Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10 5/3/83; site heurikon.UUCP
Path: utzoo!linus!vaxine!wjh12!genrad!decvax!harpo!seismo!uwvax!heurikon!jeff
From: jeff@heurikon.UUCP
Newsgroups: net.micro
Subject: Re: BRS home controllers and Cordless Phones
Message-ID: <261@heurikon.UUCP>
Date: Mon, 21-May-84 00:01:10 EDT
Article-I.D.: heurikon.261
Posted: Mon May 21 00:01:10 1984
Date-Received: Fri, 25-May-84 00:46:08 EDT
References: <1118@qubix.UUCP>
Organization: Heurikon Corp., Madison WI
Lines: 23

> >>	MOST cordless phones use the AC line to communicate to the handset.
> How do they manage that piece of magic?  The handset doesn't plug into a
> wall socket.  Do you mean they use the AC line as an antenna?  Even that is
> a little bizarre.  Many clock-radios use an additional wire in the AC cord
> as an antenna but they do not use the AC wiring.  Most of the cordless
> phones that I have seen in the stores have telescopic rod antennas.

They use two frequencies and two paths.  The base unit transmits to the
remote handset by injecting a signal into the AC power lines of the
house.  The base picks this up via a loopstick antenna *inside* the
handset.  The AC lines radiate the signal all around the house.  The
remote transmits a signal to the base using the telescopic antenna which
the base picks it up via a telescopic antenna of its own.  The handset
is rigged so that the antenna need not be up to work; there is a large
metal plate inside the case which is used if the antenna is retracted,
so the transmitter is still loaded.

(This is based on the Phone-Mate which I use.  I took the thing apart.
The hard part was finding the hidden screws which hold the case together.)
-- 
/"""\	Jeffrey Mattox, Heurikon Corp, Madison, WI
|O.O|	{harpo, hao, philabs}!seismo!uwvax!heurikon!jeff  (news & mail)
\_=_/				     ihnp4!heurikon!jeff  (mail - fast)