Taken from www.spaceweather.com this morning:
LONG-DELAY RADIO ECHOES: During the geomagnetic storm of Nov. 27th, a brief but intense G2-class event, amateur radio operator Peter Brogl of Fürth, Germany, experienced a strange phenomenon. Forty-six seconds after he transmitted his call sign at 7 MHz, he received an echo of his own transmission. "At first, I thought someone was playing tricks on me," says Brogl, "but I changed frequency, re-keyed my call sign (DK6NP), and got another echo." This went on for more than an hour, enough time for Brogl to make several recordings. First reported in 1927 by Norwegian civil engineer Jørgen Hals, long-delay radio echoes are rare and poorly understood. Unusual propagation conditions linked to solar storms is one of many possible explanations. Radio operators, if you experienced any similar phenomena on Nov. 27th between 1800 UT and 19:30 UT, please report your observations to Peter Brogl for correlation.
Any thoughts or experiences?
73 - Rob VK2GOM / G0MOH
Long Delay Echoes
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VK2GOM
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JE7IDA
Re: Long Delay Echoes
LDEs have been sometimes received around the latitude 40N.
My QTH Morioka is around 40N so a few local stations heard LDEs
which delayed a day (24hour).
LDEs often reported on 160m, 80m and sometimes on 40m.
My QTH Morioka is around 40N so a few local stations heard LDEs
which delayed a day (24hour).
LDEs often reported on 160m, 80m and sometimes on 40m.
Re: Long Delay Echoes
Intriguing observations, but by no means uncommon.
Oswald "Mike" Villard W6QYT (a professor at Stanford Research Institute in California) investigated the phenomenon and published a few scientific papers on it, including one in QST:
The Magnetospheric Echo Box - A Type of Long Delayed Echo Explained, O. G. Villard, W6QYT, et. al., QST, October 1980, p11.
A broad coverage of LDE "observations" can be found on Wikipedia here: http://en.wikipedia.org/wiki/Long_delayed_echo, with plenty of references (including a couple of Villard's papers).
Recent observations on the amateur bands by Chris Codella W2PA can be found here: http://www.w2pa.com/Home/articles/80m-echo-observations
Posted in the interests of intriguing interest.
73, Roger Harrison VK2ZRH
Oswald "Mike" Villard W6QYT (a professor at Stanford Research Institute in California) investigated the phenomenon and published a few scientific papers on it, including one in QST:
The Magnetospheric Echo Box - A Type of Long Delayed Echo Explained, O. G. Villard, W6QYT, et. al., QST, October 1980, p11.
A broad coverage of LDE "observations" can be found on Wikipedia here: http://en.wikipedia.org/wiki/Long_delayed_echo, with plenty of references (including a couple of Villard's papers).
Recent observations on the amateur bands by Chris Codella W2PA can be found here: http://www.w2pa.com/Home/articles/80m-echo-observations
Posted in the interests of intriguing interest.
73, Roger Harrison VK2ZRH
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VK2KRR
Re: Long Delay Echoes
Considering it takes at least 2 seconds for a signal to propagate to the moon and back to earth, thats quite an interesting effect having such a long delay.
I wonder where there signal goes?
I wonder where there signal goes?
Re: Long Delay Echoes
Hmmmm!
Very interesting.
I heard way back when I was a kid (a long time ago), that supposedly a television signal was witnessed some months or even a year or so after it was aired and that it was of sufficient signal strength to over ride a local transmitter? It reportably was witnessed by many viewers somewhere in Nth America. It may well have been a hoax and someone was pulling my leg
Stating the obvious, the 24 hour or so delay mentioned by JE7IDA indicates a very long signal path and/or a very dense medium it passed through to refract it back from whence it came. I guess if it was reflected from the trailing side of a departing plasma cloud or sheet that had been ejected from a solar eruption of some kind, the doppler would put it well outside the usual passband of the monitoring receiver and it would not be heard or if it was by some chance the association would not be made? Also interesting is that it has been observed over a broad range of frequencies that usually do not have a lot in common when it comes to the mechanics of signal propagation.
Perhaps it has something to do with the NASA announcement tomorrow morning
73 Dave VK3AIF
Very interesting.
I heard way back when I was a kid (a long time ago), that supposedly a television signal was witnessed some months or even a year or so after it was aired and that it was of sufficient signal strength to over ride a local transmitter? It reportably was witnessed by many viewers somewhere in Nth America. It may well have been a hoax and someone was pulling my leg
Stating the obvious, the 24 hour or so delay mentioned by JE7IDA indicates a very long signal path and/or a very dense medium it passed through to refract it back from whence it came. I guess if it was reflected from the trailing side of a departing plasma cloud or sheet that had been ejected from a solar eruption of some kind, the doppler would put it well outside the usual passband of the monitoring receiver and it would not be heard or if it was by some chance the association would not be made? Also interesting is that it has been observed over a broad range of frequencies that usually do not have a lot in common when it comes to the mechanics of signal propagation.
Perhaps it has something to do with the NASA announcement tomorrow morning
73 Dave VK3AIF
Re: Long Delay Echoes
Given that c ~ 300,000 Km/Sec
46s = 13,800,000Km
24Hr = 25,920,000,000Km which is (very roughly) three return trips from Earth to Neptune
Please excuse my skepticism, but I'm having a hard time believing 46 seconds. As for 24 hours ....
73
Iain
46s = 13,800,000Km
24Hr = 25,920,000,000Km which is (very roughly) three return trips from Earth to Neptune
Please excuse my skepticism, but I'm having a hard time believing 46 seconds. As for 24 hours ....
73
Iain
73
Iain Crawford - VK5ZD
Munno Para West, SA - PF95ih
Iain Crawford - VK5ZD
Munno Para West, SA - PF95ih
Re: Long Delay Echoes
A bit more discussion about LDE' at http://www.vhfdx.info/discuss/lde.html with plenty of links most of which I have not followed as yet.
Don't skip the contribution by James Rosa, it is fairly self explanatory
EDIT
Sorry it should have read Don't skip the contribution by "CT1DMK"
Don't skip the contribution by James Rosa, it is fairly self explanatory
EDIT
Sorry it should have read Don't skip the contribution by "CT1DMK"
Last edited by VK3AIF on Sat Dec 04, 2010 2:23 pm, edited 1 time in total.
Re: Long Delay Echoes
Well spottedA bit more discussion about LDE' at http://www.vhfdx.info/discuss/lde.html with plenty of links most of which I have not followed as yet.
If you scroll right-right down to the foot of the (very long) page, there are several links well worth exploring under ". . . the contributions I got from D.B. Muldrew." I recommend you download and read "Generation of Long-Delayed Echoes" published in the Journal of Geophysical Research, September 1979. Technical, but the explanatory bits are emninently clear and readable. LDEs having tens of seconds delay can be plausibly explained.
Similarly, download and read "The Magnetospheric Echo Box - A Type of Long-Delayed Echo Explained" published in QST, October 1980. Your effort will be well rewarded. Inspiring stuff. The authors tackle the question of hoaxes in an intelligent manner.
If you want to really get into the subject, check out Shlionskiy's 15 possible explanations for Long Delayed Echoes at:
http://heim.ifi.uio.no/~sverre/LDE/Shlionskiy15.htm.
And then The Five Most Likely Explanations for Long Delayed Echoes at: http://heim.ifi.uio.no/~sverre/LDE/
Having plowed my way through that lot, it's clear that LDEs are generated by a number of different (and bizarre) phenomena.
Posted in the interests of sharing the info.
73, Roger Harrison VK2ZRH
Re: Long Delay Echoes
No idea
73, Roger Harrison VK2ZRH
73, Roger Harrison VK2ZRH
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VK2GOM
Re: Long Delay Echoes
Nobody has mentioned the film 'Frequency' yet with the extreme LDE's Hands up who has seen it.... a 'pirate' using a Heathkit Rx as a Tcvr... mic cable conveniently just draped around the back somewhere hoping viewers won't notice.
73 - Rob VK2GOM / G0MOH
Hands up who has seen it.... a 'pirate' using a Heathkit Rx as a Tcvr... mic cable conveniently just draped around the back somewhere hoping viewers won't notice.73 - Rob VK2GOM / G0MOH
Re: Long Delay Echoes
Rob,
I think what posters are trying to discuss here is the credible,
not the incredible
G3CWI has a number of round-the-world (RTW) echo recordings on his website here: http://www.qsl.net/g3cwi/roundthe.htm
These LDEs are in the shorter-period range (sub-1 sec).
Sverre, LA3ZA, has a page on Unusual HF Propagation, which includes some illustrative audio clips - including some "Magnetospheric Echo Box" examples. See: http://www.qslnet.de/member/la3za/prop/
Tweeting is nothing new
Posted in the interests of maintining interest
73, Roger Harrison VK2ZRH
I think what posters are trying to discuss here is the credible,
not the incredible G3CWI has a number of round-the-world (RTW) echo recordings on his website here: http://www.qsl.net/g3cwi/roundthe.htm
These LDEs are in the shorter-period range (sub-1 sec).
Sverre, LA3ZA, has a page on Unusual HF Propagation, which includes some illustrative audio clips - including some "Magnetospheric Echo Box" examples. See: http://www.qslnet.de/member/la3za/prop/
Tweeting is nothing new
Posted in the interests of maintining interest
73, Roger Harrison VK2ZRH
Re: Long Delay Echoes
I have not seen the film Frequency, my son has and he must have liked it as he has mentioned it several time over the years.
My unconsidered thoughts are:
It is the LDE < 1 or 2 seconds that fascinate me, there must be a credible explanation there somewhere? I have trouble accepting normal multiple EME reflections as the attenuation would soon send the signal below the noise floor which would make its detection unlikely let alone audible and also it would be multiples of the approximate 2.5 seconds EME delay. For a reflection to return after several second transit at a useful strength it must be either focused or perhaps ducted in a "pipe" as proposed in one of the links above?
Reports seem to suggest little or no doppler shift so the reflecting surface must be reasonably stationary relative to the source so to some extent I think that rules out a normal CME directly but perhaps its effect on the trailing magnetosphere has sufficient persistence?
I'm just thinking out loud here so I had better quit while ahead but it is good to see the interest the subject has generated on the forum
My unconsidered thoughts are:
It is the LDE < 1 or 2 seconds that fascinate me, there must be a credible explanation there somewhere? I have trouble accepting normal multiple EME reflections as the attenuation would soon send the signal below the noise floor which would make its detection unlikely let alone audible and also it would be multiples of the approximate 2.5 seconds EME delay. For a reflection to return after several second transit at a useful strength it must be either focused or perhaps ducted in a "pipe" as proposed in one of the links above?
Reports seem to suggest little or no doppler shift so the reflecting surface must be reasonably stationary relative to the source so to some extent I think that rules out a normal CME directly but perhaps its effect on the trailing magnetosphere has sufficient persistence?
I'm just thinking out loud here so I had better quit while ahead but it is good to see the interest the subject has generated on the forum
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VK2HRD
Re: Long Delay Echoes
Just a thought but is the moon about 4 seconds away so it could be reflecting of that I'm not an expert but just thinking out aloud more or less
Re: Long Delay Echoes
An echo from the moon takes about 2.5 seconds.
And multiple EME reflections - yielding delays of n times 2.5 secs (5, 7.5 etc) - aren't in the picture because of the losses from dispersion of the signal over distances involved and reflection losses.
Read some of the website links posted earlier, you'll get a better idea of the group of phenomena reported.
73, Roger Harrison VK2ZRH
And multiple EME reflections - yielding delays of n times 2.5 secs (5, 7.5 etc) - aren't in the picture because of the losses from dispersion of the signal over distances involved and reflection losses.
Read some of the website links posted earlier, you'll get a better idea of the group of phenomena reported.
73, Roger Harrison VK2ZRH
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VK2HRD
Re: Long Delay Echoes
Thanks I knew it was to obvious for it to be that easy.VK2ZRH wrote:An echo from the moon takes about 2.5 seconds.
And multiple EME reflections - yielding delays of n times 2.5 secs (5, 7.5 etc) - aren't in the picture because of the losses from dispersion of the signal over distances involved and reflection losses.
Read some of the website links posted earlier, you'll get a better idea of the group of phenomena reported.
73, Roger Harrison VK2ZRH
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VK3KCX
Re: Long Delay Echoes
Hi Friends, I became interested in this phenomena a year ago when I heard myself viewtopic.php?f=45&t=11339&p=33112&hili ... cho#p33112
Now a regular 10M contact of mine (Sergey UR3CTB) has had a similar experience twice in the last few days and he has caught it on video. He asked me to post this for comment to this forum on his behalf.
http://www.youtube.com/watch?v=SJvf9Ak07MA http://www.youtube.com/watch?v=t9L3vrMwREI
- David VK3KCX
Now a regular 10M contact of mine (Sergey UR3CTB) has had a similar experience twice in the last few days and he has caught it on video. He asked me to post this for comment to this forum on his behalf.
http://www.youtube.com/watch?v=SJvf9Ak07MA http://www.youtube.com/watch?v=t9L3vrMwREI
- David VK3KCX