Extending wi-fi
 

Jim Lesurf wrote:
In article , Bill Wright
wrote:
Mark Carver wrote:
On 07/01/2014 22:04, David Woolley wrote:
The telephone wires are explicitly balanced, by being made as twisted
pairs. That balances them against environmental asymmetries.
All the overhead 'drop wires' I've ever seen close up are 'shotgun'
rather than twisted ?


Yes. Of course balanced RF feeder is not usually twisted and it does
have reasonable immunity to interference. I say 'reasonable'...

Yes. Twisting can help in some circumstances. All depends on factors like
what may be 'close' to the wires, upsetting the effect of the balancing.

Jim


The old 300 ohm feeder had to be kept away from walls and even more
important away from metal fall pipes.

Bill

Extending wi-fi
 

In message , Steve Thackery
writes
Ian Jackson wrote:

I'm sure Steve is fully aware of the problems of PLT. If not, may I
refer him to the following websites:
http://www.ban-plt.co.uk/truth-lies.php
http://www.ukqrm.org.uk/plt.php
www.elmac.co.uk/pdfs/whyPLTisbadforemc.pdf?
http://www.compliance-club.com/default.aspx?id=17
http://www.emcuk.co.uk/awareness/Pag...ples/IssuesWit
hBr oadband.htm and many more.

Thanks, Ian. I will indeed take a look at those sites when I've
finished all my university assignments that I should have done over
Christmas!

Please do - but I'm sure you can at least spare a quick few minutes here
and now having a quick look (if only to show you that things are not
quite as you thought they were). You might find that an understanding of
the problems associated with PLC might be more interesting - and
instructive - than the university stuff!
--
Ian

Extending wi-fi
 

In article , Ian Jackson ianREMOVET
scribeth thus
In message , Jim Lesurf
writes
In article , Roderick
Stewart
wrote:
On Wed, 08 Jan 2014 07:17:05 +0000, Mark Carver
wrote:


The telephone wires are explicitly balanced, by being made as twisted
pairs. That balances them against environmental asymmetries.

All the overhead 'drop wires' I've ever seen close up are 'shotgun'
rather than twisted ?

You mean parallel wires with constant spacing, like mains cable?

There are various mains cables around our house. They don't all have the
same wire spacing or diameters. Some are three wire, some are two. None, so
far as I know, behave in a balanced way at RF.

I'm no expert on domestic mains wiring but AIUI the wires to the light
fittings tend to only switch one 'arm' of the connection. If so, leaving a
'spur' of a single wire for the RF. Rather more like an antenna than
balanced impedance-matched cable. One per room. Antenna array.

But apparently OfCom have decided the result is not a "transmitter". Wonder
how many of the decision makers ever did Radio 101 at Uni...

There are lots of commercial interests who knew they had an expanding
market for PLT equipment, and in the end, I think it's a case of money
talks even more than radio amateurs do (and that's quite a lot).


A very good read on the subject here from Mark Waddell at BBC R&D...


http://www.bbc.co.uk/rd/publications/whitepaper195

and..

http://www.bbc.co.uk/rd/publications/whitepaper222
--
Tony Sayer

Extending wi-fi
 

In article , tony sayer

wrote:


A very good read on the subject here from Mark Waddell at BBC R&D...


http://www.bbc.co.uk/rd/publications/whitepaper195

and..

http://www.bbc.co.uk/rd/publications/whitepaper222

FWIW Mark was one of the people I discussed this with some time ago. Very
helpful and knowledgeable. Also kindly let me use some of his examples in
an article to illustrate the effects on radio reception in the home.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
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