This is carrier current technology. Many colleges use it to transmit local
programming to campus dormitories. The power lines radiate the rf signal so
low power can cover a very large area. The signal doesn't get through most
breaker boxes too well so it stays relatively local. I think capacitors are
used to bridge local boxes. SUNY Oswego, NY, USA used to use such a system
for their campus radio station. I haven't been up there in more than a
decade so I don't know if it is still in use.

Allen

> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of
> George Smith
> Sent: Monday, August 4, 2014 1:28 PM
> To: PICLIST Post
> Subject: Re: [EE] Wireless speakers thoughts
>=20
> Phil Keller wrote:
> > -- Delivered via SpamCon Foundation DEA: http://dea.spamcon.org
> > -- Replies will be sent to piclist@mit.edu
> > -- Additional Info: http://dea.spamcon.org/i/?v=3D73553259
> >
> >   I am involved with a local volunteer group that puts on a Ghost House
> > every Halloween.  It is setup in, and around, a historical house in the
> > middle of a shopping center parking lot.  We would like to play sounds
> > and music (HiFi not required but nice) throughout, but holes in walls
> > and ceilings for speaker wires is forbidden.  So a potential solution
> > would be wireless speakers.  The maximum distance from the transmitter
> > to the receiver is about 250 ft (or about 75 meters) with a couple of
> > walls in the way.  It would appear that Blue tooth is not a viable
solution.
> >
> >    Cost.  The completed system (1 Tx, 4 Rx) should not be more that
> > about $600.  Less is MUCH better.
> >
> Another couple of thoughts (some DIY with amp/speakers as well) would be
> to use either:-
> http://www.crazy-audio.com/projects/raspberry-pi-for-audio-distribution/
> with ethernet over mains modules.
>=20
> or
>=20
> simpler still (if you can find the hardware), Tandy/RS used to do
> intercoms that worked over main supply using low frequency RF carrier.
>=20
> George Smith
>=20
>=20
> --
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