Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: Notesfiles $Revision: 1.7.0.5 $; site trsvax
Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxn!ihnp4!inuxc!pur-ee!uiucdcs!convex!trsvax!mikey
From: mikey@trsvax
Newsgroups: net.ham-radio
Subject: Re: "PL"
Message-ID: <52800061@trsvax>
Date: Mon, 8-Jul-85 10:47:00 EDT
Article-I.D.: trsvax.52800061
Posted: Mon Jul  8 10:47:00 1985
Date-Received: Fri, 12-Jul-85 00:21:06 EDT
References: <86@biomed.UUCP>
Lines: 22
Nf-ID: #R:biomed.UUCP:-8600:trsvax:52800061:000:879
Nf-From: trsvax!mikey    Jul  8 09:47:00 1985




PL is used not just for security or access to a "private" repeater and/or
functions, but also to prevent interference.  On 10M repeaters, each
area of the country has subtones that it is supposed to use for
repeater access.  This prevents skip from one area of the country from
activating all the repeaters in another part of the country.  It also
can be used to prevent interference where repeater coverage covers
more that one metro area, for example, New York to Boston.  There are
probably some sites that if PL was not used, keying up would probably
bring up many machines in the area.

As to decoding the PL on a receiver, Kenwood did something similar 
except they use ASCII transmission of your call sign in the TR2600 
handi-talkie.  

As to the legality of PL, there really isn't a problem.  It's not
cryptic data and it conserves bandspace.

mikey at trsvax
KA5MJQ