Red Wave Radio

The WTFDA newsgroup has reports from a DXer who is picking up UHF TV stations
via moonbounce.
Now, hams have been doing this for years (mostly on 1296 Mhz), so this
shouldn't be a big surprise.

TV stations use antennas with lots of "gain" along the horizon, which is gotten
by sqeezing the signal from up and down along the horizon; this is how a 100 KW
transmitter puts out the equivalent of 5,000,000 watts. That equivalency is
only along the horizon; in fact that "beam" is so sharp that TV transmitters on
mountaintops have "down tilt" to get the signal into a valley where the people
are, rather than shooting over them.

To imagine this think of the number "8" on its side, but someone stepped on it.
That will be the vertical radiation pattern. So 5 million watts shooting along
the horizon will hit the moon if it's low on the horizon (moonrise or moonset).

Just another technique, but maxes TV DXing (FM too) an interesting hobby.

Quote:> DXer who is picking up UHF TV stations
>via moonbounce.

I'd like to hear more about this ... yeah, hams have been doing it for years,
but with HUGE HUGE antennas that yield WEAK WEAK signals ... and very narrow cw
signals, not 6mhz wide TV sigs.

Not that it can't be true, but almost too good to be true.

John WB9UAI

How could you tell unless you were getting Sporadic E and EME at the
same time (with a 3 second delay on the EME)?  Or if the station was
broadcasting a GPS clock or something?

Quote:>> DXer who is picking up UHF TV stations
>>via moonbounce.

>I'd like to hear more about this ... yeah, hams have been doing it for years,
>but with HUGE HUGE antennas that yield WEAK WEAK signals ... and very narrow cw
>signals, not 6mhz wide TV sigs.

>Not that it can't be true, but almost too good to be true.

>John WB9UAI

Quote:>> DXer who is picking up UHF TV stations
>>via moonbounce.

>I'd like to hear more about this ... yeah, hams have been doing it for years,
>but with HUGE HUGE antennas that yield WEAK WEAK signals ... and very narrow cw
>signals, not 6mhz wide TV sigs.

>Not that it can't be true, but almost too good to be true.

http://www.geocities.com/toddemslie/

(scroll down to the bottom)

High-gain low-noise preamp, 22-element Yagi.  PC-based DSP for a 2Hz
bandwidth.  (he's not getting any video - he's comparing the measured
Doppler shift vs. that predicted by science, and comparing the times of
reception to predicted moonrise/moonset at the American locations in
question.)  Of course, TV stations don't use elevation rotors; EME reception
is likely only possible when the moon is VERY close to the horizon at the
station's location.  In fact, he isn't even trying with stations that use
beam tilt.  (intentionally concentrating power *below* the horizon to better
serve close-in viewers)  

Another thing that helps is a quiet band.  The Australian UHF-TV band starts
somewhere around 520MHz; that leaves 7 or 8 USA channels that are pretty
much empty down there.

The stations in question have been WNDU-TV (ch. 16) South Bend, Indiana;
KWBT (ch. 19) Muskogee, Oklahoma; and WAPT (ch. 16) Jackson, Mississippi.
The Indiana station is somewhat tentative as the Doppler shift didn't match
predictions.  Moonrise/moonset times did though.  Theory is that WNDU's
transmitter is drifting.

I wouldn't say it's 100% certain he's received American stations.  But the
preponderance of the evidence says so.  Quite an accomplishment!
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com

Where's WTFDA newsgroup?

Mike

Quote:> The WTFDA newsgroup has reports from a DXer who is picking up UHF TV
stations
> via moonbounce.
> Now, hams have been doing this for years (mostly on 1296 Mhz), so this
> shouldn't be a big surprise.

> TV stations use antennas with lots of "gain" along the horizon, which is
gotten
> by sqeezing the signal from up and down along the horizon; this is how a
100 KW
> transmitter puts out the equivalent of 5,000,000 watts. That equivalency
is
> only along the horizon; in fact that "beam" is so sharp that TV
transmitters on
> mountaintops have "down tilt" to get the signal into a valley where the
people
> are, rather than shooting over them.

> To imagine this think of the number "8" on its side, but someone stepped
on it.
> That will be the vertical radiation pattern. So 5 million watts shooting
along
> the horizon will hit the moon if it's low on the horizon (moonrise or
moonset).

> Just another technique, but maxes TV DXing (FM too) an interesting hobby.

Quote:

>http://www.geocities.com/toddemslie/

Well shut my mouth !

Sounds good to me, congrats !

John WB9UAI
Milwaukee

6/3/02

You could narrow it down by whether the moon was above the horizon at
the receivers location. Also the matter of doppler shift from a moon
bounce.
*****

-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----==  Over 80,000 Newsgroups - 16 Different Servers! =-----

Mr. Mann was in fact doing this.  He was tracking moonset at the specific
American stations he was chasing, and he was using software to predict the
Doppler shift on the specific stations in question.

The shift on two of the three stations matched almost perfectly, as did the
moonset time.  

The Doppler on the third station didn't match up all that well.  But we're
talking about relatively small drifts; speculation is that the *transmitted*
frequency was drifting.  (the amount of drift involved is well within the
tolerance permitted by the FCC)

Quote:>> How could you tell unless you were getting Sporadic E and EME at the
>> same time (with a 3 second delay on the EME)?  Or if the station was
>> broadcasting a GPS clock or something?

The DXer in question is monitoring American stations from Perth in Western
Australia.  EME is the ONLY possible method for reception of American UHF
signals there.  

There is a very remote possibility he was actually receiving Japanese,
Korean, or Phillippines signals via TeP propagation.  But it is *extremely*
unlikely these signals would "just happen" to fade in and out at American
moonset.  (besides, if I recall properly we're at the wrong time of year for
TeP.  Unfortunately the USA is unusually poorly situated for TeP so we don't
tend to understand it as well as Australians, Japanese, and South Americans
do.)  (also, I'm not aware of any high-powered UHF stations in these
countries)  
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com

I don't think you see too much sporadic E on UHF. I can't recall ever
seeing any on that high a freq. On UHF most of your long distance
stuff is due to tropo ducting. In fact, UHF is one of the best bands
for watching tropo. Even better than VHF usually. Most of your
sporadic E skip is on lower frequencies. I hear quite a bit on 10m and
6m. Very little if any on 2m.  MK

I don't think you see too much sporadic E on UHF. I can't recall ever
seeing any on that high a freq. On UHF most of your long distance
stuff is due to tropo ducting. In fact, UHF is one of the best bands
for watching tropo. Even better than VHF usually. Most of your
sporadic E skip is on lower frequencies. I hear quite a bit on 10m and
6m. Very little if any on 2m.  MK

Quote:> > How could you tell unless you were getting Sporadic E and EME at the
> > same time (with a 3 second delay on the EME)?  Or if the station was
> > broadcasting a GPS clock or something?

> I don't think you see too much sporadic E on UHF. I can't recall ever
> seeing any on that high a freq. On UHF most of your long distance
> stuff is due to tropo ducting. In fact, UHF is one of the best bands
> for watching tropo. Even better than VHF usually. Most of your
> sporadic E skip is on lower frequencies. I hear quite a bit on 10m and
> 6m. Very little if any on 2m.  MK'

BZZZZZZZZZZZZZZ WRONG!!  There is a LOT of E on 2meters, and even higher.  E
has been reported as high as 900MHz.

Kent, K9EZ

Uh, no, Mark was right in the first place...

There *has* been E-skip on 2 meters, though it's hardly commonplace.  I
suppose there are something like 2-3 144MHz Es openings at a given location
in a given year.

But the highest frequency on which E-skip has ever been reported is a tad
above 222MHz.  (two amateur Es contacts had been made on 220MHz; there was
some thought no more would ever be made when the bottom 2MHz of the band was
removed.  Luckily that has proven wrong.)  

How much higher Es is possible is a good question.  I suppose it wouldn't be
too hard to prove a MUF up to 225MHz.  Beyond that you're into military
territory; if you did hear what sounded like an Es-propagated signal, would
they tell you where it was originating from?  Provided you could figure out
who to ask?

Now I suppose if you count meteor-scatter as E-layer propagation (which I
guess it is) then it certainly has been reported as high as the bottom end
of UHF-TV.  Seems to me 900MHz is pushing it but I don't know enough about
meteor scatter to be certain about that.  
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com