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Old 09-11-2017, 1:04 PM
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Default Microwave DX and the Pacific Question....

( I moved this topic from-- Website for Monitoring 6m Band Openings-- I am afraid I was Hijacking it )
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This morning I took the Trans-Pacific ducting issue to some other people to point me right - for I was drawing on only my personal, very limited experiences, and not being science-based at all... but I had become captive of the subject... (at least until lunch time....

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My very talented grad student doing her dissertation, research'd this challenge for me to find out what the Navy was up to. She gave me some printouts and links to a Naval project called "Tradewinds III," and I'll spare everyone the extensive lists of publications associated with it, except this one:
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http://www.dtic.mil/dtic/tr/fulltext/u2/780433.pdf
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"Natasha*," I said, reading thru her material, "this made my head hurt !"
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And it probably will do the same for anyone reading thru it's entirety... but it does deal with the the subject of tropical tropo waveguiding Very! throughly.
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In summary: its unlikely that any hams will make a terrestrial "Kwajalein-Mainland" connection... for various reasons-- One, I mentioned previously- the Altitude of the possible duct. But that is my take- and Natasha's* and Barbi's*-- but read the article(s) Guys -- someone daring out there will, someday I'm sure, prove us "Wet Blankets."
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____________________________________________
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Now, I used the term Terrestrial, for all bets are off once you take to the air. Barbi recounted a project using high altitude radio sounding devices ("radiosondes") in the Pacific. Her 'sondes microwave signals from out in the middle of the Pacific , west of Johnston island, were received by stations in Japan - which was not intended at all. Ducting?? She never inquired further....
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.............................CF
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__________________________________________
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*Not her (their) real name(s) - everyone gets a nickname here- which also becomes their radio 'callsign'- the names are select'd by group approbation and the individual's approval- they usually have to do with some personal attribute or quirk.... Mine is "Coyote"... my friend and department co-chair is "Barbi'...... I'll leave it to the imagination how we got those names .....
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Last edited by Coyote-Frostbyte; 09-11-2017 at 1:18 PM..
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Old 09-11-2017, 1:19 PM
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A friend of mine set a microwave DX record in the 1990s on 2304MHz and 3456MHz from Califirnia to Hawaii. Another friend used to camp on the beach in southern Mexico with a Yagi antenna on his old 800MHz cell phone and got the best reception pointing west. When he received his bill later many of the calls said they originated from Hawaii. All of these tropo ducting contacts were in the summer months.
prcguy

Quote:
Originally Posted by Coyote-Frostbyte View Post
( I moved this topic from-- Website for Monitoring 6m Band Openings-- I am afraid I was Hijacking it )
.
.
.
This morning I took the Trans-Pacific ducting issue to some other people to point me right - for I was drawing on only my personal, very limited experiences, and not being science-based at all... but I had become captive of the subject... (at least until lunch time....

.
My very talented grad student doing her dissertation, research'd this challenge for me to find out what the Navy was up to. She gave me some printouts and links to a Naval project called "Tradewinds III," and I'll spare everyone the extensive lists of publications associated with it, except this one:
.
.
http://www.dtic.mil/dtic/tr/fulltext/u2/780433.pdf
.
.
"Natasha*," I said, reading thru her material, "this is made my head hurt !"
.
And it probably will do the same for anyone reading thru it's entirety... but it does deal with the the subject of tropical tropo waveguiding Very! throughly.
.
In summary: its unlikely that any hams will make a terrestrial "Kwajalein-Mainland" connection... for various reasons-- One, I mentioned previously- the Altitude of the possible duct. But that is my take- and Natasha's* and Barbi's*-- but read the article(s) Guys -- someone daring out there will, someday I'm sure, prove us "Wet Blankets."
.
____________________________________________
.
Now, I used the term Terrestrial, for all bets are off once you take to the air. Barbi recounted a project using high altitude radio sounding devices ("radiosondes") in the Pacific. Her 'sondes microwave signals from out in the middle of the Pacific , west of Johnston island, were received by stations in Japan - which was not intended at all. Ducting?? She never inquired further....
.
.
.............................CF
.
.
__________________________________________
.
*Not her (their) real name(s) - everyone gets a nickname here- which also becomes their radio 'callsign'- the names are select'd by group approbation and the individual's approval- they usually have to do with some personal attribute or quirk.... Mine is "Coyote"... my friend and department co-chair is "Barbi'...... I'll leave it to the imagination how we got those names .....
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Old 09-12-2017, 12:25 AM
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Quote:
Originally Posted by prcguy View Post
A friend of mine set a microwave DX record in the 1990s on 2304MHz and 3456MHz from Califirnia to Hawaii.
That same ham made it on 5760 a few years after the 2 and 3 GHz contacts.

Quote:
Originally Posted by prcguy View Post
Another friend used to camp on the beach in southern Mexico with a Yagi antenna on his old 800MHz cell phone and got the best reception pointing west. When he received his bill later many of the calls said they originated from Hawaii. All of these tropo ducting contacts were in the summer months.
That's pretty amazing when you think of the power levels involved! I certainly believe it's possible... or was. I don't think the current digital systems would put up with it.
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Old 09-12-2017, 12:38 AM
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Quote:
Originally Posted by Coyote-Frostbyte View Post
My very talented grad student doing her dissertation, research'd this challenge for me to find out what the Navy was up to. She gave me some printouts and links to a Naval project called "Tradewinds III," and I'll spare everyone the extensive lists of publications associated with it, except this one:
I've only got time to skim the article right now, but it looks like a good read.

Quote:
Originally Posted by Coyote-Frostbyte View Post
In summary: its unlikely that any hams will make a terrestrial "Kwajalein-Mainland" connection... for various reasons-- One, I mentioned previously- the Altitude of the possible duct.
One line of thinking is if the duct doesn't extend all the way, it may be possible to enter the duct from a distance where it's at or slightly beyond the horizon. Presumably, one doesn't always have to be poking into the duct like a probe in a waveguide, maybe coupling into the open end is possible.

This is where a few permanent beacons out there in the Pacific would be useful.

Quote:
Originally Posted by Coyote-Frostbyte View Post
But that is my take- and Natasha's* and Barbi's*-- but read the article(s) Guys -- someone daring out there will, someday I'm sure, prove us "Wet Blankets."
There are some very interesting things being done on x-band at amateur power levels, and contacts out past 1000 km happen at power levels of 10 watts or less.

Quote:
Originally Posted by Coyote-Frostbyte View Post
Now, I used the term Terrestrial, for all bets are off once you take to the air. Barbi recounted a project using high altitude radio sounding devices ("radiosondes") in the Pacific. Her 'sondes microwave signals from out in the middle of the Pacific , west of Johnston island, were received by stations in Japan - which was not intended at all. Ducting?? She never inquired further...
How strong were the signals? I know of some really long haul paths that can be worked almost anytime, regardless of tropo conditions. The mode is believed to be forward scatter. These are contacts made over 2 or 3 10,000+ foot mountain ranges. They can be quite weak, but they're reliably always there.

Put a 0.5 dB noise figure in front of a 500 Hz IF bandwidth, and you can detect a signal at around -145 dBm. You'd be surprised at how far a signal will propagate when you can work that far down in the mud.
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Old 09-12-2017, 2:38 AM
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Quote:
Originally Posted by Coyote-Frostbyte View Post
everyone gets a nickname here- which also becomes their radio 'callsign'- the names are select'd by group approbation and the individual's approval- they usually have to do with some personal attribute or quirk.... Mine is "Coyote"... my friend and department co-chair is "Barbi'...... I'll leave it to the imagination how we got those names .....
Obviously, yours is due to you being wiley.

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Old 09-12-2017, 8:01 AM
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The CA to HI record breaking ham friend is N6CA and it looks like he did it on five bands 902MHz to 5760MHz. He owned Angle Linear and made some of the best communications preamps on the planet. Chip also built many beacons from 6m to 10GHz that are in HI and othe places.
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Quote:
Originally Posted by zz0468 View Post
That same ham made it on 5760 a few years after the 2 and 3 GHz contacts.



That's pretty amazing when you think of the power levels involved! I certainly believe it's possible... or was. I don't think the current digital systems would put up with it.
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Old 09-12-2017, 12:09 PM
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I talked to Hawaii once from So. Calif. Using a 16 element beam and 120 watts on 2-meter FM. No repeater, tropo ducting .
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Old 09-12-2017, 12:47 PM
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Quoting ZZ
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"How strong were the signals? I know of some really long haul paths that can be worked almost anytime, regardless of tropo conditions...."
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I asked her, but the details were sketchy...
.... "it was L-Band telemetry, approximately 2 Watts - an omni antenna.... I used a frequency that was common for my data collection equipment... that common frequency was probably the reason the Japanese heard it.... the ID in the stream identified it.... they never said just how strong it was.....the distance was in the thousands of miles..."
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Meanwhile, "Natasha" came up with plethora of information, but it all is quite dated... that which is publically releasable, anyway..... fill in the blanks.........
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_______________________________________
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It is an interesting topic, none the less. I personally love to hear all the first hand experiences... enough so that I suggested to my friend we try 'mountain-topping' on microwave this ARRL September VHF contest......
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"Lauri, that was last weekend............."
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............................CF
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Last edited by Coyote-Frostbyte; 09-12-2017 at 1:05 PM..
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Old 09-12-2017, 7:27 PM
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Smiles, Krokus....
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Wiley Coyote... I like it!............. but I'm afraid its origins are a bit more nefarious.... lol
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......................CF
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Old 09-13-2017, 1:57 AM
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Quote:
Originally Posted by Coyote-Frostbyte View Post
Smiles, Krokus....
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Wiley Coyote... I like it!............. but I'm afraid its origins are a bit more nefarious.... lol
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......................CF
Oh my, more to the mystery.

I have had a few experiences with tropospheric ducting.

The last one was working 2 meter USB from my then, Tallahassee Florida QTH with another ham operating portable from Clingmans Dome NC. The contact was as if he was next door, very powerful reception, virtually no attenuation or variability in the signal strength. Like we were connected by a waveguide. He went on to work other stations in Florida and reception lasted a couple of hours.

Back in the 1980s, I lived in Coconut Grove Florida and one afternoon, TV reception was being disrupted from another station. Tuning around on the TV, I saw Cuban TV stations across the VHF band, channels 2 to 11 . The signals were fairly clear. I then tuned in the VHF bands and received police transmissions from Cuba, perfectly.

Being that Miami area is heavily Cuban, and a portion, militantly anti Castro, reports were made on the local news that Castro had turned up the power on the island to jam Miami stations, and that the signals were so powerful as to knock the local channel 6 power house station in Princeton Florida off the air. I have a different theory on the Channel 6 station going off the air, and that is that the US state department likely requested the station to shut down that afternoon so that Cuban TV could be monitored more closely during the phenomenon.

Some interesting facts,

an ATT 900 MHZ Tropospheric link once existed between Key Largeo and a location in Cuba. It provided full time telephone circuits until it was shut down. The large dishes still exist at both ends, and there has been discussion of reestablishing the link.

South Miami Florida and Key West have extensive US Navy HF through UHF monitoring sites that are focused toward Cuba. Visitors to Truman Annex in Key West can get a glimpse of the towers and VHF UHF log periodic antennas.






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Old 09-13-2017, 11:18 AM
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Microwave DX... here is one way to do it, but it's not for the impatient.
Aircraft scatter on 5 GHz.

How to go about it:
1. get a reasonably sized dish, a transverter, PA and a fine stepping rotor.
2. spend long nights writing software to drive the rig
3. plug in an ADSB receiver dongle to get aircraft position and orient the dish
4. annoy everybody around by listening to scratchy sounds while correcting for Doppler
5 .........
6. profit (get very brief contact reports from bearded, odd looking fellows who enjoy similar things)

(there's also some slightly crazier guys doing the same thing but with the ISS )
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Old 09-13-2017, 6:16 PM
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Quote:
Originally Posted by quad_track View Post
Microwave DX... here is one way to do it, but it's not for the impatient.
Aircraft scatter on 5 GHz.
That sounds awful complicated. There are guys doing airplane scatter on 10 GHz getting 400-500 mile hops without all the automation. Just a dish on a tripod.
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Old 09-13-2017, 6:19 PM
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Quote:
Originally Posted by Coyote-Frostbyte View Post
I personally love to hear all the first hand experiences... enough so that I suggested to my friend we try 'mountain-topping' on microwave this ARRL September VHF contest......
.
"Lauri, that was last weekend............."
There's a 10 GHz contest THIS weekend. Get on the air if you have the gear.
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Old 09-13-2017, 6:30 PM
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Quote:
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That sounds awful complicated. There are guys doing airplane scatter on 10 GHz getting 400-500 mile hops without all the automation. Just a dish on a tripod.
If you are close to an airport, you can just point the antenna in the direction of the approach/glide path (will this become illegal like lasers?).

Other stations could do same at their end and get a double reflection. Like the old microwave bill board antennas.
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Old 09-13-2017, 7:06 PM
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I was sent to Nellis AFB many years ago to operate a trailer full of radar cross section measuring equipment set up near the runway. When we pointed the radar at various fighter aircraft heading out and lit up the radar it looked like they went into some kind of evasive maneuvers. I'm told many aircraft have radar warning systems and that the pilots were probably practicing something.

Be careful what bands you use bouncing off any military aircraft.
prcguy

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If you are close to an airport, you can just point the antenna in the direction of the approach/glide path (will this become illegal like lasers?).

Other stations could do same at their end and get a double reflection. Like the old microwave bill board antennas.
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Old 09-13-2017, 7:19 PM
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Quote:
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If you are close to an airport, you can just point the antenna in the direction of the approach/glide path (will this become illegal like lasers?).

Other stations could do same at their end and get a double reflection. Like the old microwave bill board antennas.
Actually, you don't need to be anywhere near the airport. If you want real distance, the airplane needs to be up high. You're not going to see whatever it is you're bouncing off of, when it's at 35,000 feet and 200 miles away. You just suddenly see a path open up, and it's got some Doppler shift. Work 'em quick!
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Old 09-13-2017, 9:08 PM
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Quote:
Originally Posted by prcguy View Post
I was sent to Nellis AFB many years ago to operate a trailer full of radar cross section measuring equipment set up near the runway. When we pointed the radar at various fighter aircraft heading out and lit up the radar it looked like they went into some kind of evasive maneuvers. I'm told many aircraft have radar warning systems and that the pilots were probably practicing something.

Be careful what bands you use bouncing off any military aircraft.
prcguy
Good point, they may have a HARM Missile hot and ready to lock in!

You might also have seen some ECM equipment returning a spoofed signal.
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Old 09-13-2017, 9:42 PM
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Quote:
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Good point, they may have a HARM Missile hot and ready to lock in!
I don't think I'd want to be playing in a microwave contest in the Persian Gulf or the Sea of Japan, but I'd be pretty confident that no HARMs are headed my way here on the mainland.

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You might also have seen some ECM equipment returning a spoofed signal.
There are some VERY interesting wave forms being heard on the 420-450 band near the coast. It's almost musical in nature. It's a radar of some sort, but I'm not sure what it's doing. I haven't heard anything of that nature on any of the higher bands... yet.

Last edited by zz0468; 09-13-2017 at 10:02 PM..
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Old 09-13-2017, 10:03 PM
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EWACS operates in the 420-450MHz band.
prcguy

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Originally Posted by zz0468 View Post
I don't think I'd want to be playing in a microwave contest in teh Persian Gulf or the Sea of Japan, but I'd be pretty confident that no HARMs are headed my way here on the mainland.



There are some VERY interesting wave forms being heard on the 420-450 band near the coast. It's almost musical in nature. It's a radar of some sort, but I'm not sure what it's doing. I haven't heard anything of that nature on any of the higher bands... yet.
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Old 09-14-2017, 12:46 AM
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Quoting PRCGuy----
.
"........I was sent to Nellis AFB many years ago to operate a trailer full of radar cross section measuring equipment set up near the runway. When we pointed the radar at various fighter aircraft heading out and lit up the radar it looked like they went into some kind of evasive maneuvers. I'm told many aircraft have radar warning systems and that the pilots were probably practicing something. "
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(and)
"Be careful what bands you use bouncing off any military aircraft...."
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.
We frequently use the test ranges and facilities on the military reservations thru out the southwest. As their guests I am very forth coming about the what, where, how's and why's of what we're doing... though similar information is not often reciprocated. I can't number the times I have gotten a call to immediately shut down a radar- with no further explaination given.
.
I'll echo-
"......Be careful what bands you use bouncing off any military aircraft...."
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.......... CF
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