wrote in :

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?

More chances to hear echos.

Because I normally only transmit on one frequency and one band at a time.

LDE's might be on any frequency and band.

Also, many commercial transmitters run more power than I do. I usually run
less than 150 watts. Although hams can run 1 kW, commercial stations can
run tens of thousands of watts.

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.

I would send about 30 wpm and listen for echos delayed by more than a few
seconds. As soon as I heard something near my frequency, I would stop and
listen. I seem to remember that some LDEs show doppler shift.

Best to be recording to document any LDEs observed.

(Short delayed echos where the signal makes one loop around the earth are
also possible, but not as interesting, also ionization trails left by
meteor are used by hams and hams bounce signals off the moon).

.....
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.

LDE's do not appear to be a common phenomina. With hundreds of thousands of
hours of operators observing each others signals while enjoying normal ham
radio operations, LDEs have occasionally be noticed and reported.

They don't happen on command. Doing the experiment would [normally] give a
negative result.

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.

You have to go to the 70 cm (420-450 MHz) band or higher frequencies before
you can use pulse or spread spectrum modes of emission, as far as I can
tell.

http://www.arrl.org/FandES/field/reg...t97/d-305.html

So, to use either on the HF bands, one would need special permission from
the FCC, as I said before.

.....
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?

As explained before, more opportunity to make observations.


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.

You make an assertion without any explanation, do you have a reason for
making such an assertion?

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 want to send faster than I can reliably copy. 35 WPM is fast
enough.


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

Your chances of hearing LDEs under those conditions are very low. Might as
well not turn on the rig at all.

If you want to observe and document LDEs you need to continuously monitor
and record large segments of the HF RF spectrum as seen at many different
locations on earth.

Now, with modern data storage media, It would not be difficult to capture,
record and store the entire HF spectrum.

A few dozen such stations, spread around the earth, data collected and
correlated, looking for signs of LDEs on a daily basis. It could be done,
using the internet for data exchange on LDE hits.

It won't be done, but it could be done.

Other than that, the only other chance would be if you could PREDICT when
LDEs would occur. Then you could send test signals and listen for echos.


QRA? 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 sci.physics bz wrote:
wrote in :

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?

More chances to hear echos.

Because I normally only transmit on one frequency and one band at a time.

LDE's might be on any frequency and band.

Also, many commercial transmitters run more power than I do. I usually run
less than 150 watts. Although hams can run 1 kW, commercial stations can
run tens of thousands of watts.

No, you have a better chance with your own transmitter that you can
fire up at any time you choose.

You can only listen on one band at a time unless you have multiple
receivers; how many HF receivers do you have?

Power is basically irrelevant.

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.

I would send about 30 wpm and listen for echos delayed by more than a few
seconds. As soon as I heard something near my frequency, I would stop and
listen. I seem to remember that some LDEs show doppler shift.

Why bother to make other than a short tranmission unless you want to
have a conversation with yourself?

Best to be recording to document any LDEs observed.

It's been documented for over 70 years; no one cares about yet another
observation.

Good for maybe a brag tape at the local ham club only.

(Short delayed echos where the signal makes one loop around the earth are
also possible, but not as interesting, also ionization trails left by
meteor are used by hams and hams bounce signals off the moon).

Meteor trail reflection has nothing to do with long delayed echos and
are not a factor at HF where long delayed echos appear.

....
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.

LDE's do not appear to be a common phenomina. With hundreds of thousands of
hours of operators observing each others signals while enjoying normal ham
radio operations, LDEs have occasionally be noticed and reported.

People seldom make a transmission then wait on a quiet frequency to see
if there is an echo. Hearing an echo during normal operations would be
highly unlikely as it would be totally wiped out by the other party's
signal.

They don't happen on command. Doing the experiment would [normally] give a
negative result.

A bit of research on the subject shows there are optimum time, season,
and frequency combinations which will highly improve the odds.

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.

You have to go to the 70 cm (420-450 MHz) band or higher frequencies before
you can use pulse or spread spectrum modes of emission, as far as I can
tell.

Duh.

Yeah, some modulations are limited to as to band.

So what? You still don't need authorization to use what is already
authorized.

Neither spread spectrum nor pulse is necessary or appropriate for listening
for long delayed echos; both are irrelevant.

http://www.arrl.org/FandES/field/reg...t97/d-305.html

So, to use either on the HF bands, one would need special permission from
the FCC, as I said before.

Let me put it a little more plainly; it would be STUPID to use spread
spectrum or pulse to look for long delayed echos.

....
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?

As explained before, more opportunity to make observations.

What, your rig doesn't have a band switch?

Something prevents you from transmitting when you want?

The 160, 75, 60, 40, 30, 20, 17, 15, 12 and 10 meter bands don't
give you enough discreat frequencies?

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.

You make an assertion without any explanation, do you have a reason for
making such an assertion?

The woodpecker was mostly continuous; you want very short transmissions and
long, quiet listening times.

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 want to send faster than I can reliably copy. 35 WPM is fast
enough.

Umm, 35 WPM is "about" 40 WPM; what's your problem?

Besides, you're listening for your echo. Don't you know what you just
sent?

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

Your chances of hearing LDEs under those conditions are very low. Might as
well not turn on the rig at all.

I'm beginng to think that might be the best course of action for you.

Actually, the conditions I described give you the best chance of hearing
an echo.

If you want to observe and document LDEs you need to continuously monitor
and record large segments of the HF RF spectrum as seen at many different
locations on earth.

Now, with modern data storage media, It would not be difficult to capture,
record and store the entire HF spectrum.

A few dozen such stations, spread around the earth, data collected and
correlated, looking for signs of LDEs on a daily basis. It could be done,
using the internet for data exchange on LDE hits.

It won't be done, but it could be done.

Of course it won't be done; it is an interesting phenomena of no
practical use, has been observed for over 70 years, and has been
reasonably explained.

The only reason to do anything with it would be personal curiousity.

Other than that, the only other chance would be if you could PREDICT when
LDEs would occur. Then you could send test signals and listen for echos.

Been done.

As I said, a little reading will show you how to greatly improve your
chances.


QRA? 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

--
Jim Pennino

Remove .spam.sux to reply.

wrote in :

In sci.physics bz wrote:
wrote in :

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?

More chances to hear echos.

Because I normally only transmit on one frequency and one band at a
time.

LDE's might be on any frequency and band.

Also, many commercial transmitters run more power than I do. I usually
run less than 150 watts. Although hams can run 1 kW, commercial
stations can run tens of thousands of watts.

No, you have a better chance with your own transmitter that you can
fire up at any time you choose.

You can only listen on one band at a time unless you have multiple
receivers; how many HF receivers do you have?

Hmmm. Let me count. There is my Drake 2b ham band rcvr, my signal/one ham
xcvr, A sony rcvr that covers from 200 kHz to 30 MHz. A radio shack rcvr that
covers about the same range. And a 38 special 30 meter qrp xcvr. Those are
all HF receivers. 5 at the moment.


Power is basically irrelevant.

Proof?

.....

I would send about 30 wpm and listen for echos delayed by more than a
few seconds. As soon as I heard something near my frequency, I would
stop and listen. I seem to remember that some LDEs show doppler shift.

Why bother to make other than a short tranmission unless you want to
have a conversation with yourself?


Might as well spend the time chatting with someone or handling traffic as
sending test transmissions. LDEs are often observed on the OTHER fellow's
signal.

Best to be recording to document any LDEs observed.

It's been documented for over 70 years; no one cares about yet another
observation.

No one? Sounds like you are projecting your feelings on others.

I didn't know that the phenomina had been explained completely.

Good for maybe a brag tape at the local ham club only.

(Short delayed echos where the signal makes one loop around the earth
are also possible, but not as interesting, also ionization trails left
by meteor are used by hams and hams bounce signals off the moon).

Meteor trail reflection has nothing to do with long delayed echos and
are not a factor at HF where long delayed echos appear.

Meteor trail reflections MIGHT have something to do with LDEs. Best not to
dismiss them until the LDE mechanism is understood.

They are usually observed at higher frequencies, where one does not normally
have a path to the distant station, but that does not mean that they don't
have an effect at HF.

.....
LDE's do not appear to be a common phenomina. With hundreds of
thousands of hours of operators observing each others signals while
enjoying normal ham radio operations, LDEs have occasionally be noticed
and reported.

People seldom make a transmission then wait on a quiet frequency to see
if there is an echo. Hearing an echo during normal operations would be
highly unlikely as it would be totally wiped out by the other party's
signal.

Not totally wiped out. Partially covered. If it is there it is still going to
be detectable.


They don't happen on command. Doing the experiment would [normally]
give a negative result.

A bit of research on the subject shows there are optimum time, season,
and frequency combinations which will highly improve the odds.

I don't know about improving the odds yet, but this is an interesting
discussion of LDE on EME[earth moon earth] (VHF and UHF).
http://www.vhfdx.net/lde.html

.....
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.

You have to go to the 70 cm (420-450 MHz) band or higher frequencies
before you can use pulse or spread spectrum modes of emission, as far
as I can tell.
....
Yeah, some modulations are limited to as to band.

So what? You still don't need authorization to use what is already
authorized.

Neither spread spectrum nor pulse is necessary or appropriate for
listening for long delayed echos; both are irrelevant.

We seem to disagree on the 'appropriate for listening for' point.

http://www.arrl.org/FandES/field/reg...t97/d-305.html

So, to use either on the HF bands, one would need special permission
from the FCC, as I said before.

Let me put it a little more plainly; it would be STUPID to use spread
spectrum or pulse to look for long delayed echos.

By all means, be plain.
[I said]
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 said]
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.

Let me go into my reasoning a bit more.

The HF woodpecker was sending pulse signals. It was apparently an 'over the
horizon' radar. It would (if there were LDEs present) have shown strong echos
from the LDE. Since the woodpecker was shifting in frequency and not looking
for echos delayed by longer than the earths diameter (or so I believe), they
probably didn't see the LDEs. But if we were recording a wide spectrum at the
time, we could see the LDEs and even determine which frequencies were
involved.

As a ham, I can't go outside the ham bands, but with FCC permission, I could
sweep each ham band at a slow enough rate to detect LDEs [and if my pulses
were spread across the spectrum a bit, I would cause very little interference
with other communications].

That is why I think pulse and SS may be useful for investigating LDEs.

Why do you think it would be stupid?

....
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?

As explained before, more opportunity to make observations.

What, your rig doesn't have a band switch?

Something prevents you from transmitting when you want?

The 160, 75, 60, 40, 30, 20, 17, 15, 12 and 10 meter bands don't
give you enough discreat frequencies?

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.

You make an assertion without any explanation, do you have a reason for
making such an assertion?

The woodpecker was mostly continuous; you want very short transmissions
and long, quiet listening times.

It didn't spend a long time on any one frequency. IIRC. It used very short
pulses. That leaves a lot of 'listen time' between pulses.

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 want to send faster than I can reliably copy. 35 WPM is fast
enough.

Umm, 35 WPM is "about" 40 WPM; what's your problem?

Besides, you're listening for your echo. Don't you know what you just
sent?

When every one sends a test transmission, one needs to be ready to respond to
a reply from someone.


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

Your chances of hearing LDEs under those conditions are very low. Might
as well not turn on the rig at all.

I'm beginng to think that might be the best course of action for you.

What is the call sign of your station?

Actually, the conditions I described give you the best chance of hearing
an echo.

If you want to observe and document LDEs you need to continuously
monitor and record large segments of the HF RF spectrum as seen at many
different locations on earth.

Now, with modern data storage media, It would not be difficult to
capture, record and store the entire HF spectrum.

A few dozen such stations, spread around the earth, data collected and
correlated, looking for signs of LDEs on a daily basis. It could be
done, using the internet for data exchange on LDE hits.

It won't be done, but it could be done.

Of course it won't be done; it is an interesting phenomena of no
practical use, has been observed for over 70 years, and has been
reasonably explained.

I am not sure all the questions have been answered.


The only reason to do anything with it would be personal curiousity.

Other than that, the only other chance would be if you could PREDICT
when LDEs would occur. Then you could send test signals and listen for
echos.

Been done.

reference?


As I said, a little reading will show you how to greatly improve your
chances.


QRA? 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