Sometime in the past week, or three (time blurs when laboring hours on the new website), I promised to tell you about my personal encounter with an LDE or long delayed echo. The reason is that this is very special territory for the inquiring minds who want to know and it is very well-established by real science as being a replicable phenomena.
So what, exactly, is a “long delayed echo?” A clip from Wikipedia in the interest of being concise because I could go on for hours about it:
“Long delayed echoes (LDEs) are radio echoes which return to the sender several seconds after a radio transmission has occurred. Delays of longer than 2.7 seconds are considered LDEs. LDEs have a number of proposed scientific origins.
These echoes were first observed in 1927 by civil engineer Jørgen Hals from his home near Oslo, Norway. Hals had repeatedly observed an unexpected second radio echo with a significant time delay after the primary radio echo ended. Unable to account for this strange phenomenon, he wrote a letter to Norwegian physicist Carl Størmer, explaining the event:
At the end of the summer of 1927 I repeatedly heard signals from the Dutch short-wave transmitting station PCJJ at Eindhoven. At the same time as I heard these I also heard echoes. I heard the usual echo which goes round the Earth with an interval of about 1/7 of a second as well as a weaker echo about three seconds after the principal echo had gone. When the principal signal was especially strong, I suppose the amplitude for the last echo three seconds later, lay between 1/10 and 1/20 of the principal signal in strength. From where this echo comes I cannot say for the present, I can only confirm that I really heard it.
Physicist Balthasar van der Pol helped Hals and Stormer investigate the echoes, but due to the sporadic nature of the echo events and variations in time-delay, did not find a suitable explanation.
Long delayed echoes have been heard sporadically from the first observations in 1927 and up to our time.”
My own LDE experience occurred in 1966, or thereabouts. It was a weekend morning,and I was on the 20-meter band using my old Johnson Pacemaker SSB transmitter at 90-watts and my somewhat improved-upon NC-300 receiver. I was on upper sideband, I was not running the amplifier, the antenna was multi-band inverted-vee at 40-feet (strung off the top of a piece of 4” irrigation pipe that another ham and I had carried on our shoulders 13-miles to get it to my house). The season was fall or spring, since the band was just opening up, and it was sunny as I recall since sun was coming into my basement ham shack which would have placed the time about 10:00 to 11:30 AM because that was when the sun came in….our house was on a hill so the basement window only got about 2-hours of sun at best.
I was calling “CQ 20, CQ 20” which is radio-ese for “Looking for someone to talk to…
As I un-keyed the mic to listen for a returning station, you can imagine my shock when I heard….ME! Except it was me delayed by 3.4 seconds, calculated from saying my then call sign and measuring the portion I’d heard on a digital sound rig much later in life.
Significantly, the signal was dead-to-nuts on frequency and it was S-9 to 20 dB over S-9 so it was stronger than heck against a very low noise level (S-2 to S-3).
I didn’t learn about LDE’s until after I had aced my First Class Commercial ticket around that time frame, so thinking back on the issue date of that (December ‘66) I reckon this took place in the fall when I was a high school senior and a nerd’s nerd in things electronic.
For the period right after the event, I was convinced it was someone simply recording my signal and playing it back with a tape recorder. But when I heard a good chunk of myself asking “…are you playing with me?” come back, I realized that there was almost no chance that someone could record and retransmit my signal that quickly for technical timing reasons that would bore you to tears.
Read moreCoping: My Long Delayed Echo /ET? Experience