Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!cica!gatech!mcnc!unccvax!dya
From: dya@unccvax.UUCP (York David Anthony @ WKTD, Wilmington, NC)
Newsgroups: sci.electronics
Subject: Tunnel Radio (was reception)
Message-ID: <1566@unccvax.UUCP>
Date: 24 Jul 89 14:40:15 GMT
References: <Jul.19.14.48.15.1989.439@athos.rutgers.edu> <81@vax87.auc.dk> <3890@phri.UUCP>
Organization: Univ. of NC at Charlotte, Charlotte, NC
Lines: 14


	[The Lincoln Tunnel authorities can break into...]
> normal re-broadcast for emergency messages.  They do this, I believe, on
> every AM channel.

	Does anyone know exactly **how** they accomplish this? The
"every AM channel" system is used in Boston (in the sort-of-tunnel
under Copley, and in the Callahan and Sumner tunnels)....

	I suspect that it is spread spectrum (of sorts) which hits
(swept) from 530 to 1600 kHz every 100 uS or so.

York David Anthony
DataSpan, Inc