (for example, a 54Mbs wireless network only gives you half that speed, if you're lucky). The difference between 85Mbs and 10Mbs seems significantly bigger than usual, though.

Blaster99

Any reviews I've seen of those homeplug things, and I didn't read that one, have indicated that you'll get a fraction (about a 10th) of the advertised speed, and that's using two plugs in the same room. I would have thought that makes sense as the noise levels must be huge in plain ol' electrical wiring.

bminish

Hope no one gets too annoyed with me Giving this thread another poke but I just found the ESB presentation on the Tuam PLT trials
http://www.engineersireland.ie/uploads/Files/SectorPapers/95/%7BE61A878A3A42417381A04F740F070874%7D_REVISED%20REV%201.PDF
ESB were none too impressed with PLT but fair play to the ESB for doing a comprehensive trial

I did the ingress part of the trial in area A. The area we tested for ingress (interference from licensed radio users) was a housing estate with underground wiring.

Now that I know the ESB results are out I'll put up my report of the ingress tests and follow up with a link to it later .

Here is the link to my report of the ingress tests as I submitted it to the ESB at the time. I have removed the names of the Key people

http://www.tradcentral.com/ei6iz/TuamReport_ESB.pdf

.brendan

gerryo

Thanks for that very interesting information