***{Does anyone have an explanation for the following? --MJ}***

Forwarding permission was given by William R. Corliss

http://www.science-frontiers.com

SCIENCE FRONTIERS, No. 159, May-Jun 2005, p. 4


GEOPHYSICS

Extreme LDEs

LDEs (Long-Delayed Echoes) are heard fairly often by radio hams. Usually,
their signals are reflected back to them delayed by just a few seconds. But
since radio waves travel 186,000 miles/second, any reflector must be located
far beyond the moon's orbit. Question: what's out there?

LDEs have been recognized and puzzled over since 1927. (SF#10, SF#39)
But so far no completely convincing explanation has been forthcoming. Three
ideas thrown on the table have been:

* Multiple trips of the signal around the world with the ionosphere's help.

* Signal trapping in ionospheric ducts.

* Reflections from distant plasma clouds.

Most LDE research has been carried out by radio hams, who have now
discovered a new twist to the LDE puzzle: some LDEs return not in
just a few seconds but in minutes and even hours! Can you imagine
a radio reflector a light-hour distant? After all, the sun is only 8
light-minutes away.

Japanese hams have been at the forefront in collecting these extremely long
LDEs. M. Obara, in Tokyo (call letters TZ6JA), summarized the situation
as follows.

All of these records (except UL7GW) indicate very long delay
times ranging from 20 minutes to 82 hours. Converting these
times to distances...corresponds to round trips of 1.8 - 297 AU
(Astronomical Unit, 1 AU = 150 million kilometers, or about
93 million miles, the distance between the Earth and the Sun).
These delay times suggest the existence of two hypothetical
*interplanetary ionospheres*, composed of numerous magnetic
and plasma tails of small planets and debris, located mainly at
the minor planet belt (asteroid belt) and the Kuiper belt (a
region beyond Neptune containing thousands of small bodies
orbiting the sun that is believed to be the spawning ground
of many short-period comets.

(Obara, Mac; "Long-Delayed Echoes: Reflections from an Ionosphere in
Space?", *CQ*, 24, Feb 2005. Cr. L.M. Nash)


SCIENCE FRONTIERS is a bimonthly collection of scientific anomalies in
the current literature. Published by the Sourcebook Project, P.O. Box 107,
Glen Arm, MD 21057 USA. Annual subscription: $8.00.

Mitchell Jones wrote:
***{Does anyone have an explanation for the following? --MJ}***


Forwarding permission was given by William R. Corliss

http://www.science-frontiers.com

SCIENCE FRONTIERS, No. 159, May-Jun 2005, p. 4


GEOPHYSICS

Extreme LDEs

LDEs (Long-Delayed Echoes) are heard fairly often by radio hams. Usually,
their signals are reflected back to them delayed by just a few seconds. But
since radio waves travel 186,000 miles/second, any reflector must be located
far beyond the moon's orbit. Question: what's out there?

LDEs have been recognized and puzzled over since 1927. (SF#10, SF#39)
But so far no completely convincing explanation has been forthcoming. Three
ideas thrown on the table have been:

* Multiple trips of the signal around the world with the ionosphere's help.

* Signal trapping in ionospheric ducts.

* Reflections from distant plasma clouds.

Most LDE research has been carried out by radio hams, who have now
discovered a new twist to the LDE puzzle: some LDEs return not in
just a few seconds but in minutes and even hours! Can you imagine
a radio reflector a light-hour distant? After all, the sun is only 8
light-minutes away.

Japanese hams have been at the forefront in collecting these extremely long
LDEs. M. Obara, in Tokyo (call letters TZ6JA), summarized the situation
as follows.

All of these records (except UL7GW) indicate very long delay
times ranging from 20 minutes to 82 hours. Converting these
times to distances...corresponds to round trips of 1.8 - 297 AU
(Astronomical Unit, 1 AU = 150 million kilometers, or about
93 million miles, the distance between the Earth and the Sun).
These delay times suggest the existence of two hypothetical
*interplanetary ionospheres*, composed of numerous magnetic
and plasma tails of small planets and debris, located mainly at
the minor planet belt (asteroid belt) and the Kuiper belt (a
region beyond Neptune containing thousands of small bodies
orbiting the sun that is believed to be the spawning ground
of many short-period comets.

(Obara, Mac; "Long-Delayed Echoes: Reflections from an Ionosphere in
Space?", *CQ*, 24, Feb 2005. Cr. L.M. Nash)


SCIENCE FRONTIERS is a bimonthly collection of scientific anomalies in
the current literature. Published by the Sourcebook Project, P.O. Box 107,
Glen Arm, MD 21057 USA. Annual subscription: $8.00.

What is the source of the echo?

I don't think they are reflections from the Kuiper Belt Objects. Their
(Kuiper Belt Objects) spatial density probably (I'm guessing this) is
not sufficient to have much of a reflection coefficient. Also the 2-way
propagation loss (Earth to Kuiper Belt, reflection loss, and then the
return path: Kuiper Belt to Earth) would be very large (that is I doubt
it would be detectable under normal transmission conditions).

Are there examples of this signal on the web?

In sci.physics Alfred A. Aburto Jr. wrote:

What is the source of the echo?

The person receiving the echo usually, though there have been some
coordinated projects.

I don't think they are reflections from the Kuiper Belt Objects. Their
(Kuiper Belt Objects) spatial density probably (I'm guessing this) is
not sufficient to have much of a reflection coefficient. Also the 2-way
propagation loss (Earth to Kuiper Belt, reflection loss, and then the
return path: Kuiper Belt to Earth) would be very large (that is I doubt
it would be detectable under normal transmission conditions).

That's why most people seem to think it is a ducting phenomena, that
and the fact the signal would have to go through the ionosphere twice,
which would be a bit hard to do on HF frequencies.

Are there examples of this signal on the web?

Probably, lots of people into research. Google is your friend.

It has been observed both with morse code and SSB.

Echos in the order of 10s of seconds are reasonably easy to observe and
can be explained by ducting.

Echos in the order of hours are thought by many to be hoaxes.

--
Jim Pennino

Remove .spam.sux to reply.

In article ,
"Alfred A. Aburto Jr." wrote:

Mitchell Jones wrote:
***{Does anyone have an explanation for the following? --MJ}***


Forwarding permission was given by William R. Corliss

http://www.science-frontiers.com

SCIENCE FRONTIERS, No. 159, May-Jun 2005, p. 4


GEOPHYSICS

Extreme LDEs

LDEs (Long-Delayed Echoes) are heard fairly often by radio hams. Usually,
their signals are reflected back to them delayed by just a few seconds. But
since radio waves travel 186,000 miles/second, any reflector must be located
far beyond the moon's orbit. Question: what's out there?

LDEs have been recognized and puzzled over since 1927. (SF#10, SF#39)
But so far no completely convincing explanation has been forthcoming. Three
ideas thrown on the table have been:

* Multiple trips of the signal around the world with the ionosphere's help.

* Signal trapping in ionospheric ducts.

* Reflections from distant plasma clouds.

Most LDE research has been carried out by radio hams, who have now
discovered a new twist to the LDE puzzle: some LDEs return not in
just a few seconds but in minutes and even hours! Can you imagine
a radio reflector a light-hour distant? After all, the sun is only 8
light-minutes away.

Japanese hams have been at the forefront in collecting these extremely long
LDEs. M. Obara, in Tokyo (call letters TZ6JA), summarized the situation
as follows.

All of these records (except UL7GW) indicate very long delay
times ranging from 20 minutes to 82 hours. Converting these
times to distances...corresponds to round trips of 1.8 - 297 AU
(Astronomical Unit, 1 AU = 150 million kilometers, or about
93 million miles, the distance between the Earth and the Sun).
These delay times suggest the existence of two hypothetical
*interplanetary ionospheres*, composed of numerous magnetic
and plasma tails of small planets and debris, located mainly at
the minor planet belt (asteroid belt) and the Kuiper belt (a
region beyond Neptune containing thousands of small bodies
orbiting the sun that is believed to be the spawning ground
of many short-period comets.

(Obara, Mac; "Long-Delayed Echoes: Reflections from an Ionosphere in
Space?", *CQ*, 24, Feb 2005. Cr. L.M. Nash)


SCIENCE FRONTIERS is a bimonthly collection of scientific anomalies in
the current literature. Published by the Sourcebook Project, P.O. Box 107,
Glen Arm, MD 21057 USA. Annual subscription: $8.00.

What is the source of the echo?

***{Frankly, it seems so bizarre to me that I can come up with only one
theory: hams are playing tricks on one another. One ham sends out a
signal, and another records it and plays it back later. In other words,
it's sort of like an internet hoax. Could that be? I don't know, but if
it isn't then this is one of the strangest things I've ever heard of.
--MJ}***

I don't think they are reflections from the Kuiper Belt Objects.

***{I totally agree. --MJ}***

Their
(Kuiper Belt Objects) spatial density probably (I'm guessing this) is
not sufficient to have much of a reflection coefficient. Also the 2-way
propagation loss (Earth to Kuiper Belt, reflection loss, and then the
return path: Kuiper Belt to Earth) would be very large (that is I doubt
it would be detectable under normal transmission conditions).

***{Again, I agree. Either it is a hoax, or some very strange physics is
involved. --MJ}***

Are there examples of this signal on the web?

***{I don't know. I subscribe to a list where the above material
appeared as a post, and it seemed so strange to me that I just passed it
on, in hopes that someone here could shed some light on it. --MJ}***

Mitchell Jones wrote in news:mjones-
:

***{Again, I agree. Either it is a hoax, or some very strange physics is
involved. --MJ}***

Are there examples of this signal on the web?

***{I don't know. I subscribe to a list where the above material
appeared as a post, and it seemed so strange to me that I just passed it
on, in hopes that someone here could shed some light on it. --MJ}***


It should be easy enough to test.
There are signals all over the shortwave bands that are transmitted by
commercial and government stations.

When LDE are observed by amateur radio operators, a search of nearby
frequencies for similar phenomina involving other signals should be
undertaken.

It is possible to make a signal so distinctive that it can not be easily
faked by a hoaxer.

It should be possible to get permission from the FCC to transmit using a
frequency hopping pattern [staying within the ham bands, of course]. Any
LDE would show the same pattern of hops. Very hard for a hoaxer to
duplicate.

Hm... while thinking about my above statements, I have thought of
something.

It makes it easier to document LDEs and look for similar effects on other
signals on nearby frequencies. It also makes it easier for a hoaxer.

The idea: using mixing techniques, one can shift the ham band frequencies
into the passband of a video recorder so that a large section of the RF
spectrum can be recorded for later playback and examination.

The idea may already be in use.

Yeah... or something similar:
http://www.tek.com/Measurement/App_N...7W_18189_1.pdf

Well, anyway, such techniques should be useful in investigating LDEs.

--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

remove ch100-5 to avoid spam trap

Mitchell Jones wrote:
In article ,
"Alfred A. Aburto Jr." wrote:


Mitchell Jones wrote:

***{Does anyone have an explanation for the following? --MJ}***



Forwarding permission was given by William R. Corliss

http://www.science-frontiers.com

SCIENCE FRONTIERS, No. 159, May-Jun 2005, p. 4


GEOPHYSICS

Extreme LDEs

LDEs (Long-Delayed Echoes) are heard fairly often by radio hams. Usually,
their signals are reflected back to them delayed by just a few seconds. But
since radio waves travel 186,000 miles/second, any reflector must be located
far beyond the moon's orbit. Question: what's out there?

LDEs have been recognized and puzzled over since 1927. (SF#10, SF#39)
But so far no completely convincing explanation has been forthcoming. Three
ideas thrown on the table have been:

* Multiple trips of the signal around the world with the ionosphere's help.

* Signal trapping in ionospheric ducts.

* Reflections from distant plasma clouds.

Most LDE research has been carried out by radio hams, who have now
discovered a new twist to the LDE puzzle: some LDEs return not in
just a few seconds but in minutes and even hours! Can you imagine
a radio reflector a light-hour distant? After all, the sun is only 8
light-minutes away.

Japanese hams have been at the forefront in collecting these extremely long
LDEs. M. Obara, in Tokyo (call letters TZ6JA), summarized the situation
as follows.

All of these records (except UL7GW) indicate very long delay
times ranging from 20 minutes to 82 hours. Converting these
times to distances...corresponds to round trips of 1.8 - 297 AU
(Astronomical Unit, 1 AU = 150 million kilometers, or about
93 million miles, the distance between the Earth and the Sun).
These delay times suggest the existence of two hypothetical
*interplanetary ionospheres*, composed of numerous magnetic
and plasma tails of small planets and debris, located mainly at
the minor planet belt (asteroid belt) and the Kuiper belt (a
region beyond Neptune containing thousands of small bodies
orbiting the sun that is believed to be the spawning ground
of many short-period comets.

(Obara, Mac; "Long-Delayed Echoes: Reflections from an Ionosphere in
Space?", *CQ*, 24, Feb 2005. Cr. L.M. Nash)


SCIENCE FRONTIERS is a bimonthly collection of scientific anomalies in
the current literature. Published by the Sourcebook Project, P.O. Box 107,
Glen Arm, MD 21057 USA. Annual subscription: $8.00.

What is the source of the echo?


***{Frankly, it seems so bizarre to me that I can come up with only one
theory: hams are playing tricks on one another. One ham sends out a
signal, and another records it and plays it back later. In other words,
it's sort of like an internet hoax. Could that be? I don't know, but if
it isn't then this is one of the strangest things I've ever heard of.
--MJ}***


I don't think they are reflections from the Kuiper Belt Objects.


***{I totally agree. --MJ}***


Their
(Kuiper Belt Objects) spatial density probably (I'm guessing this) is
not sufficient to have much of a reflection coefficient. Also the 2-way
propagation loss (Earth to Kuiper Belt, reflection loss, and then the
return path: Kuiper Belt to Earth) would be very large (that is I doubt
it would be detectable under normal transmission conditions).


***{Again, I agree. Either it is a hoax, or some very strange physics is
involved. --MJ}***


Are there examples of this signal on the web?


***{I don't know. I subscribe to a list where the above material
appeared as a post, and it seemed so strange to me that I just passed it
on, in hopes that someone here could shed some light on it. --MJ}***

Something that could be done is to get a number of spatially separated
observers to record the arrival times of the echos then using the time
differences and then known lat/long of the observers one could start
estimating the location of the source (or echos) --- assuming long range
propagation over/around the Earth. This would be very much like SOFAR
localization (for unknown source and known recievers) or something like
LORAN navigation (know sources and unknown reciever position). It would
take some effort (coordinated effort) to do this but one could then
isolate the source (if any) ...

In sci.physics bz wrote:

It should be easy enough to test.
There are signals all over the shortwave bands that are transmitted by
commercial and government stations.

You would never hear anything due to the continuous transmission.

You have to make a short transmission then listen on the now quite
transmission frequency.

When LDE are observed by amateur radio operators, a search of nearby
frequencies for similar phenomina involving other signals should be
undertaken.

Been done.

It is possible to make a signal so distinctive that it can not be easily
faked by a hoaxer.

If it is long enough you can get a transmitter finger print that
makes the transmitter pretty much unique.

It should be possible to get permission from the FCC to transmit using a
frequency hopping pattern [staying within the ham bands, of course]. Any
LDE would show the same pattern of hops. Very hard for a hoaxer to
duplicate.

You don't need permission to do this and it has been done.

Hm... while thinking about my above statements, I have thought of
something.

It makes it easier to document LDEs and look for similar effects on other
signals on nearby frequencies. It also makes it easier for a hoaxer.

The idea: using mixing techniques, one can shift the ham band frequencies
into the passband of a video recorder so that a large section of the RF
spectrum can be recorded for later playback and examination.

The idea may already be in use.

The basic idea has been in use for decades.

Yeah... or something similar:
http://www.tek.com/Measurement/App_N...7W_18189_1.pdf

Well, anyway, such techniques should be useful in investigating LDEs.

--
bz

Long delayed echos were first noted about 70 years ago; this is NOT
a new find.

They have been investigated by many people over the years and are
reproducable in the range of 10s of seconds.

It is believed by many that the echos of hours duration are hoaxes.

No one cares much other than those interested in propogation.

You will not observe the phenomena unless you make a transmission,
go silent, and listen for the echo. This means it will only be noted
by those doing communications or tests, and never by a broadcaster.

--
Jim Pennino

Remove .spam.sux to reply.

wrote in :

In sci.physics bz wrote:

It should be easy enough to test.
There are signals all over the shortwave bands that are transmitted by
commercial and government stations.

You would never hear anything due to the continuous transmission.

I was talking about modes of transmission that are NOT continuous.
Some transmit data in packets. Often transmit and receive frequencies are
different, leaving times that one can listen for echos.

You have to make a short transmission then listen on the now quite
transmission frequency.

My amateur call sign is N5BZ. I understand 'QSK' which means 'I can hear
between my dots' and is also called 'full breakin'.

When LDE are observed by amateur radio operators, a search of nearby
frequencies for similar phenomina involving other signals should be
undertaken.
Been done.
It is possible to make a signal so distinctive that it can not be easily
faked by a hoaxer.

If it is long enough you can get a transmitter finger print that
makes the transmitter pretty much unique.

Pretty much true. Keying transients tend to be rather specific to a
particular transmitter.


It should be possible to get permission from the FCC to transmit using a
frequency hopping pattern [staying within the ham bands, of course]. Any
LDE would show the same pattern of hops. Very hard for a hoaxer to
duplicate.

You don't need permission to do this and it has been done.

You need special permission to use any 'unusual transmission mode', at
least you did a few years ago when I last I checked, pulse modulation (in
all its forms) was prohibited below 400 MHz. 'Broadcasting' was also
prohibited. I think that the FCC now licenses 'beacons' which broadcast
signals for checking propagation. But any kind of spread spectrum
transmission would normally be prohibited, as far as I know, without an FCC
waver.

.....

Long delayed echos were first noted about 70 years ago; this is NOT
a new find.

They have been investigated by many people over the years and are
reproducable in the range of 10s of seconds.

It is believed by many that the echos of hours duration are hoaxes.

No one cares much other than those interested in propogation.

You will not observe the phenomena unless you make a transmission,
go silent, and listen for the echo. This means it will only be noted
by those doing communications or tests, and never by a broadcaster.

LDE's have been observed by people other than the sender, so, assuming that
a commercial point to point data link is using packet transmissions, it is
certainly possible to observe LDE's on their signals.

A few years ago, the Russian 'woodpecker', a band hopping pulsed radar
signal that moved around the shortwave bands, would have provided a good
signal to watch for LDE's

73 de N5BZ







--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

remove ch100-5 to avoid spam trap

In article ,
"Alfred A. Aburto Jr." wrote:

Mitchell Jones wrote:
In article ,
"Alfred A. Aburto Jr." wrote:


Mitchell Jones wrote:

***{Does anyone have an explanation for the following? --MJ}***



Forwarding permission was given by William R. Corliss

http://www.science-frontiers.com

SCIENCE FRONTIERS, No. 159, May-Jun 2005, p. 4


GEOPHYSICS

Extreme LDEs

LDEs (Long-Delayed Echoes) are heard fairly often by radio hams.
Usually,
their signals are reflected back to them delayed by just a few seconds.
But
since radio waves travel 186,000 miles/second, any reflector must be
located
far beyond the moon's orbit. Question: what's out there?

LDEs have been recognized and puzzled over since 1927. (SF#10, SF#39)
But so far no completely convincing explanation has been forthcoming.
Three
ideas thrown on the table have been:

* Multiple trips of the signal around the world with the ionosphere's
help.

* Signal trapping in ionospheric ducts.

* Reflections from distant plasma clouds.

Most LDE research has been carried out by radio hams, who have now
discovered a new twist to the LDE puzzle: some LDEs return not in
just a few seconds but in minutes and even hours! Can you imagine
a radio reflector a light-hour distant? After all, the sun is only 8
light-minutes away.

Japanese hams have been at the forefront in collecting these extremely
long
LDEs. M. Obara, in Tokyo (call letters TZ6JA), summarized the situation
as follows.

All of these records (except UL7GW) indicate very long delay
times ranging from 20 minutes to 82 hours. Converting these
times to distances...corresponds to round trips of 1.8 - 297 AU
(Astronomical Unit, 1 AU = 150 million kilometers, or about
93 million miles, the distance between the Earth and the Sun).
These delay times suggest the existence of two hypothetical
*interplanetary ionospheres*, composed of numerous magnetic
and plasma tails of small planets and debris, located mainly at
the minor planet belt (asteroid belt) and the Kuiper belt (a
region beyond Neptune containing thousands of small bodies
orbiting the sun that is believed to be the spawning ground
of many short-period comets.

(Obara, Mac; "Long-Delayed Echoes: Reflections from an Ionosphere in
Space?", *CQ*, 24, Feb 2005. Cr. L.M. Nash)


SCIENCE FRONTIERS is a bimonthly collection of scientific anomalies in
the current literature. Published by the Sourcebook Project, P.O. Box
107,
Glen Arm, MD 21057 USA. Annual subscription: $8.00.

What is the source of the echo?


***{Frankly, it seems so bizarre to me that I can come up with only one
theory: hams are playing tricks on one another. One ham sends out a
signal, and another records it and plays it back later. In other words,
it's sort of like an internet hoax. Could that be? I don't know, but if
it isn't then this is one of the strangest things I've ever heard of.
--MJ}***


I don't think they are reflections from the Kuiper Belt Objects.


***{I totally agree. --MJ}***


Their
(Kuiper Belt Objects) spatial density probably (I'm guessing this) is
not sufficient to have much of a reflection coefficient. Also the 2-way
propagation loss (Earth to Kuiper Belt, reflection loss, and then the
return path: Kuiper Belt to Earth) would be very large (that is I doubt
it would be detectable under normal transmission conditions).


***{Again, I agree. Either it is a hoax, or some very strange physics is
involved. --MJ}***


Are there examples of this signal on the web?


***{I don't know. I subscribe to a list where the above material
appeared as a post, and it seemed so strange to me that I just passed it
on, in hopes that someone here could shed some light on it. --MJ}***

Something that could be done is to get a number of spatially separated
observers to record the arrival times of the echos then using the time
differences and then known lat/long of the observers one could start
estimating the location of the source (or echos) --- assuming long range
propagation over/around the Earth.

***{Yes, that might work if one could predict that an echo would occur,
but I got the impression from reading the article that these things
don't occur very predictably. "Fairly often" sounds pretty random to me.
--MJ}***

This would be very much like SOFAR
localization (for unknown source and known recievers) or something like
LORAN navigation (know sources and unknown reciever position). It would
take some effort (coordinated effort) to do this but one could then
isolate the source (if any) ...

In sci.physics bz wrote:
wrote in :

In sci.physics bz wrote:

It should be easy enough to test.
There are signals all over the shortwave bands that are transmitted by
commercial and government stations.

You would never hear anything due to the continuous transmission.

I was talking about modes of transmission that are NOT continuous.
Some transmit data in packets. Often transmit and receive frequencies are
different, leaving times that one can listen for echos.

Why bother if you have a transmitter of your own?

You have to make a short transmission then listen on the now quite
transmission frequency.

My amateur call sign is N5BZ. I understand 'QSK' which means 'I can hear
between my dots' and is also called 'full breakin'.

LDE is usually several seconds to 10s of seconds; that would be very
slow CW with a dot spacing of say 20 seconds.

When LDE are observed by amateur radio operators, a search of nearby
frequencies for similar phenomina involving other signals should be
undertaken.
Been done.
It is possible to make a signal so distinctive that it can not be easily
faked by a hoaxer.

If it is long enough you can get a transmitter finger print that
makes the transmitter pretty much unique.

Pretty much true. Keying transients tend to be rather specific to a
particular transmitter.

But pointless.

No one is going to know you are looking for echos unless you announce
the fact.

No one is going to know what time you will do it unless you announce
the fact.

No one is going to know what band or frequency you will use unless you
announce the fact.

If you are worried about possible hoaxing, keep your mouth shut and just
do the experiment.


It should be possible to get permission from the FCC to transmit using a
frequency hopping pattern [staying within the ham bands, of course]. Any
LDE would show the same pattern of hops. Very hard for a hoaxer to
duplicate.

You don't need permission to do this and it has been done.

You need special permission to use any 'unusual transmission mode', at
least you did a few years ago when I last I checked, pulse modulation (in
all its forms) was prohibited below 400 MHz. 'Broadcasting' was also
prohibited. I think that the FCC now licenses 'beacons' which broadcast
signals for checking propagation. But any kind of spread spectrum
transmission would normally be prohibited, as far as I know, without an FCC
waver.

You don't need permission or anything other than your license to do spread
spectrum or set up a propagation beacon, but that is totally irrelevant.

Long delayed echos were first noted about 70 years ago; this is NOT
a new find.

They have been investigated by many people over the years and are
reproducable in the range of 10s of seconds.

It is believed by many that the echos of hours duration are hoaxes.

No one cares much other than those interested in propogation.

You will not observe the phenomena unless you make a transmission,
go silent, and listen for the echo. This means it will only be noted
by those doing communications or tests, and never by a broadcaster.

LDE's have been observed by people other than the sender, so, assuming that
a commercial point to point data link is using packet transmissions, it is
certainly possible to observe LDE's on their signals.

Why would you bother?

A few years ago, the Russian 'woodpecker', a band hopping pulsed radar
signal that moved around the shortwave bands, would have provided a good
signal to watch for LDE's

No, it would not have.

73 de N5BZ

If you want to look for echos, turn on the rig, find a quite spot in
any band of your choice, send "vvv de n5bz" at about 40 WPM, and listen
for an echo.

I wouldn't bother listening for more that about 60 seconds.

--
Jim Pennino

Remove .spam.sux to reply.