It was our signal, same speed, same automatic
keying characteristics, same everything. We had a tape
of it for a long time, and I had a copy of the tape, but at some
point, years ago, I lost it or erased it.
LDEs are real. It appears the most logical solution is some
sort of ducting, the signal returning to earth in a moving path,
which accounts for it being heard only briefly at the originating
wrote an interesting article on LDE that is at his website
: http://w5htw.home.att.net/index.html. With Edís kindly permission the article
is printed below.
is a silent key -12/17/2010. His site is nonactive.)
LDES - LONG DELAYED ECHOS
There are stories told in the cult books of radio signals
being heard again years after the radio station left the air.
One such story involved a broadcast AM station that had closed
down, yet the radio signal was heard nearly two years after the
station went off the air.
Those stories are like the UFO and ghost stories.
They have no foundation.
LDEs, though, are very real. What they are not,
are attempts by some alien space craft to contact us. What
they are is an as-yet unexplained electromagnetic phenomena relating
to radio waves. In the 1960s Stanford University's
Physics Lab tried to find an explanation for them but LDEs have
no apparent useful purpose, so allocating much in the way of scientific
time or funds is pretty unlikely. The study closed with
only a few suggestions.
There are some facts available about the standard LDE.
First, it does not show signs of Doppler shift. It is on
frequency, it remains on frequency for the duration, and the pitch,
if it is CW, remains steady.
Secondly, it is rarely a full transmission. It
is segments, often very short segments, only five or six seconds,
of a transmission. It may not begin at the beginning,
and it may not end at the ending of the original transmission.
It is not complete.
Third it does
not fade in or fade out. It is "there."
At least that is true of the one I heard that was so clearly identifiable.
It turns on, and then it turns
Fourth, they have been showing up LONG before computer
sound cards. While it is possible one or two could be a
hoax, it is highly unlikely.
Fifth, they are not limited to the ham bands.
Sixth, reports of them are mostly in the 3 to 18 mhz range. Occasionally one is heard above that, and
on very rare occasions, one below that. This could
be because most radio activity
is in that range, so it really isn't a defining fact, but it is
a point to consider.
MY OWN EXPERIENCE
To my knowledge I have heard only one LDE. It
is possible I have heard others, but did not recognize them as
such, perhaps due to crowded band conditions, or other situations.
The one I heard, though, was unmistakable. To explain it,
I have to set the scene a bit. This was in 1967, in the
I was a government radio operator/tech at a somewhat
isolated radio relay site. We ran a CW net that was used almost
entirely for the purpose of establishing contact and setup procedures
for RTTY operations. Hence it carried very little, and very
intermittent, CW traffic. We ran three or four transmitters
simultaneously, depending upon time of day. We ran four
receivers (Collins 51J3/R388) models in a console. There was a
J38 straight key for our use. There was also a Frederick
Electronics Baudot to Morse converter, that converted 5-level punched paper (or plastic)
TTY tape to Morse. We ran what is typically know
as a "guard" frequency. You've heard them on the
marine bands. It sends something like: VVV VVV
VVV DE KGP444 KGP444
KGP444 QSX 4/6/10 K And then there is silence.
That is the listening period.
Our machine sent this (and this is a fictitious call
sign, not the one we used)
VVV VVV VVV DE AAA123 AAA123 AAA123 VVV VVV VVV DE AAA123 AAA123 AAA123 VVV VVV VVV DE AAA123 AAA123 AAA123 QSX 4/6/10 K (In the day time the freqs would change to 6/10/13)
at 18 wpm, took just about one full minute. The tape then
looped (using "letters" characters) for another full
minute, during which time any station could call in.