I don't remember any 100-HZ tone, but after CONELRAD, there was
the EBS or Emergency Broadcast System. It may have started as
early as the sixties and was still in use well in to the
nineties, but it used a pair of tones that are around 100 HZ
apart, but are not harmonicly related. The idea was that radio
and television stations who were part of the daisy chain would
have receivers with decoders similar to pagers that were
fixed-tuned to other radio and television stations up-stream
from them. The receivers normally remained silent but would turn
on when they heard eight seconds of those two tones together
which were sounded for ten seconds as a very rawcus chord.

	As a broadcasting student in college during the early
seventies, I remember the news wire machines we had in the
newsroom. There was an authentication system to verify alerts
sent over the news wires because People were afraid that a
prankster might trigger an alert by faking the signal so there
were a few measures in place to verify that an alert was for
real. I don't know that much was done on the radio side of
things, but we did have a news wire teletype in the news room
and every month, a different colored envelope arrived at the
station. The envelope was not to be opened unless an alert was
sent over the wire. There was supposed to be a code sequence
sent in the message and you were then supposed to open the
envelope which would contain a card with the same sequence
printed on it. At that point, it was probably time to drop
everything and go out and start looting or something. Well, the
idea was to authenticate the alert.

	I don't think there was ever a malicious alert, but we
apparently had a pretty good scare in the sixties when a
national alert was triggered by accident. I really don't know
much more than that.

Mike Keithley writes:
> Concerning the 1 KHz tone, I seem to remember that there was 1 100 hertz 
> modulation tone associated with it.
> 
> ----- Original Message -----
> From: Martin McCormick <[log in to unmask]>
> To:  [log in to unmask]
> Date: Monday, Nov 14, 2011 09:32:14
> Subject: Re: A Bit of Radio History
> 
> >
> >
> >       I do remember the CONELRAD tests.
> >
> >       Radio and television stations would broadcast an
> > introductory message as to what was about to happen. The carrier
> > would go down for 15 seconds. Then, it would come back up for
> > another 15 seconds. It was down for yet another 15 seconds and
> > when it came back up, there was a 1 KHZ tone for maybe another
> > 15 seconds. CONELRAD receivers had to detect the two drops in
> > carrier plus the tone and that initiated the CONELRAD condition.
> >
> >       My father was a science teacher at a school in Tulsa,
> > Oklahoma at the time and had gone in to the teachers' lounge or
> > maybe the school office for something and turned on the radio.
> > He first thought the radio was broken because there were only
> > two signals on the air. Then, he was reminded of the test which
> > went for half an hour or so and then all other stations came
> > back on and things were normal.
> >
> >       I think the test was done every year for a while. I
> > don't remember the first test, but the one in 1957 or 1958
> > featured a talk by our state's governor at the time.
> >
> >       I bet the station engineers loved this test if their
> > station was one of the CONELRAD stations because they had to run
> > all this stuff that you couldn't test any other time and it had
> > to work perfectly this one day and, of course, be ready to
> > switch in on a moment's notice.
> >
> >       Tulsa had a 50,000-watt station KVOO at 1170 which was
> > one of the CONELRAD stations so they had to electrically chop
> > off part of their antenna to tune it up on 1240. I am sure this
> > was accomplished by large contactors which are just huge relays,
> > but still, when else could you make sure it worked?
> >
> >       The other 50,000-watt station in Tulsa was KRMG at 740.
> > I have no idea, for sure if they were the 640 CONELRAD station,
> > but they would have had to add some electronic length to their
> > masts to reach 640.
> >
> >       It did work, however, so it just shows you what people
> > do when they need to.
> >
> >       Something else you might find interesting during those
> > days was a plan to use AM broadcast transmitters as data links
> > for RTTY and Morse.
> >
> >       There was an article in "QST" several years ago about
> > WSM 650 in Nashville TN. They actually had a FSK encoder on
> > their 50-KW transmitter which shifted the carrier maybe 50 HZ
> > and would have let them send RTTY to suitable decoders. An
> > average citizen listening to WSM would have noticed nothing
> > unusual. The article described the test transmission as a loop
> > sending the call letters and the word "test."
> >
> > Lloyd Rasmussen writes:
> > > I don't remember hearing any of those celebrity PSA's, but they aren't
> > > very
> > > different from what FEMA tells us today at ready.gov or other 
> websites.
> 
>