antentopSince2 July

Ham Spirit
Antentop Free E-Magazine
Free Choice

 

 

Free Antentop Amateur Open Book
Antentop Album
Antentop Survey

 

 

 

Antentop is FREE e-magazine devoted to Antennas and Amateur Radio an

Special page devoted to

Long Delay Echoes

Custom Search

 

ANTENTOP- 01- 2007, # 009

Long Delay Echoes

 

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 site.  

Ed

 

Ed 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.

(I.G.: Ed 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 off. 

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 Far East.

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)

That sequence, 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. 

 

 

www.qrz.com

 

 

http://www.antentop.org/

Page 65

64 65 66 67

 

 

QRP Transceivers and PA from Accessible Parts IP for QRP Antentop Book Radio Antenna Engineering Book Antentop Printed and e- magazines
 


 

 

Just for Fun:

Map IP Address
Powered byIP2Location.com

Thanks for your time!

Last Updated:

August 2, 2016 23:35

Antentop Home Page

Free Antentop Open Book