Ethernet Over Power Lines

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datman

Ethernet Over Power Lines
« on: 10 May 2008, 10:17 pm »
I had an interesting experience today.  I was listening to my new 97dB efficient speakers using my Transporter as a source and I noticed a faint but real clicking sound in the background on quiet passages.  Once I determined it was coming from the Transporter, I experimented by removing my Ethernet Over Wireless adaptor and reverting to full wireless operation.  The differences were NOT subtle.  The clicking noise vanished.  The overall sound quality became fuller and considerably more robust.  These are difference I NEVER expected.

Apparently there are artifacts that make their way into the signal when using Ethernet over power line adaptors.  I don't know why this is (aren't 1's and 0's just 1's and 0's?)  All I know is the differences are dramatic.

TONEPUB

Re: Ethernet Over Power Lines
« Reply #1 on: 11 May 2008, 12:34 am »
Noise is noise...

If you really want your transporter to sound better, hardwire it and don't go wireless at all.



NewBuyer

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Re: Ethernet Over Power Lines
« Reply #2 on: 11 May 2008, 02:24 am »
Definitely this is not a common trait of powerline adapters in general - if anything, the opposite is true (they are usually very robust and immune to power line noise). Further, the ethernet spec places pulse transformers on the line jacks, for further isolation.

It sounds like one or more of your power line adapter(s) might have a fault, or possibly your ethernet cable.

Philistine

Re: Ethernet Over Power Lines
« Reply #3 on: 11 May 2008, 02:59 am »
Definitely this is not a common trait of powerline adapters in general - if anything, the opposite is true (they are usually very robust and immune to power line noise). Further, the ethernet spec places pulse transformers on the line jacks, for further isolation.

It sounds like one or more of your power line adapter(s) might have a fault, or possibly your ethernet cable.


I use wireless and powerline adapters (not at the same time) and agree that powerline adapters work great, with no noise or interference issues.  Only problem is when using power conditioners and surge suppressors.




chadh

Re: Ethernet Over Power Lines
« Reply #4 on: 11 May 2008, 03:53 am »
Its a fairly popular misconception to believe that a wired ethernet connection provides a stronger or cleaner or in some way better connection than a wireless ethernet connection.  The fact is, you either have a connection or you don't, there is no good, better or best.  There is either a connection or no connection. 
 

When using the wired connection, the wireless receiver in the squeezebox is turned off.  At the very least this means that there are different opportunities for noise to enter the system, depending on how the squeezebox is connected.  For example, if my wireless phone or cell phone operates on a frequency that is similar to my wireless network's, noise from that system may pollute my audio signal if my squeezebox is connected wirelessly.  The phones will have no effect while using an ethernet cable.  It's not a question of whether the signal from the PC is "stronger", but whether it is polluted.  I don't think this is controversial.

Chad

wilsynet

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Re: Ethernet Over Power Lines
« Reply #5 on: 11 May 2008, 08:06 am »
Practically speaking, if you have a good wireless connection free of too much interference and noise you're probably doing alright and it doesn't matter.  But it's not right to say that there is no good, better and best ... in fact there is, and the 802.11 family of protocols have built in adaptive rate selection to deal with the very real physical phenomenon of varying signal quality.

Also, there are multiple checksums at multiple layers, at layer 2 (802.3, 802.11), layer 3 (IP), layer 4 (udp, tcp). A lot of paranoia all to ensure *not* that data isn't corrupted, but rather, to ensure that data which *is* corrupted doesn't go unrecognized.  There isn't much you can do when you've lost the packet:  either move on to the next packet, or negotiate a resend of the lost packet.  If this happens often enough then your connection slows to a crawl as we have to resend all sorts of stuff that's already been sent.

If I want something to be rock solid reliable and not have to worry about interference, congestion and latency then I'll take a wired ethernet connection every time.

When I say wired ethernet, I don't mean the data over AC power lines stuff.  A noisy AC line is going to play havoc with the quality of the data.  And we'll get into this send, timeout, resend business.  If I had to guess, I'd say the clicks and pops probably come from Squeezebox being starved of data.

« Last Edit: 11 May 2008, 08:19 am by wilsynet »

NewBuyer

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Re: Ethernet Over Power Lines
« Reply #6 on: 12 May 2008, 12:26 am »
...the data over AC power lines stuff.  A noisy AC line is going to play havoc with the quality of the data...I'd say the clicks and pops probably come from Squeezebox being starved of data.

This has never been an issue at all, in my experience. However, it is true that these devices work best on the same in-wall circuit leg, and that longer distances can be an issue. But if you get a good signal between the powerline adapters (and remember you should NOT use powerstrips or filters between these products and the wall socket), then you should find that AC line noise (within reason) is not relevant here - these adapters are after all specifically made to handle this. The data "quality" is not an issue whatsoever when these devices are used as intended.

wilsynet

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Re: Ethernet Over Power Lines
« Reply #7 on: 12 May 2008, 03:37 am »
I think that's right.  Can't disagree with that.

My tendency is toward wired ethernet (802.3) first, then wireless (802.11) but that's because it's what I'm most experienced with both in my home and at my job.  But there's a good mix of personal bias in there which probably just illustrates my ignorance of good alternatives like HomePlug.

Thanks for keeping me honest. =)

bbaker6212

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Re: Ethernet Over Power Lines
« Reply #8 on: 24 Jul 2008, 05:15 am »
This is really cool to know. I was wondering how the SqueezeBox,  or other audio streaming (over ethernet) devices would work over PowerLine Communication (PLC, or "HomePlug") adapters.