Linksys Incorporates HomePlug Networking

mattyohe writes "It seems that Linksys is one of the first to prepare release for their ethernet router that uses the HomePlug 1.0 spec. Linksys claims the Instant Powerline EtherFast Router performs well by using the OFDM (Orthogonal Frequency Division Multiplexing) scheme. OFDM forms numerous signals into a single signal for transmission and then is used again to find and automatically adapt to the specific frequency combination that enables successful communication. This product currently uses 56 bit DES encryption and would be excellent for networking in the home enviroment. Never worry about not having enough rj-45 jacks at a lan party, bring some power strips!"

Comments

Question I can't find an answer to on their site

[luge]

What happens on the PC side of the question? Like, do I have to buy a device that takes up a slot internally or is USB? Or can I just plug that device into a pre-existing ethernet slot? Obviously, some type of PC->poweroutlet adapter is necessary, but where are they? [Oh, and less importantly... can I run this through my surge protector?]

Re:From an audio perspective....

[Jeffrey Baker]

Aw, c'mon. Insightful? It's easy to build a highly regulated DC power supply from arbitrarily noisy AC power mains. High capacitance, quality power transformers, noise chokes, power entry modules: all these components on a modern power supply are there to filter out noise. In low-power components like DACs and preamplifiers, the regulated power rails should have a VERY high noise rejection from ~0 into the low MHz. IC regulation isn't practical in power amplifiers, but really impressive capacitors are practical and a good design will have power supply noise well below signal level or throughout the audible band.

In other words, I wouldn't sweat it for audio uses. If it really bothers you, power your audio equipment through a real UPS with a lead-acid battery and inverter. That should brick-wall filter any noise from your mains.

You misunderstood

[Ungrounded Lightning]

Aw, c'mon. Insightful? It's easy to build a highly regulated DC power supply from arbitrarily noisy AC power mains.

He's not talking about coupling through the power supply. He's talking about capacitive coupling.

Yes, he has a valid concern. The power lines carry 60 HZ and a lot of harmonics of it - all low frequency stuff - plus switching noise - higher frequency stuff but more intermittent, except for commutator noise which (as you probably know from listening to AM while running an electric drill) is all over the map. Not to mention fluorescent and other arc lamps and switching power supplies - all over the ultrasonic-to-radio ranges.

The higher the frequency the easier it couples - in direct proportion. Beyond the audio range it can still cause some trouble, but not as much.

This technology is running in the tens of megabits over a noisy channel, so it will be running a goodly fraction of that in bandwidth. The question is mostly whether the LOW end is well above the audio and FM multiplex subcarrier range.

Don't bet on that. The audio range is just as useful as an equivalent bandwidth above it, so unless the designers were trying to avoid hi-fi and telephone interference they probably used it.

I have a few other concerns:

How does it behave in the presence of interference from commutator-based motors (drills, vacuum cleaners, blenders, mixers, hedge trimmers, etc.), switching power supplies (computers, peripherals, compact fluorescents), and arc lamps (standard fluorescents, high-pressure vapor)?

How does it behave in the presence of other similar devices in other houses attached to the same power transformer? (Like X10 it probably won't go THROUGH the transformer enough to notice.)?

Will you need a coupling capacitor between the two sides (or in industrial situations, the three phases) of your feed to get the other half (two-thirds) of your outlets to work?

Will the default configuration share your internet and intranet with your neighbors?

On the other hand, can you feed a neighbor deliberately, to cut a deal to share a DSL or Cable drop?